Dermis: Cells week 6

Cellular primordial dermis

The cells of the primordial dermis are derived from somite mesoderm and other subjacent mesenchymal tissues. At 6 weeks of gestational age, the cells are densely packed and connected by tight junctions, and therefore function as a syncytium. Despite their morphological lack of differentiation, they actively secrete collagen types III and I.

Cellular Primordial Dermis

This thin-section light micrograph shows a flattened "pavement epithelium" periderm, and a single layer of keratinocytes over a highly cellular presumptive dermis (the next six or eight cells down). One early vascular structure with a lumen is seen on the right side of the image. Note how little extracellular matrix is present and compare to later points in development. Also note how homogeneous the cell population appears.