Maternal peripartum and fetal perirenal and omental adipose tissue dynamics: Analysis of fatty acid composition and adipocyte morphology in sheep

Abstract

Fatty acids (FAs) play essential roles in fetal development and physiological processes, serving as precursors for signaling molecules, structural components of cellular membranes, and components of lipids in energy reserves. The long-term storage of FAs in adipocyte triacylglycerols provides the growing fetus with structurally and functionally different FAs, which have diverse effects on developmental and metabolic health.

Adipose tissue samples were obtained from perirenal, omental, mediastinal, mesenteric, subcutaneous, and periorbital depots of six pregnant ewes and six fetuses. Histological analysis of adipocyte sizes was performed using the QuPath and Adipocyte Tools, and gas chromatography–mass spectrometry was employed to analyze FA compositions. Principal component analysis was utilized to identify patterns in FA profiles separating maternal and fetal tissues.

Analysis of adipocyte size distribution revealed significantly larger adipocytes in ewes compared with fetuses. Maternal perirenal and omental adipose tissues contained the largest cells. Monounsaturated FAs and biologically active long-chain n-3 and n-6 polyunsaturated FAs were more abundant in fetal tissues, while saturated FAs were more abundant in maternal tissues.

In conclusion, fetal and maternal adipose tissues demonstrated significant differences in morphology and FA composition, reflecting their distinct functional roles. While fetal FA composition is heavily influenced by fetoplacental FA transfer, and the observed FA patterns are consistent with endogenous metabolic processing in fetuses, further transcriptomic data will be required for more detailed metabolic interpretation. Still, these findings could reflect a degree of metabolic independence of fetuses in this ruminant model and help generate hypotheses for future translational studies.