Cell contact-dependent mechanisms specify taste bud pattern during a critical period early in embryonic development.
After gastrulation, the pharyngeal endoderm is specified to give rise to taste receptor organs without further signaling from other embryonic tissues. We hypothesized that intercellular signaling might be responsible for the specification of taste buds. To test if and when this signaling was occurring, intercellular contacts were transiently disrupted in cultures of pharyngeal endoderm from axolotl embryos, and the number, size, and distribution of taste buds analyzed. Disruption of cell contacts at progressive time points, from neurula to late tail bud stages, revealed a critical period, during mid-tail bud stages, when disruption of cell contacts resulted in a significant increase in taste bud number and size. The spatial distribution of taste buds was also altered; taste buds were more clustered in explants disrupted during the critical period. These effects were not due to general alterations in mitosis and apoptosis. Rather, at least three aspects of taste bud patterning, i.e., number, size, and distribution, are governed by mechanisms dependent on normal cell contacts during a concise time window. Furthermore, our findings are consistent with specification of taste buds by means of lateral inhibitory signaling, which we hypothesize results from cell contact-dependent or short-range diffusible signals.
Parker
Mark A
MA
Department of Cell and Developmental Biology and Rocky Mountain Taste and Smell Center, University of Colorado Health Sciences Center, Denver, 80262, USA.
Bell
Melanie L
ML
Barlow
Linda A
LA
D000557:Ambystoma; D000818:Animals; D019521:Body Patterning; D002450:Cell Communication; D016923:Cell Death; D002462:Cell Membrane / Q000378:metabolism; D049109:Cell Proliferation; D047108:Embryonic Development; D004707:Endoderm / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D007091:Image Processing, Computer-Assisted; D016014:Linear Models; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D010614:Pharynx / Q000196:embryology; D051381:Rats; D015398:Signal Transduction; D013650:Taste Buds / Q000196:embryology*; D013997:Time Factors