Proliferation and apoptosis in normal bitch mammary tissues in relation to progesterone level

Abstract

The objective of this study was to investigate the proliferating activity and apoptosis in canine normal mammary tissues in different cycle stages. Mammary tissues were collected from five beagle bitches at six different estrous stages: anestrus, proestrus, estrus, early diestrus, mid diestrus, and late diestrus. The expression of Ki-67 protein and apoptotic bodies was evaluated by avidin-biotin-peroxidase complex (ABC) method and TUNEL assay, respectively. Percentage of Ki-67 positive cells and apoptotic bodies was calculated. The significant highest percentage of Ki-67 positive cells and apoptotic bodies was observed at mid diestrus. Positive correlation was found mainly in the alveolar epithelium between progesterone levels and percentage of Ki-67 positive cells, as well as between progesterone levels and apoptosis. In conclusion, the results from the present study suggested that progesterone may influence on proliferation and apoptosis in canine mammary tissue. © 2010 Springer-Verlag London Limited.