The microstructure and gene expression of lactating and non-lactating mammary gland tissue in the dairy cow. (A) Paraffin sections of bovine mammary gland in the lactation period (100×). (B) Paraffin sections of bovine mammary gland in the non-lactation period (100×). In (A) and (B), the MG sections were stained with hematoxylin-eosin using standard procedures. Nuclei are dyed blue by hematoxylin, and the cytoplasm is stained pink by eosin. Hematoxylin-eosin stained sections were analyzed using light microscopy. (C) Expression of α-casein in lactating bovine mammary glands (100×). (D) Expression of α-casein in non-lactating bovine mammary glands (100×). In (C) and (D), nuclei are in blue as marked by DAPI, and the α-casein signal is in green. Alpha-casein was detected using immunofluorescence using an anti-α-casein antibody followed by HRP-conjugated goat anti-rabbit IgG and analysis using fluorescence microscopy. (E) Expression of αs1-casein mRNA in lactating and non-lactating bovine mammary glands using real-time PCR.