The prenatal development of the human femur

Abstract

The study reported here is the result of a detailed investigation of the changes in shape of the femur with growth and torsion, the type, rate and character of ossification, and the onset, subsequent course, and general features of remodeling.Forty pairs of femurs, from a series of embryos and fetuses ranging from 26 to 342 mm in crown-rump length, were measured, radiographed, and sectioned for microscopic study.A primary bony collar was present before the end of the embryonic period, and in a 27 m m embryo it extended for about one-fifth of the length of the femur. Erosion of the collar was evident at 34 mm, and invasion and destruction of calcified cartilage were occurring by 37 mm. Cartilage canals first appeared in the proximal epiphysis at 57 mm and in the distal epiphysis at 61 mm.Along with the progression of endochondral ossification proximally and distally and the establishment of growth zones, periosteal bone formation also proceeded in both directions, and, until 275 mm, extended about 1 mm beyond the zones of cartilage destruction. After 275 mm, the extents of periosteal and endochondral ossification were the same and at term occupied almost four-fifths of the length of the femur.Trabeculation of the bony collar was first noted at 37 mm. Fusion of endochondral trabeculae with the inner aspect of the periosteal shell began by 61 mm. A central marrow cavity free of trabeculae was present at 86 mm and thereafter. Evidence of reconstruction appeared in both proximal and distal ends by 92 mm, and was consistently present in both ends in all specimens of 111 m m and larger.

Submicroscopic Structure of Bovine Articular Cartilage in Prenatal and Early Postnatal Period

“…Similarly to S t 0 c k weI I (1971 a), our material from the 8th to 10th week revealed in the intercellular substance of the middle layer blood capillaries and erythrocytes deposited partly among chondroblasts, partly phagocytized. In the later period capillaries did not occur in the joint cartilage, which agrees with observations of Gar dner and Gray (1970). In the later period of development (16th to 23th week after fertilization) appear in the superficial layer besides chondroblasts also temporary types of cells which we reported already before (H 0 r k y 1983,1985), which have already some characteristic typical of chondroblasts of the middle layer.…”

Submicroscopic Structure of Articular Cartilage in Human Embrya Six to Eleven Weeks Old

“…Simultaneously with this process, blood vessels grow into-·the cartilaginous primordium from perichondrium (Haines 1933;Hurrel 1934;Levene 1964;Lufti 1970, Stockwell 1971Agraval et al 1984). They do not, however, penetrate to the region of the future articular cartilage (Gray and Gardner 1969;Gardner and Gray 1970) ,and disappear in around the 10th week. Before the joint cavity is formed, a fairly large number , of tiny cavities appear in the mesenchyme in the contact area of the future articular surfaces of bones.…”

Ultrastructural Studies of Initial Stages of Mineralization of Long Bones and Vertebrae in Human Fetuses

“…In the matrix, a gradual increase in the amount of proteoglycans and fine collagenous fibers is observed [Glenister, 1976], giving by the middle of the 2 month of gestation the typical appearance of cartilaginous matrix. The earliest signs of ossification of bone rudiments were found in human embryos in the humerus at the beginning of the 8th week after fertilization (Gray and Gardner, 1969], The ossification of the femur took place slightly later [Gardner and Gray, 1970]. At the beginning a bony collar surrounds the midportion of the cartilaginous model.…”