A quantitative study of collagen production by human smooth muscle cells during intestinal morphogenesis.

Differentiating mesenchymal cells and the extracellular matrix that these cells produce constitute the structural basis for developing organs. The splanchnopleuric mesenchyme surrounding the developing gut and respiratory tubes provides connective tissue cells to the lamina propria/submucosa and smooth muscle cells to the muscularis musosae/muscularis externa. In human fetal intestine, the identity of the matrix-producing cell or cells has begun to be elucidated. The smooth muscle cell is one of the sources of collagen fibers in the extracellular matrix in the developing human fetal intestine and collagen production is a significant function of smooth muscle cells during intestinal organogenesis. The aim of the current study was the quantitative investigation of collagen production by human fetal intestinal smooth muscle cells in various stages of development (10 to 23 weeks of gestational age). Identification of the mesenchymal cells/extracellular matrix was confirmed by immunohistochemical techniques using the following monoclonal antibodies: actin, desmin, vimentin, collagen IV and fibronectin. Histochemical stains for the presence of extracellular matrix components were also performed. Immunohistochemical analysis and the results of the histochemistry of the fetal human intestine in various stages of development revealed that the muscle cells of the muscularis externa contribute to the production of collagen in collaboration with the mesenchymal cells. This is more evident between 10 to 14 weeks of gestational age.