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Spermatogenesis
- 1. Dr SIVARAJ S DEPT OF PHYSIOLOGY ALL INDIA INSTITUTE OF MEDICAL SCIENCES NEW DELHI
- 2. The process by which sperm develop to become mature sperm, capable of fertilizing an ovum
- 5. Testis and surrounding structures
- 6. Further development of Spermatozoa Mobility Capacitation Role of Leydig cells Secreting male sex hormone testosterone
- 7. Role of Sertoli cells Also called Nurse cells Provides nutrition Blood Testis Barrier Secretes ABP, inhibin, Mullerian inhibiting substance(MIS)
- 8. Interrelationships between the hypothalamus, anterior pituitary, and testes
- 9. Semen Volume 1.5- 4.5 ml White, opalescent colour Slightly alkaline pH 100-125 million sperms/ml
- 10. Influencing factors Endocrine environment Temperature Dietary factors vitamin A,B,E Radiation exposure Smoking, Alcohol Infectious diseases
- 11. Summary Spermatogenesis Produce mature spermatocytes Produce haploid gamates Cell proliferation Maintenance of a reserve germ cell population Spermatids mature into spermatozoa Acquire motility Capable of fertilizing ovum.
Notes de l'éditeur
- During f ormat ion of t he embr y o, t he pr imor dial germ c ells migr at e int o t he t estes and becomeimmatur e germ c ells c alled s permatogonia, whic h liein t wo or t hr ee lay er s of t he inner sur f ac es of t he s eminiferous t ubules ( a c r oss sec t ion of one is shown in F igur e 80- 2A ) . T he spermatogonia begint o under go mitotic div ision, beginning at puber t y , and c ontinually pr olifer at e and dif f erentiat e t hr ough def init e st ages of dev elopment t o f orm sperm,as shown in F igur e 80- 2B
- 3 mm/min speed in female genital tract... Normal temp 32c. kept cool by air circulating around the scrotum and probably by heat exchange in a countercurrent fashion between the spermatic arteries and veinsWash away the inhibitory factors, t he membrane at t he head of t he sperm ( t he ac r osome) becomesmuc h weak er ,T he membrane of t he sperm also becomesmuc h mor e permeable t o c alcium ions, so c alcium now enter s t he sperm in abundanc e Testosterone is necessary for normal sperm development. It activates genes in Sertoli cells, which promote differentiation of spermatogonia.
- Secrete androgen-binding protein (ABP), which concentrates testosterone in close proximity to the developing gametesTestosterone is needed in very high quantities for maintenance of the reproductive tract, and ABP allows a much higher level of fertility
- Dietary deficiencies (such as vitamins B, E and A), anabolic steroids, metals (cadmium and lead),radiation exposure, alcohol, and infectious diseases will also
- Maintenance of a reserve germ cell populationProduction of new spermatogonia is faster than maturation of spermatozoa