Morphology and functional organization of subcutaneous adipose tissue: modern concepts of structural and functional heterogeneity and age-related changes (systematic literature review)

Introduction. Subcutaneous adipose tissue represents a complex multi-component system playing a pivotal role in metabolic, immunological, and thermoregulatory processes. Contemporary understanding of structural and functional heterogeneity of adipose tissue has fundamentally changed our perception of its role in metabolic disease pathogenesis and aging processes.
Objective. To conduct a systematic analysis of current data on morphological organization of subcutaneous adipose tissue, its layered structure, and age-related changes with emphasis on clinical significance for aesthetic medicine.
Materials and methods. A systematic literature search was performed in PubMed, Scopus, Web of Science, and RSCI databases for the period 2015-2024. Keywords included: "subcutaneous adipose tissue", "dermal white adipose tissue", "superficial fascia", "aging", "morphology". Of 89 sources analyzed, 52 were included in the final analysis according to inclusion criteria.
Results. Subcutaneous adipose tissue is characterized by pronounced morphological heterogeneity and can be divided into dermal white adipose tissue (dWAT) and superficial white adipose tissue (sWAT). dWAT is localized in the lower dermis as discrete adipose clusters, while sWAT forms a continuous layer separated from dWAT by the superficial fascia. dWAT cells are characterized by smaller size (30-50 μm), high expression of UCP1 and PRDM16 markers, and active participation in wound healing and thermoregulation. sWAT contains large adipocytes (80-130 μm) organized into lobules separated by fibrous septa. Age-related changes include progressive reduction in dWAT volume (up to 40% by age 60), altered collagen I/III ratio, decreased vascularization and lymphatic drainage. Molecular aging mechanisms are associated with suppressed PPARγ and CEBPα expression and reduced Wnt/β-catenin signaling pathway activity.
Conclusion. Understanding the morphological heterogeneity of subcutaneous adipose tissue is critically important for developing personalized approaches in aesthetic medicine. Future research should focus on studying molecular mechanisms of different adipocyte population differentiation and developing targeted methods for age-related change correction.

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