Ann Anat ;Sep. Histologically, there are four types of fat tissue cells which are currently recognized white, brown, beige, and perivascular adipocytes. Therefore, in this study we are reviewing the most recent data regarding the origin, structure, and oncocytic papilloma mechanisms involved in the development of adipocytes.
White adipocytes can store triglycerides oncocytic papilloma a consequence of lipogenesis, under the regulation of growth hormone or leptin and adiponectin, and release fatty acids resulted from lipolysis, under the regulation of the sympathetic oncocytic papilloma system, glucocorticoids, TNF-α, insulin, and natriuretic peptides.
Brown adipocytes possess a mitochondrial transmembrane protein thermogenin or UCP1 which allows heat generation.
Recently, thermogenic, UCP positive adipocytes have been identified in the oncocytic papilloma white adipose tissue and have been named beige adipocytes. The nature of these oncocytic papilloma is still controversial, as current theories are suggesting their oncocytic papilloma either by transdifferentiation of white adipocytes, or by differentiation from an own precursor oncocytic papilloma. Perivascular adipocytes surround most of the arteries, exhibiting a supportive role and being involved in the maintenance of intravascular temperature.
Thoracic perivascular adipocytes resemble brown adipocytes, while abdominal ones are more similar to white adipocytes and, consequently, are involved in obesity-induced inflammatory reactions. The factors involved in the regulation of adipose stem cells differentiation may represent potential pathways to inhibit or to divert adipogenesis.
Further investigations are necessary to complete the knowledge about adipose tissue and the development of a new generation of therapeutic tools based on molecular targets.