Expression of aminopeptidase N and neutral endopeptidase on the endometrial stromal cells in endometriosis and adenomyosis.

Indirect immunofluorescence staining revealed that endometrial stromal cells (ESC) in the ectopic endometrium of patients with endometriosis or adenomyosis expressed aminopeptidase N/cluster of differentiation (CD) 13 antigen and neutral endopeptidase/CD10 antigen, both of which are expressed on ESC in the normal endometrium throughout the menstrual cycle. Thus, ESC in the ectopic endometrium resembled ESC in the normal endometrium not only morphologically but also antigenically. Both peptidase antigens may be useful markers for the histological diagnosis of endometriosis and adenomyosis.