Comprehensive Gynecology 7th Edition PDF

Any screen. Any time. Anywhere. Activate the eBook version e. of this title at no additional charge. Expert Consult eBooks give you the power to browse and find content, view enhanced images, share notes and highlights—both online and offline. Unlock your eBook...

Any screen. Any time. Anywhere. Activate the eBook version e. of this title at no additional charge. Expert Consult eBooks give you the power to browse and find content, view enhanced images, share notes and highlights—both online and offline. Unlock your eBook today. 1 Visit expertconsult.inkling.com/redeem Scan this QR code to redeem your eBook through your mobile device: 2 Scratch off your code 3 Type code into “Enter Code” box 4 Click “Redeem” 5 Log in or Sign up 6 Go to “My Library” Place Peel Off It’s that easy! Sticker Here For technical assistance: email [email protected] call 1-800-401-9962 (inside the US) call +1-314-447-8200 (outside the US) Use of the current edition of the electronic version of this book (eBook) is subject to the terms of the nontransferable, limited license granted on expertconsult.inkling.com. Access to the eBook is limited to the first individual who redeems the PIN, located on the inside cover of this book, at expertconsult.inkling.com and may not be transferred to another party by resale, lending, or other means. Obstetrics & Gynecology Books Full  Comprehensive Gynecology Obstetrics & Gynecology Books Full This page intentionally left blank       Obstetrics & Gynecology Books Full Comprehensive Gynecology 7th Edition Roger A. Lobo, MD Professor, Obstetrics and Gynecology Division of Reproductive Endocrinology Columbia University New York, New York David M. Gershenson, MD Professor Gynecologic Oncology and Reproductive Medicine University of Texas MD Anderson Cancer Center Houston, Texas Gretchen M. Lentz, MD Professor, Obstetrics and Gynecology Adjunct Professor, Urology Division Director, Urogynecology Urogynecology and Female Urology Clinic University of Washington Medical Center Seattle, Washington Fidel A. Valea, MD Professor and Vice-Chair of Education Residency Program Director Fellowship Director, Division of Gynecologic Oncology Department of Obstetrics and Gynecology Duke University School of Medicine Durham, North Carolina Obstetrics & Gynecology Books Full 1600 John F. Kennedy Blvd. Ste 1800 Philadelphia, PA 19103-2899 Comprehensive Gynecology ISBN: 978-0-323-32287-4 Copyright © 2017 by Elsevier, Inc. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Details on how to seek permission, further information about the Publisher’s permissions poli- cies and our arrangements with organizations such as the Copyright Clearance Center and the Copyright Licensing Agency, can be found at our website: www.elsevier.com/permissions. This book and the individual contributions contained in it are protected under copyright by the Publisher (other than as may be noted herein). Notices Knowledge and best practice in this field are constantly changing. As new research and experience broaden our understanding, changes in research methods, professional practices, or medical treatment may become necessary. Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds, or experiments described herein. In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a profes- sional responsibility. With respect to any drug or pharmaceutical products identified, readers are advised to check the most current information provided (i) on procedures featured or (ii) by the manufacturer of each product to be administered, to verify the recommended dose or formula, the method and duration of administration, and contraindications. It is the responsibility of practitioners, relying on their own experience and knowledge of their patients, to make diagnoses, to determine dosages and the best treatment for each individual patient, and to take all appropriate safety precautions. To the fullest extent of the law, neither the Publisher nor the authors, contributors, or editors, assume any liabil- ity for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein. Previous editions copyrighted 2012, 2007, 2001, 1997, 1992, and 1987. Library of Congress Cataloging-in-Publication Data Lobo, Roger A., editor. | Gershenson, David M. (David Marc), 1946- , editor. | Lentz, Gretchen M., editor. | Valea, Fidel A., editor. Comprehensive gynecology / [edited by] Roger A. Lobo, David M. Gershenson, Gretchen M. Lentz, Fidel A. Valea. 7 edition. | Philadelphia : Elsevier, | Preceded by Comprehensive gynecology / [edited by] Gretchen M. Lentz... [et al.]. 6th ed. c2012. | Includes bibliographical references and index. LCCN 2015038440 | ISBN 9780323322874 (hardcover : alk. paper) | MESH: Genital Diseases, Female. | Genital Neoplasms, Female. LCC RG101 | NLM WP 140 | DDC 618.1--dc23 LC record available at http://lccn.loc.gov/2015038440 Executive Content Strategist: Kate Dimock Senior Content Development Specialist: Rae Robertson Publishing Services Manager: Patricia Tannian Project Manager: Stephanie Turza Design Direction: Brian Salisbury Printed in China Last digit is the print number: 9 8 7 6 5 4 3 2 1 Obstetrics & Gynecology Books Full Contributors Arnold Advincula, MD Deborah S. Cowley, MD Levine Family Professor of Obstetrics and Gynecology at Columbia Professor, Psychiatry and Behavioral Sciences University Medical Center University of Washington Vice Chair of Women’s Health and Chief of Gynecology Seattle, Washington Department of Obstetrics and Gynecology Mary Segars Dolan, MD Columbia University Associate Professor of Gynecology and Obstetrics New York, New York Emory University School of Medicine Ellen S. Baker, MD Atlanta, Georgia Department of Gynecologic Oncology Sarah K. Dotters-Katz, MD University of Texas MD Anderson Cancer Center Clinical Instructor and Fellow Houston, Texas Obstetrics and Gynecology Jamie N. Bakkum-Gamez, MD University of North Carolina Associate Professor of Obstetrics and Gynecology Chapel Hill, North Carolina Mayo Clinic Nataki C. Douglas, MD, PhD Rochester, Minnesota Assistant Professor Diane C. Bodurka, MD Obstetrics and Gynecology Professor and Vice President Medical Education Columbia University Medical Center Gynecologic Oncology and Reproductive Medicine New York, New York University of Texas MD Anderson Cancer Center Sean C. Dowdy, MD Houston, Texas Professor of Obstetrics and Gynecology Geneviève Bouchard-Fortier, MD, SM Mayo Clinic Department of Gynecologic Oncology Rochester, Minnesota University of Toronto Linda O. Eckert, MD Toronto, Ontario, Canada Professor, Obstetrics and Gynecology Sarah M. Carlson, MD University of Washington Department of Obstetrics and Gynecology Seattle, Washington Einstein Medical Center Jonathan R. Foote, MD Philadelphia, Pennsylvania Fellow, Division of Gynecologic Oncology Janet Choi, MD Department of Obstetrics and Gynecology Medical Director Duke University Medical Center Colorado Center for Reproductive Medicine Durham, North Carolina New York, New York Michael Frumovitz, MD Leslie Clark, MD Associate Professor and Fellowship Director Clinical Fellow Gynecologic Oncology and Reproductive Medicine Division of Gynecologic Oncology University of Texas MD Anderson Cancer Center University of North Carolina Houston, Texas Chapel Hill, North Carolina Carolyn Gardella, MD Robert L. Coleman, MD Associate Professor, Obstetrics and Gynecology Professor and Deputy Chair University of Washington; Department of Gynecologic Oncology and Reproductive Medicine Gynecology Service Chief of Surgery University of Texas MD Anderson Cancer Center Veterans Administration Puget Sound Houston, Texas Seattle, Washington Allan Covens, MD Paola Alvarez Gehrig, MD Chair, Department of Gynecologic Oncology Professor and Chief University of Toronto; Division of Gynecologic Oncology Head, Department of Gynecologic Oncology University of North Carolina Sunnybrook Health Sciences Centre Chapel Hill, North Carolina Toronto, Ontario, Canada v Obstetrics & Gynecology Books Full vi Contributors David M. Gershenson, MD Jeffrey A. Kuller, MD Professor Professor of Obstetrics and Gynecology Gynecologic Oncology and Reproductive Medicine Division of Maternal-Fetal Medicine University of Texas MD Anderson Cancer Center Duke University Medical Center Houston, Texas Durham, North Carolina Jennifer Bushman Gilner, MD, PhD Eduardo Lara-Torre, MD Fellow, Clinical Associate Interim Chair and Vice-Chair for Academic Affairs Obstetrics and Gynecology Residency Program Director of Obstetrics and Gynecology Duke University Department of Obstetrics and Gynecology Chapel Hill, North Carolina Carilion Clinic; Associate Professor of Obstetrics and Gynecology and Pediatrics Jay Goldberg, MD Virginia Tech Carilion School of Medicine and Research Institute Professor Roanoke, Virginia Department of Obstetrics and Gynecology Einstein Medical Center; Gretchen M. Lentz, MD Director Professor, Obstetrics and Gynecology Philadelphia Fibroid Center Adjunct Professor, Urology Philadelphia, Pennsylvania Division Director, Urogynecology Urogynecology and Female Urology Clinic, University of Laura J. Havrilesky, MD Washington Medical Center Department of Obstetrics and Gynecology Seattle, Washington Division of Gynecologic Oncology Duke University Medical Center Roger A. Lobo, MD Durham, North Carolina Professor, Obstetrics and Gynecology Division of Reproductive Endocrinology Cherie Hill, MD Columbia University Assistant Professor of Gynecology and Obstetrics New York, New York Emory University School of Medicine Atlanta, Georgia Karen H. Lu, MD Chair and Professor Anuja Jhingran, MD Gynecologic Oncology and Reproductive Medicine Professor University of Texas MD Anderson Cancer Center Department of Radiation Oncology Houston, Texas University of Texas MD Anderson Cancer Center Houston, Texas Vicki Mendiratta, MD Associate Professor James M. Kelley III, JD Obstetrics and Gynecology Shareholder and Partner University of Washington Elk and Elk Co. Ltd. Seattle, Washington Cleveland, Ohio Larissa A. Meyer, MD Sanaz Keyhan, MD Assistant Professor Clinical Instructor Gynecologic Oncology and Reproductive Medicine Department of Obstetrics and Gynecology University of Texas MD Anderson Cancer Center Duke University School of Medicine Houston, Texas Durham, North Carolina Lisa Muasher, MD Rosanne M. Kho, MD Associate Residency Program Director Associate Professor Department of Obstetrics and Gynecology Director, Benign Gynecologic Surgery Duke University School of Medicine Cleveland Clinic Durham, North Carolina Cleveland, Ohio Suheil J. Muasher, MD Anna C. Kirby, MD Professor of Obstetrics and Gynecology Department of Obstetrics and Gynecology Duke University School of Medicine University of Washington Durham, North Carolina Seattle, Washington James W. Orr, Jr., MD Mukta Krane, MD Florida Gynecologic Oncology, 21st Century Oncology Associate Professor of Surgery Medical Director, Regional Cancer Center Department of Surgery Lee Memorial Health Systems Division of General Surgery Fort Myers, Florida University of Washington Medical Center Seattle, Washington Obstetrics & Gynecology Books Full  Contributors vii Thomas M. Price, MD Kathleen M. Schmeler, MD Associate Professor of Obstetrics and Gynecology Department of Gynecologic Oncology Duke University University of Texas MD Anderson Cancer Center Durham, North Carolina Houston, Texas Beth W. Rackow, MD Judith Ann Smith, PharmD Assistant Professor, Obstetrics and Gynecology Associate Professor Division of Reproductive Endocrinology Obstetrics, Gynecology, and Reproductive Sciences Columbia University UTHealth—University of Texas Medical School at Houston New York, New York Houston, Texas Pedro T. Ramirez, MD Pamela T. Soliman, MD Professor Associate Professor Department of Gynecologic Oncology and Reproductive Medicine Gynecologic Oncology and Reproductive Medicine University of Texas MD Anderson Cancer Center University of Texas MD Anderson Cancer Center Houston, Texas Houston, Texas Katherine Rivlin, MD Anil K. Sood, MD Department of Family Planning and Obstetrics-Gynecology Professor and Vice Chair Columbia University Medical Center Gynecologic Oncology and Reproductive Medicine New York, New York University of Texas MD Anderson Cancer Center Houston, Texas David T. Rock, MD Fellowship Director, Society of Gynecologic Oncology Breast Premal H. Thaker, MD Fellowship Associate Professor, Gynecologic Oncology Regional Breast Care, 21st Century Oncology Obstetrics and Gynecology Regional Cancer Center Washington University School of Medicine Lee Memorial Health Systems St. Louis, Missouri Fort Myers, Florida Mireille Truong, MD Timothy Ryntz, MD Assistant Professor Assistant Professor Department of Obstetrics and Gynecology Obstetrics and Gynecology Virginia Commonwealth University Columbia University School of Medicine Richmond, Virginia New York, New York Fidel A. Valea, MD Mila Pontremoli Salcedo, MD Professor and Vice-Chair of Education Professor Residency Program Director Department of Gynecology and Obstetrics Fellowship Director, Division of Gynecologic Oncology Federal University of Health Sciences/Irmandade Santa Casa de Department of Obstetrics and Gynecology Misericordia/Porto Alegre Duke University School of Medicine Rio Grande do Sul, Brazil; Durham, North Carolina Visiting Scientist Carolyn Westhoff, MD Department of Gynecologic Oncology and Reproductive Medicine Sarah Billinghurst Solomon Professor of Reproductive Health University of Texas MD Anderson Cancer Center Columbia University Medical Center Houston, Texas New York, New York Samith Sandadi, MD Breast Fellow, Society of Gynecologic Oncology Florida Gynecologic Oncology, 21st Century Oncology Regional Cancer Center Lee Memorial Health Systems Fort Myers, Florida Obstetrics & Gynecology Books Full This page intentionally left blank       Obstetrics & Gynecology Books Full Preface Try to learn something about everything and everything about something. Thomas Huxley Comprehensive Gynecology is now in its seventh edition, and it is In this edition, we have provided the most important refer- humbling to note that it has almost been 30 years since the first ences in the body of the chapter, allowing the reader to have edition was published in 1987. immediate access to the source, rather than having to search for The current editors are indebted to our mentors who pio- the reference. However, we have maintained a full bibliography neered the original work. The contributions of Drs. William for many chapters, available online. Droegemueller, Authur L Herbst, Daniel R. Mishell, Jr., and In this edition we have also provided video content to make Morton A. Stenchever were monumental and provided the this a more visual experience for the reader. New and better illus- impetus for our following in their footsteps. We are also saddened trations have also been added to assist in visual learning. The by the fact that in 2015, we lost Mort, who is now in a better cover is also a departure from our previous editions and speaks to place. Also, as we close out this edition, we have just learned that our wish to impart a visual experience and emphasize contempo- we have also lost our esteemed mentor, Dan Mishell, who passed rary techniques of minimally invasive procedures for gynecologi- away in May 2016. Both men have contributed so much to the cal surgery. field, and to us personally, and have done so much to improve Nearly every chapter has maintained key points of impor- the lives of women. tance, which have been bundled together in an online synop- In line with the quote above from Huxley, the British biolo- sis of the entire book. This will allow rapid assessment of the gist and philosopher, we continue to attempt to be comprehen- content of each chapter for more in-depth reading of areas of sive. We want the reader to be comfortable with all aspects of greater interest as well as provide key learning facts in all areas gynecology; some readers will wish to be more expert in certain of gynecology. subspecialty areas such as urogynecology, oncology, or reproduc- We hope readers will enjoy this edition and learn as much as tive endocrinology. they can from this ever-evolving field in order to provide better In this edition we are privileged to welcome Fidel Valea as health care for women. one of the editors, taking over the duties from Vern L. Katz, who We would like to give a big thanks to our editors, Kate elected to retire. We would like to thank Vern once again for his Dimock, and particularly Rae Robertson, who have stewarded contributions. us through this process. Rather than adding new chapters, we have split some in two We would also like to give a big thank you, with great appre- to provide better focus on the subject areas, and also organized ciation and love, to our families, without whose support and the chapters to provide better flow. We have added several encouragement this project could not have been accomplished. co-authors, continuing the trend we established with the previ- ous edition. This is a major departure from the early editions, Roger A. Lobo, MD where the four editors wrote all of the chapters. We feel adding David M. Gershenson, MD additional talent to the authorship provides a more comprehen- Gretchen M. Lentz, MD sive and validated approach to the dissemination of knowledge Fidel A. Valea, MD in gynecology. ix Obstetrics & Gynecology Books Full This page intentionally left blank       Obstetrics & Gynecology Books Full Contents Part I BASIC SCIENCE 12 Pediatric and Adolescent Gynecology 219 Gynecologic Examination, Infections, 1 Fertilization and Embryogenesis 1 Trauma, Pelvic Mass, Precocious Puberty Meiosis, Fertilization, Implantation, Embryonic Eduardo Lara-Torre and Fidel A. Valea Development, Sexual Differentiation 13 Family Planning 237 Thomas M. Price Katherine Rivlin and Carolyn Westhoff 2 Reproductive Genetics 22 14 M  enopause and Care of the Jennifer Bushman Gilner, Jeffrey A. Kuller, Mature Woman 258 and Fidel A. Valea Endocrinology, Consequences of Estrogen 3 Reproductive Anatomy 48 Deficiency, Effects of Hormone Therapy, Gross and Microscopic, Clinical Correlations and Other Treatment Options Fidel A. Valea Roger A. Lobo 4 Reproductive Endocrinology 77 15 Breast Diseases 294 Neuroendocrinology, Gonadotropins, Detection, Management, and Surveillance Sex Steroids, Prostaglandins, Ovulation, of Breast Disease Menstruation, Hormone Assay Samith Sandadi, David T. Rock, James W. Orr, Jr., Nataki C. Douglas and Roger A. Lobo and Fidel A. Valea 5 E  vidence-Based Medicine and Clinical 16 S  pontaneous Abortion and Recurrent Epidemiology108 Pregnancy Loss 329 Jonathan R. Foote and Laura J. Havrilesky Etiology, Diagnosis, Treatment Sanaz Keyhan, Lisa Muasher, and Suheil J. Muasher 6 Medical-Legal Risk Management 119 James M. Kelley III and Gretchen M. Lentz 17 Ectopic Pregnancy 348 Etiology, Pathology, Diagnosis, Management, Fertility Prognosis Rosanne M. Kho and Roger A. Lobo Part II COMPREHENSIVE EVALUATION OF THE FEMALE 18 Benign Gynecologic Lesions 370 Vulva, Vagina, Cervix, Uterus, Oviduct, Ovary, 7 H  istory, Physical Examination, and Ultrasound Imaging of Pelvic Structures Preventive Health Care 129 Mary Segars Dolan, Cherie Hill, and Fidel A. Valea Vicki Mendiratta and Gretchen M. Lentz 19 Endometriosis 423 8 I nteraction of Medical Diseases Etiology, Pathology, Diagnosis, Management and Female Physiology 144 Arnold Advincula, Mireille Truong, and Roger A. Lobo Sarah K. Dotters-Katz and Fidel A. Valea 20 A  natomic Defects of the Abdominal Wall 9 Emotional Aspects of Gynecology 153 and Pelvic Floor 443 Depression, Anxiety, Posttraumatic Stress Abdominal Hernias, Inguinal Hernias, and Pelvic Disorder, Eating Disorders, Substance Use Organ Prolapse: Diagnosis and Management Disorders, “Difficult” Patients, Sexual Function, Anna C. Kirby and Gretchen M. Lentz Rape, Intimate Partner Violence, and Grief 21 L  ower Urinary Tract Function Deborah S. Cowley and Gretchen M. Lentz and Disorders 474 10 Endoscopy: Hysteroscopy and Laparoscopy 190 Physiology of Micturition, Voiding Dysfunction, Indications, Contraindications, and Complications Urinary Incontinence, Urinary Tract Infections, Sarah M. Carlson, Jay Goldberg, and Gretchen M. Lentz and Painful Bladder Syndrome Anna C. Kirby and Gretchen M. Lentz 22 Anal Incontinence 505 Diagnosis and Management Part III GENERAL GYNECOLOGY Gretchen M. Lentz and Mukta Krane 11 C  ongenital Abnormalities of the Female 23 Genital Tract Infections 524 Reproductive Tract 205 Vulva, Vagina, Cervix, Toxic Shock Syndrome, Anomalies of the Vagina, Cervix, Uterus, and Adnexa Endometritis, and Salpingitis Beth W. Rackow, Roger A. Lobo, and Gretchen M. Lentz Carolyn Gardella, Linda O. Eckert, and Gretchen M. Lentz xi Obstetrics & Gynecology Books Full xii Contents 24 Preoperative Counseling and Management566 34 Fallopian Tube and Peritoneal Preoperative Evaluation, Informed Consent, Carcinoma781 Perioperative Planning, Surgical Site Infection Kathleen M. Schmeler and David M. Gershenson Prevention, and Avoidance of Complications 35 Gestational Trophoblastic Disease 787 Jamie N. Bakkum-Gamez, Sean C. Dowdy, Hydatidiform Mole, Nonmetastatic and and Fidel A. Valea Metastatic Gestational Trophoblastic Tumor: 25 P  erioperative Management of Diagnosis and Management Complications583 Geneviève Bouchard-Fortier and Allan Covens Fever, Respiratory, Cardiovascular, 36 Molecular Oncology in Gynecologic Cancer 801 Thromboembolic, Urinary Tract, Gastrointestinal, Immunologic Response, Cytokines, Oncogenes, Wound, and Operative Site Complications; and Tumor Suppressor Genes Neurologic Injury; Psychological Sequelae Premal H. Thaker and Anil K. Sood Leslie Clark and Paola Alvarez Gehrig 26 Abnormal Uterine Bleeding 621 Etiology and Management of Acute and Chronic Excessive Bleeding Part V REPRODUCTIVE ENDOCRINOLOGY Timothy Ryntz and Roger A. Lobo AND INFERTILITY 37 P  rimary and Secondary Dysmenorrhea, Premenstrual Syndrome, and Part IV GYNECOLOGIC ONCOLOGY Premenstrual Dysphoric Disorder 815 Etiology, Diagnosis, Management 27 Principles of Radiation Therapy and Vicki Mendiratta Chemotherapy in Gynecologic Cancer 635 38 P  rimary and Secondary Amenorrhea Basic Principles, Uses, and Complications and Precocious Puberty 829 Judith Ann Smith and Anuja Jhingran Etiology, Diagnostic Evaluation, Management 28 Intraepithelial Neoplasia of the Lower Roger A. Lobo Genital Tract (Cervix, Vagina, Vulva) 655 39 Hyperprolactinemia, Galactorrhea, Etiology, Screening, Diagnosis, Management and Pituitary Adenomas 853 Mila Pontremoli Salcedo, Ellen S. Baker, Etiology, Differential Diagnosis, and Kathleen M. Schmeler Natural History, Management 29 Malignant Diseases of the Cervix 666 Roger A. Lobo Microinvasive and Invasive Carcinoma: 40 Hyperandrogenism and Androgen Excess 865 Diagnosis and Management Physiology, Etiology, Differential Diagnosis, Anuja Jhingran and Larissa A. Meyer Management 30 Neoplastic Diseases of the Vulva 685 Roger A. Lobo Lichen Sclerosus, Intraepithelial Neoplasia, 41 Polycystic Ovary Syndrome 881 Paget Disease, and Carcinoma Roger A. Lobo Michael Frumovitz and Diane C. Bodurka 42 Infertility 897 31 Malignant Diseases of the Vagina 704 Etiology, Diagnostic Evaluation, Intraepithelial Neoplasia, Carcinoma, Sarcoma Management, Prognosis Diane C. Bodurka and Michael Frumovitz Roger A. Lobo 32 Neoplastic Diseases of the Uterus 714 43 In Vitro Fertilization 924 Endometrial Hyperplasia, Endometrial Carcinoma, Janet Choi and Roger A. Lobo Sarcoma: Diagnosis and Management Pamela T. Soliman and Karen H. Lu Index937 33 Neoplastic Diseases of the Ovary 733 Screening, Benign and Malignant Epithelial and Germ Cell Neoplasms, Sex-Cord Stromal Tumors Robert L. Coleman, Pedro T. Ramirez, and David M. Gershenson Obstetrics & Gynecology Books Full Part I BASIC SCIENCE 1 Fertilization and Embryogenesis Meiosis, Fertilization, Implantation, Embryonic Development, Sexual Differentiation Thomas M. Price Several areas of medical investigation have brought increased pairs. Two meiotic cell divisions are required to produce haploid attention to the processes of fertilization and embryonic devel- gametes. In the human female, oogonia enter meiosis in “waves” opment, including teratology, stem cell research, immunogenet- (Fig. 1.1)— that is, not all oogonia enter meiosis at the same ics, and assisted reproductive technology. The preimplantation, time. Meiosis initiation is dependent on mesonephric-produced implantation, and embryonic stages of development in the retinoic acid (Childs, 2011). human can now be studied because of the development of Oocytes in the first substage of prophase, leptotene, are found newer techniques and areas of research. This chapter considers in the human fetal ovary as early as 10 weeks’ gestation. With the processes of oocyte meiosis, fertilization and early cleavage, increasing gestational age, greater proportions of oocytes in later implantation, development of the genitourinary system, and sex stages of meiosis may be observed, and by the end of the second differentiation. trimester of pregnancy, the majority of oocytes in the fetal ovary have cytologic characteristics that are consistent with the diplo- tene/dictyotene substages of prophase I of meiosis I (the stage at OOCYTE AND MEIOSIS which the oocytes are arrested until ovulation) (Fig. 1.2). Meiosis is preceded by interphase I during which DNA rep- The oocyte is a unique and extremely specialized cell. The pri- lication occurs, thus transforming the diploid oogonia with a mordial germ cells in both males and females are large eosino- DNA content of 2N to an oocyte with a DNA content of 4N. philic cells derived from endoderm in the wall of the yolk sac. Meiosis is defined in two stages. The first, known as the reduc- These 700 to 1300 cells migrate to the germinal ridge by way of tion division (division I, or meiosis I) initiates in the fetal ovary the dorsal mesentery of the hindgut by ameboid action by 5 to but is then arrested and completed at the time of ovulation. 6 weeks. Oogenesis begins with the replication of the diploid Meiosis I starts with prophase I (prophase includes leptotene, oogonia through mitosis to produce primary oocytes, reaching zygotene, pachytene, and diplotene), which occurs exclusively a peak number of 600,000 (95% prediction interval: 70,000- during fetal life and sets the stage for genetic exchange that 5,000,000) at 18 to 22 weeks of gestation. Through apoptosis ensures genetic variation in our species (Fig. 1.3). Leptotene is the numbers decline to about 360,000 (95% prediction inter- val: 42,000 to 3,000,000) at menarche (Wallace, 2010). As can be seen, there is a large variance among individuals and a direct Relative Abundance of Germ Cell Types in Human Fetal Ovary correlation between the number of fetal oocytes and the age of menopause. Accelerated apoptosis is seen in Turner syndrome Primordial Oogonia Oocytes undergoing resulting in few oocytes at birth (Modi, 2003). germ meiosis The meiotic process actually begins at 10 to 12 weeks’ gesta- cells Oocytes at tion and is the mechanism by which diploid organisms reduce diplotene their gametes to a haploid state so that they can recombine again during fertilization to become diploid organisms. In humans, this process reduces 46 chromosomes to 23 chromosome struc- tures in the gamete. The haploid gamete contains only one chromosome for each homologous pair of chromosomes, so it 1 2 3 4 5 6 7 8 9 has either the maternal or paternal chromosome for each pair, Months Gestation but not both. Meiosis is also the mechanism by which genetic Figure 1.1 Diagrammatic representation of the different meiotic exchange is completed through chiasma formation and cross- cell types and their proportions in the ovary during fetal life. (Cour- ing over (recombination) between homologous chromosome tesy of Edith Cheng, MD.) 1 Obstetrics & Gynecology Books Full 2 Part I BASIC SCIENCE 3rd month 4th month 7th month 9th month Dictyotene (resting stage) Mitosis and Up to Up to first meiosis zygotene diplotene MEIOSIS I Birth 1st polar body Anaphase I Puberty formation Meiosis Oocytes Ovulation continues mature each cycle Fertilization Degeneration 2nd polar body of polar bodies MEIOSIS II formation diploid egg pronucleus nucleus Meiosis complete sperm pronucleus Figure 1.2 Diagram of oocyte meiosis. For simplicity, only one pair of chromosomes is depicted. Prophase stages of the first meiotic division occur in the female during fetal life. The meiotic process is arrested at the diplotene stage (“first meiotic arrest”), and the oocyte enters the dictyotene stages. Meiosis I resumes at puberty and is completed at the time of ovulation. The second meiotic division takes place over several hours in the oviduct only after sperm penetration. (Courtesy of Edith Cheng, MD.) proportionately the most abundant of all the prophase I sub- stages in the early gestations. Cells in this meiotic phase are characterized by a large nucleus with fine, diffuse, string-like chromatin evenly distributed within the nucleus (Fig. 1.3, A). Chromatin of homologous pairs occupies “domains” and does not occur as distinct linear strands of chromosomes. The zygo- tene substage is defined by the initiation of pairing, which is A B characterized by the striking appearance of the synaptonemal complex formation in some of the chromosomes (Fig. 1.3, B). There is cytologic evidence of chromosome condensation and linearization, and the chromatin is seen as a fine, string- like structure. The pachytene substage is the most easily recog- nizable period of the prophase and is characterized by clearly defined chromosomes that appear as continuous ribbons of thick beadlike chromatin (Fig. 1.3, C). By definition, this is C D the substage in which all homologues have paired. In this sub- stage, the paired homologues are structurally composed of four Figure 1.3 Fetal ovary with fluorescent in situ hybridization. The closely opposed chromatids and are known as a tetrad. The fre- first three images are meiotic cells from a 21-week fetal ovary. A, quency of oocytes in pachytene increases with gestational age Fluorescent in situ hybridization (FISH) with a whole chromosome probe for chromosome X was completed to visualize the pairing and peaks in the mid-second trimester of pregnancy (at about characteristics of the X chromosome during leptotene. B, Zygo- 20 to 25 weeks’ gestation). The diplotene substage is a stage tene. C, Pachytene. D, Image of a meiotic cell from a 34-week fetal of desynapsis that occurs as the synaptonemal complex dis- ovary that underwent dual FISH with probes for chromosomes 13 solves and the two homologous chromosomes pull away from (green signal) and 21 (red signal) to illustrate the pairing character- each other. However, these bivalents, which are composed of istics of this substage of prophase in meiosis I. (Courtesy of Edith a maternally and a paternally derived chromosome, are held Cheng, MD.) together at the centromere and at sites of chiasma formation Obstetrics & Gynecology Books Full  1 Fertilization and Embryogenesis 3 that represent sites where crossing over has occurred (Fig. 1.3, the oocyte, receives the majority of the cytoplasm, and the other D). In general, chiasma formation occurs only between chro- becomes the first polar body. The polar body is located in the matids of homologous pairs and not between sister chromatids. perivitelline space between the surface of the oocyte (oolemma) Usually, one to three chiasmata occur for each chromosome and the zona pellucida (ZP). arm. Oocytes at this stage of prophase I constitute the majority Meiosis II is rapid with the oocyte advancing immediately of third-trimester fetal and newborn ovaries. Diplotene merges to metaphase II where the sister chromatids for each chromo- with diakinesis, the last substage of meiosis I, and is a stage of some are aligned at the equatorial plate, held together by spindle transition to metaphase, lasting many years in humans (Speed, fibers at the centromere. With sperm penetration, meiosis II is 1985). completed with extrusion of the second polar yielding a haploid With puberty, folliculogenesis occurs with progression of oocyte (1N), entered by a haploid (1N) sperm (Fig. 1.4). the follicle, consisting of the oocyte and granulosa cells from primordial to antral characterized by granulosa cell prolifera- tion, development of gonadotropin receptors, and expression of FERTILIZATION AND EARLY CLEAVAGE enzymes for sex steroid production (Baerwald, 2012). It takes approximately 85 days for a follicle to mature to the point of In most mammals, including humans, the egg is released from ovulation. There is no change in the chromosome stage during the ovary in the metaphase II stage (Fig. 1.5). When the egg folliculogenesis. enters the fallopian tube, it is surrounded by a cumulus of granu- Meiosis I resumes with the surge of luteinizing hormone losa cells (cumulus oophorus) and intimately surrounded by a prior to ovulation completing metaphase, anaphase, and telo- clear zona pellucida (ZP). Within the zona pellucida are both phase. The result is two daughter cells, which are diploid (2N) the egg and the first polar body. Meanwhile, spermatozoa are in DNA content but contain 23 chromosome structures, each transported through the cervical mucus and the uterus and into containing two closely held sister chromatids. One daughter cell, the fallopian tubes. Figure 1.4 Diagram of oocyte meiosis. For simplicity, only three pairs of chromosomes are depicted (1 to 4). Prophase stages of the first meiotic division, which occur in most mammals during fetal life. The meiotic process is arrested at the diplotene stage (“first meiotic arrest”), and the oocyte enters the dictyate stages (5 to 6). When meiosis is resumed, the first maturation division is completed (7 to 11). Ovulation occurs usually at the metaphase II stage (11), and the second meiotic division (12 to 14) takes place in the oviduct only after sperm penetration. (From Tsafriri A. Oocyte maturation in mammals. In: Jones RE, ed. The Vertebrate Ovary. New York: Plenum; 1978.) Obstetrics & Gynecology Books Full 4 Part I BASIC SCIENCE Posterior wall of uterus Blastocysts Morula Eight-cell Four-cell Two-cell Zygote Oocyte stage stage stage penetrated by sperm Follicle Oocyte Secondary approaching in tube Growing follicle follicle maturity Mature follicle Early primary follicle Oocyte Blood vessels Epithelium Corpus albicans Released oocyte Mature corpus luteum Ruptured follicle Atretic (degenerating) follicle Developing Endometrium Connective tissue corpus Coagulated blood luteum Figure 1.5 Summary of the ovarian cycle, fertilization, and human development during the first week. Stage 1 of development begins with fertilization in the uterine tube and ends when the zygote forms. Stage 2 (days 2 to 3) comprises the early stages of cleavage (from 2 to about 32 cells, the morula). Stage 3 (days 4 to 5) consists of the free (unattached) blastocyst. Stage 4 (days 5 to 6) is represented by the blastocyst attaching to the posterior wall of the uterus, the usual site of implanta- tion. The blastocysts have been sectioned to show their internal structure. (From Moore KL, Persaud TVN. The Developing Human: Clinically Oriented Embryology. 7th ed. Philadelphia: WB Saunders; 2003.) Although 20 million to 200 million sperm may enter the in the head of the sperm, which will subsequently bind the vagina during intercourse, only 1 in 25,000 will make it to ZP. Chemotaxis is shown by a greater number of sperm in the the fallopian tubes (Williams, 1993). This journey involves ampullary portion of the fallopian tube containing a cumulus- processes of capacitation, chemotaxis, hyperactivated motil- oocyte-complex (COC) compared with the side lacking a COC. ity, and acrosome reaction (Fig. 1.6). Capacitation precedes In vitro, follicular fluid acts as a chemoattractant, possibly due all other changes and involves initial removal of cholesterol to progesterone, but the exact responsible constituent(s) of the from the plasma membrane altering the permeability and flu- fluid continues to be debated (Eisenbach, 1999). Hyperacti- idity. This allows the influx of calcium and bicarbonate with vated motility involves increased vigorous movement of the many downstream effects such as increased cyclic adenosine sperm in order to penetrate the cumulus (granulosa) cells sur- monophosphate (cAMP), protein tyrosine phosphorylation, rounding the oocyte and is most likely due to progesterone. and activation of protein kinases (Aitken, 2013). A function A major action of progesterone is to increase calcium influx of capacitation is to allow localization of protein complexes into the sperm with multiple downstream effects. Likely, the Obstetrics & Gynecology Books Full  1 Fertilization and Embryogenesis 5 Zona pellucida Perivitelline space Corona radiata Cytoplasm of oocyte Second meiotic metaphase 1 2 3 First polar body 4 Plasma membrane A of oocyte Sperm nucleus Acrosome Plasma Perforations in Plasma Enzymes Sperm in cytoplasm containing containing membrane acrosome wall membrane breaking down of oocyte without its chromosomes enzymes of sperm of oocyte zona pellucida plasma membrane 1 2 3 4 B Figure 1.6 Acrosome reaction and a sperm penetrating an oocyte. The detail of the area outlined in A is given in B. 1, Sperm during capacitation, a period of conditioning that occurs in the female reproductive tract.2, Sperm undergoing the acrosome reaction, during which perforations form in the acrosome. 3, Sperm digesting a path through the zona pellucida by the action of enzymes released from the acrosome. 4, Sperm after entering the cytoplasm of the oocyte. Note that the plasma membranes of the sperm and oocyte have fused and that the head and tail of the sperm enter the oocyte, leaving the sperm’s plasma membrane attached to the oocyte’s plasma membrane. (From Moore KL, Persaud TVN. The Developing Human: Clinically Oriented Embryology. 7th ed. Philadelphia: WB Saunders; 2003.) progesterone concentration increases as the sperm approaches Binding results in fenestrations forming between the plasma the egg, resulting in more aggressive motility. When the egg is membrane and the underlying acrosome membrane releasing reached, receptor complexes on the outer most plasma mem- enzymes including acrosin (a serine protease) to locally degrade brane bind to specific ZP glycoprotein receptors (primarily ZP the ZP (Chiu, 2014). 3). These interactions are very species specific. Human sperm As many sperm may initially bind the ZP, a mechanism must can only bind to the ZP of human, baboon, and gibbon oocytes. be in place to prevent fertilization by more than one sperm Obstetrics & Gynecology Books Full 6 Part I BASIC SCIENCE (polyspermia). With initial binding of the sperm membrane to or preimplantation genetic screening (PGS) for chromosome the oolemma, a calcium-dependent release of cortical granules abnormalities (Fig. 1.8). This technique involves removal of up occurs. Cortical granules are vesicles containing protein made to 20 TE cells from the day 5 blast for analysis. For PGD of during oogenesis and located in the periphery of the cell. Con- single-gene disorders, DNA is extracted from the cells and the tents are released into the perivitelline space and function to mutation analyzed by polymerase chain reaction (PCR) ampli- modify ZP proteins and enlarge the perivitelline space to prevent fication or single nucleotide polymorphism (SNP) microarray. sperm entry (Talbot, 2003). With sperm entry, the oocyte com- For PGS of chromosomal defects such as aneuploidy or struc- pletes its second meiotic division, casting off the second polar tural rearrangements, analysis of DNA is performed with com- body into the perivitelline space. parative genomic hybridization (CGH)-array (Fiorentino, 2014) The majority of a single sperm enters the oocyte, and this is or partial genomic sequencing (next-generation sequencing). indeed the case during intracytoplasmic sperm injection (ICSI) for infertility. Only the centrioles and the nucleus survive, whereas mitochondria in the midpiece and tail are destroyed. IMPLANTATION The sperm centrioles interact with α-tubulin from the oocyte to form a microtubule network for migration of pronuclei and Implantation consists of apposition, attachment, and invasion. subsequent separation of chromosomes during the first mitosis This complex process has much redundancy and involves mul- (Schatten, 2009). Thus mitochondria are of maternal origin, tiple factors including ovarian hormones, cytokines, transcrip- whereas centrioles are paternal. tion factors, growth factors, and extracellular matrix proteins Early cell division (cleavage) is not synchronous and varies in (ECMs) (Table 1.1). Both the endometrium and the embryo time (Fig. 1.7). Time intervals from two pronuclei to two-cell, produce these factors. Communication between the embryo two-cell to three-cell, three-cell to four-cell, and four-cell to five- and the endometrium is key. Implantation occurs 7 to 10 days cell are 26 hours, 12 hours, 0.8 hours, and 14 hours, respectively, after ovulation corresponding to cycle days 21 to 24 of an idyllic as determined with time-lapse photography during in vitro fer- 28-day cycle with ovulation on day 14. During apposition the tilization (IVF) (Meseguer, 2011). A significant number of fertil- human embryo is oriented with the ICM and polar TE (TE next ized oocytes do not complete cleavage for a number of reasons, to the ICM) adjacent to the endometrium. including failure of appropriate chromosome arrangement on For attachment to the endometrium, the embryonic cells the spindle, specific gene defects that prevent the formation of must first be expelled from the surrounding ZP in the process the spindle, and environmental factors. Importantly, teratogens of “hatching.” Hatching involves rupture of the ZP in one small acting at this point are usually either completely destructive or area as opposed to a general dissolution of the entire ZP. This cause little or no effect. Twinning may occur by the separation may involve hydrostatic pressure from inside the ZP and from of the two cells produced by cleavage, each of which has the zonalytic proteases produced by the TE and endometrium. potential to develop into a separate embryo (Hall, 2003). Twin- These cysteine proteases, named cathepsins, are essential for ning may occur at any stage until the formation of the blastocyst hatching. Attachment of the embryonic cells to the endometrial (blast), because each cell is totipotent. Both genetic and environ- cells involves cell adhesion proteins, integrins, and ECM pro- mental factors are probably involved in the causation of twin- teins such as fibronectin, laminin, and collagen. Integrins are cell ning. surface proteins, which bind extracellular matrix proteins and are expressed on both the luminal epithelium and TE. Invasion of the TE cells next occurs by penetrating between MORULA AND BLASTULA STAGE: the luminal epithelial cells, through the basement membrane EARLY DIFFERENTIATION and into the stroma of the endometrium. These initial TE cells After fertilization, the zygote (the term for a fertilized egg) has a form the extravillous trophoblasts (EVTs), which invade down diameter of 83 to 105 μm and undergoes rapid mitotic division to the inner third of the myometrium for anchoring and into to reach the next stage of approximately 16 cells called a morula. the spiral arteries for remodeling. During spiral artery remod- After 4 to 5 days traversing the fallopian tube, the embryo arrives eling, endovascular EVT disorganize and partially replace the into the uterine cavity at the blast stage. The blast is character- smooth muscle wall and the vascular endothelial cells. Prolif- ized by a cavity (blastocoele) and differentiation of cells into the eration of endovascular EVT leads to plugging and obstruction trophectoderm (TE), which will ultimately produce the fetal of the decidual spiral arteries resulting in a decrease in blood membranes and placenta and the inner cell mass (ICM), which flow and oxygen tension. Low oxygen promotes the proliferation will produce the fetus. During IVF, the blast forms 5 days after and transformation of cytotrophoblast to syncytiotrophoblast. fertilization with a diameter of 155 to 265 μm consisting of Prior to 8 weeks’ gestation, nutrition to the embryo is derived about 40 TE cells and 20 ICM cells. In the human, implan- from endometrial gland secretion and plasma seeping through tation generally takes place 3 days after the embryo enters the the obstructed spiral arteries into the intervillous space. With uterus. The development of the blast with the separation of the continued remodeling of the spiral arteries, patency is reestab- ICM from the developing TE together make up the first stage of lished and maternal blood cells enter the intervillous space at differentiation in the embryo. Differentiation within the ICM around 9 weeks’ gestation with a rise in oxygen tension. Lack proceeds fairly rapidly, and if separation of cells and twinning of adequate EVT invasion and spiral artery remodeling is a key occur at this point, the twins may be conjoined in some fashion. feature in preeclampsia, intrauterine growth restriction, and still- Advances in assisted reproductive technology and genetics birth (Brosens, 2002). now provide practitioners assess to the early embryo for pre- The idea of low oxygen tension during early embryo develop- implantation genetic diagnosis (PGD) of single-gene disorders ment has been explored with IVF. With a limited number of Obstetrics & Gynecology Books Full  1 Fertilization and Embryogenesis 7 A B C D E F Figure 1.7 Six photomicrographs of fresh, unmounted human eggs and embryos. A, Recently retrieved human oocyte surrounded by cumulus cells. B, Fertilized oocyte demonstrating male and female pronuclei and both polar bodies at approximately 11 and 12 o’clock position. C, Two-cell zygote with scattered cumulus cells remaining attached to the zone pellucida. D, Eight-cell zygotes. E, Blastocyst with the inner cell mass seen at 12 o’clock. F, A hatching blastocyst in which a portion of the trophectoderm has extruded from the zona pellucida at the 4 o’clock position. (Courtesy of Douglas Raburn, PhD.) Obstetrics & Gynecology Books Full 8 Part I BASIC SCIENCE Fertilization Egg cell (ovum) ICSI Sperm Needle A Interruption of ZP on day 3 with laser or acid digestion B Preimplantation Genetic Screening (PGS) by 1. Array comparative genomic hybridization or 2. Next generation sequencing Removal of prolapsed TE C cells on day 5 for testing Preimplantation Genetic Diagnosis (PGD) by 1. Polymerase chain reaction amplification or D 2. Single nucleotide polymorphism microarray Figure 1.8 Schematic of preimplantation testing. A, Commonly the oocyte is fertilized with a single sperm using the technique of intracy- toplasmic sperm injection (ICSI). This precludes the possibility of contamination from sperm remaining attached to the outside of the embryo during embryo biopsy. B, On day 3 of culture, when the embryo has cleaved to about eight cells, a small opening is made in the zona pellucida (ZP) with either a laser or brief exposure to an acid solution. C, By day 5 of culture, the embryo has progressed to the blastocyst stage and a portion of the trophectoderm (TE) cells have prolapsed out the opening in the zona pellucida. These cells are removed for subsequent DNA isolation. D, DNA from trophectoderm cells is used to determine chromosome number, insertions, and deletions for preimplantation genetic screening (PGS) using techniques of array comparative genomic hybridization (aCGH) or next-generation sequencing (NGS). DNA may also be used to detect single-gene abnormalities for different diseases using single nucleotide polymorphism (SNP) microarray or polymerase chain reaction (PCR) amplification in the process of preimplantation genetic diagnosis (PGD). Table 1.1 Events of Implantation trials, culturing embryos in 5% oxygen as opposed to 20% oxy- Event Days after Ovulation gen results in a modest increase in the implantation rate (Bon- Zona pellucida disappears 4-5 tekoe, 2012). Blastocyst attaches to epithelial surface 6 Villous trophoblast form finger-like projections extending of endometrium into the intervillous space and thus surrounded by mater- Trophoblast erodes into endometrial 7 nal blood. Syncytiotrophoblast form the outer layer with an stroma underlying layer of precursor cytotrophoblast surrounding Trophoblast differentiates into cytotro- 7-8 phoblastic and syncytial trophoblastic matrix containing capillaries, fibroblasts, and macrophages. layers Cytotrophoblasts become less numerous as pregnancy pro- Lacunae appear around trophoblast 8-9 gresses. Blastocyst burrows beneath endometrial 9-10 Blood levels of the pregnancy hormone human chorionic surface gonadotropin (hCG) can be detected within 48 hours of implan- Lacunar network forms 10-11 tation. Regular hCG is produced by the syncytiotrophoblast of Trophoblast invades endometrial sinu- 11-12 placental villi. Blood levels peak at 56 to 68 days, reach a nadir at soids, establishing a uteroplacental 18 weeks, and then remain fairly constant until delivery. Gonad- circulation otropin-releasing hormone (GnRH) produced in the cytotro- Endometrial epithelium completely cov- 12-13 phoblast and syncytiotrophoblast induces expression of hCG. In ers blastocyst Strong decidual reaction occurs in stroma 13-14 spontaneous pregnancies hCG can be detected 9 days following follicle rupture observed by ultrasound. In IVF pregnancies, the Obstetrics & Gynecology Books Full  1 Fertilization and Embryogenesis 9 hormone can be found 8 days after embryo transfer. hCG levels rise, exponentially up to 8 weeks from the last menstrual period, but the doubling time increases as the level increases. For example, in a conception cycle with ovulation on cycle day 14, the doubling time from cycle days 25 to 37 for hCG is 1.6 days and from days 38 to 44 it is 2.3 days (Zegers-Hochschild, 1994). The doubling time is independent of the number of gestations, although the absolute hCG level is higher for multiple pregnancies. The classic action of regular hCG is maintenance of the corpus luteum (CL) by binding the luteinizing hormone (LH) receptor for continued estrogen and progesterone production. Yet other identified actions include promotion of angiogen- esis in the uterus, myometrial relaxation, inhibition of immune interaction at the utero-placental interface, stimulation of fetal testosterone production, and mediation of hyperemesis through receptors in the brain. Hyperglycosylated hCG (H-hCG) is produced by the EVT. H-hCG is key in promoting angiogenesis and cell invasion and cor- respondingly is found in the early first trimester. The protein does Figure 1.9 Photomicrograph of the Arias-Stella reaction. hCG not activate the LH receptor and does not preserve CL function. action results in nuclear enlargement in endometrial glandular cells Instead it appears to function via the transforming growth factor (arrows) resulting in visual characteristics of malignant cells. Magnifi- cation, ×200. (Courtesy of Rex Bentley, MD.) beta (TGF-β) receptor (Berndt, 2013). Low levels of H-hCG indi- cate poor EVT development and are associated with spontaneous abortion and early preeclampsia (Fournier, 2015). A functional progesterone receptor requires interaction with “chaperone” proteins. In mice, one of these proteins, named FK506 binding protein 52 (FKBP52), is expressed in the endo- DECIDUALIZATION metrium during the window of receptivity, and a loss of function Progesterone is responsible for “decidualization” of the endo- mutation disrupts decidualization. metrium. This refers to morphologic and functional changes in LIF is a cytokine produced by endometrial glandular cells stromal cells. In humans, stromal cells close to the spiral arteries around the time of implantation. LIF acts on EVT to increase undergo progesterone-induced decidual changes in the late secre- the fibronectin production necessary for embryo attachment and tory phase, and this process progresses throughout the stroma invasion. Mice lacking expression of LIF (knockout) have both with implantation and hCG production. A pregnancy within failure of decidualization and implantation (Chen, 2000). the uterus is not required and decidualization is a common find- Indian hedgehog (Ihh) protein is a morphogen produced ing with ectopic pregnancies. Decidual cells show morphologic by luminal epithelial cells under the control of progesterone. changes of increased size with increased glycogen and lipid accu- Morphogens are signaling proteins that diffuse throughout the mulation (Maruyama, 2008). With pregnancy the endometrium decidua yielding a concentration gradient. Signaling is depen- is now referred to as the decidua, separated into areas of the decidua dent on the concentration in a given area. Ihh knockout mice fail basalis or placentalis, which interacts with the TE (area of mature to decidualize or implant (Ramathal, 2010). placenta), the decidua vera or parietalis (decidua distant from the implantation site), and the decidua capsularis (surrounding the EMBRYO-ENDOMETRIAL COMMUNICATION embryo on the side opposite the placenta). Another classic histologic change seen in early pregnancy is Implantation involves molecular interactions between the embryo the Arias-Stella reaction (Fig. 1.9). This occurs in the glandular and the adjacent endometrium. For example, the embryo produces cells with a hallmark of nuclear enlargement. These cells may be heparin-binding epidermal growth factor-like growth factor (HB- misinterpreted as atypical or malignant. In the presence of hCG, EGF), which is both found on the cell membrane and is released from the Arias-Stella reaction may be seen in extrauterine tissues such the cell (soluble). HB-EGF induces expression of itself in the adjacent as endometriosis, vaginal adenosis, paraovarian cysts, and muci- endometrial cells (auto-induction loop). HB-EGF on the endome- nous cystadenomas (Arias-Stella, 2002). trial cells then acts to attach the embryo via EGF receptors expressed Morphologically luminal epithelial cells develop extensions on the embryo (Lim, 2009). Additionally, the soluble HB-EGF from of the plasma membrane called pinopods (also called uterodomes) the embryo induces expression of cyclooxygenase to increase prosta- during the window of receptivity. Pinopods function to release cyclin (PGI2) in the endometrium resulting in enhanced endometrial key proteins including leukemia inhibitory factor (LIF) through vascular permeability to help with embryo invasion (Kim, 1999). exocytosis and apocrine secretion (Kabir-Salmani, 2005). Downstream effects of progesterone-dependent decidualiza- IMMUNOLOGY OF IMPLANTATION tion have not been completely elucidated, but loss-of-function studies show the necessity of transcription factors including The paternal contribution to the embryo results in the mother CCAAT/enhancer binding protein Beta (C/EBPβ), Homeo- being exposed to allogenic cells. Although villous trophoblasts box A10 (Hoxa10), Forkhead/winged helix protein (Fox01), do not express major human leukocyte antigens (HLA), the and chicken ovalbumin upstream promoter (COUP-TFII). EVTs express HLA-C, E, and G, which may be recognized by Obstetrics & Gynecology Books Full 10 Part I BASIC SCIENCE the maternal immune system. Thus the maternal immune sys- vessels can be seen about 2 days later and develop when mesenchy- tem must be locally suppressed to prevent rejection. mal cells known as angioblasts aggregate to form masses and cords The majority of immune cells in the decidua are uterine natural called blood islands. Spaces then appear within these islands, and the killer (uNK) cells. These cells are present in the secretory endome- angioblasts arrange themselves around these spaces to form primi- trium, under the control of progesterone, and increase in number tive endothelium. Isolated vessels form channels and then grow with pregnancy to form an infiltrate around the invading EVT. into adjacent areas by endothelial budding. Primitive blood cells These cells start to dissipate in the second trimester. uNK cells are develop from endothelial cells as the vessels develop on the yolk sac not cytotoxic to trophoblast cells and in fact appear to be support- and allantois. However, blood formation does not begin within the ive. A low number of uNK cells in the decidua of early pregnancy embryo until the second month of gestation, occurring first in the is associated with poor invasion of the EVT. Cytokines such as developing liver and later in the spleen, bone marrow, and lymph interferon gamma and angiogenic factors secreted by uNK cells nodes. Separate mesenchymal cells surrounding the primitive endo- are key to proper EVT development and function. thelial vessels differentiate into muscular and connective tissue T-helper (Th) cells are also found in the decidua and are elements. The primitive heart forms in a similar manner from mes- functionally classified as Th1 (cellular immunity), Th2 (humoral enchymal cells in the cardiogenic area. Paired endothelial channels, immunity), Th3 (production of transforming growth factor-beta called heart tubes, develop by the end of the third week and fuse to for immunosuppression), and Tr1 (production of interleukin 10 form the primitive heart. By the twenty-first day, this primitive heart for immunosuppression) (Saito, 2007). In early pregnancy, there has linked up with blood vessels of the embryo, forming a primitive is an increase in the percentage of decidual Th2 and Th3 cells. cardiovascular system. Blood circulation starts about this time, and T-regulatory cells (Tregs) function in antigen recognition for the cardiovascular system becomes the first functioning organ sys- future immune tolerance. Mice lacking Treg cells experience abor- tem within the embryo (Clark, 1987). All the organ systems form tion when mated with an allogenic male but not when mated with between the fourth week and seventh week of gestation. a syngenic male (Darasse-Jèze, 2006). These cells are key in devel- A teratogenic event that takes place during the embryonic oping tolerance to male antigens. Development of immunity to period gives rise to a constellation of malformations related to the specific paternal antigens may explain observations including lower organ systems that are actively developing at that particular time. preeclampsia rates in women exposed to their partner’s semen prior Thus cardiovascular malformations tend to occur because of tera- to pregnancy compared with women conceiving with donor insem- togenic events early in the embryonic period, whereas genitouri- ination (Salha, 1999), and the lower preeclampsia rate in the second nary abnormalities tend to result from later events. Teratogenic pregnancy with the same partner as opposed to a new partner. effects before implantation often cause loss of the embryo but not malformations. The effects of a particular teratogen depend on the individual’s genetic makeup, other environmental factors in play EARLY ORGANOGENESIS IN THE at the time, the embryonic developmental stage during which the EMBRYONIC PERIOD teratogenic exposure occurred, and in some cases the dose of the During the third week after fertilization, the primitive streak forms teratogen and the duration of exposure. Some teratogens in and in the caudal portion of the embryonic disk, and the embryonic of themselves are actually harmless, but their metabolites cause disk begins to grow and change from a circular to a pear-shaped the damage. Teratogens may be chemical substances and their configuration. At that point the epithelium superiorly is considered by-products, or they may be physical phenomena, such as tem- ectoderm and will eventually give rise to the developing central ner- perature elevation and irradiation. The embryo is most sensitive to vous system, and the epithelium facing downward toward the yolk teratogens during organogenesis of the embryonic period from 18 sac is endoderm. During this week the neuroplate develops with its to 56 days postconception. Prior to day 18, exposure is most likely associated notochordal process. By the sixteenth day after concep- to result in either embryo death with miscarriage or no effect, as tion the third primitive germ layer, the intraembryonic mesoderm, the majority of cells are pluripotent (Polifka, 2002). Teratogen begins to form between the ectoderm and endoderm. Early meso- exposure after the embryonic period of development may injure derm migrates cranially, passing on either side of the notochordal or kill the embryo or cause developmental and growth retardation process to meet in front in the formation of the cardiogenic area. but usually will not be responsible for specific malformations. The The heart soon develops from this area. Later in the third week, period of embryonic development is said to be complete at 56 extraembryonic mesoderm joins with the yolk sac and the develop- days (8 weeks) from fertilization or 70 days (10 weeks) from the ing amnion to contribute to the developing membranes. last menstrual period followed by the fetal stage. An intraembryonic mesoderm develops on each side of the noto- chord and neural tube to form longitudinal columns, the paraxial mesoderm. Each paraxial column thins laterally into the lateral plate DEVELOPMENT OF THE GENITOURINARY mesoderm, which is continuous with the extraembryonic meso- SYSTEM derm of the yolk sac and the amnion. The lateral plate mesoderm is separated from the paraxial mesoderm by a continuous tract of The development of the genital organs is intimately involved mesoderm called the intermediate mesoderm. By the twentieth day, with the development of the renal system. paraxial mesoderm begins to divide into paired linear bodies known as somites. About 38 pairs of somites form during the next 10 days. Eventually a total of 42 to 44 pairs will develop, and these will give RENAL DEVELOPMENT rise to body musculature (O’Rahilly, 1979). Nephrogenic cords develop from the intermediate mesoderm as Angiogenesis, or blood vessel formation, can be seen in the extra- early as the 2-mm embryo stage, beginning in the more cephalad embryonic mesoderm of the yolk sac by day 15 or 16. Embryonic portions of the embryo. Three sets of excretory ducts and tubules Obstetrics & Gynecology Books Full  1 Fertilization and Embryogenesis 11 develop bilaterally (Little, 2010). The first, the pronephros, with In the male the mesonephric ducts open into the urethra as its pronephric ducts, forms in the most cranial portion of the the ejaculatory ducts. Also in the male, mesenchymal tissue sur- embryo at about the beginning of the fourth week after con- rounding the developing urethra where it exits the bladder devel- ception. The tubules associated with the duct probably have no ops into the prostate gland, through which the ejaculatory ducts excretory function in the human, but the caudal end will form traverse. Figure 1.10 demonstrates graphically the development the adrenal gland. Late in the fourth week, a second set of tubules, of the male and female urinary systems. the mesonephric tubules, and their accompanying mesonephric The epithelium of the female urethra is derived from endo- ducts begin to develop. These are associated with tufts of cap- derm of the vesicourethral canal. The urethral sphincter devel- illaries, or glomeruli, and tubules for excretory purposes. Thus ops from a mesenchymal condensation around the urethra the mesonephros functions as a fetal kidney, producing urine after the division of the cloaca in the 12- to 15-mm embryo. for about 2 or 3 weeks. As new tubules develop, those derived Following the opening of the anal membrane at the 20- to from the more cephalad tubules degenerate. Usually about 40 30-mm stage, the puborectalis muscle appears. At 15 weeks’ mesonephric tubules function on either side of the embryo at gestation, striated muscle can be seen, and a smooth muscle any given time. The gonads arise from the central region of the layer thickens at the level of the developing bladder neck, mesonephros. The metanephros, or permanent kidney, begins forming the inner part of the urethral musculature. Thus the its development early in the fifth week of gestation and starts urethral sphincter is composed of both central smooth muscle to function late in the seventh or early in the eighth week. The and peripheral striated muscle. The sphincter develops primar- metanephros develops both from the metanephrogenic mass of ily in the anterior wall of the urethra in a horseshoe or omega mesoderm, which is the most caudal portion of the nephrogenic shape (Matsuno, 1984). cord, and from its duct system, which is derived from the meta- nephric diverticulum (ureteric bud). It is a cranially growing outpouching of the mesonephric duct close to where it enters MOLECULAR BASIS OF SEX the cloaca. The metanephric duct system gives rise to the ureter, DIFFERENTIATION the renal pelvis, the calyces, and the collecting tubules of the adult kidney. A critical process in the development of the kidney Genetic sex is determined at the time of conception. A Y chro- requires that the cranially growing metanephric diverticulum mosome is necessary for the development of the testes, and the meets and fuses with the metanephrogenic mass of mesoderm testes are responsible for the organization of the sexual duct so that formation of the kidney can take place. Originally the system into a male configuration and for the suppression of metanephric kidney is a pelvic organ, but by differential growth the paramesonephric (müllerian) system of the female. In the it becomes located in the lumbar region (Moritz, 1999). absence of a Y chromosome or in the absence of a gonad, devel- The fetus produces urine starting at 8 weeks’ gestation opment will be female in nature. Male differentiation is deter- (Underwood, 2005). Starting in the second trimester, fetal mined by expression of the SRY gene found on the short arm urine is a major contributor to amniotic fluid volume. The fetus of the Y chromosome. SRY protein is a transcription factor and may swallow the amniotic fluid and recirculate it through the expression is unique to the Sertoli cell of the developing testis. digestive system. Congenital abnormalities that impair normal SRY induces expression of another transcription factor, SOX9, development or function of the fetal kidneys generally result in which is also obligatory for male sex differentiation. A loss of little or no amniotic fluid (oligohydramnios or anhydramnios), function mutation of either SRY or SOX9 results in XY sex whereas structural abnormalities of the gastrointestinal tract or reversal, in which genetic males are phenotypic females. Several neuromuscular conditions that prevent the fetus from swallow- genes regulate SRY/SOX9 expression including Wilms’ tumor ing can lead to excess amniotic fluid (polyhydramnios).