Oestrogen receptor alpha in female fetal, infant, and child mammary tissue

Oestrogen receptor alpha (ER alpha) expression was studied in female mammar y tissue from a series of 35 samples obtained post-mortem, ranging from fet uses of 13 weeks' gestation to prepubertal children of 12 years. Immunocyto chemistry was performed on formalin-fixed tissue after microwave antigen re trieval. ER alpha was present in epithelial cell nuclei from the 30th week of gestation onwards and was markedly up-regulated shortly after birth. For up to 3 months thereafter, progesterone receptor was also expressed, indic ative that the ER alpha was functional. During this period, ER alpha was al so present in epithelial cell cytoplasm. From this perspective of the devel oping breast, it is suggested that an early postnatal component should be a dded to the prenatal oestrogen hypothesis; further, the significance of ER alpha cytoplasmic staining in the adult breast also merits review. Copyrigh t (C) 2000 John Wiley & Sons, Ltd.