Structural and ultrastructural characteristics of interrenal gland and chromaffin cell of matrinxã, Brycon cephalus Gunther 1869 (Teleostei-Characidae).

This work presents the structure and ultrastructure of the interrenal gland and chromaffin cells, as well as the morphology of the head kidney of Brycon cephalus. The head kidney is composed of fused bilateral lobes located anterior to the swim bladder and ventrolateral to the spinal column. The parenchyma revealed lympho-haematopoietic tissue, melano-macrophage centres, interrenal gland and chromaffin cells. The interrenal gland consisted of cords or strands of cells grouped around the posterior cardinal vein and their branches. Chromaffin cells are found in small groups, closely associated with the interrenal gland and/or under the endothelium of the posterior cardinal vein. So far, the ultrastructural analysis has revealed only one interrenal cell type which contained abundant smooth endoplasmic reticulum and numerous mitochondria with tubulo-vesicular cristae, characteristic of steroid-producing cells. Two types of chromaffin cells were observed. The first type was characterized by the presence of vesicles with round, strongly electron-dense granules, which were eccentrically located. Such cells were interpreted as noradrenaline cells. Meanwhile, cells which contained smaller vesicles and electron-lucent granules, with a small halo separating the granule from the vesicular limiting membrane, were identified as adrenaline cells.

Rhythm of development in the oocyte of the tilapia Oreochromis niloticus L. (Pisces: Cichlidae); a morphometric and histochemical study.

The ovary of the tilapia Oreochromis niloticus was studied morphologically and morphometrically; the zonas granulosa and radiata, the ooplasm and the yolk globules were studied histochemically. The ovary is of typical teleostean type consisting of a wall and developing oocytes. The development of oocytes has been divided into 10 cytological stages. Histochemically the zona radiata and yolk globules contain glycoprotein (neutral mucopolysaccharides and protein radicals alpha-amino groups, cystine, cystein, tyrosin, tryptophane, and arginine. The zona granulosa and ooplasm contain neutral and carboxylate acid mucopolysaccharides and protein radicals alpha-amino group, cystein, cystine, tyrosin, arginine, and tryptophane.