IN-VITRO MORPHOMETRIC AND PROLIFERATIVE VARIATIONS IN VIP-IMMUNOREACTIVE PITUITARY-CELLS INDUCED BY ESTRADIOL

Using double labelling for proliferating cell nuclear antigen (PCNA) a nd vasoactive intestinal peptide (VIP), a study was conducted to eluci date the repercussions of the addition of estradiol to monolayer pitui tary cultures on the morphology, size, number, mitotic index and PCNA labelling index of VIP-immunoreactive cells, comparing the results wit h those obtained in control cultures. The addition of estradiol (100 n M) over 3 h of incubation led to a significant increase (p < 0.01) in the cellular, cytoplasmic and nuclear areas of VIP-immunoreactive cell s and in the number of these cells. The same treatment elicited an eve n greater increase in the mitotic index (p < 0.01) and PCNA labelling index (p < 0.01) of VIP-immunoreactive cells. The results obtained sug gest that estrogens induce proliferation and hyperplasia of in vitro V IP-immunoreactive pituitary cells.