Development and differentiation of adipose tissue

Abstract

For years adipose tissue has been considered inert, serving only as a depot of energy surplus. However, there have been recent changes, undoubtedly due to advancement of methods for studying the morphology and metabolic activities of adipose tissue (microdialysis and adipose tissue catheterization). In normal-weight subjects, adipose tissue makes 10-12% with males and 15-20% with females. About 80% of adipose tissue is located under the skin, and the rest envelops the internal organs. With humans there are white and brown adipose tissues, which is predominant with infants and small children. From a histological point of view, it is a special form of reticular connective tissue, which contains adipocytes with netlike structure. Human adipose tissue has four types of adrenergic receptors with different topographic dispositions, which manifest different metabolic activity of adipocytes of particular body organs. Changes in adipose tissue are associated with the process of adipocyte differentiation. Critical moments for this process are last months of pregnancy, the first six months of infancy and then puberty. However, the differentiation process may also begin during maturity. Namely, as size of adipocytes can increase to a certain limit, this process can be activated after reaching a "critical" adipocyte volume. The differentiation process is affected by a number of hormones (insulin, glucagon, corticosteroids, somatotropin (STH), thyroid gland hormones, prolactin, testosterone), but also by some other substances (fatty acids, prostaglandins, liposoluble vitamins, butyrate, aspirin, indomethacin, metylxanthine, etc.).