Spermatogenesis bds


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Spermatogenesis bds

  1. 2. testis <ul><li>Normal spermatogenesis can occur only if the testes are at a temperature lower than that of the abdominal cavity. </li></ul><ul><li>When they are located in the scrotum, they are at a temperature about 3°C lower than the abdominal temperature. </li></ul>
  2. 3. epididymis <ul><li>The long length of the duct of the epididymis provides storage space for the spermatozoa and allows them to mature. </li></ul><ul><li>A main function of the epididymis is the absorption of fluid. </li></ul><ul><li>Another function may be the addition of substances to the seminal fluid to nourish the maturing sperm </li></ul>
  3. 4. Vas deferens <ul><li>conveys mature sperm from the epididymis to the ejaculatory duct and the urethra. </li></ul>
  4. 5. Seminal vesicle <ul><li>The function of the seminal vesicles is to produce a secretion that is added to the seminal fluid. The secretions nourish the spermatozoa. </li></ul><ul><li>During ejaculation the seminal vesicles contract and expel their contents into the ejaculatory ducts, thus washing the spermatozoa out of the urethra. </li></ul>
  5. 7. Ejaculatory duct <ul><li>their function is to drain the seminal fluid into the prostatic urethra. </li></ul>
  6. 8. prostate <ul><li>The prostate produces a thin, milky fluid containing citric acid and acid phosphatase that is added to the seminal fluid at the time of ejaculation </li></ul><ul><li>The prostatic secretion is alkaline and helps neutralize the acidity in the vagina. </li></ul>
  7. 9. Structure of testis
  8. 12. <ul><li>Gametogenesis (gamete formation) is the process of formation and development of specialized generative cells, gametes . </li></ul>
  9. 13. <ul><li>Gamete maturation is called spermatogenesis in males and oogenesis in females. </li></ul>
  10. 15. SPERMATOGENESIS <ul><li>Spermatogenesis is the sequence of events by which spermatogonia are transformed into mature sperms . This maturation process begins at puberty. </li></ul>
  11. 17. <ul><li>Spermatogonia , which have been dormant in the seminiferous tubules of the testes since the fetal period, begin to increase in number at puberty. </li></ul><ul><li>After several mitotic divisions, the spermatogonia grow and undergo changes. </li></ul>
  12. 19. <ul><li>Sertoli cells lining the seminiferous tubules support and nurture the germ cells and may be involved in the regulation of spermatogenesis. </li></ul>
  13. 20. <ul><li>Spermatogonia are transformed into primary spermatocytes , the largest germ cells in the seminiferous tubules. </li></ul>
  14. 21. <ul><li>Each primary spermatocyte subsequently undergoes a reduction division-the first meiotic division-to form two haploid secondary spermatocytes , which are approximately half the size of primary spermatocytes. </li></ul>
  15. 23. <ul><li>Subsequently, the secondary spermatocytes undergo a second meiotic division to form four haploid spermatids, which are approximately half the size of secondary spermatocytes. </li></ul>
  16. 24. spermiogenesis <ul><li>The spermatids are gradually transformed into four mature sperm by a process known as spermiogenesis </li></ul>
  17. 27. <ul><li>The entire process of spermatogenesis, which includes spermiogenesis, takes approximately 2 months. </li></ul><ul><li>When spermiogenesis is complete, the sperms enter the lumina of the seminiferous tubules. </li></ul>
  18. 31. <ul><li>Sperms are transported passively from the seminiferous tubules to the epididymis , where they are stored and become functionally mature. </li></ul>
  19. 32. <ul><li>The epididymis is the elongated coiled duct along the posterior border of the testis . </li></ul><ul><li>It is continuous with the ductus deferens (vas deferens), which transports the sperms to the urethra. </li></ul>
  20. 33. <ul><li>Mature sperms are free-swimming, actively motile cells consisting of a head and a tail . </li></ul>
  21. 35. <ul><li>The head of the sperm forms most of the bulk of the sperm and contains the haploid nucleus. </li></ul><ul><li>The anterior two thirds of the nucleus is covered by the acrosome , a caplike saccular organelle containing several enzymes. </li></ul>
  22. 36. <ul><li>When released, these enzymes facilitate dispersion of the follicular cells of the corona radiata and sperm penetration of the zona pellucida during fertilization. </li></ul>
  23. 37. <ul><li>The neck of the sperm is the junction between the head and tail. </li></ul><ul><li>The tail of the sperm consists of three segments: middle piece, principal piece, and end piece </li></ul>
  24. 38. <ul><li>The tail provides the motility of the sperm that assists its transport to the site of fertilization. </li></ul><ul><li>The middle piece of the tail contains mitochondria, which provide the adenosine triphosphate necessary for activity. </li></ul>
  25. 39. Laboratory tests for male infertility <ul><li>Semen analysis </li></ul><ul><ul><li>Gold standard test for infertility </li></ul></ul><ul><ul><li>Components of semen </li></ul></ul><ul><ul><ul><li>Spermatozoa derive from the seminiferous tubules. </li></ul></ul></ul><ul><ul><ul><li>Coagulant derives from the seminal vesicles </li></ul></ul></ul><ul><ul><ul><li>Enzymes to liquefy semen derive from the prostate gland. </li></ul></ul></ul>
  26. 40. <ul><ul><li>Components evaluated in a standard semen analysis </li></ul></ul><ul><ul><ul><li>Volume </li></ul></ul></ul><ul><ul><ul><ul><li>Volume does not correlate with the number of sperm. </li></ul></ul></ul></ul><ul><ul><ul><li>Sperm count </li></ul></ul></ul><ul><ul><ul><ul><li>Normal is 20 to 150 million sperm/mL. </li></ul></ul></ul></ul><ul><ul><ul><li>Sperm morphology </li></ul></ul></ul><ul><ul><ul><ul><li>Morphology is very abnormal in reconnections of a vasectomy. </li></ul></ul></ul></ul><ul><ul><ul><li>Sperm motility </li></ul></ul></ul><ul><li>Serum gonadotropins, testosterone, prolactin </li></ul>