Experimental fusion of the naturally cleft, embryonic chick palate.
The palatal shelf medial edges of day 8 (Hamburger-Hamilton [HH] stages 32-33) and day 9 (HH stage 35) embryonic chicks were surgically disrupted in ovo and in vitro in an attempt to discover if the naturally cleft chick palate could be induced to fuse experimentally. At HH stages 32-33 (day 8) the chick palatal shelves were apart at the time of in ovo operation. Consequently, their medial edges did not fuse but rather underwent embryonic would healing with re-epithelialisation (which often formed needle track invaginations), but no signs of inflammation or scar or scab tissue formation. Conversely, at HH stage 35 (day 9) the palatal shelves are in contact at the time of in ovo operation and so underwent fusion. The extent of palatal fusion depended upon the extent of initial medial edge epithelial disruption. Fusion did not spread from the operated sites to adjacent unoperated areas, where the palatal shelves were in contact with each other. Occasional epithelial seams were formed, but these persisted and did not undergo cell death. There was no evidence of inflammation or scar or scab tissue at the operated sites. Abnormal bony and muscular blastemae appeared in the continuity zones of these experimentally intact chick palates. Mortality was high for embryos operated upon in ovo. Palatal shelves explanted from HH stages 32, 33, and 35 chick embryos and cultured in vitro with their medial edges in contact did not fuse unless their medial edge epithelia were surgically disrupted, in which cases fusion always occurred regardless of the stage of the explanted shelves.(ABSTRACT TRUNCATED AT 250 WORDS)
D000818:Animals; D002470:Cell Survival; D002642:Chick Embryo; D002972:Cleft Palate / Q000196:embryology; D004195:Disease Models, Animal; D007839:Functional Laterality; D009924:Organ Culture Techniques; D010159:Palate / Q000166:cytology / Q000196:embryology* / Q000601:surgery