Cellular proliferation in the anterior pituitary of the rat during the postnatal period

Cellular proliferation in the anterior pituitary of 2-, 8-, 15- and 30-day-old rats was examined by injection of bromodeoxyuridine 1 h before autopsy. Bromodeoxyuridine incorporated into DNA was detected immunohistochemically by use of a monoclonal antibody. The highest rate of cell proliferation was found in 2-day-old animals; it decreased thereafter during the postnatal period. Possible toxic effects of colchicine on cellular proliferation were examined. Colchicine treatment (10 mg/kg in 8- and 30-day-old animals) significantly decreased the number of bromodeoxyuridine-labelled cells/mm2 in 8-day-old rats. Some sections were doubly immunostained for bromodeoxyuridine and various pituitary hormones. The proportion of doubly-immunostained cells to all proliferating cells was generally low, ranging from 23% at 2 days to 32% at 30 days of age.