The mesenchymal cells of the presumptive dermis differentiate into fibroblasts which secrete most of the extracellular matrix. Fibroblasts are typically elongated and interspersed among the delicate banded extracellular fibrils.
Endothelial cells, which will form the vascular system of the dermis, are identifiable as early as the 6th weeks of gestation.
Schwann cells, which will form the perineural tissue, are also derived from the primitive mesenchyme.