Histological and Morphometrical Studies on the Rat Nipple during the Reproductive Cycle

摘要: Histological changes in the rat nipple during reproductive cycle were observed. In virgin and first half (days 5 10) of pregnancy, had a dull conical shape germinative layer epidermis, thicker than that skin surrounding nipple, deeply ingrew into dermis basal region. From second 15 20) pregnancy to post-weaning period, appeared columnar many wrinkles observed wall especially lactating period. Collagen fibers longitudinally running mainly comprised became loose lactation. Small numbers elastic parallel with smooth muscles also wall, these increased number thickness from most frizzy structures Around lactiferous sinus, muscle cells arranged but few seen concentric layer, period sinus was distended epithelial folds Morphometrical analysis indicated length reached maximum on day lactation, approximately 3.7 times The outer diameter lactation twice virgin. size decreased gradually after weaning. These observations suggest histological characterized by hyperplasia epidermis hypertrophy connective tissue pregnancy.