basement membrane development trait Any measurable or observable characteristic related to the morphology or physiology during formation and differentiation of the extracellular supportive tissue closely adjacent to the basal surface of the epithelium of muscle cells, fat cells and Schwann cells, which is comprised of type IV collagen, laminin, and sulfated proteoglycans and other components. Trait.ontology VT:0003044 basement lamina formation basement membrane formation connective tissue development trait