OOCYTE GROWTH IN THE CHICKEN - RECEPTORS AND MORE

The laying hen's left ovary (the ovary on the right side regresses dur ing embryonic development) at any given time contains 5-8 follicles wi th vitellogenic oocytes, i.e., female germ cells of increasing size ra nging from 8 to approx. 30 mm in diameter. Between the 8 mm and the 30 mm cell lie about 7 days of massive growth of the oocyte, which in es sence occurs via accumulation of yolk. While the chemical composition of the oocyte content, i.e., the yolk, is well known, the origin(s) of this material, its models) of accumulation in the oocyte, and the cel l biological details of the oocyte's specialized machineries for maint enance of structural organization and stability have only recently bee n begun to be elucidated. Here, we outline recent findings in the foll owing areas: ii) the role of low density lipoprotein receptor family m embers in the transport of yolk precursors from the plasma compartment into oocytes; these findings have implications for metabolic events i n certain other tissues such as the brain; and (ii) the synthetic and structural specialization of the granulosa cells, which surround the o ocyte within the ovarian follicle, as a model for epithelial cell biol ogy.