Chapter 27 Male & Female Reproductive Systems 59 slides 1 Male Reproductive Anatomy The sperm-producing testes or male gonads lie within the scrotum. From the testes, the sperm are delivered to the body exterior through a system of ducts: Epididymis Ductus Deferens Ejaculatory Duct Urethra Accessory sex glands, which also empty into the above ducts during ejaculation are: seminal vesicles, prostate and bulbourethral glands. 2 Male Reproductive Anatomy 3
Male Reproductive Anatomy 4 The Scrotum is a sac of skin and superficial fascia that hands outside the abdominopelvic cavity at the root of the penis. contains two oval-shaped testes. vulnerable location, however, because viable sperm cannot be produced in abundance at core body temperature of (37 degrees C), the superficial location of the scrotum is about 3 degrees C lower. tighty-whiteys, tight jeans, etc... cram the testicles next to the body s core, raising its temperature and reducing fertility. 5 The Scrotum When it is cold, the testes are pulled closer to the warmth of the body wall, and the scrotum becomes shorter and heavily wrinkled, increasing its thickness and reducing heat loss. Dartos Muscle is a smooth muscle layer that wrinkles the scrotal skin. Cremaster Muscle is skeletal muscle (arises from the internal oblique muscles) that elevate the testes. Cremasteric Reflex: Touch inner thigh, testes rise up. It indicates an intact S2 - S3 - S4 dermatome. When it is warm, the scrotal skin is flaccid and loose to increase the surface area for cooling. 6
The Testis 4 cm long and 2.5 cm wide. surrounded by 2 tunics (coverings): Outer tunic is the tunica vaginalis. derived from the outpocketing of the peritoneum. Deep tunic is the tunica albuginea. the fibrous capsule of the testicle. has septa extending into the testicle dividing each into 250 to 300 lobules. each lobule contains 1 to 4 tightly coiled seminiferous tubules where the sperm is actually formed. smooth muscle-like myoid cells that surround each seminiferous tubule squeeze the sperm out of the testicles. these merge to form a tubulus rectus, a strait tubule that conveys sperm into the rete testis then to the epididymis. 7 The Testis 8 Seminiferous Tubule 9
The Testicles lying in the soft tissue surrounding the seminiferous tubules are the interstitial cells also called Leydig Cells. These cells produce androgens (testosterone). Abdominal Aorta has branches just below the superior mesenteric artery called the gonadal arteries, with subsequent testicular arteries. Testicular veins draining the testes arise from a network called the pampiniform plexus that surrounds the portion of the testicular artery within the scrotum like a climbing vine. absorbs heat from the blood before it enters testes. 10 Testicular Cancer Testicular Cancer rare. 1 in 50,000 males. most common cancer in young men (age 15 to 35). some who get it have a history of mumps or orchitis. most important risk factor is cryptorchidism, which is non-descent of the testes. most common sign is a painless, solid mass felt on self-exam of the testicle. if detected early, success rate is over 90%, but comes at the removal of the testicle (orchiectomy) usually in combination with radiation or chemo. 11 The Penis is a copulatory organ, designed to deliver sperm into the female reproductive tract. the penis and scrotum together, make up the external reproductive structures, or external genitalia, of the male. Penis consists of an attached root and a free shaft or body that ends in an enlarged tip, the glans penis. The skin covering the penis is loose, and it slides distally to form a cuff called the prepuce or foreskin, around the glans. Foreskin can be removed via circumcision. 12
The Penis The dorsal and ventral surfaces are named in reference to the erect penis. Internally, the penis contains: the spongy urethra Corpus Spongiosum that surrounds the urethra. expands distally to form the glans expands proximally to form the bulb of the penis (the penis root) is erectile tissue. Corpora Cavernosa are paired dorsal erectile tissues. surrounded by the tunica albuginea proximal ends form the crura of the penis. is erectile tissue. 13 The Epididymis the cup-shaped collection of tubing on the posterior portion of each testicle. store and pass nutrients to the many sperm stored there. takes one sperm about 20 days to move down the full length of it which is about 20 feet. during this trip the viable ones learn to swim. if they are not viable or are stored for months, then they are phagocytized by the epithelial cells there. sperm are ejaculated from the epididymis via smooth muscle contraction. 14 Vas Deferens & Ejaculatory Duct The ductus deferens or vas deferens is about 45 cm long. runs upward within the spermatic cord from the epididymis through the inguinal canal into the pelvic cavity. its terminal end expands to form the ampulla of the ductus deferens. it joins the duct of the seminal vesicle to form the very short ejaculatory duct. each ejaculatory duct enters the prostate, then empties into the urethra. 15
Vasectomy office surgical procedure, where the doctor makes a small incision or puncture into the scrotum, pulls out a loop of the vas deferens, cuts it, ligates (ties) off the ends and cauterizes (burns) the end of each. After ~2 weeks and at least 2 sperm counts with no visible sperm, then the vasectomy is considered complete and the man can have intercourse again. Men HAVE fathered children after a vasectomy who had sex right away before all sperm was removed. reversal can be done but is about 50% effective. sperm and testosterone production are unaffected and any sperm produced, are later phagocytized. ejaculatory volume / appearance is essentially same. sperm only account for about 1-5% of ejaculate volume. 16 Vasectomy 17 Urethra terminal portion of the male duct system. conveys both urine & semen at different times. there is a medical problem where the ejaculate goes backwards called retrograde ejaculation into the bladder and is voided later with the urine. has 3 anatomical regions: prostatic urethra traversing the prostate center. membranous urethra in the urogenital diaphragm. spongy (penile) urethra traverses the ventral side of the penis. 18
Male Reproductive Structures 19 Male Reproductive Structures 20 The Seminal Vesicles lie on the posterior bladder surface is about the size of your 5th finger (pinky). contains a fluid made up of: fructose sugar ascorbic acid a coagulating enzyme (vesiculase) prostaglandins other sperm motility enhancers joins the ductus deferens to form the ejaculatory duct. seminal fluid accounts for 60% of ejaculate volume. 21
Prostate a single, midline, doughnut-shaped gland about the size of a peach pit. prostatic gland secretion enters the prostatic urethra via several ducts when prostatic smooth muscle contracts during ejaculation. makes up 33% of ejaculate volume. it is a milky, slightly acidic fluid that contains: citrate (a nutrient source for sperm) enzymes (fibrinolysin, hyaluronidase, acid phosphatase) PSA (prostate specific antigen) elevated in diseases of the prostate including prostate cancer and benign prostatic hypertrophy. 22 Bulbourethral Glands are pea-sized glands below the prostate. produce a thick, clear mucus, which drains into the spongy urethra when males are sexually aroused and neutralizes traces of acidic urine in the urethra! 23 Spermatogenesis 24
Spermiogenesis: Spermatids to Sperm 25 Semen contents: sperm bulbourethral gland secretions seminal vesicle secretions prostatic secretions prostaglandins to decrease viscosity of the mucus on the cervix also stimulates reverse peristalsis of the uterus hormone relaxin to enhance sperm motility. alkaline with a normal ph of 7.2 to 7.6 seminalplasmin: antibiotic that suppresses the female immune response 26 Erection enlargement and stiffening of the penis. to facilitate vaginal penetration when not sexually aroused, arterioles supplying the erectile tissue are constricted and the penis is flaccid. during sexual excitement, parasympathetic reflex is triggered that promotes release of nitric oxide locally. Nitric oxide relaxes vascular smooth muscle, causing the arterioles to dilate, which allows the erectile bodies to fill with blood. expansion compresses the draining veins and allows the corpora cavernosa to remain full and erect. 27
Ejaculation is the propulsion of semen from the male duct system. erection is under parasympathetic control. ejaculation is under sympathetic control. reproductive ducts and accessory glands contract, emptying their contents into the urethra. bladder sphincter muscle constricts, preventing expulsion of urine or reflux of semen into the bladder bulbospongious muscles of the penis under go a rapid series of contractions, propelling semen from the urethra. This entire event is climax or orgasm. 28 Male Secondary Sex Characteristics features induced in the non-reproductive organs by testosterone, make an appearance at puberty. these include: pubic hair axillary hair facial hair chest hair deepening of voice as larynx enlarges. skin thickens and becomes oilier (acne prone). bones grow and increase in density. skeletal muscles increase in size and mass. epiphyseal plate closure occurs in response to rising estrogen levels at puberty. 29 Ovary ovaries are the female gonads produce the ova (eggs). produce the female sex hormones estrogen and progesterone each is anchored in the pelvis by 2 ligaments: ovarian ligament anchors the ovary medially toward the uterus the ovarian ligament are enclosed by the broad ligament. suspensory ligament anchors it laterally to pelvic wall the suspensory ligament and the mesovarium are part of the broad ligament, a peritoneal fold that tents over the uterus and supports the uterine tubes, uterus, and vagina 30
Ovary embedded in the highly vascular connective tissue of the ovary cortex are many tiny saclike structures called ovarian follicles. each follicle consists of an immature egg, called an oocyte. surrounding the oocyte are called follicle cells if one cell layer is present, and granulosa cells when more than one layer is present. each month, in adult women, one of the ripening follicles ejects its oocyte from the ovary in an event called ovulation. after ovulation, the ruptured follicle is transformed into the corpus luteum, which eventually degenerates. 31 Uterine Tubes Uterine tubes are also called fallopian tubes or oviducts. the released ova enters the uterine tube via the Fimbriae - Infundibulum - Ampulla, then after traversing the uterine tube enters the uterus via the isthmus. there is a gap between the ovary and the fimbriae and an ovulated oocyte is cast in to the peritoneal cavity and many oocytes are lost there! the beating cilia on the fimbriae do create a current to encourage the entry of the ova. smooth muscular contractions and cilia move the ova too. 32 Uterus located in the pelvis anterior to the rectum posterior-superior to the bladder normally it is flexed anteriorly. can be retroverted, especially in older women. top is called the fundus central part is the body narrow part joining to the cervix is the isthmus the inferior part is the cervix. internal os and external os are the two ends of the cervical canal. cervical mucus keep bacteria and sperm out, except at midcycle when it becomes less viscous! 33
Female Reproductive Organs 34 Ovary 35 Ovary 36
Prolapse of the Uterus despite the many anchoring ligaments, the principal support of the uterus is provided by the muscles of the pelvic floor, namely the muscles of the urogenital and pelvic diaphragms. These muscles are sometimes torn during childbirth. the now unsupported uterus may sink inferiorly, until the tip of the cervix protrudes through the external vaginal opening. this has to be surgically corrected. 37 Vagina is a thin-walled tube about 3 to 4 inches long. has the bladder anterior to it and the rectum posterior to it. the urethra is embedded in its anterior wall! the vaginal mucosa has NO glands. it is lubricated by the cervical mucous glands. the epithelial cells of the vagina release large amounts of glycogen, which is anaerobically metabolized to lactic acid by resident bacteria. this makes the vagina acidic, which keeps it free of infection but is also hostile to sperm. 38 Female Reproductive Organs 39
Endometrium 40 Vulva (Pudendum) 41 Vulva (Pudendum) 42
Vagina The ph of the vagina in adolescents is actually alkaline, and they teen and younger age group are more predisposed because of this to be more biologically prone to sexually transmitted diseases. In virgins, the mucosa near the distal vaginal orifice forms an incomplete partition called the hymen. it is very vascular and will bleed with 1 st intercourse. durability, however varies and can be easily ruptured by sports, tampon insertion, or pelvic exam occasionally its impervious and is surgically opened 43 Vulva (Pudendum) also called the external female genitalia. the mons pubis is the fatty, rounded area overlying the pubic symphysis. covered by hair after puberty. running posteriorly from the mons pubis are two elongated, hair-covered fatty skin folds, the labia majora (majus). are the female homologue of the male scrotum. enclose the labia minora (minus). are two thin, hair-free folds homologous to the ventral penis. enclose the vestibule which houses the external opening of the urethra and vagina. 44 Vulva (Pudendum) flanking the vaginal opening are the pea-size greater vestibular glands. homologous to the bulbourethral glands of males. release mucus into the vestibule to help keep it moist and lubricated, facilitating intercourse. at the extreme posterior end of the vestibule the labia minora come together to form a ridge called the fourchette. anterior to the vestibule is the clitoris. is homologous to the penis of the male. richly innervated with sensory nerves to facilitate female arousal. Has erectile tissue in it too. 45
Mammary Glands are present in both males and females. normally only function in females biological role is to produce milk for breast feeding. are modified sweat glands. slightly below the center of each breast is a ring of pigmented skin called the areola which surrounds a central protruding nipple. large sebaceous glands in the areola make it slightly bumpy and produce sebum that reduces chapping and cracking of the skin during breast feeding. internally has 15 to 25 lobes containing alveoli that produce the milk. milk exits via the lactiferous ducts. 46 Mammary Glands 47 Ovarian Cycle The Follicular Phase period of follicle growth typically indicated as lasting from 1 st to 14 th days. The Luteal Phase is the period of corpus luteum activity typically indicated as lasting from 14 th to 28 th days. Ovulation occurs at about day 14. only 15% of women have 28 day cycles. normal cycles run 21 to 40 days in length. 48
On day 1 of the cycle, rising levels of GnRH from the hypothalamus stimulate increased production and release of FSH and LH. The LH surge will trigger the ovulation at day 14. The role of FSH spiking at this time is not well known. Rising progesterone and estrogen blood levels exert a powerful negative feedback on LH and FSH to drop it. 49 Days 1 to 5 are the Menstrual Phase where the uterus sheds all but the deepest parts of the endometrium. Days 6 to 14 is the proliferative phase where the endometrium rebuilds itself. Days 14 ovulation Day 15 to 28 is the secretory phase where rising progesterone from the corpus luteum primes the uterus. 50 Menopause most women peak their reproductive abilities at about age 20. after that, ovarian function gradually declines till about age 50, when menopause begins. The quality of the DNA in eggs is less reliable by age 40 to 50, when genetic diseases such as Trisomy 21 or Down s Syndrome are more likely to occur. 51
Meiotic Events & Follicle Development in the Ovary 52 Meiotic Events & Follicle Development in the Ovary 53 Meiotic Events & Follicle Development in the Ovary 54
Meiotic Events & Follicle Development in the Ovary 55 Meiotic Events & Follicle Development in the Ovary 56 Meiotic Events & Follicle Development in the Ovary 57
Meiotic Events & Follicle Development in the Ovary 58 Meiotic Events & Follicle Development in the Ovary 59