Study the schematic diagram of sperm development and the image below, noting the relationships of the developing sperm and sustentacular Sertoli cells. Next, examine these two examples of testis (sample1, sample 2  at higher magnification. Carefully examine the cells inside a seminiferous tubule and distinguish sperm in the various stages of spermatogenesis and spermiogenesis. In a tubule cut transversely, identify:

• Sustentacular or Sertoli cells (Sc) (with their distinctive nucleoli)
• Spermatogonia (Sg)
• Primary spermatocytes (Ps)
• Secondary spermatocytes are short-lived and difficult to find, so don’t spend time looking for these
• Early and late spermatids (Es, Ls)
• Spermatozoa (Sz)
• Myoid cells (M)

Finally, in the interstitial tissue between the seminiferous tubules, identify the interstitial cells or Leydig cells as seen in the image at the right. These cells are large, round pale-staining cells. They secrete testosterone, which is taken up by the Sertoli cells and concentrated within the seminiferous tubules where it serves an essential role in spermatogenesis.

Clinical notes: Failure of the testes to descend into the scrotum during fetal development (cryptorchidism) maintains their temperature at 37℃. This temperature inhibits spermatogenesis, although testosterone production can still occur. Excessive blood flow or dilated vasculature in the scrotum (varicocoele) is another potential cause of infertility and can be surgically corrected.

Most cases of testicular cancer (95%) are of germ cell origin. The rest are derived from Sertoli cells or Leydig cells. IUSM’s own Dr. Lawrence Einhorn discovered a cure for testicular cancer over 40 years ago.
 

Now for the intratesticular ducts.