[Functional morphology of breast APUD cells in dysplasia and neoplastic processes].

Histochemical and immunohistochemical methods were used to examine 29 malignant tumors (18 lobular and 11 invasive carcinomas) and 34 fibroadenomas of the mammary gland (MG). APUD cells containing serotonin, melatonin, and beta-endorphine were shown to be present in the duct epithelium of the normal MG and its pericanalicular fibroadenoma. APUD cells were detected in 21 of the 29 malignant tumours of MG. Hormonal differences of APUD cells were found in poorly and well differentiated carcinomas: the former contained serotonin, melatonin, and beta-endorphine (inhibitors of proliferation), the latter--insulin and adrenocorticotropic hormone (stimulators of cell division). Such differences in the endocrine function of MG malignant tumors are likely to be significant in the clinical course and determination of prognosis for carcinomas of various differentiation.