Abstract
Histological studies of sagittal sections through the distal end of the femur of rats 69 days old, and thyroidectomized between 15 and 29 days after birth, reveal a marked overgrowth of the epiphyseal cartilage close to the junction with the metaphysis. This area is also characterized by deficient calcification and invasion of blood vessels, as in typical rickets. Part of these rats were fed the Steenbock and Black 1 diet No. 2965. Cod liver oil added to this diet in amounts varying from 2 per cent of the diet up to a quantity where food became objectionable, did not prevent the development of rickets in these rats. Other thyroidectomized rats of the same age were fed a diet consisting of table scraps of the various kinds of food constituting the dietary of well-nourished individuals. These rats also developed rickets but in a somewhat lesser degree. Unthyroidectomized control rats of the same litter, living on identical dietaries, did not develop rickets, as determined by histological examination of the epiphysis of the long bones. These experiments demonstrate the necessity of the thyroid hormone for the complete utilization of cod liver oil.
This is a preliminary report.
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