Vascular Construction of the Bone Marrow in Human Fetus Part 2. Vascular Construction of the Bone Marrow in the Atlas, Epistropheus, Sacrum and Coccyx

With the use of transparent and stained tissue specimens injected with dye into the bone marrow vessels of the atlas, epistropheus, sacrum, and coccyx in 60 human fetuses over two months old, the author studied development of the bone-marrow blood vessels and obtained the following results: 1. Atals: Nutrient artery and vein are observed radiating from radix arcus vertebrae; and cartilage canals are recognized in forea articularis and tuberculum dorsale. 2. Epistropheus: In the arch and the body, the distribution of blood vessels and growth of cartilage canals resemble those in the thoracic vertebra, but cartilage canals entering from anterior and posterior sides play a role in the formation of primitive bone marrow space in the body unlike that in the case of the thoracic vertebra. By the sixth embryonal month the dens begins to possess its own nutrient artery and vein. From these findings it is assumed that the dens morphologically corresponds to the body of atlas. 3. Sacrum: The manner of blood vessel distribution in the bone marrow of the sacrum is similar to that in a thoracic vertebra but its distribution is not so dense. The growth of cartilage canal in the body of vertebra is quite good and it shows no tendency to deteriorate even in the terminal embryonal stage. On the pars lateralis of the sacrum independent, new nutrient arteries and veins are recognized. 4. Coccyx: The growth of blood vessels is poor in coccyx, and only cartilage canals entering from the anterior and posterior sides can be observed, but no bone marrow formation