Hair follicle destruction and regeneration in guinea pig skin after cutaneous freeze injury.

We have investigated the histological changes in hair follicles in guinea pig skin after standardized moderate and severe cryosurgery injuries. Hair follicles were permanently destroyed by cryosurgery, but more than one mechanism may be operative during follicle destruction and shedding. The mechanism depends upon the severity of the freeze. After a light freeze injury, the changes are predominantly within the hair follicle. The hair is shed at the surface and there is selective autolysis of follicular cells, but dermal connective tissue is preserved and there is little surrounding damage. However, after a severe cryoinjury as used in "tumor doses," there is destruction of dermal connective tissue and dermal scarring. The necrotic dermis is shed, taking with it the dead follicles and morphologically normal elastic tissue.