Journal of Animal Science, Vol 69, Issue 2 599-608, Copyright © 1991 by American Society of Animal Science

JOURNAL ARTICLE

Histological evaluation of ovine mammary tissue xenografted into cyclosporine-treated mice

T. E. Daniel, R. M. Akers and T. B. McFadden
Dept. of Dairy Sci., Virginia Polytechnic Institute and State University, Blacksburg 24061-0315.

Histological and pathological alterations of ovine mammary parenchyma xenografted into cyclosporine-treated mice were studied. Forty-two mature, virgin female mice were assigned randomly to one of four treatments: 1) control, 2) control + estrogen/progesterone, 3) cyclosporine, and 4) cyclosporine + estrogen/progesterone. All mice received two subcutaneous mammary tissue explants taken from an estrogen and progesterone-primed ewe. After 3, 7, 14, 21, and 35 d, mice were killed and tissue was removed for an evaluation of epithelial morphology on a scale from 1 (poor) to 5 (excellent). Leukocyte type and number were determined in subepithelial stroma. The mean epithelial score for tissue collected on d 7 and d 21 were higher (P less than .05) for cyclosporine treatments (3.0) than for controls (1.6). Scores also were greater (P less than .01) when cyclosporine was combined with estrogen and progesterone than when cyclosporine was the sole treatment (3.8 vs 2.3). Epithelial scores for tissue recovered from mice given cyclosporine and steroids up to 35 d were not different from those of explants fixed at zero time. However, scores were lower (P less than .05) for three of five time periods for explants recovered from mice given cyclosporine alone. Lymphocyte number was higher (P less than .07) in controls (66) than in mice given cyclosporine and steroids (13 per field). The correlation between lymphocyte number and epithelial score was -.55. These results indicate that ovine mammary tissue xenografted into mice treated with cyclosporine can maintain a normal histological structure for an extended period of time.