Cytoplasmic estrogen receptor concentrations in the endometrium of Finnish and Japanese women.

Cytoplasmic estrogen receptor concentrations in the endometrium were determined in 13 Finnish and 20 Japanese women. All the women were premenopausal and aged between 40 and 50. The concentration of estrogen receptors in the proliferative endometrium for Finnish women was 246.9 +/- 46.2 fmol/mg protein (mean +/- S.E.M.) and that for Japanese women 45.7 +/- 17.1 fmol/mg protein. The difference is significant (P less than 0.01). In the secretory endometrium the corresponding figures were 97.8 +/- 33.7 fmol/mg protein for Finnish and 20.0 +/- 6.4 fmol/mg protein for Japanese women (P less than 0.05). During the proliferative phase the serum estrone concentration was significantly higher in Finnish than in Japanese women (P less than 0.05).