Changes in adipose tissue of the rat due to early undernutrition followed by rehabilitation. 1. Body composition and adipose tissue cellularity.

1. Male Black and White Hooded rats were allocated at birth to foster mothers in litters of three, nine or sixteen. At weaning animals from each of these litter sizes were ad lib.-fed on a stock diet forming three ad lib.-fed control groups. At weaning further animals from litters of nine and sixteen were fed on the stock diet in restricted amounts until 12 weeks of age. These undernourished animals were then rehabilitated by being allowed ad lib. access to the stock diet. 2. Five animals from each group were killed at various stages of the experiment, their bodies analysed for fat and nitrogen, and the size and number of cells determined in four specific fat depots. 3. The previously undernourished rats failed to make a complete recovery and were significantly smaller than ad lib.-fed animals from the same litter at 32 weeks of age when the experiment was terminated. 4. The previously undernourished rats from litters of nine deposited a significantly greater porportion of fat in their bodies during rehabilitation than ad lib.-fed animals from litters of nine over the same gain in body-weight. The previously undernourished rats from litters of sixteen deposited the same proportion of fat in their bodies during rehabilitation as ad lib -fed animals from litters of three, nine and sixteen over the same gain in body-weight. 5. There were no significant differences in apparent or total fat cell numbers between ad lib.-fed animals and undernourished-rehabilitated animals at any of the four sites studied at 32 weeks of age.