Histometrical Studies on the Tissue Growth of the Aorta in a Human Fetus

Abstract

We investigated histometrically the age change on the wall of aortic biginning parts of 30 fetus from the middle of 3rd prenatal month to 10th month. Results are summerized as follows:
1. The thickness of intima does not show so remarkable a change from 3rd to 10th month.
2. The thickness of media grows straightly with age and in 10th prenatal month becomes 1.6 times as large as that of 3rd month.
3. The thickness of the elastic membranes and the smooth muscle fibers with increasing ages, has no remarkable change, and in 10th month, is 1.1 or 1.2 times as large as that of 3rd month. The elastic membranes and smooth muscle fibers show the same thickness from 3rd to 10th month.
4. There is no change in degree of wave curvature of internal elastic membrane in all above months.
5. The number of the elastic membranes and the smooth muscle fibers contained in intima per unit thickness does not change in all above months.
6. There is no change in the density of the elastic membranes and the smooth muscle fibers in unit area. Besides, the density of the smooth muscle fibers is just half of that of elastic membranes.