Endocrine cells are normal inhabitants of the para-urethral, Bartholin's and endocervical glands and of mesonephric rests. All these cells were characterized as serotonin-storing cells. In the para-urethral and Bartholin's glands, serotonin-containing cells were most often found in the transitional epithelium of excretory ducts. Endocrine cells participated in some pathological conditions. Abundant argentaffin cells were observed among the terminal ductules in chronic bartholinitis and serotonin-storing cells were identified in a peculiar ectocervical epithelium. Numerous serotonin-storing cells were detected in a well-differentiated adenocarcinoma of cervix occurring in a patient with the Peutz-Jeghers syndrome. Argyrophilic cells were present in cases of endometrial carcinomas; a striking feature was the demonstration of gut peptide hormones in an unusual type of endometrial adenocarcinoma. Finally, serotonin-storing cells were a constituent of Brenner tumours. It is suggested that a similar endocrine pattern may be shared by tissues originating from both Müllerian ducts and the urogenital sinus.