GROWTH OF THE MAMMARY-GLAND IN RHINO MOUSE

The rhino mouse, so called because of its characteristic rhinocerous-l ike skin cannot raise its young. Although the animal has rudimentary m ammary glands, these are thought to be defective due to their impossib ility to raise their young. Morphological observations of the female m ammary glands of rhino mice (hr(rh)/hr(rh)) were carried out and the r esults were compared with those of their normal litter mates (hr(rh)/) at various ages from 1 month to 1 year. No morphological differences in mammary gland development was seen between the rhino mice and thei r normal litter mates, and normal secretory changes were observed in t he rhino mice after delivery. Mouse mammary tumor virus (MMTV) express ion and the occurrence of hyperplastic alveolar nodule (HAN) were anal ogous to these features in phenotypically normal hr(rh)/+ mice. Furthe r, the sweat glands in the rhino mouse were normal. Thus, anomalies in the rhino mouse appeared to be limited to the skin and pilosebaceous apparatus.