Silver-stained nucleolar organizer regions in the normal, hyperplastic and neoplastic endometrium.

The numbers of silver-stained nucleolar proteins (AgNORs) were counted in hyperplastic and neoplastic lesions of the endometrium and compared with those of normal proliferative and secretory phase endometrium. In glandular cells in the normal menstrual cycle, the mean number of AgNORs in proliferative phase endometrium (3.8) was significantly higher than that in secretory phase endometrium (2.7, P less than 0.05). The mean number of AgNORs in well-differentiated endometrioid type adenocarcinoma (5.5) was significantly higher than that in both complex hyperplasia without cytological atypia (3.6, P less than 0.01), and simple hyperplasia (3.3, P less than 0.01). Mean AgNOR counts in complex hyperplasia with cytological atypia were greater than those in both complex hyperplasia without cytological atypia (P less than 0.05) and simple hyperplasia (P less than 0.05). Thus, complex hyperplasia with cytological atypia appears to be a direct precursor of well-differentiated endometrioid type adenocarcinoma. These findings suggest that the mean numbers of AgNORs are increased in neoplastic changes in the endometrium, and the one-step colloid method for AgNORs may therefore be a simple and useful technique to examine proliferative activity in neoplastic and pre-neoplastic endometrial cells.