The extracellular matrix surrounding the oocyte before ovulation is called perivitelline membrane (PL) in avian species. We previously reported that one of its components, ZPC, is produced in the ovarian granulosa cells by the stimulation of follicle-stimulating hormone and testosterone. Another component, ZP+, is synthesized in the liver, and might be transported to surface of the oocyte in the follicles. These glycoproteins are assembled to form a three-dimensional network of coarse fiber

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... een the granulosa cells and the oocyte. In order to address the mode of PL formation, we investigated the progressive changes in contents of ZP+ and ZPC in PL during the follicular development in quail ovary. Western blot analysis using specific antisera indicated that ZP+ band was first appeared as 31 kDa in molecular mass when the granulosa layer was isolated from the fourth largest follicle, and the intensity of the band was dramatically increased after the follicle matured to the third largest one. On the other hand, immunoreactive ZPC appeared as early as in the granulosa layer obtained from the small yellow follicles (SYF), and the intensity of the immunoreactive band increased progressively during follicular development. The immunohistochemical analysis indicated that the immunoreactive ZP+ and ZPC were not detected on the sections of follicular wall of the very small stroma-embedded white follicles. The immunoreactive ZPC was detected in the PL of SYF sections, whereas no detectable ZP+ was seen in the SYF sections. These results demonstrated that the accumulation of ZP+ was not synchronized to that of ZPC in the PL during follicular development. Alternatively, the accumulation of ZPC in the PL was preceded to that of ZP+ during follicular development in quail ovary.