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Soft Tissue Tumors

Adipose tissue

Embryology and physiology of adipose tissue


Reviewer: Vijay Shankar, M.D. (see Reviewers page)
Revised: 30 October 2012, last major update August 2012
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.

Embryologic development of adipose tissue
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● Stage I: prior to 14 weeks of gestation, loose spindle cells and ground substance are present
● Stage II: aggregates of mesenchymal cells condense around proliferating primitive blood vessels
● Stage III: capillaries proliferate into rich network, preadipocytes become stellate and organize into lobules
● Stage IV: fine lipid vacuoles develop within cytoplasm
● Stage V: adipocytes accumulate within rich capillary network and perilobular mesenchyme condenses at periphery of lobule to form fibrovascular septa at week 24 (Early Hum Dev 1983;8:1)
● Brown fat has similar development, but contains large mitochondria with uncoupling protein 1 (OMIM 113730); white fat progenitor cells can also induce brown adipogenesis through mir 16a signaling pathway (PLoS Biol 2012;10:e1001314)
● Brown fat deposits are well established by month 5 of gestation, particularly in posterior cervical, axillary, suprailiac and perirenal regions
● Adipocyte development is closely associated with angiogenesis: (a) fat appears first in well vascularized regions; (b) adipocytes synthesize lipoprotein lipase (transports serum triglycerides into adipocytes), which is transferred to luminal surface of capillary endothelium; (c) vasculature functions as a progenitor niche and may provide signals for adipocyte development (Science 2008;322:583)

Pathophysiology
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● Fat development is controlled by CHOP gene, which mediates differentiation of fibroblasts into adipocytes and growth arrest of terminally differentiated adipocytes; translocation of CHOP in myxoid liposarcomas may remove normal inhibition on CHOP
● At birth, amount of adipose tissue increases for next 10 years with overall growth; at puberty, adipocytes increase in size and number
● Brown fat is widely distributed in children in interscapular region, around neck vessels and muscles, around mediastinal structures, near lung hila and around abdominal viscera
● Some adipocytes may originate from neural crest (Development 2007;134:2283)

End of Soft Tissue Tumors > Adipose tissue > Embryology and physiology of adipose tissue


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