Non-neoplastic testicular tissue

(A) Normal maturing spermatogenesis demonstrates different phases of sperm (ie, germ cell) development, with the most immature elements (eg, spermatogonia) near the basement membrane and increased maturation (eg, primary spermatocytes, secondary spermatocytes, and spermatids) as they move towards the tubule lumen. Immature germ cells are round with moderate amounts of cytoplasm. Spermatozoa (examples in circle) appear as clusters of small dark "tear-drops" (tails are not visible with an H&E stain). Intratubular Sertoli cells are also present but are often obscured due to the large number of maturing germ cells.

(B) Clusters of pink steroid-producing Leydig cells (asterisks, also seen in image D) are present within the intertubular spaces.

(C) Seminiferous tubules with thickened basement membranes and immature germ cells (arrows) are consistent with "maturation arrest." The immature germ cells include spermatogonia/spermatocytes only; no spermatozoa are seen. Patients with these findings may present with oligospermia.

(D) In "Sertoli only syndrome," germ cells are absent and only Sertoli cells are present. The Sertoli cells, which are easily visualized in the absence of germ cells, demonstrate small round nuclei with prominent nucleoli and loose, wavy cytoplasm (compare with image A). Patients with Sertoli only syndrome present with azoospermia.