HISTOCHEMICAL AND ELECTRON MICROSCOPIC OBSERVATIONS ON THE STEROID HORMONE-SECRETING CELLS IN THE TESTIS OF THE JAPANESE RED-BELLIED NEWT, CYNOPS PYRRHOGASTER PYRRHOGASTER

The testis of the Japanese red-bellied newt, Cynops pyrrhogaster pyrrhogaster, caught in the middle of May was investigated in order to demonstrate the presence of steroid hormone (SH)-secreting cells, by means of histochemical and electron microscopic techniques. The newt testis is divided into two main parts of spermatogenetic stages. The anterior part is immature and consists of many seminal cysts containing spermatogonia and spermatocytes. The posterior part is mature and made up of many cysts containing mature spermatozoa and glandular tissue. Histochemical studies revealed Δ⁵-3β-hydroxysteroid dehydrogenase (Δ⁵-3β-HSD) activity in the pericystic cells of the mature part, weak in those before spermiation, then gradually becoming more intense in the pericystic cells just after spermiation. Activity was most pronounced in the outer layer of cells of the glandular tissue which originate from the pericystic cells. In contrast to this, the Δ⁵-3β-HSD reaction was entirely negative in the pericystic cells of the immature part, the Sertoli cells, and the inner cells of the glandular tissue originating from the Sertoli cells. Electron microscopic observation of the pericystic cells and glandular tissue gave further information on the histochemical features. The pericystic cells in the immature part are fibroblast-like cells. The cell organelles of these cells are poorly developed except for rough-surfaced endoplasmic reticulum and rod-shaped mitochondria. In the mature part, the fibroblast-like cells are transformed into cells characteristic of SH-secreting cells. In the cytoplasm, the amount of smooth-surfaced endoplasmic reticulum increases and typical globular mitochondria with tubular cristae take the place of the rod-shaped mitochondria. In addition, a number of lipid droplets and lipofuscin granules appear. Most of the fine structures of the outer layer of the cells of the glandular tissue were found to be similar in appearance to those of the SH-secreting cells in mammals and other vertebrates. These results strongly suggest that, as in the other urodeles, the SH-secreting cells in the testis of the Japanese red-bellied newt are the pericystic cells in the mature part and in the outer layer of cells of the glandular tissue.