Exogenous vitellogenesis and micropinocytosis in the lizard, Podarcis sicula, treated with follicle-stimulating hormone.
The regulation of oocyte growth and of exogenous vitellogenesis by micropinocytosis has been studied in lizard Podarcis sicula kept at 28 degrees during the winter stasis and stimulated by follicle-stimulating hormone (FSH). Under these experimental conditions, oocyte auxocytosis as well as vitellogenesis is stimulated, while the follicular hierarchy is preserved. At the ultrastructural level, the flow of exogenous yolk precursors toward the oocyte increases and the pathway taken by them through intercellular spaces and zona pellucida is the same as that taken by peroxidase (tracer). Yolk precursor endocytosis is found only in oocytes greater than 1500 microns in diameter and takes place through the formation of several coated pits and vesicles. It is suggested that membrane receptors necessary for micropinocytosis are available only in such oocytes. Last, a different permeability of the ovarian follicle to exogenous yolk precursors during the different stages of oocyte growth and endovarian control of vitellogenesis are suggested.
Limatola
E
E
Department of Evolutive and Comparative Biology, Faculty of Science, University of Naples, Italy.
Filosa
S
S
D000818:Animals; D002452:Cell Count; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology*; D006735:Horseradish Peroxidase / Q000378:metabolism; D008116:Lizards / Q000502:physiology*; D009865:Oocytes / Q000187:drug effects / Q000502:physiology / Q000648:ultrastructure; D006080:Ovarian Follicle / Q000187:drug effects / Q000502:physiology / Q000648:ultrastructure; D010873:Pinocytosis / Q000187:drug effects; D014818:Vitellogenesis / Q000187:drug effects
D005640:Follicle Stimulating Hormone; D006735:Horseradish Peroxidase