Abstract
Ovarian tumours arising in dogs following administration of diethylstilbœstrol consist of proliferating surface epithelium and epithelial cell-groups closely resembling the sub-surface epithelial structures (SES) found in normal canine ovaries. The main points of similarity of the neoplastic groups to normal SES were: (a) Frequent direct attachment to the surface epithelium, (b) Limitation to the outer part of the ovarian cortex, (c) Epithelial nature and general histological features, (d) Production of a histochemically identical mucinous secretion and intracytoplasmic droplets.
The epithelial proliferation was derived mainly from the surface epithelium but some may have come from pre-existing SES. Follicular growth and maturation were suppressed.
Histochemical observations on secretory activity indicate that lesions on serosal surfaces and in lymph nodes were metastases of ovarian origin.