Histochemical observations on the interstitial tissue of fish testis

A histochemical study has been made of the testicular interstitial tissue of the marine teleost (Belone belone) during the breeding season. The interstitial tissue lying in between the lobules consists of compressed stromal elements having very little cytoplasm, which do not develop the morphological and histochemical features of steroid gland cells of mammalian ovary and testis. However, the lobule boundary cells are greatly hypertrophied. They show abundant cytoplasm, and they develop the morphological and histochemical features of steroid-secreting cells. These histochemical features are the presence of diffuse sudanophilic lipoproteins and deeply sudanophilic lipid droplets consisting of either phospholipids, or phospholipids and triglycerides. The functional significance of these histochemical features of lobule boundary cells in the teleost testis is discussed in the light of recent researches carried out on the steroid-producing cells in the mammalian ovary and testis. These comparisons have suggested that the lobule boundary cells of the teleost testis are the steroid scretors.