Morphometrical analysis of Sertoli cell ultrastructure during the seminiferous epithelial cycle in rats

Stage-dependent variations of Sertoli cell organelles during the seminiferous epithelial cycle were analyzed morphometrically in rats by use of a point-counting method. Cyclic changes in volume and surface area of various organelles were observed. Mitochondria and rough endoplasmic reticulum increased at stages VII-VIII and stage VII, respectively. Lipid droplets accumulated markedly after spermiation, decreased rapidly after meiotic division, and remained at low levels for stages IV-VIII. The most prominent change was a topographic alteration of the Golgi apparatus. It was usually located exclusively in the basal cytoplasm, but shifted upwards to the mid and apical cytoplasm at stages VII-VIII. This shift may be implicated in an increase of plasma membrane and lysosomes in these regions. Consecutive increases of primary and secondary lysosomes were observed twice in the basal and mid cytoplasm. The first peak of the primary lysosomes at stage IV was followed by the first peak of the secondary lysosomes at stage VI; and the second peak of the primary lysosomes at stages VII-IX was followed by the second peak of the secondary lysosomes at stage IX. These consecutive increases may indicate that Sertoli cells anticipate the increase of structures to be removed and accordingly produce primary lysosomes before their appearance.