Testis morphology in the sexually mature male. (a), In a 2-year-old adult and sexually mature male, the anterior part of the testis (APT) near the lung (Lu) is reduced but still present. The first testis lobe possesses three parts easily identified at the morphological examination: a transluscent region at the apex corresponds to a recently appeared zone with early spermatogenic stages (ZES), a central white zone contains spermatozoa (ZS) and the posterior orange region corresponds to the glandular tissue (GT). The basis of the mesorchium (M) is observed in a depression at the surface of the testis. (b), section of the ZES showing lobules (Lo) with a central cavity whose walls contain cysts (Cy) including proliferating spermatogonia. (c), section of the ZS in which lobules contain cysts with spermatozoa (Spz). An efferent duct (ED) is also observed. d and e, sections of the glandular tissue. The glandular tissue (GT) results from the transformation of lobule somatic cells after spermatozoa extrusion. Germ cells (arrowheads) with a typical polylobular nucleus are present either in the lumen (d) or in the vicinity (e) of the efferent ducts (ED).