Localization of the mRNA encoding the zona protein ZP3α in the porcine ovary, oocyte and embryo by non-radioactivein situ hybridization

Abstract

The mRNA of the zona pellucida glycoprotein ZP3 alpha was localized in frozen sections of pig ovaries, isolated oocytes and early embryos by in situ hybridization using biotinylated oligonucleotide probes. In follicles, the distribution of mRNA for ZP3 alpha was correlated with the developmental stage: in primordial and primary follicles, the mRNA was shown to be predominantly localized in the oocyte. In secondary follicles, mRNA was found in both the oocyte and follicle cells. In tertiary and preovulatory follicles, the follicle cells showed distinct staining, whereas the oocyte was labelled weakly. In the early embryo, i.e. 2 days after fertilization, mRNA for ZP3 alpha could not be demonstrated. Our results suggest that, in the pig, the zona pellucida protein ZP3 alpha is synthesized by the oocyte and the follicle cells in sequence. After fertilization, synthesis of ZP3 alpha is terminated.

Detection of zona pellucida proteins during human folliculogenesis

“…This could conflict with the concept that primordial follicles, including the oocyte, are quiescent until selected into the growth pool. Evidence of at least one of the ZP proteins within oocytes of a majority of primordial follicles in other mammalian species (Kang, 1974;Wolgemuth et al, 1984;Epifano et al, 1995;Grootenhuis et al, 1996;Kolle et al, 1996;Martinez et al, 1996) confirms our observation that appearance of these proteins does not signify recruitment.…”

“…Coexistence in the human oocyte and granulosa cells would concur with observations in a number of mammalian species (Wolgemuth et al, 1984;Lee and Dunbar, 1993;Grootenhuis et al, 1996;Kolle et al, 1996;Martinez et al, 1996;Prasad et al, 2000;Bogner et al, 2004), with the exception of the mouse, where detection is limited to the oocyte (Epifano et al, 1995;El-Mestrah et al, 2002). Although coexistence of ZP protein in both the oocyte and the granulosa cells is associated with developing follicles, the stage at which ZP protein is initially detected varies in the above studies.…”

“…ZP synthesis has been confirmed by the presence of mRNA using in situ hybridization in both the oocyte and the granulosa cells of porcine and Macaca fascicularis secondary follicles (Kolle et al, 1996;Martinez et al, 1996). In the oocyte, the level of ZP mRNA increased throughout the secondary follicular stage peaking in the small antral follicle when the oocyte acquires maximum size (Roller et al, 1989;Epifano et al, 1995;Bogner et al, 2004).…”

“…Although coexistence of ZP protein in both the oocyte and the granulosa cells is associated with developing follicles, the stage at which ZP protein is initially detected varies in the above studies. ZP proteins in granulosa cells are detected consistently at the secondary stage of follicular development (Wolgemuth et al, 1984;Lee and Dunbar, 1993;Grootenhuis et al, 1996;Kolle et al, 1996;Martinez et al, 1996;Prasad et al, 2000;Bogner et al, 2004). When all three proteins were assessed concurrently (Martinez et al, 1996;Bogner et al, 2004), only one protein was detected in granulosa cells in the primary follicle whereas, by the secondary stage, all three proteins were present in granulosa cells.…”

“…Expression of the gene for at least one of the ZP proteins has been demonstrated in quiescent early porcine (Kolle et al, 1996) and mouse (Epifano et al, 1995) follicles. In the mouse follicle, ZP synthesis is confined solely to the oocyte (Epifano et al, 1995;El-Mestrah et al, 2002).…”