The growth and development of fat cells in infancy.

Abstract

Studies on the development of adipose tissue in infancy would seem essential to test the hypothesis that adult fat stores relate to the numbers of fat cells developed during early childhood. Thirty infants aged from 1-28 months and 13 fetuses of approximately 11-16 weeks of gestation obtained at therapeutic abortion and two preterm infants of 28 weeks of gestation were studied. The cells of both fetal and infant adipose tissue were separated from connective tissue and fixed by treatment with osmium tetroxide in buffered collidine using a method modified from Hirsch and Gallian (J. Lipid Res.,9:100(1968) for estimation of cell size and number. In fetal and early infancy there are two populations of cells in adipose tissue. Small cells found in tissue before birth and the first months of postnatal life do not contain fat. The larger cells, which are fat containing, represent maturing fat cells. They are cells which include fat cells recognized by previous workers but up to 24.6% were found to be less than 25 micron in diameter. Small cells in the early stages of fat accumulation may make an important contribution to the cell population of fat mass. It is apparent that increasing fat accumulation in the first 6-12 months of life, as demonstrated by increased skinfold thickness measurements, is associated with increasing fat cell size and that this association bears a linear relationship.