Histology of the stroma in developing rat subcutaneous adipose tissue.

Microscopic changes in the stroma of developing adipose tissues were studied. An organized arrangement of collagen fibers was associated with spindle-shaped cells with basophilic cytoplasm. An unorganized arrangement of collagen fibers was associated with cells of irregular shape, little cytoplasmic basophilia and a large pale-staining nucleus. Adipocyte development was apparent only in unorganized collagen fibers. The unorganized stroma was located near muscle-tendon junctions. Other aspects of muscle were surrounded by organized stroma. Physical interactions between expanding muscle and connective tissue cells may prevent or delay collagen maturation, resulting in a matrix suitable for adipocyte development.