Eur J Anat, 3 (2): 79-85 (1999)

In vivo studies on cytodifferentiation of pituitary aromatase- immunoreactive cells

Carretero J., Vazquez G., Martin-Clavijo A., Rubio M., Hernandez E., Moro J.A., Gato A., Barbosa E., Vazquez R.

Laboratorio de Neuroendocrinologia, Inst. Neurociencias Castilla y Leon, Facultad de Medicina, Avda. Alfonso X El Sabio s/n, E-37007 Salamanca, Spain

ABSTRACT We have recently described the presence of aromatase P450 in the adult rat hypophysis. This enzyme is responsible for the aromatization of testosterone into estradiol and has been implicated in prenatal cerebral differentiation and evolution. However, the ontogeny of hypophyseal aromatase is completely unknown and no information is available as to whether its appearance is related or not to the differentiation of the classic hypophyseal cell types from Rathke's pouch. Aiming to analyze the ontogeny of hypophyseal aromatase expression and to correlating this with hypophyseal cell differentiation, here we performed an immunocytochemical study of the hypophyses of rat fetuses from day 13.5 to 19 of prenatal development. The immunohistochemical expression of the enzyme was first observed on day E17 and this increased on day 19. The significant increase in cells immunoreactive to the enzyme (p<0.05) coincided with an increase in their mitotic index (p<0.05) from day 17 to day 19 and with a significant increase (p<0.05) in cellular size. Our results demonstrate the prenatal expression of hypophyseal aromatase and suggest a possible relationship between such expression and the differentiation of hormone-producing cells whose secretion is subject to regulation by gonadal steroids.

Keywords: aromatase, animal tissue, aromatization, article, cell differentiation, cytology, fetus, hypophysis, immunocompetent cell, immunoreactivity, in vivo study, mitosis index, nonhuman, ontogeny, protein expression, rat