An obligatory role for @entity172 in growth, development, and functions of the mammary gland is well established, but the roles of the two @entity172 receptors remain unclear. With the use of specific antibodies, it was found that both @entity172 receptors, @entity7605 and @entity12209 , are expressed in the @entity35 mammary gland but the presence and cellular distribution of the two receptors are distinct. In prepubertal @entity35 , @entity7605 was detected in 40% of the epithelial cell nuclei. This decreased to 30% at puberty and continued to decrease throughout pregnancy to a low of 5% at day 14. During lactation there was a large induction of @entity7605 with up to 70% of the nuclei positive at day 21. Approximately 60-70% of epithelial cells expressed @entity12209 at all stages of breast development. Cells coexpressing @entity7605 and @entity12209 were rare during pregnancy, a proliferative phase, but they represented up to 60% of the epithelial cells during lactation, a postproliferative phase. Western blot analysis and @entity969 gradient centrifugation confirmed this pattern of expression. During pregnancy, the proliferating cell nuclear antigen was not expressed in @entity7605 -positive cells but was observed in 3-7% of @entity12209 -containing cells. Because more than 90% of @entity12209 -bearing cells do not proliferate, and 55-70% of the dividing cells have neither @entity7605 nor @entity12209 , it is clear that the presence of these receptors in epithelial cells is not a prerequisite for @entity172 -mediated proliferation.

XXXX receptors alpha and beta in the rodent mammary gland.

@entity172 :: ('MESH:D004967', 'Chemical') :: ['estrogen'] @entity7605 :: ('24890(Tax:10116)', 'Gene') :: ['ERalpha'] @entity12209 :: ('25149(Tax:10116)', 'Gene') :: ['ERbeta'] @entity969 :: ('MESH:D013395', 'Chemical') :: ['sucrose'] @entity35 :: ('10116', 'Species') :: ['rat', 'rats']
@entity172 :: (MESH:D004967,Chemical) :: ['Estrogen']
