FINE STRUCTURE OF INTRATESTICULAR EXCRETORY PATHWAY IN GUINEA PIG

The seminiferous tubules are continuous with a short and narrower tubule, the intermediate region, lined by cylindrical Sertoli-like cells; these contain mitochondria, granules, vacuoles, cisternae, lysosomes and fibrils. The epithelium abruptly becomes low and cuboidal in the tubuli recti, where the cells have no apical differentiations and contain only few granules, cisternae and mitochondria. The tubuli recti open in a labyrinth of interconnected spaces, the rete testis, which has two main parts: one, near the ductuli efferentes, is the mediastinal rete testis, the interstitium of which has abundant connective tissue fused with the tunica albuginea testis; by contrast, the interstitium of the peripheral rete testis, next to the tubuli recti, contains numerous Leydig cells. The epithelium in both segments is quite similar, low and cuboidal, with mitochondria, some vacuoles and lysosomes. Very few, irregular microvilli and occasional cilia were found in the apical border. The typical limiting membrane of the seminiferous tubules is found also in the intermediate region, the tubuli recti and the peripheral rete testis. In the mediastinal rete testis, instead of this limiting complex, there is only a basal lamina. In the intermediate region we did not find the plugs described by other workers. Furthermore our morphological evidence does not support the concept of an important active transport in the rete testis. © 1969 Springer-Verlag.