Use of polymer casts or metal particle infusion of ducts to study antigen uptake in the guinea pig mammary gland.

Microcorrosion casts were made of the duct system of guinea pig mammary glands by intramammary infusion of Mercox polyester resin following involution of the glands after the first lactation. The acinar configuration of the involuted gland was apparent on examination of the casts by scanning electron microscopy (SEM). Surface features, which were readily identified as those of imprints of ductal epithelium, were visible at higher magnifications. The morphology of these casts corresponded to the patterns observed by SEM of ethanol cryofractured specimens of mammary tissue. Cryofractured specimens of guinea pig mammary glands were also examined by SEM following intramammary infusion of tantalum. Tantalum particles were observed within the lumina of many ducts. Large phagocytic cells within the lumina were shown to contain tantalum by using back scatter imaging in conjunction with secondary imaging.