An ultrastructural study of the Sertoli cell in the Shiba goat.

The ultrastructure of the Shiba goat Sertoli cell was observed using light and transmission electron microscopy. In the basal portion of the Sertoli cell, the nucleus was located near the basement membrane and was irregular in outline. A number of filaments with intermediate width were observed around the nucleus. A multivesicular nuclear body, composed of numerous vesicles of different sizes and ribosome-like structures, was detected within the nucleus. The majority of cell organelles was situated in this basal portion of the cytoplasm. Oval mitochondria were randomly distributed. A well-developed laminated smooth endoplasmic reticulum (sER) was frequently found within the cytoplasm of Sertoli cell. Lysosomes and large lipid droplets were also recognized. While, the outline of the basal lamina was almost straight. No nodular processes were observed in the lamina. The Golgi complex appeared only in the supranuclear region. In the middle and apical portions of the Sertoli cell, elongated mitochondria and microtubules were oriented parallel to the long axis of the cell. The laminated sER was also detected in these portions. The apical head of slightly-elongated spermatids was occasionally surrounded by the laminated sER. The head of maturing spermatids without laminated sER revealed a bleb-like shape. The microfilament bundles at the ectoplasmic specialization site were regularly arranged. Judging from the present observations, we have suggested that only the multivesicular nuclear body and the laminated sER may be the peculiar structures which are commonly found in the Sertoli cell of ruminants.