Hairlessness in Mus musculus. A pathologic study.

The homozygous albino hairless mice at birth have hair bulbs and follicles the same as normal mice. Hairs develop and grow the same as in normal mice. However, about the sixth to eighth day hairs in the skin around the nose begin to disappear. This depletion of hairs continues over the head, neck, back, and abdomen of all mice in the same pattern. Essentially every hair over the entire body is absent macroscopically by the 30th to 40th day except for the vibrissae. A progressive atrophy of the hair bulbs and follicles is the basis for the absence of hairs after the first pelage. Only a rare follicle with a hair is present histologically in the adult mice. There are a few cysts in the dermis resulting from dilated residual hair follicles.