134758.fig.001
Figure 1: Developmental stages of adipose tissue (adapted from Brooks and Perosio, [17]). Phase 1: emergence of loose connective tissue composed of an amorphous ground substance and stellate cells (filed). Phase 2: aggregates of mesenchymal cells (filed) are condensed around proliferating primitive blood vessels (bold ovals). Phase 3: mesenchymal cells differentiating into stellate preadipocytes within a glomerulus. Phase 4: appearance of adipocytes with multiple small lipid droplets closely packed around the capillaries. Phase 5: fat lobule with many unilocular cells (clear circles) is evident. This developmental process (phase 1 to 5) occurs between the 14- and 23-week gestation period. From 23 to 29 weeks, the number of fat lobules is relatively constant. From the 23rd to 29th week and throughout postnatal life, the growth of adipose tissue is determined mainly by an increase in size of the fat lobules arising from adipocyte hypertrophy and enlargement of adipose capillaries.