Abstract
The effects of cell stage and day of embryo collection on the pronase-induced zona pellucida morphology in pig embryos were investigated. Three hundred and seventy-two two-to eight-cell embryos were treated for 3.0 min in 5.0% pronase in Whitten's Medium. Responses in zona pellucida morphology observed after pronase treatment were: (1) absent, (2) stretched and (3) intact. Each pig was coded as to the type of zona pellucida morphology its embryos possessed after enzyme treatment according to the following scale: (1) — only intact, (2) — intact and stretched, (3) — only stretched, (4) — stretched and absent and (5) — only absent. Also, the number of embryos of a particular cell stage was expressed as a fraction of the total number of embryos collected from each pig. The incidence of intact zonae pellucidae was greatest (P<.05) among two- to three-cell embryos and the incidence of absent zonae pellucidae was greatest (P<.05) among six-to eight-cell embryos. A significant correlation (r = .79) was observed between day of embryo collection and coded zona pellucida morphology. The results suggest that the pronase-induced zona pellucida morphology observed is dependent on cell stage and day of embryo collection. Copyright © 1982. American Society of Animal Science . Copyright 1982 by American Society of Animal Science