[Histology of the ovary of Macrodon ancylodon (Bloch and Schneider, 1801) Teleostei: Sciaenidae). Oogenesis. Post-ovulatory follicles. Atresia].

: The reproductive cycle of Teleostean fishes may be studied from different points of view. One of them is to examine the histological changes that take place in the gonad. A histological description of the gonad is to be done first. In this work we have studied the oogenesis, atresia and post-ovulatory follicles of Macrodon ancylodon. Specimens were collected from April 1982 to May 1983 on the coast of Rio de la Plata (Montevideo, Uruguay). Material used was preserved in neutralized 10% formalin inbedded in paraffin and paraffin-celloidin, sectioned at 5 - 10 microns and stained with haematoxilin-eosin. Pas-haematoxilin, and specific techniques for lipid detection were used. Six oogenetic stages were recognized: oogonias, and basophilic, lipid yolk vesicles, protein yolk vesicles, matures and ripe hydrated oocytes. Theca and granulosa are negative to lipid and cholesterol histochemic reaction techniques. Post-ovulatory follicles show structural degenerative changes. Two types of atresia are described: hypertrophic and nonhypertrophic, which apparently would not have an endocrine function. It is important to recognize post-ovulatory follicles to establish the spawning pattern and also to recognize atretic follicles due to their incidence in the fecundity of a species.