Effects of cold on the skeletal growth of albino rats.

Two groups of male albino rats of 26 days old, were kept at 5°C and 28°C respectively. Their growth was studied by weekly gross measurements and biweekly radiographic investigations for 16 weeks. Compared with the controls at 28°C, the rats kept at 5°C showed the following effects of cold in their growth: (1) Smaller measurements at all ages; (2) Slower growth rates in the first two to four weeks; (3) Relatively shorter tail and shorter feet but body weight was the same as the controls of the same body lengths irrespective of age; (4) Shorter but relatively thicker bones; (5) A disto-proximal stunting gradient was observed in the tail and limb bones, showing more severe effect in the distal segments and decreasing effect in the proximal segments; (6) Retardation of skeletal maturational status in the naked appendages (tail and foot); (7) Decreased number (1.4) of ossified caudal vertebrae. The above phenomena were discussed as results of possible reduction of blood flow to the skeletal tissue on cold exposure.