Comparative folliculogenesis and spermatogenesis of four teleost fish from a Reservoir in south‐eastern Brazil

Martins, Y.S., Moura, D.F., Santos, G.B., Rizzo, E. and Bazzoli, N. 2009. Comparative folliculogenesis and spermatogenesis of four teleost fish from a Reservoir in south‐eastern Brazil. —Acta Zoologica (Stockholm). 91 : 466–473. This study provides a comparative analysis of gametogenesis of neotropical teleosts Metynnis maculatus, Megalancistrus parananus, Cichla kelberi and Satanoperca pappaterra, through histological, histochemical and histometric techniques. In the ooplasm of C. kelberi and S. pappaterra conspicuous lipid vesicles were observed, which are characteristic of pelagic eggs produced by marine fishes. Perinucleolar oocytes were identified in the testis of S. pappaterra suggesting that this species is protogynous without functional hermaphroditism, an unusual pattern for neotropical fresh‐water fishes. The spermatozoa of the studied species have rounded heads, a characteristic of fish that externally fertilise their eggs. The follicular (granulosa) cells of the vitellogenic oocytes from the studied species were cuboidal or columnar, however, in C. kelberi there were columnar follicular cells at the vegetal pole and cuboidal cells at the animal pole. Variations of the histochemical content were detected in the cortical alveoli and follicular cells of vitellogenic oocytes showing differences in the mechanisms to block polyspermy and egg adhesiveness. Larger oocytes were recorded in species which demonstrated parental care behaviour and smaller oocytes were noted in those species with fractioned spawning.