Testes (testicles), Biology

TESTES (TESTICLES) -

  1. 2 in number (Diarchic). Pinkish in colour. Oval shaped.
  2. 4-5 cms long, 2.5 cm wide and 3 cm thick. Mesodermal.
  3. In embryonic stage attached to kidney by mesorchium membrane.
  4. In embryo at 7th month of division descend down in scrotel sac. Condition is extra abdominal, due to it 3°C less temperature is available, helpful in spermatogenesis.
  5. Both scrotel sac internally separated by septum scroti. External by a scar-like raphe.
  6. In scrotel sac fat layer is absent, involuntary muscles are dertos tunic present.
  7. Lumen of scrotel sac is vaginal coelome, in it testes present.
  8. Vaginal coelome is connected to main coelome by inguinal canal.
  9. In some cases testes do not descend down in sac, condition is cryptorchidism such animals are high flankers (sperm are not produced)
  10. Testes is attached to pre position by spermatic cord (gonadial artery, gonadial vein, nerve and connective tissue present).
  11. Testis is attached to wall of scrotel sac by elastic structure i.e. gubernaculum cordis.
  12. Unit of testis is seminiferous tubule where sperms are manufactured by spermatogenesis. All tubules form a cord of 200-400 meter. These tubules are spreaded in connective tissue.
  13. In tissue interstitial cells or cells of Leyding present. These cells secrete testastaron or androgen hormones to control secondary sexual characters.
  14. Outside each seminiferous tubule, tunica propria present. Inside it germinal epithelium or basement membrane present. Made up of cuboidal epithelium.
  15. Epithelium consists of P.G.C. and few sertoli cells.
  16. P.G.C. (Primordial germ cells) are endodermal in nature.
  17. P.G.C. are responsible for spermatogenesis.
  18. Different stages of formation of sperms can be seen as spermatogonia, primary spermatocyte, sec. spermatocyte, spermatid and sperms.
  19. Sertoli cells or nurse cells or sustentacular cells are nourishing cells i.e. provide glycogen as food to develope sperms. So sperm's head is embeded in sertoli cells.
  20. Around testes, testicular capsule present made up of 2 layers.
  21. Outer is tunica vaginalis & inner is tunica albuginea.
  22. From tunica albuginea straight vertical spetum mediastinum is originated from it septula testes are given out to form 200-300 compartments.
  23. In each compartment seminiferous tubule present.
  24. On tunica albuginea, mediastinum & septule testes, a membrane present rich in blood supply. This membrane is tunica vescularosa.
  25. Surgical removal of testes is orchidectomy & gonad is castration or gelding.

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Posted Date: 10/3/2012 5:04:59 AM | Location : United States







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