EXPRESSION AND LOCALIZATION OF MEMBERS OF THE FIBROBLAST-GROWTH-FACTOR FAMILY IN THE BOVINE MAMMARY-GLAND

The goal of the study was to examine the expression and localization o f members of the fibroblast growth factor family in the bovine mammary gland during different developmental and functional stages. Mammary t issue was obtained from German Brown Swiss cows(n = 23) during defined stages of mammogenesis (before and during pregnancy), lactogenesis, p eak and late lactation, and involution. Extracted mRNA was analyzed by reverse transcription polymerase chain reaction and RNase protection assay. The tissue content of fibroblast growth factor-1 and fibroblast growth factor-2 was determined by radio-immunoassay, and the localiza tion of fibroblast growth factor-2 was determined by immunohistochemis try. The highest mRNA concentration for fibroblast growth factor-1, -2 , and -7 and their receptors was detected in the glands of virgin heif ers or primigravid heifers during involution; less abundant fibroblast growth factor mRNA was detected during lactogenesis and galactopoiesi s. Tissue protein concentrations of fibroblast growth factor-1 and fib roblast growth factor-2 showed similar tendencies. Immunoreactive fibr oblast growth factor-2 was observed during mammogenesis and involution in endothelial cells, ductal epithelial cells, myoepithelial cells, a nd some alveolar cells. After positive staining, fibroblast growth fac tor-2 could only be observed in endothelial and myoepithelial cells du ring lactogenesis and could only be observed in myoepithelial cells du ring galactopoiesis, Expression, tissue concentration, and distinct lo calization suggest that fibroblast growth factors may be important in the local regulation of the bovine mammary gland.