Scanning electron microscopic study of the fibrous rings of the arterial orifices in embryos of the 7th and 8th weeks

The arterial fibrous rings were investigated in human embryos aged 7 and 8 weeks under light and scanning electron microscopes. In the present study it was shown that the arrangement of collagen and formation of fibres changes rapidly within one week. In the 7th week there are no collagen fibres and the netlike fibrils extend between processes of fibroblasts. At the end of the 8th week the collagen fibres are formed and they have different arrangements in the particular layers of the fibrous rings. (Folia Morphol 2010; 69, 3: 180–183)