Chapter 26: Reproductive System Chapter 26: Reproductive System: Reproductive System Only system not essential to life of individual Zygote: Diploid cell Gonads: Reproductive organs (testes / ovaries) Gametes: Reproductive cells (sperm / egg) Similar to Marieb & Hoehn – Figure 26.1 Chapter 26: Reproductive System Chapter 26: Reproductive System Testes: Cryptorchidsm (“hidden testis”) Male Reproductive Anatomy: • Testes (spermatozoa production) • Descent of the testes (~ 7 months in utero) • Undescended testis(es) (spermatozoa transport) • Duct system • ~ 3% full-term (~ 30% premies) • Glands (seminal fluids) • Undescended = sterile Semen = spermatozoa (20 – 100 million) + seminal fluids (2 – 5 ml) Chapter 26: Reproductive System Chapter 26: Reproductive System Leydig Cells (interstitial cells) Testes: Testes - Histology: • Testosterone production Spermatic Cord: • Includes ductus deferens, blood vessels, nerves, and lymphatic vessels • Passes via inguinal canal (weak point – inguinal hernia…) Scrotum: • Divided internally into two chambers Seminiferous Tubule • Cremaster Muscles: Regulate testes location (cold = muscle contraction) • Sperm development ~ 97.0F • Each testis divided into lobules (tunica albuginea) Seminiferous Tubules: Slender, tightly coiled tubules (~ 0.5 miles / testis); sperm production Sertoli Cells (sustentacular cells) Rete Testis: • Spermatogenesis Passageways collecting sperm from seminiferous tubules 1 Chapter 26: Reproductive System Chapter 26: Reproductive System Spermatogenesis (sperm production): Anatomy of a Sperm: (Diploid) Spermatogonia (stem cell) • ~ 14 yrs. of age Mitosis • 9 week process • 400 million / day 1) Head: • Nucleus - contains DNA Primary (Diploid) Spermatocyte • Acrosomal cap • Hydrolytic enzymes • Egg penetration Meiosis (crossing over) 2) Midpiece: • Mitochondria - ATP Spermatids 3) Tail: (Haploid) • Flagellum - movement Spermiogenesis Lack most intracellular structures Lumen of • Nutrients from environment Spermatozoa seminiferous tubule (Haploid) Chapter 26: Reproductive System Chapter 26: Reproductive System Male Reproductive Tract: Male Reproductive Accessory Glands: 1) Epididymis: Functions: 1) Activate spermatozoa • 7 m long; move immature sperm via currents (2 week journey) 2) Provide nutrients (power mitochondria) A) Monitors / Adjusts tubule fluid composition 3) Propel sperm / fluids (peristalsis) B) Recycles damaged / non-utilized sperm 4) Provide buffers (neutralize urethra / vagina) C) Facilitates functional maturation of sperm • Secrete chemicals that prevent capacitation (mobile sperm) • Sperm activated via seminal fluids & female reproductive tract 2) Ductus Deferens: 1) Seminal Vesicles (60% semen volume): • ~ 18 in. long; thick layer of smooth muscle • [fructose] = Activate sperm • Propel sperm via peristaltic contractions • Prostaglandins = smooth muscle contraction • Stores sperm (several months) • Fibrinogen = temporary clot in vagina • Ejaculatory Duct: Portion through prostate gland • Buffers = Neutralize acids 3) Urethra 2) Prostate Gland (30% semen volume): • Seminalplasmin (antibiotic) 3) Bulbourethral Glands (5% semen volume): • Thick, alkaline solution (buffer / lubricant) Chapter 26: Reproductive System Chapter 26: Reproductive System Penis: Male Reproductive System - Hormones: (-) 1) Root • Maintains accessory Gonadotropin-releasing Hypothalamus • Attaches penis to body wall glands Hormone (GnRH) 2) Shaft (erectile tissue) • Stimulates metabolic processes (-) • Corpora cavernosa / Corpus spongiosum (-) • Secondary sex 3) Glans Luteinizing Follicle-stimulating characteristics Anterior Pituitary • Prepuce (foreskin) Hormone (LH) Hormone (FSH) • Influences brain Sexual Response: development 1) Erection = Enlargement / stiffening of the penis • Parasympathetic reflex: Testes • Nitric oxide relaxes erectile tissue sphincters • Bulbourethral gland stimulated (pre-ejaculate) Leydig Sertoli Cells Cells 2) Ejaculation = Propulsion of semen from duct system Spermatogenesis / Ejaculate: Testosterone • Accessory glands contract (seminal fluids) Spermiogenesis • 2 – 5 ml semen (+) • Bladder sphincters contract (close off bladder) • ~ 20 – 100 million sperm Inhibin • Penis musculature rhythmically contracts (semen = 200 in / sec) 2 Chapter 26: Reproductive System Chapter 26: Reproductive System Females: • Ovaries (egg production) Ovary: • Duct / Development System • Composed of cortex (egg formation) and medulla (blood/nerve supply) • Function: 1) Production of eggs (ova) 2) Secretion of sex hormones Oogenesis (ovum production – long process): Primary Oocytes (~ 400,000) Atresia: Degeneration of primary oocytes • ~ 500 eggs released / life Oogonia 1st polar body 2nd polar body Secondary Mature Oocyte Ovum Mitosis Meiosis (I) Meiosis (II) After Before Birth At Puberty Fertilization Chapter 26: Reproductive System Chapter 26: Reproductive System Ovary: Ovary: • Oogenesis occurs within ovarian follicles: • Oogenesis occurs within ovarian follicles: Primordial Follicle: Primordial Follicle: Primary Oocyte + Follicle cells Primary Oocyte + Follicle cells Ovarian Cycle: (~ 28 days) Ovarian Cycle: (~ 28 days) (Graafian Follicle) Only one oocyte ovulated / cycle 1) Primary Follicle 2) Secondary Follicle 3) Tertiary Follicle 4) Ovulation 5) Corpus Luteum Follicle cells enlarge / replicate Fluid-filled cavity forms Central chamber appears (antrum) Primary oocyte matures Follicle cells collapse; Zona Pellucida: between follicle cells 15 mm diameter; bulge in to secondary oocyte form endocrine structure (1st polar body formed) Increased surface area ovarian wall appears Pregnancy = CL remains Ovarian wall ruptures around egg for absorption No Pregnancy = CL degenerates (12 days) Chapter 26: Reproductive System Chapter 26: Reproductive System Duct / Development System: 1) Mechanical protection Duct / Development System: Uterus layers = Endometrium / myometrium • Oocytes pass through Fallopian tubes to uterus 2) Nutritional support • Uterine (Menstrual) Cycle: 3) Waste removal 1) Menses: Endometrium sloughs off from uterine wall (~ 7 days) 4) Ejection Infundibulum: Ampulla: 2) Proliferative Phase: Cells multiple across endometrium ( ~ 7 days) Expanded funnel Middle segment of tube 3) Secretory Phase: Endometrial glands enlarge / increase secretions • ~ 14 days; prepares uterus for embryo Fundus Fimbriae: Finger-like projections Uterus (collect egg) Body Isthmus: Connection of tube to uterus wall Cervix Trip takes 3 – 4 days Fertilization must occur within • Ciliated columnar epithelium ~ 24 hours of release • Thick smooth muscle layer 3 Chapter 26: Reproductive System Chapter 26: Reproductive System Duct / Development System: Hormonal Regulation of Female Reproductive Cycle: Birth Control Pill • Vagina: Elastic, muscular tube between uterus and external environment 1) Passageway for elimination of menstrual fluids 2) Receives penis during sexual intercourse E2 triggers LH surge Corpus Luteum = Follicle cells LH surge triggers ovulation • Release progesterone 3) Holds spermatozoa prior to uterus entrance • Maintains uterine lining 4) Forms birth canal during fetus delivery Stratified squamous epithelium Devoid of glands (mucus = cervix) Very slight keratinization Follicular cells = Estrogen Support bacteria (= lactic acid) • Stimulated by FSH Inhibits FSH release 4 .