Within the same individual, alongside mature male gametes, female oogonia
also develop (Coe 1931b).
, shells of ostracods and molluscs--found in the lacustrine clay at the bottom of the Pantene/Brauksas I-2006 section, together with pollen of aquatic plants suggest that the clay was deposited in an oligotrophic lake during the late glacial.
The six ovaries used in this study ranged in age from 7 to 11 weeks postconception and contained only oogonia
Sastry (1965), for instance, demonstrated that bay scallops require a minimum temperature for activation of the oocyte growth phase, and although oogonia
can develop below this threshold, further differentiation only occurs at warmer temperatures.
A small minority of the remaining 600 valid histological specimens were bisexual juveniles with vestigial gonads containing chromatin nucleolar oogonia
, undeveloped spermatic tissue, or both (Fig.
were observed as round or ovoid cells and ranged from 15-20 [micro]m in diameter (Fig.
and early oocytes were present with diameters of approximately 20 [micro]m and arranged along the oogenic follicle (Fig.
For an indeterminate spawner like sardine, where recruitment of new spawning batches of oocytes occurs continuously and directly from the oogonia
, fast resorption is necessary because the aggregation of old POFs would restrict the space available for the development of new oocytes.
We also characterized 6 substages of oocyte and 2 structural indicators of spawning: oogonia
(Po0), previtellogenic oocyte primary (Pol), previtellogenic oocyte secondary (Po2), vitellogenic primary oocyte (Vol).
Immature Ovary contains oogonia
and oocytes from primary growth (stage I).
In January, most clams were in the resting phase, although a small number of females showed small oogonia
on their follicular epithelium.
The defining female characteristics were the formation of protogonial germ tissue into spherical germ cell nests, separation of a tissue layer from the outer epithelial layer of the lobe-forming ovarian walls, a tissue bud growing from the suspensory tissue that helped form the ovary wall, and the proliferation of oogonia