IMMUNOCYTOCHEMICAL CHARACTERIZATION OF PORCINE ZONA-PELLUCIDA DURING FOLLICULAR DEVELOPMENT

Sections of bovine ovaries fixed in Bouin's fluid or methanol-acetic a cid and embedded in paraffin were incubated with chicken polyclonal an tibodies to HPLC-purified zona glycoproteins ZP3 alpha and ZP3 beta. O ocytes of primordial follicles as well as of primary follicles showed weak labelling with anti-ZP3 alpha and antiZP3 beta. No immunostaining could be observed in the follicle cells. The ZP of primary follicles displayed distinct immunoreactivity for both ZP3 alpha and ZP3 beta. I n secondary follicles, distinct labelling with anti-ZP3 beta and weak labelling with anti-ZP3 alpha could be seen in the oocyte. The ZP show ed immunoreactivity with antibodies to ZP3 alpha and ZP3 beta. Both an tibodies labelled single follicle cells. In tertiary follicles, the oo cytes were weakly labelled with anti-ZP3 alpha and anti-ZP3 beta. Some granulosa cells showed staining for ZP3 alpha and ZP3 beta. The ZP di splayed strong immunoreactivity for ZP3 beta and ZP3 alpha. Cells of t he corona radiata were strongly immunopositive for ZP3 alpha and ZP3 b eta. Similar histotopography of immunoreactive cells could be seen in preovulatory follicles. The characteristic pattern observed for the di stribution of ZP3 alpha and ZP3 beta strongly suggests that in the por cine ovary both the oocyte and the follicle cells contribute to the sy nthesis of the ZP, perhaps in sequence.