抄録
Vitellogenesis in oviparous species corresponds to accumulation of nutrients in oocytes and their storage as yolk used by embryos and larvae during their development. In fish the main yolk component is vitellogenin (VTG) a glycophospholipoprotein synthesized by the liver under estrogenic induction and specifically incorporated into oocytes by receptor-mediated endocytosis. We have cloned the 91 kDa VTG receptor in rainbow trout. Its transcription occurs very early in young previtellogenic ovarian follicles when the oocyte sets up the necessary molecules and tools for its subsequent endocytotic activity. Lipid droplets are the other important yolk moiety. They could come from the sequestration of VLDL in outer somatic oocyte envelopes by specific receptors with O-linked sugar domain. These two ovarian receptors are members of the LDLR superfamily. They exhibit strong homology with oviparous ovarian follicle receptors. A review of oviparous species LRPs ensuring a pivotal event in the reproductive function is given, with special emphasis to chicken yolk receptors.
