Follicle formation in the embryonic chick thyroid. II. Reorganization after dissociation.

Abstract

The events which occur after reaggregation of dissociated embryonic chick thyroid cells are described. Although the cells rearrange themselves into follicles within a few hours after being packed by centrifugation, their complex cytoarchitecture is not maintained. The first sign of an impending change is the accumulation of large numbers of dense bodies in the apical cytoplasm. Shortly thereafter other types of lytic bodies become numerous, and blebs containing cytoplasmic membranous components appear at the apical cell surfaces. A short time later the basal cytoplasm contains large residual bodies concomitant with a reduction in the extent of the canalicular endoplasmic reticulum and an increase in the number of free ribosomes. With the passage of time there is a progressive decrease in the size and number of residual bodies, and the channels of rough endoplasmic reticulum reappear until the normal thyroid pattern is restored. Lytic phenomena coupled with vesiculation of the endoplasmic reticulum have been linked with control of function in several organs. Therefore, the results are discussed in terms of a possible realtionship between lytic activity and the reestablishment of thyroid function after dissociation.