Histological distribution of MTV antigen in mice detected by immuno-peroxidase staining.

Histological localization of mammary tumor virus (MTV) antigen was investigated using a variety of organs high (DD/Tbr, SHN, SLN, GR) and low (BALB/c) mammary cancer mice strains and immuno-peroxidase staining with MTV antigen. Except for BALB/c strain mice, the mammary gland and mammary tumors were generally positive. Accessory male genital organs including the prostate, seminal vesicle, and coagulating gland also demonstrated a positive reaction, but the testis and female genital organs including uterus and ovaries did not. MTV antigen was also revealed in the serous acini of the salivary gland in both sexes. The site of positive reaction in the accessory male sex organs and salivary gland was located in the apical portion of the secretory epithelial cells and their secretory substance. Localization and intensity of antigenic expression of MTV detected histologically were comparable to results obtained by immunodiffusion test and radioimmunoassay. These evidences support the idea that MTV is transmitted horizontally via seminal fluid or saliva.