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- 1.
- 2. The Male ReproductiveSystem
- 3. Testes - produce spermcells developed from germ cells in seminiferous tubule - secret testosterone by interstitial (Leydig) cells
- 4.
- 5. Scrotum protect testes and maintainthe temperature of the testes 2 degrees lower than body temperature.
- 6. Epididymus the storage siteof sperm cells. It absorbs about 90% of the fluid secreted by the testis. Sperm remain stored here for 40-60 days and are absorbed if not ejaculated prior to that time.
- 9. The fluid expelled during orgasm Mixtureof secretion from epididymis, seminal vesicle, prostate, and bulbourethral gland. Semen (seminal fluid )
- 10. Major constituents ofsemen • Sperm • Fructose • Clotting and anticoagulant factors • Prostaglandins • Spermine
- 11. produce ATP for spermmotility. enzymes used to dissolve a path to penetrate the egg gene
- 12. Sperm cells fromepididymis are present at a count of 50-120 million sperm/mL. Sperm count decreased from 113 million sperm/mL in 1940 to 66 million sperm/mL in 1990. Semen volume dropped by 19%. < 20-25 million/ml = infertility (sterility)
- 13. Fructose produced by the seminalvesicles provides a source of energy for the sperm.
- 14. Clotting and anticoagulant factors produced byseminal vesicles and prostate. Semen clots like blood. About 15-30 minutes later, anticoagulant factors dissolve the clot.
- 15. Prostaglandins produced by the prostateand seminal vesicles, stimulate peristaltic contractions of the female reproductive tract that may help draw semen into the uterus.
- 16. Spermine is a basethat reduces acidity of the female vagina, increasing the survival rate of sperm.
- 17. Male Sexual Response 1) erectionof the penis, allowing it to penetrate the female vagina 2) ejaculation, expelling semen into the vagina.
- 18. Ejaculation Initiated by sympathetic nerveimpulses The ducts and accessory glands contract, emptying their contents into the urethra. The urethral sphincters constrict. The bulbospongiosus muscles of the penis contract rapidly and rhythmically, propelling semen from the urethra.
- 19. Fate of spermcells capacitated (test tube?) viable for 2 days (egg: 12-24 hr) Only ~ 100 reach the destination. Only one sperm fertilizes the egg.
- 20. Refractory Period A periodfollowing ejaculation and lasting anywhere from 10 minutes to a few hours impossible to attain another erection and orgasm
- 21. Semen analysis Motility>60% shouldbe motile with in 3hrs of collection. Count >40 million /ml is normal. Liquify-should liquify with in half an hour. Morphology->80% should have normal morphology
- 22. The Male ReproductiveSystem in Midsagital View Figure 28.1
- 23. MALE REPRODUCTIVE SYSTEM TESTIS - thick connective tissue capsule - connective tissue septa divide testis into 250 lobules TUNICA ALBUGINEA (1) SEMINIFEROUS TUBULES - each lobule contains 1-4 seminiferous tubules and interstitial connective tissue - produce sperm INTERSTITIAL TISSUE - contains Leydig cells which produce testosterone (2) RECTUS TUBULES (3) RETE TESTIS (4) EFFERENT DUCTULES (5) EPIDIDYMIS
- 24. MALE REPRODUCTIVE SYSTEM SERTOLI CELLS SPERMATOGONIA 1ºSPERMATOCYTE 2º SPERMATOCYTE SPERMATIDS SPERMATOGENESIS SPERMATOGONIA 1º SPERMATOCYTE 2º SPERMATOCYTE SPERMATIDS SERTOLI CELLS: - columnar with adjoining lateral processes - Sertoli-Sertoli junctions divide seminiferous tubules into basal and adluminal compartments - extend from basal lamina to lumen
- 25. Basal Lamina 2n 2n Spermatogonia(stem cells) 2n mitosis Daughter cell Type A spermatogonium remain at basal lamina as a precursor cell Daughter cell Type B Spermatagonium Moves to adluminal compartment n n 1° spermatocyte n Meiosis I completed 2° spermatocyte n n n n Early spermatids n n n n Late spermatids Meiosis II
- 26. MALE REPRODUCTIVE SYSTEM SPERMATOGENESIS THREE PHASES: (1) Spermatogonial Phase (Mitosis) (2) Spermatocyte Phase (Meiosis) (3) Spermatid Phase (Spermiogenesis) - acrosome formation; golgi granules fuse to form acrosome that contains hydrolytic enzymes which will enable the spermatozoa to move through the investing layers of the oocyte - flagellum formation; centrioles and associate axoneme (arrangement of microtubules in cilia) - changes in size and shape of nucleus; chromatin condenses and shedding of residual body (cytoplasm)
- 27. MALE REPRODUCTIVE SYSTEM HORMONAL REGULATION OF MALE REPRODUCTIVE FUNCTION HYPOTHALAMUS REGULATES ACTIVITY OF ANTERIOR PITUITARY (ADENOHYPOPHYSIS) ADENOHYPOPHYSIS SYNTHESIZES HORMONES (LH and FSH) THAT MODULATE ACTIVITY OF SERTOLI AND LEYDIG CELLS Luteinizing Hormone (LH): stimulates testosterone production by Leydig cells Follicle Stimulating Hormone (FSH): stimulates production of sperm in conjunction with testosterone by regulating activity of Sertoli cells SERTOLI CELLS STIMULATED BY FSH AND TESTOSTERONE RELEASE ANDROGEN BINDING PROTEIN WHICH BINDS TESTOSTERONE; THEREBY INCREASING TESTOSTERONE CONCENTRATION WITHIN THE SEMINIFEROUS TUBULES AND STIMULATING SPERMATOGENESIS
- 29. SPERMATOGENESIS DEFINITION: Thedevelopment and maturation of spermatozoa is called spermatogenesis. It consists of two parts Spermatocytogenesis. Spermiogenesis.
- 30. The spermformation involves two steps : in the first step spermatogenic cells form rounded cells called spermatids which in the second step differentiate into specialized cells known as sperms. These processes are labeled respectively as Spermatocytogenesis Spermiogenesis
- 31. Site of spermformation Seminiferous tubules of Testis
- 33. Spermatocytogenesis The primitive sexcells appear earliest in 4th week of intra uterine life in the wall of yolk sac as primordial germ cells They migrate to the developing testes and lie dormant among the cells lining the seminiferous tubules
- 34. Spermatocytogenesis At puberty thegerm cells awaken and start the actual process of spermato genesis These cells increase in number by simple mitosis to form cells known as spermatogonia ; type- A and type- B. Type-B spermatogonia, replicate DNA to have 46 double structured chromosomes to begin meiosis-1 and are called primary spermatocytes.
- 37. Spermatocytogenesis (cont.) Assteps of spermatogenesis continue the spermatocytes progressively move from basement membrane to the luminal side of seminiferous tubule The cells of Sertoli provide nutrition and pockets of support to developing spermatocytes
- 38. Spermatocytogenesis (cont.) Thespermatocytes in different stages of development remain attached by cytoplasmic bridges All the spermatocytes are not in the same stage of development in the seminiferous tubules
- 39. SPERMIOGENESIS Transformation ofspermatids into a tailed,motile spermatozoa is called spermiogenesis. Spermatozoa are mature germ cells,haploid and posses a - Head Middlepiece Tail .
- 40. About 512 spermatozoadevelop from a single spermatozoa.
- 41. SPERMIOGENESIS Spermatids arerounded cells. They modify to assume specific shape of the sperm. This process is called Spermiogenesis. In it they elongate and reorganize internal structure to acquire the particular shape.
- 42. SPERMIOGENESIS (Cont.) Thechanges include ; 1. Golgi apparatus forms acrosomal cap-proteolytic enzymes 2. Nucleus is condensed 3. Centrioles: make collar around neck 4. Microtubules, form flagellum, 5. Mitochondria arrange as spiral around neck Excess cytoplasm cast off as residual body Cytoplasmic bridges break and sperms release from Sertoli cells to lie free in lumen of seminiferous tubules. About 74 days are required to go from a spermatogonium to a sperm
- 44. SPERMIOGENESIS (cont.) Amature sperm has head, neck and tail From lumen of seminiferous tubules sperms enter duct of epididymis They take 20 days to travel this 4-6 meter long tortuous duct If ejaculation does not occur they die and degenerate
- 45. Abnormal sperms They arewith: Two heads Two tails or: Dwarf Giant Contrary to oocytes abnormal sperms are seen more frequently
- 46. Hormonal Regulation ofTesticular Function 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 ABP binding of testosterone enhances spermatogenesis
- 48. Hormonal Regulation ofTesticular Function Feedback inhibition on the hypothalamus and pituitary results from: Rising levels of testosterone Increased inhibin
- 49. BLOOD TESTIS BARRIER Tight junctions between adjacent sertoli cells near the basal lamina form a blood testis barrier. It prevents large molecules from passing from the interstital tissue and part of tubule near basal lamina to the region near tubular lumen(adluminar compartment), and lumen.
- 51. significance Blood testisbarrier protects different stages of spermatogenesis from blood borne toxic substance and from circulating antibodies. It prevents entry of byproducts of gametogenesis into the blood that is why autoimmune reaction does not occur.
- 52. Androgens - Includes testosterone,DHT & androstenedione - Testosterone serves as a prohormone for Dihydrotestosterone (DHT) Oestradiol
- 53. TESTOSTERONE C19 steriod,secreted bycholesterol in the leydig cells. Androstenedione secreted from adrenal cortex.
- 54.
- 55. Regulation of secretion •Oestrogen – similar to Testosterone • Inhibin inhibits FSH secretion at A.P level
- 56. T DHT DHT-R T- R R R T- R Nucleus 90% 10% 5-reductase cytoplasm
- 57. Testosterone & DHT •growth of genitals in a boy • production of sperm • growth of facial, pubic & axillary hairs • muscular development • growth of larynx & voice deepens • inhibition of bone growth • thickening of skin, loss of s.c. fat • behavioral changes in men • nitrogen retaining effect • erythropoietin secretion increased • Increased LDL & decreased HDL
- 58. Composition ofHuman Semen. 1.Color: White, opalescent 2. Specific gravity: 1.028 3. pH: 7.35–7.50 4.Sperm count: Average about 100 million/mL, with fewer than 20% abnormal forms 5.Other components: From seminal vesicles (contributes 60% of total volume) Fructose (1.5-6.5 mg/mL) Phosphorylcholine Ergothioneine Ascorbic acid Flavins Prostaglandins Spermine
- 59. - From prostate(contributes 20% of total volume) Citric acid Cholesterol, phospholipids Fibrinolysin, fibrinogenase Zinc Acid phosphatase Phosphate Buffers Bicarbonate Hyaluronidase
- 60. Semen analysis Motility>60% shouldbe motile with in 3hrs of collection. Count >40 million /ml is normal. Liquify-should liquify with in half an hour. Morphology->80% should have normal morphology
- 61. Table 25–5 Distributionof Gonadal Steroids and Cortisol in Plasma. % Bound to Steroid % Free CBG GBG Albumin Testosterone 2 0 65 33 Androstenedione 7 0 8 85 Estradiol 2 0 38 60 Progesterone 2 18 0 80 Cortisol 4 90 0 6
Editor's Notes
- #24 tight junctions of lateral processes may temporarily open to permit the passage of spermatogenic cells toward the lumen