[Morphological study of adipose tissue during the first year of life (author's transl)].

Forty-one sample of adipose tissue were obtained by needle biopsy from thirty-two newborn at term and nine infants between two and 12 months. Number of fat cells of the newborn with birth-weights appropriate, large and low for their gestational age were similar (6-7 X 10(9). The babies whose birth weights were large for their gestational age showed a significant increase (p less than 0.001) in size of the fat cells (m + SD = 71.3 +/- 7.9), compared with those of low birth weight and control samples: 41.2 +/- 3.6 and 55.6 +/- 3.9 micrometer respectively. Percentage of body fat increases from a mean figure of 13.8% at birth to 24.9% at three months, in babies of normal weight. Growth of fat deposits is due to an increase in the size of adipose cells, reaching a mean value of 85.2 micrometer, without differences in number of fat cells present at birth. In the newborn as in infants diameter of fat cells has an important and positive correlation with the body weight and fat quantity. The same type of relationship exists between infants age and diameter of fat cells (r = 0.93). Four obese infants studied showed an increase in size of fat cells (m + SD = 112.7 +/- 10.9 micrometer) without modification in number of cells.