EN
Bovine mammary gland is a unique organ with regard to its frequently repeating cycles of growth and involution throughout the life of an animal. In literature there is only scarce information concerning development of its specific epithelium and in particular about the stem and progenitor cells. Knowledge about this subject is essential in terms of further improvement of dairy cows production capacity in the future. It may also provide an answer to the question concerning the lack of carcinogenesic transformation in bovine mammary gland, as frequency of tumours in this tissue equals zero. The morphological features of human mammary gland are more similar to those in cattle than in rodents, commonly used for carcinogenetic studies. The results obtained on the bovine model may also constitute a basis for understanding fundamentals of carcinogenesis in human mammary gland.To confirm the presence of mammary stem cells, many in vitro and in vivo studies were conducted with the use of transplantation, electron microscopy, functional techniques, flow cytometry, scanning cytometry and microarrays. Unfortunately, until now no universal molecular marker was found which could make it easier to identify these cells. It has been suggested that the population of cells Sca-1pos CD45neg, for which the lack of steroid receptors is characteristic, may indicate the stem cell population. In our current studies it was found that in the mammary gland tissue, parallel to Sca-1pos CD45neg cells, a population of Sca-1pos CD45pos cells exists which might be of hematopoietic origin.This non-epithelial lineage may enrich the stem/progenitor cell population in the mammary gland facilitating mammary gland renewal.