4/7/2016 Learning Objectives for Reproduction Male Reproductive System 1. Male and female reproductive anatomy 2. Male and female gamete and sex hormone production • Testes (within the scrotum) produce sperm and regulation • Sperm are delivered to the exterior through a 3. Changes that occur in sperm and egg before and during system of ducts fertilization (chromosome number reduction) – Epididymis, ductus deferens, ejaculatory duct, and 4. Fetal Development the urethra 5. Adaptations to maternal body during pregnancy 6. Guest lecturer –Dr. Jason Ross (Estrus cycle and Porcine Reproduction) Overview of Reproductive System Ureter Urinary bladder • Secondary sex characteristics Prostatic urethra Peritoneum – develop at puberty to attract a mate Seminal Membranous urethra • pubic, axillary and facial hair vesicle Ampulla of Urogenital • scent glands, body morphology and low‐pitched voice ductus diaphragm deferens in males Pubis Ejaculatory Corpus duct cavernosum Rectum Corpus Prostate spongiosum Bulbourethral Spongy urethra gland Epididymis Anus Glans penis Bulb of penis Prepuce Ductus (vas) Testis External deferens Scrotum urethral orifice Figure 27.1 The Scrotum The Scrotum • Sac of skin and superficial fascia • Temperature is kept constant by two sets of – Hangs outside the abdominopelvic cavity muscles – Contains paired testes – Smooth muscle that wrinkles scrotal skin (dartos • 3C lower than core body temperature (temperature muscle) necessary for sperm production) – Bands of skeletal muscle that elevate the testes (cremaster muscles) 1 4/7/2016 Countercurrent Heat Exchanger Urinary bladder Superficial inguinal ring (end of inguinal canal) Testicular artery Spermatic cord Ductus (vas) deferens Penis Autonomic Middle septum nerve fibers of scrotum Pampiniform Cremaster muscle venous plexus External spermatic Epididymis fascia Tunica vaginalis (from peritoneum) Superficial fascia Tunica albuginea containing Scrotum dartos of testis muscle Internal spermatic Skin fascia Figure 27.2 The Testes Spermatic cord Blood vessels • Blood supply and nerves –testicular arteries Ductus (vas) –testicular veins deferens Head of epididymis Testis •Spermatic cord encloses: Efferent ductule Seminiferous – nerve fibers tubule Rete testis Lobule – blood vessels Straight tubule Septum Tunica albuginea Body of epididymis – lymphatics Tunica vaginalis Duct of epididymis Cavity of Tail of epididymis tunica vaginalis (a) Figure 27.3a Seminal Vesicles Prostate viscous alkaline seminal fluid milky, slightly acid fluid Spermatic Ducts – Fructose, ascorbic acid, – Contains citrate and coagulating enzyme and enzymes • Epididymis (head, body and tail) prostaglandins – 70% of the volume of – Plays a role in the – 6 m long coiled duct semen activation of sperm – site of sperm maturation and storage (fertile for 60 days) Accessory Glands • Ductus deferens (peristalsis during orgasm) Bulbourethral Glands – 45 cm long Prior to ejaculation ‐ thick, clear mucus – Lubricates the glans penis • Ejaculatory duct – Neutralizes traces of acidic urine in the urethra – 2 cm 2 4/7/2016 Semen Semen • Mixture of sperm and accessory gland • Alkalinity neutralizes acid in the male urethra secretions and female vagina • Contains nutrients • Antibiotic chemicals destroy certain bacteria • Protects and activates sperm • Only 2–5 ml of semen are ejaculated, • Facilitates sperm movement containing 20–150 million sperm/ml • Prostaglandins in semen – Decrease the viscosity of mucus in the cervix – Stimulate reverse peristalsis in the uterus Sertoli cell function Lumen Mature Sperm • Nourish developing spermatozoa Spermatogonium • Intracellular junctions form blood‐testes barrier Sertoli cell • Produce inhibin – represses FSH • Secrete androgen‐binding protein (ABP) Basal Lamina • Produce mullerian duct‐inhibiting substance surrounding seminiferous (MIS) tubule Leydig cell Leydig Cell Function Spermatozoon • Secrete androgens – Testosterone – Dihydrotestosterone – Androstenedione – Dihydroepiandrosterone Sustentacular = sertoli Interstitial = leydig 3 4/7/2016 Figure 27.15 DNA turned off Meiosis events: 1. Introduce genetic variability 2. Reduction of chromosome number Testicular hormones • Leydig: FSH increases LH receptor number • Leydig: LH increases Testosterone (T) synthesis • Sertoli: FSH stimulates production of androgen‐binding protein (ABP) • ABP binds T, thus increasing concentration in Testes • Increased T stimulates spermatogenesis Figure 27.13 Testosterone Functions • Differentiation of fetal male internal genitalia • Spermatogenesis • Development of secondary sexual characteristics • Libido • Muscle development, skeletal growth • Red blood cell production 4 4/7/2016 Female Reproductive System Secondary Sex Organs • Female Duct system • Produce and deliver gametes uterine tubes, uterus, vagina • Provide nutrition • and room for External genitalia fetal – clitoris, labia minora, and labia majora development – • Give birth accessory glands beneath skin provide • Nourish infant lubrication Figure 28.2 Figure 28.3a Uterine Tubes Uterus • Ampulla • Cervix: narrow neck, or outlet; projects into – Usual site of fertilization the vagina • Ciliated fibriae of infundibulum move oocyte • Fundus: rounded superior region into uterine tube • Isthmus: narrowed inferior region • Oocyte is carried along by peristalsis and ciliary action • Cervical glands secrete mucus • Nonciliated cells nourish the oocyte and the – block sperm entry except during midcycle sperm 5 4/7/2016 Vagina Oogenesis and Sexual Cycle • Birth canal and organ of copulation • Sexual cycle ‐ events recurring every month when • Extends between the bladder and the rectum pregnancy does not occur from the cervix to the exterior – ovarian cycle = events in ovaries – • Urethra embedded in the anterior wall Menstrual/estrous cycle = parallel changes in uterus • Reproductive cycle ‐ events occurring between fertilization and birth Ovarian Cycle • Monthly series of events associated with the maturation of an egg Primary Vesicular Corpus follicle follicle luteum Degenerating Secondary Ovulation • Two consecutive phases corpus luteum follicle – Follicular phase: period of follicle growth – Ovulation occurs midcycle Follicular Ovulation Luteal phase phase – Luteal phase: period of corpus luteum activity Figure 27.20b Follicular Phase Follicular Phase • Primordial follicle becomes primary follicle 3. Primary follicle becomes a secondary follicle 1. The primordial follicle is activated • Stratified epithelium (granulosa cells) forms around • Squamouslike cells become cuboidal oocyte 2. Follicle enlarges to become a primary (1) follicle • Granulosa cells and oocyte guide one another’s development 4. Secondary follicle becomes a late secondary follicle • Theca and granulosa cells cooperate to produce estrogens • Zona pellucida forms around the oocyte • Fluid begins to accumulate 6 4/7/2016 Follicular Phase 5. Late secondary follicle becomes a vesicular follicle • Antrum forms and expands to isolate the oocyte with its corona radiata on a stalk • Vesicular follicle bulges from the external surface of the ovary • The primary oocyte completes meiosis I E2 synthesis: two‐cell model Figure 28.14 Hypothalamus Hypothalamus 5 GnRH 4 Positive feedback exerted 8 Travels via portal blood by large in estrogen 1 output. LH Anterior pituitary 1 5 Progesterone LH surge Estrogen Inhibin FSH FSH LH Ruptured 6 22 follicle 8 3 Slightly elevated 7 estrogen Thecal and rising cells (a) Fluctuation of gonadotropin levels: Fluctuating inhibin levels of pituitary gonadotropins (follicle‐stimulating levels. Granulosa Androgens Corpus luteum cells Mature follicle Ovulated hormone and luteinizing hormone) in the blood Convert secondary regulate the events of the ovarian cycle. Inhibin androgens to 2 oocyte estrogens Late follicular and Early and midfollicular phases luteal phases Figure 27.19 Figure 27.20a 7 4/7/2016 Function/Targets of E2 Menstruation in mammals? Main E2 target is reproductive tract • Loss of endometrial lining through blood flow 1. Vaginal mucous increased limited to primates 2. Increased blood flow • Other species resorb the lining 3. Genital swelling • Menstrual cycle/Estrous cycle 4. Growth of Uterus Estrous v Estrus Ovulation • Estrous = the cycle • Ovary wall ruptures and expels the secondary • Estrus –stage of the estrous cycle when oocyte with its corona radiata animals are in behavioral heat (high estrogen) • Mittelschmerz: twinge of pain sometimes felt at ovulation • Mono‐ or Poly‐ovulatory Luteal Phase Luteal Phase • Ruptured follicle collapses • If no pregnancy, the corpus luteum • Granulosa cells and internal thecal cells form degenerates into a corpus albicans corpus luteum • If pregnancy occurs, corpus luteum produces • Corpus luteum secretes progesterone and hormones until the placenta takes over estrogen 8 4/7/2016 Maternal Recognition of Pregnancy Cow: Interferon Tau Pig: Estrogen Horse: Conceptus/unknown protein – secreted by blastocyte within 9 days of conception – prevents involution of corpus luteum – detected by pregnancy tests Hormone Levels and Pregnancy Uterine (Menstrual/Estrous) Cycle • Cyclic changes in endometrium in response to ovarian hormones • Three phases 1. Menstrual/resorbtion phase 2. Proliferative (preovulatory) phase 3. Secretory (postovulatory) phase (most constant in length) Uterine Cycle • Menstrual/resorbtive phase – Ovarian hormones are at their lowest levels – Gonadotropins are beginning to rise – Stratum functionalis is shed and the menstrual flow occurs 9 4/7/2016 Uterine Cycle Uterine Cycle