| Abstract: | By means of transmissive electron microscopy stages of morphogenesis have been studied in the pulmonary trunk wall of 12 healthy human embryos and fetuses of 5-24-week-old. There is a close dependence in development of the smooth muscle component of the middle tunic, elastic and collagenous fibers of the pulmonary trunk wall. In the early prenatal morphogenesis of the pulmonary trunk fibrillogenesis develops intensively, overtakes the differentiation time of myocytes from mesenchymal cells, the collagenous fibers appearing earlier than the elastic ones. The structures, that ensure solidity of the vascular wall (collagenous fibers), appear in embryogenesis earlier that those, ensuring its elasticity (ability to reversible deformity). |
