5 research outputs found
Leydig cells in
No full textMales of Myleus ternetzi, at various maturation stages were netted in a French Guyana river. Testes were histologically and ultrastructurally analysed. Leydig cells were always
present in large numbers. In mature or almost mature testes, they were characterized by a large
spherical nucleus and an extensively developed smooth endoplasmic reticulum (SER) composed of very
narrow tightly packed tubules. In regressed testes, most of the Leydig cells had a smaller nucleus
with an irregular shape, a disorganized SER and the fine structure of the mitochondria was
greatly affected. These changes would reflect different phases throughout a metabolic cycle in relation to spermatogenesis
Biologie de la reproduction de Myleus ternetzi
No full textL'histologie des gonades de 187 mâles et 149 femelles de Myleus ternetzi pêchés dans des rivières guyanaises a été étudiée. Les stades et le cycle de la spermatogenèse ont été analysés à l'aide d'une méthode téréologique. L'ovogenèse a été étudiée et le stade de maturation de chaque femelle déterminé. La vitellogenèse est discontinue et au moins trois pontes pourraient avoir lieu lors de la saison de reproduction. La fécondité relative est d'environ 10 000 ovocytes par kilogramme par ponte. Bien que aptes à se reproduire toute l'année, la plupart des Myleus ternetzi se reproduiraient juste avant la grande saison des pluies.The histology of the gonads of 187 males and 149 females of Myleus ternetzi collected in Guyanan rivers has been studied. A stereological method was used to analyse the spermatogenetic stages and cycle. Ovogenesis was studied and the ovogenetic stage of every female was determined. Vitellogenesis appears to be discontinuous and at least three spawnings may occur during the breeding season. The mean fecundity is around 10 000 oocytes per kilogram per spawning. Myleus ternetzi is able to breed throughout the year but most animals breed just before the major wet season
