Page 800 - Atlas of Histology with Functional Correlations

FIGURE 20.5 ■ Testis: seminiferous tubules (transverse section). Stain:

hematoxylin and eosin (plastic section). ×80.

FIGURE 20.6 | Testis: Spermatogenesis in

Seminiferous Tubules (Transverse Section)

A higher magnification of a seminiferous tubule (8) allows identification of
different cell types. Each seminiferous tubule (8) is surrounded by a layer of
connective tissue with fibrocytes (11) and an inner basement membrane (3).

Between each seminiferous tubules (8) are interstitial fibrocytes (11), blood
vessels (5), nerves, lymphatic vessels, and the testosterone-producing interstitial
cells (of Leydig) (1, 12).

The stratified germinal epithelium consists of supporting or Sertoli cells (6,
10) and different spermatogenic cells (7). Sertoli cells (6, 10) are elongated cells

with irregular outlines that extend from the basement membrane (3) to the lumen
of the seminiferous tubule (8). The nuclei of Sertoli cells (6, 10) are ovoid, or
elongated, and contain fine, sparse chromatin. A distinct and dense-staining

nucleolus distinguishes Sertoli cells (6, 10) from the spermatogenic cells (7).

The immature spermatogenic cells, the spermatogonia (7), are adjacent to
the basement membrane (3) and divide mitotically to produce two types of
spermatogonia: The pale type A spermatogonia (7b) have a light-staining
cytoplasm and a round or ovoid nucleus with pale, finely granular chromatin;

and the dark type A spermatogonia (7a) with darker chromatin.

Type A spermatogonia (7a) serve as stem cells for the germinal epithelium

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