ULTRASTRUCTURAL-CHANGES IN FAT-CELLS AND BLOOD CAPILLARIES OF THE MAMMARY-GLAND IN STARVED MICE

The effects of starvation on fat cells and blood capillaries of the fi rst abdomino-inguinal mammary gland in mice were investigated by Light and transmission electron microscopy. The body weight of starved mice abruptly decreased to approximately 70% of that of controls at 3 days of starvation and, thereafter, gradually decreased. In adipose tissue s of mammary stroma, multilocular fat cells increased in number and cl ustered during starvation to a glandular appearance at 6 days. Collage n fibers increased in amount around mammary ducts and buds. By electro n microscopy, multilocular fat cells possessed numerous mitochondria, small lipid droplets, and plasmalemmal vesicles, while endothelial cel ls of the blood capillaries showed numerous pinocytotic vesicles plus short marginal folds and microvillous processes. These observations pr ove that the number of pinocytotic vesicles in blood capillary endothe lium is closely related with the increased amount of lipid of fat cell s in the mammary gland during starvation.