| Abstract: | Patterns of cell proliferation show two distinct domains around avian pharyngeal closing plates as they form, perforate, and rupture. Pouch endoderm and groove ectoderm are in one domain showing 81–86% proliferation, which suggests relatively rapid growth. Cells in epithelia that comprise the pharyngeal closing plates contiguous with pouch and groove epithelia are vital but are dividing at a significantly lower percentage (62–64%). This phenomenon is similar to the lag in growth reported for cells in the oral membrane around the time of rupture (Miller and Olcott, 1989: Anat. Rec., 223:204–208), is consistent with Waterman's suggestion (1985: Anat. Rec., 211:450–457) that cellular reorganization, rather than massive degeneration, is a major mechanism of initial perforation, and suggests that differential growth is a contributor to perforation and rupture of chick pharyngeal closing plates. © 1993 Wiley-Liss, Inc. |
