CHANGES IN THE HORMONE DEPENDENCY OF EPITHELIAL-CELL PROLIFERATION IN THE GENITAL-TRACT OF MICE FOLLOWING NEONATAL ESTROGEN-TREATMENT

The genital tract epithelium of the female laboratory mouse has been widely studied as a model of oestrogen-dependent growth and proliferation. Perturbation of the hormonal imprinting of these tissues during neonatal development has also been used to study the development of pathological abnormalities, particularly in the cervical epithelium. This study demonstrates that mice treated neonatally from days 1-5 with supraphysiological concentrations of oestrogen are able to maintain high levels of proliferation following the removal of the ovaries later in adult life. This high level of proliferation was shown to be independent of the ovarian oestrogens and of oestrogens produced peripherally by aromatisation. These results suggest conversion of the genital tract in these mice to a fully hormonal "independent" state. However, neonatal treatment with oestrogen was not found to produce a uniform change to hormonal independence. Further challenge of the adult ovariectomised mice with oestrogen, demonstrated that a population of cells still retained the ability to respond to the mitogenic influence of this hormone.