Histological response of bovine mammary tissue to an intracisternal bead device.

Placement of an intracisternal bead device into teat cisterns of dairy cows at drying off was studied. Histological analysis of teat cisternal tissues from quarters fitted with devices demonstrated significant elevation in leukocyte infiltration and hypertrophy of the epithelial lining. Tissue changes ranged from degeneration and sloughing of surface cells of double-layered epithelia to marked thickening and lysis of cisternal epithelium, leaving only the basement membrane intact. Quantification of mammary parenchymal components from quarters fitted with devices demonstrated no differences in percentage area occupied by alveolar epithelium, lumen, and intraalveolar stroma from unfitted control quarters. However, quantification of leukocyte numbers demonstrated slightly greater leukocytosis into tissues of quarters fitted with devices in comparison with controls. Devices were successful in stimulating a localized leukocytosis into teat cisternal tissues, which may serve to amplify the leukocyte response to mastitis-causing organisms once they penetrate the teat duct.