Mammary gland remodelling is strictly related to intracellular signals and stem cell biology. Among the best candidates to identify the nature and development of mammary cells are cytokeratin 19 (CK19), the Na-K-Cl cotransporter (NKCC1) and receptor of estrogen alpha (ERα). In this study, we analyzed the expression of these genes in ewe mammary glands from prepubertal stage to involution. Using Real time PCR we showed that NKCC1 transcription was significantly down regulated during lactation and at involution in comparison to the expression measured in the prepubertal group. No significant differences were found in CK19 expression, whereas ERa transcription was significantly down regulated before lambing, during lactation and at involution. In situ hybridization analysis confirmed quantitative data and localized the CK 19 transcript at basal and luminal compartment of terminal ductal unit (TDU) of prepubertal mammary glands. NKCC1 expression was also present in lactating glands and ERα in connective tissue surrounding TDU. The characterization and identification of mammary developmental markers in the tissue of dairy animals is necessary to gain knowledge in mammary gland biology.
