Experimental manipulation of desmosome formation.

In the corneal epithelium of the embryonic chick there is a 3- to 4-fold increase in desmosomes between the 15th and 16th days of incubation which has not been noted in earlier studies of this tissue. This finding has made it feasible to study the effects of the local cell environment on desmosome formation. Cells of 15-day corneas which were forming desmosomes rapidly, were dispersed and combined in culture with cells from 10-day corneas which were forming few desmosomes. Surfaces of the same 15-day cell which were confronted with either another 15-day cell or a 10-day cell were compared. Desmosomes formed preferentially on the surface adjacent to a like cell. When 15-day cells were confronted with pigment cells, desmosomes formed almost exclusively on the surface adjacent to a like cell. Evidence for such localized differences on the same cell surface emphasize the importance of the immediate cell environment in desmosome formation. The observation that single desmosome plaques form occasionally on lateral cell surfaces has been noted previously. This finding was confirmed.