Anatomical variation of the oestrogen receptor in the non-neoplastic myometrium of fibromyomatous uteri.

Myometrial tissues from a total of 30 normal and 30 fibromyomatous uteri were compared in order to assess whether the oestrogen receptor distribution is similar for both types. All patients concerned were premenopausal with no history of exogenous hormone usage. Material taken from the subserosal, midmyometrial and subendometrial regions of both the fundus and the lower segment was stained by immunocytochemistry for the oestrogen receptor. No significant difference in the oestrogen receptor content was noted between the fundus and the lower segment in either the normal or the fibromyomatous myometria. Similarly, the phase of the menstrual cycle did not affect the total receptor content of either group of tissue. The oestrogen receptor content in the non-neoplastic portion of the fibromyomatous myometria was highest in the subendometrial and lowest in the subserosal region. The differences in receptor content between normal and fibromyomatous myometria were minimal in the subendometrial region but marked in the subserosal region. The myometrium of fibromyomatous uteri thus expresses significantly increased levels of oestrogen receptor, and the pathogenesis of fibromyomata may be related to an inherent abnormality in the myometrium.