Changes in parafollicular cells of rats neonatally treated with estradiol.

The parafollicular cells of male and female rats neonatally (3rd day) treated with a single dose (1 mg) of estradiol dipropionate, and sacrificed in peripubertal (38th day) or adult (80th day) period of life, were investigated. These studies included examinations of silver-stained properties of parafollicular cells, morphometric analyses of both the cells and nuclear area and ultrastructural characteristics. Estradiol treatment led to a significant increase of the cellular and nuclear area (micron 2) in both females and males. Different from intact animals remarkable degranulation and hyperplasia of parafollicular cells were evident in estradiol-treated rats. It may be concluded that this sexual hormone applied in neonatal period has an effect on parafollicular cells expressed up to adult period of life.