The Female Reproductive System PDF

THE FEMALE REPRODUCTIVE SYSTEM FEMALE REPRODUCTION  Unlike males, who are able to produce sperm cells throughout their reproductive lives, females produce a finite number of egg cells.  During early fetal development germ cells migrate into the ovaries and differentiate into...

THE FEMALE REPRODUCTIVE SYSTEM FEMALE REPRODUCTION  Unlike males, who are able to produce sperm cells throughout their reproductive lives, females produce a finite number of egg cells.  During early fetal development germ cells migrate into the ovaries and differentiate into oogonia OOGONIA  The oogonia divide by mitosis for the next few months and some differentiate into primary oocytes.  By fifth (5th) month there are about 7M million primary oocytes, but most will degenerate during the next 2 months OOGONIA  Those that remain will be surrounded by a single layer of squamous epithelial cells (follicle cells) called a primordial follicle.  Degeneration of primary oocytes continues.  At birth =1million primordial follicles  At puberty 400,000 remain  Only 400-500 will reach maturity OVARIAN CYCLE  Monthly changes that occur in the ovary during a woman’s reproductive life.  Each month FSH stimulates primordial follicles to grow and mature (follicular phase)  Ovulation- release of the egg (LH) If fertilization does not occur,  Luteal phase the corpus the corpus luteum luteum produces progesterone that degenerates, within 2 weeks maintains uterine walls into a mass of scar tissue called the corpus albicans OOGENESIS Meiosis – PMAT1 PMAT2 Mitosis – PMAT 2n = diploid N = haploid Human = 2n=46 6 LIFE HISTORY OF OOGONIA  As a fetus, oogonia divide to produce millions by mitosis but most degenerate (atresia)  Some develop into primary oocytes & stop in prophase stage of meiosis I  200,000 to 2 million present at birth  40,000 remain at puberty but only 400 mature during a woman’s life  Each month, hormones cause meiosis I to resume in several follicles so that meiosis II is reached by ovulation  Penetration by the sperm causes the final stages of meiosis to occur 7 OOGENESIS: BEFORE BIRTH  During fetal development, oogonia (stem cells) divide by mitosis to make primary oocytes  Primary oocytes begin meiosis and stop in prophase I until puberty  Primordial follicles: Support cells that surround the oocyte in the ovary  2 million present at birth  400,000 remain at puberty 8 OOGENESIS: AFTER PUBERTY  Each month, hormones cause several follicles to develop, which triggers the primary oocyte to resume meiosis I  Polar bodies: When the cell divides, all the cytoplasm and organelles stay with one of the new cells, the other cell is just DNA, and is called a polar body and is discarded  Secondary oocyte: The stage at which ovulation occurs. 9 OOGENESIS: AFTER PUBERTY  The secondary oocyte begins meiosis II, but stops in metaphase II  The secondary oocyte is ovulated  Meiosis II is completed only if it is fertilized. 10 FOLLICLE DEVELOPMENT 1. Primordial follicle: one layer of squamous- like follicle cells surrounds the oocyte 2. Primary follicle: two or more layers of cuboidal granulosa cells enclose the oocyte 3. Secondary follicle: has a fluid-filled space between granulosa cells that coalesces to form a central antrum 4. Graafian follicle: secondary follicle at its most mature stage that bulges from the surface of the ovary 5. Corpus luteum : ruptured follicle after ovulation produces progesterone that maintains the uterine walls 11 OVARY HISTOLOGY 12 CORPUS LUTEUM AND CORPUS ALBICANS GRAAFIAN FOLLICLE Fluid filled antrum 14 Oocyte 2° Granulosa cells Stalk Corona radiata Zona pellucida CORPUS LUTEUM  After ovulation, the remains of the follicle are transformed into a structure called the corpus luteum.  If a pregnancy occurs, it produces progesterone to maintain the wall of the uterus during the early period of development. OVARIES  Each follicle consists of an immature egg called an oocyte  Cells around the oocyte are called:  Follicle cells (one cell layer thick)  Stimulated to mature by FSH from the pituitary gland  Granulosa cells (when more than one layer is present)  Thecal cells: Cells in the ovarian stroma  Thecal & granulosa cells work together to produce estrogen  A protective layer of glycoprotein forms around the egg called the zona pellucida 16 OVARY HISTOLOGY 17 Primary Follicle 1° Oocyte (arrested in prophase I) Nucleus Primordial follicle Zona pellucida Thecal cells Granulosa cells 18  Fluid-filled SECONDARY FOLLICLE antrum 19 CORPUS ALBICANS  If fertilization does not occur, the corpus luteum will begin to break down about 2 weeks after ovulation.  Degeneration occurs when fibroblasts enter the corpus luteum and a clump of scar tissue forms called the corpus albicans. OVARIAN AND UTERINE CYCLES GROSS ANATOMY  The ovaries are solid, ovoid structures, about 2 cm in length and 1 cm in width.  Like the testes, they develop from embryonic tissue along the posterior abdominal wall, near the kidneys.  Accessory organs include the uterine tubes, uterus, and vagina. UTERINE TUBES (FALLOPIAN TUBES)  Receive the ovulated oocyte and provide a site for fertilization  Empty into the superolateral region of the uterus via the isthmus  Expand distally around the ovary forming the ampulla  The ampulla ends in the funnel-shaped, ciliated infundibulum containing fingerlike projections called fimbriae 23 UTERINE TUBES (FALLOPIAN TUBES)  Function: events occurring in the uterine tube  Fimbriae sweep oocyte into tube, cilia & peristalsis move it along, sperm reaches oocyte in ampulla, fertilization occurs within 24 hours after ovulation & zygote reaches uterus about 7 days after ovulation 24 FALLOPIAN TUBE HISTOLOGY 25 Cilia sweep egg/zygote toward the uterus UTERUS  Hollow, thick-walled organ located in the pelvis anterior to the rectum and posterosuperior to the bladder  Body: Major portion of the uterus  Fundus: Rounded region superior to the entrance of the uterine tubes  Isthmus: Narrowed region between the body and cervix 26 UTERUS 27  UTERINE HISTOLOGY  Endometrium  Simple columnar epithelium  Stroma of connective tissue and endometrial glands Stratum functionalis: Shed during  menstruation Stratum basalis: Replaces stratum functionalis each month  Myometrium  3 layers of smooth muscle  Perimetrium  Visceral peritoneum 28 UTERINE HISTOLOGY 29 ENDOMETRIUM 30 Simple columnar epithelium Endometrial glands ENDOMETRIUM  Proliferative phase: glands and blood vessels scattered throughout the functional zone with little or no branching.  New glands form and endometrium thickens.  Secretory phase: glands are enlarged and have branches. Preparing the endometrium for implantation  If no implantation then endometrium breaks down and menstruation begins. FEMALE: LATERAL VIEW 32 CERVIX  Narrow lower neck of the uterus which projects into the vagina inferiorly  Cervical canal – cavity of the cervix that communicates with:  The vagina via the external os  The uterine body via the internal os  Cervical glands secrete mucus that covers the external os and blocks sperm entry except during midcycle 33 Endocervical canal Fornix 34 VAGINA  Thin-walled tube lying between the bladder and the rectum, extending from the cervix to the exterior of the body  Wall consists of three coats: fibroelastic adventitia, smooth muscle muscularis, and a stratified squamous mucosa  Mucosa near the vaginal orifice forms an incomplete partition called the hymen  Vaginal fornix: upper end of the vagina surrounding the cervix 35 FEMALE EXTERNAL GENITALIA  Mons pubis: fatty pad over the pubic symphysis  Labia majora & minora: folds of skin encircling vestibule where find urethral and vaginal openings  Clitoris: small mass of erectile tissue  Bulb of vestibule: masses of erectile tissue just deep to the labia on either side of the vaginal orifice  Perineum: Area between the vagina and anus 36 FEMALE EXTERNAL GENITALIA Perineum 37 BARTHOLIN’S GLANDS (AKA: VESTIBULAR GLANDS)  The Bartholin's glands are located on each side of the vaginal opening.  They secrete fluid that helps lubricate the vagina.  Sometimes the ducts of these glands become obstructed.  Fluid backs up into the gland and causes swelling (Bartholin's cyst) 38 MAMMARY GLANDS  Modified sweat glands that produce milk (lactation)  Amount of adipose determines size of breast  Milk-secreting glands open by lactiferous ducts at the nipple  Areola is pigmented area around nipple  Suspensory ligaments suspend breast from deep fascia of pectoral muscles (aging & Cooper’s droop)  Mammary line is a thickened ridge of embryonic tissue that extends from the axilla to the groin. 39 BREAST 40  BREAST  Prolactinfrom from Prolactin the the pituitary pituitary gland gland stimulates stimulates the the synthesissynthesis of of milk milk Oxytocin  Oxytocinfrom fromthe the posterior posterior pituitary pituitarygland gland stimulates milk stimulates milk ejection ejection 41 LYMPHATIC DRAINAGE  Lymph nodes draining the breast are located in the axilla. 42 REVIEW & EXPLORE 1. What is the reproductive system? 2. Define gonad. 3. How does the differentiation of the reproductive system occur in females? 4. When and how does the human reproductive system mature? 5. List organs of the female reproductive system.