Proportions of vitellogenic
and previtellogenic oocytes were established.
Oogonia were detected in the central germinal zone in multiplication, previtellogenic and vitellogenic
(primary and secondary) stages and the mature stage of oogenesis.
3B), along with formation of oogonia, previtellogenic oocytes, and vitellogenic
oocytes in females, but without any mature ovules (Fig.
The first visible sing of atresia in vitellogenic
oocytes (stage 5 atretic oocytes), was the thickening of the zona radiata.
mechanisms are central to species success in any given habitat, because they reflect species reproductive response to nutrients (Eckelbarger, 1994).
The most advanced germ cells in this phase were primary and secondary vitellogenic
oocytes, which increased in diameter because of increased yolk in the cytoplasm.
While two of three August females exhibited early atresia (Table 2) and may not have ovulated, there was no sign of atresia in the vitellogenic
follicles of the third female.
These strategies relate to the pattern and time lag in which the pre-vitellogenic oocytes (primary growth) are recruited to compose the stock of vitellogenic
oocytes (secondary growth).
For morphological analyses, i.e., diameter of vitellogenic
oocytes, the pellucid zone thickness and the follicular cell height, we selected 50 undamaged oocytes without retraction and with cuts crossing the nucleus for each of the studied species.
Stage III: late development or oogenesis, this phase is characterized by a narrowing of the connective tissue in favour of vitellogenic
The presence of elevated GSIs and mature, vitellogenic
oocytes was used to estimate reproductive season in weeks for each population of fishes.
The oocyte types I and II (not vitellogenic
) were observed in all stages of the reproductive cycle.