Cell Proliferation in Chick Oral Membrane Lags Behind that of Adjacent Epithelia at the Time of Rupture

Sue Ann Miller and Christopher W. Olcott
Department of Biology, Hamilton College, Clinton, New York


Radioautographic analysis showed that ectoderm and endoderm cells in chick oral membrane continued to label with tritiated thymidine through the period of rupture, but their frequency of labeling was significantly lower than those of adjacent epithelia. Frequency of labeling increased in adjacent ectoderm and endoderm, while oral membrane rates remained relatively low, suggesting that growth in the membrane lags relative to adjacent epithelia. Relatively greater proliferation in adjacent epithelia could generate tension and pull apart the thinned oral membrane. Differentials in rates of cell proliferation, when considered along with knowledge of cellular rearrangements following changes in basal lamina and matrical components, suggest that differential growth is an important force in rupture of the avian oral membrane.

Anatomical Record 223:204-208 (1989)

Figure 5 Graphic display of average proliferation indices at five sites in 11 embryos shows differentials that occurred when adjacent epithelia increased rate of labeling while oral membrane cells lagged at lower frequencies of labeling.

Figure 1 Typical sample sites around the oral membrane in a sagittal section. Boxes represent placement of the ocular grid over ectoderm on the maxillary and mandibular processes (stomodeum) and endoderm in the preoral gut and pharynx. The entire oral membrane consituted one site.

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