Hormonal regulation of gap junction differentiation.

Abstract

Thin-section, tracer and freeze-cleave experiments on hypophysectomized Rana pipiens larvae reveal that gap junctions form between differentiating ependymoglial cells in response to thyroid hormone. These junctions assemble in large particle-free areas of the plasma membrane known as formation plaques. Between 20 and 40 h after hormone application, formation plaque area increases approximately 26-fold while gap junction area rises about 20-fold. The differentiation of these junctions requires the synthesis of new protein and probably RNA. Based on inhibitor experiments, it can be reported that formation plaques develop at about 16-20 h after hormone treatment and stages in the construction of gap junctions appear 4-8 later. Gap junction subunits are probably synthesized and inserted into formation plaque membrane during the differentiation of the anuran ependymoglia cells.