REPRODUCTIVE SYSTEM.pdf

THE REPRODUCTIVE SYSTEM: Male reproductive system Female reproductive system Pregnancy & Human development Anthony Sarfo, Pharm. D., MPSGH, MPhil. Lecturer, Pharmacology & Toxicology. CUSoP [email protected] Room 202 SoP Block 0506444791  HUMAN ANA T OMY &...

THE REPRODUCTIVE SYSTEM: Male reproductive system Female reproductive system Pregnancy & Human development Anthony Sarfo, Pharm. D., MPSGH, MPhil. Lecturer, Pharmacology & Toxicology. CUSoP [email protected] Room 202 SoP Block 0506444791  HUMAN ANA T OMY & P HY S I OL OGY OU T L I N E Semester 2 1. The Cardiovascular System: Blood, heart, blood vessels 2. The lymphatic system 3. Immune system 4. Respiratory system 5. Digestive system 6. Urinary system, Fluid, Electrolyte, and Acid-Base Balance 7. The Reproductive System: Male & Female reproductive systems, Pregnancy & human development 2  GENERAL OBJECTIVES After the class students should be able to; 1. describe a detailed anatomy and physiology of the male and female reproductive systems 2. understand the processes leading to pregnancy and human development 3. familiarize themselves with various disease/abnormal conditions associated with human reproduction. 3  OVERVIEW Humans produce offspring by sexual reproduction Fertilization of haploid secondary oocyte produced by the ovaries of females by haploid sperm cell produced by the testes of males The resulting diploid cell, the zygote, contains one set of chromosomes from each parent. This zygote undergoes series of process in the female → foetus This lecture looks at the distinct anatomy and physiology of male and female reproductive organs that facilitate offspring production. 4  OVERVIEW The primary sex organs (gonads) are the testes in males—produce the male gamete or sex cell (sperm) the ovaries in females—produce the female gamete or sex cell (ova or egg) the gonads also secrete a variety of steroid hormones commonly called sex hormones. The remaining reproductive structures—ducts, glands, and external genitalia—are the accessory reproductive organs. 5  SEX HORMONES Androgens (males), and Estrogens and Progesterone (females) Roles: Enhance development and function of the reproductive organs Sexual behavior and drives 6  THE MALE REPRODUCTIVE SYSTEM 7  OBJECTIVES Anatomy of the Male Reproductive System The external genitalia (Scrotum, Testes, Penis) The Male Duct System The Male Accessory Glands Semen Physiology of the Male Reproductive System Male Sexual Response Spermatogenesis Hormonal Regulation of Male Reproductive Function 8 THE MALE REPRODUCTIVE SYSTEM 9 EXTERNAL GENITALIA Scrotum, Penis, Testes* 10  EXTERNAL GENITALIA Male external genitalia consist of the SCROTUM and the PENIS 11  THE SCROTUM Sac of skin and superficial fascia that hangs outside the abdominopelvic cavity at the root of the penis Contains paired oval testes separated by a midline septum Its external positioning keeps the testes 3C lower than core body temperature (needed for sperm production) 12  THE SCROTUM Intrascrotal temperature is kept constant by two sets of muscles: Cremaster – bands of skeletal muscle that elevate the testes Dartos – smooth muscle which tightens the scrotal skin (wrinkled in appearance), to reduce heat loss. 13 S C R OT AL S AC S, D A R T OS & C R EMA S TER MU S C LES 14 SCROTUM TIGHT AND RELAXED 15  INGUINAL HERNIAS A portion of the intestines pushes through the abdominal wall and into the groin or scrotum. The hernia is apparent as a bulge or swelling in the groin area. It can be corrected with surgery 16  TESTES Each testis is surrounded by: an outer two-layered serous membrane called the tunica vaginalis a dense white fibrous capsule called tunica albuginea internally Septa divide the testis into 250-300 lobules, each containing 1-4 tightly coiled seminiferous tubule Seminiferous tubules: Produce the sperm Converge to form a straight tubule that conveys sperm into the rete testis 17  TESTES From the rete testis, the sperms leave the testis via efferent ductules and then enter the tail of the epididymis and stored until ejaculation Surrounding the seminiferous tubules are interstitial cells (Leydig cells) that produce androgens (most importantly testosterone) Spermatic cord –encloses nerve fibers, blood vessels and lymphatics that supply the testes cooler venous blood in paired pampiniform plexus cools arterial blood before it enters the testes Both divisions of the autonomic nervous system serve the testes 18 19 TESTES 20  CRYPTORCHIDISM Normally testes descend spontaneously (80% of cases) during the first year of life. In cryptorchidism, testes do not descend into the scrotum 3% of full-term & 30% of premature infants Untreated: results in sterility & a greater risk of testicular cancer surgical treatment necessary before 18 months 21 CRYPTORCHIDISM 22  HYDROCELE Fluid in the membranes surrounding the testes may be present at birth or may develop later in life May cause swelling of the testicle but are generally painless. If a large amount of fluid is present, a doctor may need to draw it out with a needle. 23 HYDROCELE 24  TESTICULAR CANCER Men younger than 40 years (15-34). Cause: unknown the condition is more prevalent in males who have a history of cryptorchidism It occurs in the sperm-producing cells early sign: a mass in the testis, pain, discomfort Treatment involves removal of the affected testis—orchiectomy. 25  TESTICULAR TRAUMA Most testicular injuries occur when the testicles are struck, hit, kicked, or crushed, usually during sports. Even the slightest injury to the testicles can cause severe pain, bruising or swelling. 26  TESTICULAR TORSION Occurs when the testicle twists on the spermatic cord. Blood supply to the testicle is cut off resulting in extreme pain and tissue necrosis. Causes: trauma to the testicles, strenuous activity, or for no apparent reason at all 27  THE PENIS A copulatory organ designed to deliver sperm into the female reproductive tract Passageway for urine Consists of an attached root and a free shaft that ends in the glans penis 28  THE PENIS Distal end of the penis is covered by cuff of skin- prepuce or foreskin Circumcision – surgical removal of the foreskin after birth Important to reduces rick of infections Uncircumcised & Circumcised penis 29  THE PENIS: INTERNAL Urethra and three cylindrical bodies of erectile tissues (corpus spongiosum, corpora cavernosa & crus) Corpus spongiosum – surrounds the urethra and expands to form the glans and bulb of the penis Corpora cavernosa – paired dorsal erectile bodies bound by fibrous tunica albuginea Spongy network of connective tissue and smooth muscle riddled with vascular spaces. During sexual excitement, the vascular spaces fill with blood, causing the penis to enlarge and become rigid—erection Crus – proximal end of the penis surrounded by the ischiocavernosus muscle; anchors the penis to the pubic arch. 30 31  HYPOSPADIAS A birth defect in which the opening of the urethra is in the wrong place, such as the underside of the penis. Surgery can correct it. 32  PHIMOSIS A tightening of the foreskin of the penis, which is common in newborns and young children and usually resolves without treatment. If it interferes with urination, circumcision may be recommended 33  AMBIGUOUS GENITALIA A very rare condition in which a child is born with genitals that aren't clearly male or female. In most boys born with this disorder, the penis may be very small or nonexistent but testicular tissue is present. Fewer cases, the child may have both testicular and ovarian tissue. 34 35  MICROPENIS A rare disorder where the penis, although normally formed, falls well below the average size, as determined by standard measurements. Average (erect penis) Length—13.12 cm Circumference—11.66 cm Micropenis—erect length < 9.3 cm 36  THE MALE REPRODUCTIVE DUCT SYSTEM Epididymis, Vas Deference, Urethra 37  EPIDIDYMIS Stores sperms until ejaculation Its head joins the efferent ductules and caps the superior aspect of the testis The duct of the epididymis has stereocilia that; absorb excess testicular fluid pass nutrients to the sperm 38  EPIDIDYMIS Immature, nearly non-motile sperms gain the ability to swim as they move along its tortuous course (a trip that takes about 20 days) Sperm can be stored in the epididymis for several months. If they are held longer, epithelial cells of the epididymis eventually phagocytize them. Upon ejaculation, the epididymis contracts expelling sperm into the ductus or vas deferens. 39  EPIDIDYMITIS Inflammation of the epididymis It is usually caused by infection or by the sexually transmitted disease chlamydia, and results in pain and swelling at the back of one testicle. 40  D UCTUS D EFERENS ( V A S D EFERENS ) Propels sperm from the epididymis to the urethra Runs from the epididymis through the inguinal canal into the pelvic cavity Its terminus expands to form the ampulla and then joins the duct of the seminal vesicle to form the ejaculatory duct Each ejaculatory duct enters the prostate, and there it empties into the urethra. 41  DUCTUS DEFERENS (VAS DEFERENS) VASECTOMY – cutting and ligating the ductus deferens, which is a nearly 100% effective form of birth control Reversal success rate is about 50%. 42  URETHRA Conveys both semen and urine (at different times) Consists of three regions Prostatic – portion surrounded by the prostate Membranous – lies in the urogenital diaphragm Spongy or penile – runs through the penis and opens to the outside at the external urethral orifice 43 Male reproductive system accessory glands: S em i nal vesi c l es, P r o st ate g l and , C o wper 's g l and 44  SEMINAL VESICLES Lie on the posterior wall of the bladder and secrete 60-70% of the volume of semen. Joins the ductus deferens to form the ejaculatory duct. Sperm (from vas deferens) and seminal fluid (from seminal vesicle) mix in the ejaculatory duct and enter the prostatic urethra during ejaculation Seminal fluid a yellowish viscous alkaline fluid contains fructose sugar, citric acid, a coagulating enzyme (vesiculase), and prostaglandins. 45  B U L BO - UR ETHRAL G L A N DS ( COW P ER’S G L A N DS) Pea-sized glands inferior to the prostate Produce thick, clear mucus prior to ejaculation that neutralizes traces of acidic urine in the urethra 46  PROSTATE GLAND Doughnut-shaped gland that encircles part of the urethra Secretes a milky, slightly acid fluid which contains citrate, enzymes (including fibrinolysin, hyaluronidase, and acid phosphatase), and prostate-specific antigen (PSA) Plays a role in activating sperm and accounts for one- third of the semen volume 47  PROSTATE DISORDERS Prostate cancer. Benign prostate hypertrophy (BPH) Prostate surrounds a portion of the urethra, any infection, enlargement, or tumor can obstruct the flow of urine. Urination is painful and difficult 48  SEMEN Milky white, sticky mixture of sperm and accessory gland secretions viscous alkaline fluid containing fructose, ascorbic acid, fibrinolysin and prostaglandins Provides a transport medium and nutrients (fructose), protects and activates sperm and facilitates their movement 49  SEMEN Prostaglandins in semen: decrease the viscosity of mucus in the cervix facilitate the movement of sperm through the female reproductive tract—reverse peristalsis The hormone relaxin enhances sperm motility The relative alkalinity of semen (pH 7.2–8.0), neutralizes the acid environment found in the male urethra and female vagina. Seminal plasmin – antibiotic chemical that destroys certain bacteria. Clotting factors coagulate semen immediately after ejaculation—stick to the walls of the vagina, then fibrinolysin liquefies the sticky mass— to facilitate swimming. Only 2-5 ml of semen are ejaculated (10% sperm), but it contains 20- 150 million sperm/ml 50 MALE SEXUAL RESPONSE 51  PHASES OF THE MALE SEXUAL RESPONSE The chief phases of the male sexual response are 1. erection of the penis, which allows it to penetrate the female vagina 2. ejaculation, which expels semen into the vagina. 52  ERECTION During sexual excitement, the erectile tissue fills with blood causing the penis to enlarge and become rigid During sexual arousal, a parasympathetic nerve reflex promotes the release of nitric oxide. Nitric oxide dilates the arteries supplying the penis and causes erectile tissue to fill with blood. Erection is initiated by sexual stimuli including: Touching the genital skin, mechanical stimulation of the penis, erotic sights, sounds and smells Erection can be induced or inhibited solely by emotional or higher mental activity. 53 54  EJACULATION The propulsion of semen from the male duct system At ejaculation, sympathetic nerves serving the genital organs cause: bladder sphincter muscle to constrict, preventing the expulsion of urine. reproductive ducts and accessory organs to contract and empty their contents into the urethra. propulsion of semen from the urethra. Semen in the urethra triggers a spinal reflex through somatic motor neurons. the bulbospongiosus muscles of the penis propel semen at a speed of up to 500 cm/s these rhythmic contractions are accompanied by intense pleasure and many systemic changes, such as generalized muscle contraction, rapid heartbeat,55 and elevated blood pressure.  EJACULATION The entire ejaculatory event is referred to as climax or orgasm Orgasm is quickly followed by resolution Erection→ Orgasm→ resolution→ latent/refractory period→ erection The latent period lengthens with age. 56  IMPOTENCE (ERECTILE DYSFUNCTION) The inability of an adult male to ejaculate or to attain or hold an erection long enough for sexual intercourse 57  IMPOTENCE (ERECTILE DYSFUNCTION) Possible cause insufficient release of appropriate neurotransmitter, and perhaps nitric oxide diabetes mellitus physical abnormalities of the penis syphilis vascular disturbances (arterial or venous obstructions) neurological disorders, testosterone deficiency drugs (alcohol, antidepressants, antihistamines, antihypertensives, narcotics, nicotine, and tranquilizers). Psychic factors fear of causing pregnancy fear of sexually transmitted diseases Sildenafil religious inhibitions emotional immaturity 58 SPERMATOGENESIS 59  SPERMATOGENESIS The sequence of events that produces sperm/spermatozoa in the seminiferous tubules of the testes. The process begins around the age of 14 years (and often earlier) and continues throughout life. About 400 million sperm cells/day 60  SPERMATOGENESIS Humans have 23 pairs of homologous chromosomes (from each parent)—carry genes that code for the same traits. Gametes only have 23 chromosomes and are said to be haploid (n) chromosomal number. Gamete formation is by meiosis, in which the number of chromosomes is halved (from 2n to n) 61 THE HUMAN LIFE CYCLE 62  SPERMATOGENESIS Cells making up the walls of seminiferous tubules are in various stages of cell division Primordial germ cells (that arise from the yolk sac) develop into spermatogonia which then enter the testes during the fifth week of development Spermatogonia actively begin dividing into sperm at puberty. 63 SPERMATOGENESIS 64  SPERMATOGENESIS Spermiogenesis – spermatids lose excess cytoplasm and form a tail, becoming sperm 65  SPERMATOGENESIS Sperm has three major regions Head – contains DNA and has a helmetlike acrosome containing hydrolytic enzymes that allow the sperm to penetrate and enter the egg Midpiece – contains mitochondria spiraled around the tail filaments Tail – a typical flagellum produced by a centriole 66  SUSTENTACULAR/SERTOLI CELLS Spermatocytes and spermatids are nearly enclosed in sustentacular cells, which: provide essential nutrients to dividing cells move them along to the lumen secrete testicular fluid that provides the transport medium for sperm phagocytose the excess cytoplasm sloughed off during maturation to sperm forms blood-testis barrier regulate the effects of testosterone and FSH 67  HORMONAL REGULATION OF MALE REPRODUCTIVE FUNCTION 68  BRAIN-TESTICULAR AXIS Hormonal regulation of spermatogenesis and testicular androgen production involve the hypothalamus, anterior pituitary gland and the testes H-P-Testes axis The hypothalamus releases gonadotropin- releasing hormone (GnRH) GnRH stimulates the anterior pituitary to secrete FSH and LH FSH causes sustentacular cells to release androgen-binding protein (ABP) LH stimulates interstitial cells to release testosterone 69  MA L E S EC O N DA R Y S E X C H A R A C TE RI STICS Male hormones make their appearance at puberty and induce changes in nonreproductive organs, including Appearance of pubic, axillary and facial hair Enhanced hair growth on the chest and deepening of the voice Skin thickens and becomes oily Bones grow and increase in density Skeletal muscles increase in size and mass Testosterone is the basis of libido in both males and females 70  STERILITY/INFERTILITY Doesn’t produce sperm at all OR doesn't produce enough sperm (oligospermia). Effect: inability to fertilize a secondary oocyte NB. It does not imply impotence Possible causes abnormalities of the reproductive organs inflammation in the genitals alcoholism x-rays infections malnutrition significantly higher-than-normal scrotal temperature In vitro fertilization and artificial insemination can aid infertility 71  THE FEMALE REPRODUCTIVE SYSTEM  OBJECTIVES Anatomy of the Female Reproductive System The Ovaries The Female Duct System (vagina, uterus, oviduct) The External Genitalia (vulva) The Mammary Glands Physiology of the Female Reproductive System Oogenesis The Ovarian Cycle Hormonal Regulation of the Ovarian Cycle The Uterine (Menstrual) Cycle Effects of Estrogens and Progesterone Female Sexual Response 73  FEMALE REPRODUCTIVE ANATOMY Internal genitalia – ovaries and the duct system Ovaries are the primary female reproductive organs Make female gametes Secrete female sex hormones (estrogens and progesterone) Female duct system include vagina, uterus, uterine tubes. External genitalia - external sex organs 74 FEMALE REPRODUCTIVE ANATOMY 75 THE OVARIES 76  THE OVARIES Paired organ on each side of the uterus held in place by several ligaments Ovarian ligament: anchors the ovary medially to the uterus Suspensory ligament: anchors the ovary laterally to the pelvic wall Mesovarium ligament: suspends the ovary Broad ligament – contains the suspensory ligament and the mesovarium 77 THE OVARIES 78 THE OVARIES 79  THE OVARIES Blood supply – ovarian arteries and the ovarian branch of the uterine artery. Surrounded externally by a fibrous tunica albuginea, which is covered by a layer of epithelial cells called the germinal epithelium 80 81  THE OVARIES Embedded in the ovary cortex are ovarian follicles Each follicle consists of; oocyte (immature egg) Follicle cells (one cell layer thick) Granulosa cells (when more than one layer is present) Primordial follicle – one layer of squamous-like follicle cells surrounds the oocyte. Primary follicle – two or more layers of cuboidal or columnar granulosa cells enclose the oocyte. Secondary follicle – has a fluid-filled space between granulosa cells that coalesces to form a central fluid-filled called antrum. Graafian follicle – secondary follicle at its most mature stage that bulges from the surface of the ovary. Ovulation – ejection of the oocyte from the ripening follicle. Corpus luteum – ruptured follicle after ovulation 82 83 THE FEMALE REPRODUCTIVE DUCT SYSTEM Fallopian tubes, Uterus, Vagina 84  U TER I NE TU B ES (FAL L OP I AN TU B ES OR OV I D UCTS) Receive the ovulated oocyte and provide a site for fertilization. Enter into the superolateral region of the uterus via the isthmus Distal end of each tube expand around the ovary forming the ampulla The ampulla ends in the funnel-shaped infundibulum bearing ciliated fingerlike projections called fimbriae The uterine tubes have no contact with the ovaries and the ovulated oocyte is cast into the peritoneal cavity Beating cilia on the fimbriae create currents to carry the oocyte into the uterine tube, where it begins its journey towards the uterus. 85 UTERINE TUBES (FALLOPIAN TUBES OR OVIDUCTS) 86  THE UTERUS (WOMB) 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 87 THE UTERUS 88  THE UTERUS Cervix – narrow neck 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 fills the cervical canal and covers the external os to block spread of bacteria and sperm entry except at midcycle 89  SUPPORTS OF THE UTERUS Mesometrium – portion of the broad ligament that supports the uterus laterally Lateral cervical ligament – extend from the cervix and superior part of the vagina to the lateral walls of the pelvis Uterosacral ligament – paired ligaments that secure the uterus to the sacrum Round ligament – bind the anterior wall to the labia majora 90 S UP P OR TS OF T HE U T ER U S 91  HYSTERECTOMY Surgical removal of the uterus Indications for surgery endometriosis, ovarian cysts, excessive bleeding, cancer (of cervix, uterus or ovaries). 92 UTERINE WALL 93  UTERINE WALL Composed of three layers Perimetrium: outermost serous layer; the visceral peritoneum Myometrium: middle layer; interlacing layers of smooth muscle Endometrium: mucosal lining of the uterine cavity 94  Endometrium Has two chief layers Stratum functionalis: Undergoes cyclic changes in response to ovarian hormones Is shed during menstruation Stratum basalis: Forms a new functionalis after menstruation ends Does not respond to ovarian hormones 95 96  UTERINE VASCULAR SUPPLY Uterine arteries – arise from the pelvis, ascend along the sides of the uterus and send branches into the uterine wall. Arcuate arteries – branches of the uterine arteries in the myometrium that give rise to radial branches. Radial branches – descend into the endometrium and give rise to: Straight arteries to the stratum basalis Spiral arteries to the stratum functionalis Degeneration and regeneration of spiral arteries causes the functionalis to shed during menstruation 97  THE VAGINA Thin-walled tube extending from the cervix to the exterior of the body. Provides a passageway for birth, menstrual flow and is the organ of copulation 98  THE VAGINA Wall consists of three coats: stratified squamous mucosa (vaginal lumen) smooth muscle muscularis (middle layer) fibroelastic adventitia (deep layer) Mucosa near the vaginal orifice forms an incomplete partition called the hymen Imperforate hymen??? Vaginal fornix – upper end of the vagina surrounding the cervix Presence of a series of transverse folds called rugae Function??? Vaginal 99 pessaries THE EXTERNAL GENITALIA (THE VULVA) 10 0  VULVA (PUDENDUM) Lies external to the vagina and includes the mons pubis, labia, clitoris and vestibular structures Mons pubis – round, fatty area overlying the pubic symphysis Labia majora – elongated, hair-covered, fatty skin folds homologous to the male scrotum Labia minora – hair-free skin folds lying within the labia majora Greater vestibular glands Pea-size glands flanking the vagina Homologous to the bulbourethral glands Keep the vestibule moist and lubricated during sexual excitement Clitoris Erectile tissue hooded by the prepuce Homologous to the penis: innervated by sensory nerve endings sensitive101to touch, becomes swollen with blood and erect during sexual arousal VULVA (PUDENDUM) 10 2 THE MAMMARY GLANDS 10 3  THE MAMMARY GLANDS Modified sweat glands consisting of 15-25 lobes that radiate around and open at the nipple Areola – pigmented skin surrounding the nipple Within the lobes are smaller units called lobules Lobules contain glandular alveoli that produce milk in lactating women Compound alveolar glands pass milk to lactiferous ducts which open to the outside 104 THE MAMMARY GLANDS 10 5 OOGENESIS 10 6  OOGENESIS: Fetal stage In the fetal period, oogonia (2n) multiplies by mitosis, enters growth phase and lay in nutrient reserves. Transform into primary oocytes (primordial follicle) and begin meiotic division but stop in prophase I 7 million (2 million present at birth) 10 7  OOGENESIS: Puberty onwards At puberty, 250,000 primary oocytes (primordial- primary) remain only 500 mature during a woman’s life Each month, one activated primary oocyte continue meiosis I to produce two haploid cells first polar body secondary oocyte Secondary oocyte begins meiosis II, arrests in metaphase II and is ovulated (vesicular follicle) 10 8  OOGENESIS: Fertilization stage If an ovulated secondary oocyte is not penetrated by sperm, it deteriorates. If penetrated by sperm, the secondary oocyte completes meiosis II, yielding: one large ovum (a functional gamete) a tiny second polar body 10 9 110  FEMALE REPRODUCTIVE CYCLE THE OVARIAN CYCLE & THE UTERINE (MENSTRUAL) CYCLE 111 The Ovarian Cycle & The Uterine (Menstrual) Cycle 112 T he Ovari an C y c le & T he U t er i ne ( Menst r u al ) C y c l e 113  THE OVARIAN CYCLE Monthly series of events associated with the maturation of an egg. Follicular phase – period of follicle growth (days 1–14) Ovulation occurs midcycle Luteal phase – period of corpus luteum activity (days 14–28) 114  The Follicular Phase The primordial follicle becomes a primary follicle The primordial follicle (1), squamous-like cells surrounding the primary oocyte grow and becomes cuboidal cells and the oocyte enlarges to form a primary follicle (2) The primary follicle becomes a secondary follicle Follicular cells proliferate to form a stratified epithelium (granulosa cells) around the primary oocyte. Tissue condenses around the follicle to form theca folliculi. Theca folliculi and granulosa cells cooperate to produce estrogens (3) and (4). Oocyte secretes a glycoprotein-rich substance that form zona pellucida. A fluid-filled cavity called antrum is formed and primary follicle grows to become secondary follicle (5). The secondary follicle becomes a vesicular follicle The antrum expands to isolate the oocyte and its surrounding granulosa cells called corona radiata. The secondary follicle become vesicular follicle. The primary oocyte completes meiosis I to form secondary 115 oocyte and the stage is set for ovulation (6). The Follicular Phase 116  Ovulation Ovulation occurs when the ovary wall ruptures and expels the secondary oocyte (7) 1-2% of ovulations release more than one secondary oocyte, which if fertilized, results in fraternal twins. Signs of Ovulation Mittelschmerz – a tinge of pain sometimes felt at ovulation Increase in basal body temperature Changes in cervical mucus Cervix softens 117  The Luteal Phase After ovulation, the ruptured follicle collapses, antrum fills clotted blood, granulosa cells enlarge and along with internal thecal cells form the corpus luteum (8) The corpus luteum secretes progesterone and estrogen No Pregnancy: Corpus luteum degenerates in 10 days and its hormonal output stops leaving a scar known as corpus albicans (9) Pregnancy: Corpus luteum produces hormones until the placenta takes over that role (at about 3 months) 118  UTERINE (MENSTRUAL) CYCLE Series of cyclic changes that the uterine endometrium goes through in response to ovarian hormones in the blood Days 1-5: Menstrual phase – uterus sheds all but the deepest part of the endometrium Days 6-14: Proliferative phase – endometrium rebuilds itself Days 15-28: Secretory phase – Endometrium prepares for implantation of the embryo 119  HORMONAL CHANGES IN THE FEMALE REPRODUCTIVE CYCLE 12 0  FEMALE SEXUAL RESPONSES Sexual excitement The clitoris, vaginal mucosa, and breasts engorge with blood. Vestibular glands lubricate the vestibule and facilitates entry of the penis. Orgasm accompanied by muscle tension, increase in pulse rate and blood pressure, and rhythmical contractions of the uterus. females do not have a refractory period after orgasm and can experience multiple orgasms in a single sexual experience. Orgasm is not essential for conception 121 ESTROGEN-INDUCED SECONDARY SEX CHARACTERISTICS Growth of the breasts Increased deposition of subcutaneous fat, especially in the hips and breasts Widening and lightening of the pelvis Growth of axillary and pubic hair 12 2 D I S ORDER S IN T HE FEMA L E R EP R OD UCT IVE S Y S T EM Menstrual Abnormalities Amenorrhea Dysmenorrhea Premenstrual syndrome (PMS) Ovarian Cysts Endometriosis Female Infertility Breast Cysts and Benign Tumors Cervical Cancer Pelvic Inflammatory Disease Vaginal infections 12 3  MENS T R U A L A B N OR MA L I TIES Amenorrhea is the absence of menstruation Primary amenorrhea: a woman has never menstruated Secondary amenorrhea: the skipping of one or more periods Dysmenorrhea: pain associated with menstruation Primary dysmenorrhea: painful menstruation with no detectable organic disease Secondary dysmenorrhea: painful menstruation that is frequently associated with a pelvic pathology Premenstrual syndrome (PMS) severe physical and emotional distress that occurs late in the postovulatory phase of the menstrual cycle and sometimes extends into the menstrual phase. Signs and symptoms include edema, weight gain, breast swelling and tenderness, abdominal distension, backache, joint pain, constipation, skin eruptions, fatigue and lethargy, greater need for sleep, depression or anxiety, irritability, mood swings, headache, poor coordination and clumsiness, and cravings for sweet or 12 salty foods 4  OVARIAN CYSTS Ovarian cysts are fluid-containing sacs within the ovary Follicular cysts may occur in the ovaries of elderly women, in ovaries that have inflammatory diseases, and in menstruating females 12 5  ENDOMETRIOSIS Endometriosis is characterized by the growth of endometrial tissue outside the uterus. Symptoms include premenstrual pain or unusual menstrual pain 12 6  FEMALE INFERTILITY Female infertility, or the inability to conceive, may be caused by ovarian disease, tubal obstruction, and certain conditions of the uterus. Infertility treatment: fertility drugs, donor (artificial) insemination, or surgery. 12 7  BREAST CYSTS AND BENIGN TUMORS a breast lump OR one or more cysts (fluid-filled sacs) in the breast. 12 8  P EL V IC IN FL A MMAT O R Y D I S EA SE A collective term for any extensive bacterial infection (primarily involving Chlamydia trachomatis, Neisseria gonorrhoeae, Bacteroides, Peptostrepto- coccus, and Gardnerella vaginalis) of the pelvic organs, especially the uterus, uterine tubes, or ovaries. 12 9  PREGNANCY & HUMAN DEVELOPMENT  OVERVIEW OF DEVELOPMENT The term pregnancy refers to events that occur from the time of fertilization (conception) until the infant is born. First trimester (zygote-wk 12) Second trimester (wk 13- wk 24) Third trimester (wk 25- wk 36/birth) The pregnant woman’s developing offspring is called the conceptus (that which is conceived). The time during which development occurs is referred to as the gestation period. Fertilization (zygote) through week 8—embryo Week 9 through birth—fetus At birth, it is an infant. 131  1 ST WEEK (DAY 1-7) OF DEVELOPMENT Events leading to fertilization Fertilization is most likely to occur if intercourse takes place during a 3-day window—from 2 days before ovulation to 1 day after ovulation. (safe periods???) Only about 100 out of the millions of sperms reach the vicinity of the secondary oocyte Sperm capacitation—a series of functional changes that cause the sperm’s tail to beat even more vigorously, removal of cholesterol, glycoproteins, and proteins from the plasma membrane around the head of the sperm cell by secretions in the female reproductive tract. Only capacitated sperm are capable of being attracted by and responding to chemical factors produced by the surrounding cells13 of the ovulated oocyte. 2 133  1 ST W EEK (D A Y 1 - 7 ) OF D EV EL OPMEN T Events leading to fertilization Sperm pernitrates the corona radiata and binds to ZP3 receptor on the zona pellucida→ rise in Ca2+ and acrosomal reaction (hyaluronidase, acrosin, proteases) → penetration of the zona pellucida. Block to Polyspermy Processes to ensure one-sperm-per-oocyte fast block to polyspermy—depolarization of oocyte cell membrane slow block to polyspermy—Once the sperm head has entered the oocyte→ release of Ca2+ from oocyte ER→ release of zonal inhibiting proteins (ZIPs) from oocyte vesicles→ destruction of ZP3s and harden the entire zona pellucida In the rare cases of polyspermy that do occur, the embryos contain too much genetic material and die. 13 4  1 ST W EEK (D A Y 1 - 7 ) OF D EV EL OPMEN T Events leading to fertilization Completion of Meiosis II and Fertilization to form zygote 135  1 ST WEEK (DAY 1-7) OF DEVELOPMENT Zygote to Blastocyst formation Cleavage Begins some 24 to 36 hours after fertilization a period of fairly rapid mitotic divisions of the zygote goal is to produce small cells with a high surface-to-volume ratio, which enhances their uptake of nutrients and oxygen and the disposal of wastes. It also provides a large number of cells to serve as building blocks for constructing the embryo. first cleavage, division of the zygote→ two identical cells called blastomeres→→→ 16 or more cells (morula) Early blastocyst; the morula hollows out, fills with fluid, and “hatches” from the zona pellucida. Late blastocyst, composed of an outer sphere of trophoblast cells and an eccentric cell cluster called the inner cell mass 13 6 Ectopic Pregnancy??? 137  1 ST W EEK ( D A Y 1 - 7 ) OF D EV EL OPMEN T Implantation Occurs some six to seven days after ovulation Surging levels of ovarian hormones (oestrogens and progesterone) prepares the endometrium integrin proteins on the trophoblast cells bind to the extracellular matrix components (collagen, fibronectin, laminin, and others) of the endometrial cells selectin proteins on the trophoblast cells bind to selectin-binding carbohydrates on the inner uterine wall, and the blastocyst implants in the uterus. trophoblast cells also secrete and display several factors with immunosuppressive effects that protect the trophoblast (and the developing embryo) from attack by the mother’s immune cells. 13 8 139  1 ST W EEK ( D A Y 1 - 7 ) OF D EV EL OPMEN T 7 days after fertilization, blastocyst attaches more firmly and burrows in Endometrium becomes more vascularised The decidua—the modified portion of the endometrium that develops after implantation. decidua basalis provides large amounts of glycogen and lipids for the developing embryo and fetus and later becomes the maternal part of the placenta 14 0  2 ND W K OF D EV ’ T ( 8 - 1 4 D A Y S ) Development of the Trophoblast the trophoblast develops into two layers (syncytiotrophoblast and cytotrophoblast) syncytiotrophoblast secretes enzymes that enable the blastocyst to penetrate the uterine lining by digesting and liquefying the endometrial cells. Another secretion of the trophoblast is human chorionic gonadotropin (hCG) rescues the corpus luteum from degeneration and sustains its secretion of progesterone and oestrogens to maintain the uterine lining until placenta takes over The presence of hCG in maternal blood or urine is an indicator of pregnancy and is detected by home pregnancy tests. Cells of the embryoblast also differentiate into two layers : a 141 hypoblast (primitive endoderm) and epiblast (primitive ectoderm). 142  2 ND WK OF DEV’T (8-14 DAYS) Development of the Amnion A small cavity appears within the epiblast and eventually enlarges to form the amniotic cavity As the amniotic cavity enlarges the amnion is formed The amniotic cavity becomes filled with amniotic fluid Initially derived from maternal blood. Later, from the fetus urine Amniotic fluid serves as shock absorber for the fetus, helps regulate fetal body temperature, helps prevent the fetus from drying out, prevents adhesions between the skin of the fetus and surrounding tissues. 14 Amniocentesis??? 3  2 ND WK OF DEV’T (8-14 DAYS) Development of the Yolk Sac Cells at the edge of the hypoblast forms the exocoelomic membrane. Together with the hypoblast, the exocoelomic membrane forms the wall of the yolk sac The yolk sac has several important functions in humans: supplies nutrients to the embryo during the second and third weeks of development is the source of blood cells from the third through sixth weeks contains the first cells (primordial germ cells) that will eventually migrate into the developing gonads, differentiate into the primitive germ cells, and form gametes forms part of the gut (gastrointestinal tract) functions as a shock absorber; and helps prevent drying out of the embryo. ALLANTOIS a small vascularized outpouch formed by the wall of the yolk sac during the 3rd week function in the early formation of blood and blood vessels, and it is 14 associated with the development of the urinary bladder. 4 145  2 ND WK OF DEV’T (8-14 DAYS) Development of Sinusoids the syncytiotrophoblast expands and develops small spaces called lacunae Later fuse to form lacunar networks endometrial capillaries around the developing embryo dilate to form maternal sinusoids maternal blood and secretions from the endometrial glands flow through the lacunar networks Maternal blood is both a rich source of materials for embryonic nutrition and a disposal site for the embryo’s wastes. 14 6 147  2 ND WK OF DEV’T (8-14 DAYS) Development of the Chorion The extraembryonic mesoderm, together with the two layers of the trophoblast (the cytotrophoblast and syncytiotrophoblast), forms the chorion The chorion surrounds the embryo and, later, the fetus The chorion also protects the embryo and fetus from the immune responses of the mother in two ways: It secretes proteins that block antibody production by the mother. It promotes the production of T lymphocytes that suppress the normal immune response in the uterus. It also produces human chorionic gonadotropin (hCG) The connecting stalk which is the future umbilical cord is formed. 14 8  3 RD WK OF DEV’T (DAY 15 -21) Gastrulation Formation of the primary germ layers; ectoderm, mesoderm, endoderm the major embryonic tissues from which the various tissues and organs of the body develop The endoderm—epithelial lining of the GIT, respiratory tract, and several other organs. The mesoderm—muscles, bones, and other connective tissues, and the peritoneum. The ectoderm—the epidermis of the skin and the nervous system 14 9  3 RD W K O F D E V ’ T ( D A Y 1 5 - 2 1 ) NEURULATION The process by which nervous system structures (the neural plate, neural folds, and neural tube) form from the ectoderm. By about week 5 all basic brain structures is formed from the neural tube Neural tube defects (NTDs) 150 151 NEURULATION 15 2  3 R D W K OF D EV ’ T ( D A Y 1 5 - 2 1 ) Development of the Cardiovascular System At the beginning of the third week, angiogenesis begins necessary because there is insufficient yolk in the yolk sac and ovum to provide adequate nutrition for the rapidly developing embryo Blood formation begins within the embryo at about the fifth week in the liver and the twelfth week in the spleen, red bone marrow, and thymus. The heart forms from splanchnic mesoderm in the head end of the embryo on days 18 and 19 15 3  3 RD WK OF DEV’T (DAY 15 -21) Development of the Chorionic Villi and Placenta Placentation is the process of forming the placenta, the site of exchange of nutrients and wastes between the mother and fetus. Chorionic villi finger like projections of chorion projects into the endometrial wall of the uterus blood capillaries develop in the chorionic villi blood vessels in the chorionic villi connect to the embryonic heart by way of the umbilical arteries and umbilical vein through the connecting stalk, which will eventually become the umbilical cord. NB: fetal blood capillaries within the chorionic villi project into the lacunae—(bathed by the maternal blood) so maternal and fetal blood vessels do not join, and the blood they carry does not 15 4 normally mix—exchange is by diffusion In some cases, the umbilical vein is used to transfuse blood Placenta previa into a fetus or to introduce drugs for various medical Placenta abruptio 155 treatments HORMONES SECRETED BY THE PLACENTA 15 6  4 TH - 8 TH WK OF DEV’T (1-2 months) Organogenesis all major organs appear during this time. by the end of the eighth week, all of the major body systems have begun to develop, although their functions for the most part are minimal. 15 7  EVENTS OF FETAL DEVELOPMENT Ninth week until birth (3rd month onwards) The fetal period is a time of rapid growth of the body structures that were established in the embryo. During the first half of this period, cells are still differentiating into specific cell types to form the body’s distinctive tissues and are completing the fine details of body structure. All organ systems are laid down during the embryonic period; growth and tissue/organ specialization are the major events of the fetal period. NB: The greatest amount of growth occurs in the first 8 weeks of life, when the embryo grows from one cell to a fetus of 1 inch. 15 8 159 160  ASSIGNMENT Teratogens Prenatal Diagnostic Tests Maternal Changes during Pregnancy 161  PARTURITION (BIRTH) Parturition is the culmination of pregnancy—giving birth to the baby. It usually occurs within 15 days of the calculated due date (280 days from the last menstrual period). The series of events that expel the infant from the uterus are collectively called labor 16 2  LABOR Initiation of Labor During the last few weeks of pregnancy, estrogens reach their highest levels in the mother’s blood. 16 3  LABOR (a) Dilation stage (early). The baby’s head is engaged in the true pelvis. (b) Late dilation. The baby’s head rotates so that its greatest dimension is in the anteroposterior axis as it moves through the pelvic outlet. (c) Expulsion stage. The baby’s head extends as it reaches the perineum and is delivered. (d) Placental stage. After the baby is delivered, The placenta and its attached fetal membranes are detached by the continuing uterine contractions and removed. 16 4  A d ju st ments Of T he I nf ant T o Ex t r auter i ne L i f e Taking the First Breath and Transition After the umbilical cord is clamped, carbon dioxide accumulates in the infant’s blood, causing respiratory centers in the brain to trigger the first inspiration. Once the lungs are inflated, breathing is eased by the presence of surfactant, which decreases the surface tension of the alveolar fluid. During transition, the first 8 hours after birth, the infant is physiologically unstable and adjusting. The infant wakes approximately every 3–4 hours in response to hunger. 165  LACTATION The breasts are prepared for lactation during pregnancy by high blood levels of estrogen, progesterone, and placental lactogen. Colostrum, a premilk fluid, is a fat-poor fluid that contains more protein, vitamin A, and minerals than true milk. It is produced toward the end of pregnancy and for the first two to three days after birth. True milk is produced around day 3 in response to suckling At first, ovulation and menses are absent or irregular during nursing, but in most women the ovarian cycle is eventually reestablished while still nursing. 16 6  LACTATION True milk is produced around day 3 in response to suckling, which stimulates the hypothalamus to prompt anterior pituitary release of prolactin and posterior pituitary release of oxytocin. Prolactin stimulates milk production and oxytocin triggers milk let-down. Continued breast-feeding is required for continued milk production. 16 7  BREAST MILK ADVANTAGES Breast milk has advantages for the infant: Its fats and iron are better absorbed and its amino acids are metabolized more efficiently than those of cow’s milk. It has a host of other beneficial chemicals, including, IgA, complement, lysozyme, interferon, and lactoperoxidase, that protect infants from life-threatening infections. Its natural laxative effect helps to cleanse the bowels of meconium , a tarry green-black paste containing sloughed- off epithelial cells and other substances. 16 8  CLINICAL APPLICATIONS Obstetrics deals with the management of pregnancy, labor, and the neonatal period, the first 28 days after birth. Prenatal development is the time from fertilization to birth and is divided into three periods of three calendar months each, called trimesters. The first trimester is the most critical stage of development, during which the rudiments of all the major organ systems appear, and also during which the developing organism is the most vulnerable to the effects of drugs, radiation, and microbes. The second trimester is characterized by the nearly complete development of organ systems. By the end of this stage, the fetus assumes distinctively human features. The third trimester represents a period of rapid fetal growth. During the early stages of this period, most of the organ systems are becoming fully16 functional. 9  CLINICAL TERMS Ectopic pregnancy is the development of an embryo or fetus outside the uterine cavity. Dystocia , or difficult labor, may result either from an abnormal position of the fetus or a birth canal of inadequate size to permit vaginal delivery. In a breech presentation, the fetal buttocks or lower limbs, rather than the head, enter the birth canal first. The neonatal period is the four-week period immediately after birth Physiological jaundice ??? 17 0  CLINICAL TERMS Multiple Pregnancy Dizygotic (fraternal) twins develop from two zygotes produced by the fertilization of two oocytes by two spermatozoa in the same ovulatory cycle. Dizygotic twins may be of the same sex or different sexes and are not alike Monozygotic (identical) twins form from a single zygote In Vitro Fertilization and Artificial Implantation to fertilize a human oocyte in vitro (outside the body), culture it to the blastocyst stage, and then perform artificial implantation, leading to a full term development and delivery 171 SWEET MOTHER, GOD BLESS YOU 17 2