Vascular Construction of the Bone Marrow in Human Fetus Part 3. Blood Vessels in the Bone Marrow of Clavicle

Ossification of the middle part of clavicle derived from the connective-tissue ossification, and in epiphysis the primitive bone marrow origiantes from mesenchymal tissue possessing blood vessels. As for the nutrient foramen, its site, the number, and the angle of penetration into bone wall are not so uniform as in the case of long bone. This seems to be due to the peculiar ossification of the clavicle. Nutrient artery and vein do not necessarily penetrate into the bone wall together and when the two are in company, the nutrient vein usually occupies the position superior to the artery, and often two or three veins are found. Furthermore, one to several auxiliary nutrient foramens ran be observable. The manners of branching and distribution of main nutrient artery and vein are rather regular. On the fourth embryonal month the cartilage canals containing arteries and veins make their appearance on both epiphyses, and by the fifth embryonal month they are connected with the bone marrow of epiphysis