Abstract
The following diet, when fed to the young rat, in a comparatively short time (three to five weeks) produces rickets. The diet is composed of:
This diet is extremely poor in fat-soluble A, the anti-xerophthalmic substance. Young rats develop xerophthalmia when placed upon it in from four to five weeks. Its proteins are of good quality and are supplied in abundance (21 per cent.). The phosphorus content is relatively low (0.209 gms. per 100 gms. of the food mixture). The calcium content is approximately the optimum.
The gross evidences of rickets in the rats eating the faulty ration were briefly these: deformities of the thorax consisting in flattening or hollowing along the line of costochondral junctions; pigeon breast; enlargement and distortion of the costochondral junctions; fractures of the ribs; enlargements of the ends of all the long bones; diminished resistance of the bone to cutting; great diminution in the tensile strength; and finally, the presence of a zone of a white or pale yellow color, between the cartilage and the shaft, visible to the naked eye, the rachitic metaphysis.
The microscopic evidences of rickets in the skeleton of the rats receiving the diet were convincing. There was increased thickness and great irregularity of the proliferative cartilage which extended in irregular prolongations toward the shaft, complete absence of calcium deposition in the cartilage or great defects in calcification, the presence of an intermediate zone between cartilage and shaft, the zone already alluded to as the rachitic metaphysis, composed of cartilage in all stages in the process of metaplasia into osteoid, osteoid trabeculz, blood vessels accompanied by marrow elements, irregular deposits of calcified intercellular substance encased in osteoid and, finally, by broad osteoid investments of the trabeculz of the shaft.
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