Adipocyte development in the rat hypodermis.

The relationship between hair-follicle development and adipocyte formation in the rat hypodermis was studied. Skin samples from rats of various body weights were prepared for histological, histochemical, and electron microscopic analysis. Adipocyte formation in the rat hypodermis was linked spatially and temporally with hair-follicle growth and development. Cells trapped along the invading edge of hair follicles developed into adipocytes after the descent of the follicles through the dermis. Histochemical characteristics of the outermost cells of hair follicles indicated hypoxic conditions. These conditions may have directed a vascularization process that resulted in a network of adipocytes and capillaries around these follicles. Thus, under normal conditions, adipocyte formation is an integral phase of hair-follicle development in the rat.