Morphological characteristics of neonatal adipose tissue.

The aim of the present work was to study the morphological characteristics of neonatal adipose tissue using rats as an animal model. The results revealed that the subcutaneous adipose tissue of newborns consists of packets of unilocular adipose cells (one large lipid drop occupying the whole cell and pushing the cytoplasm and the nucleus to the cell periphery) and some multilocular fat cells (several lipid droplets of different size and an almost centrally located nucleus). All the adipocytes demonstrated positive immunohistochemical expression for leptin, whereas the multilocular adipose cells were positive for cyclin D1. These findings suggest that the multilocular adipose cells are preadipocytes that have not yet finished proliferation and differentiation and could under some external and/or internal stimuli conclude their development and become mature unilocular adipocytes, thus increasing fat mass.