Congenital malformations, induced in rats by maternal nutritional deficiency, date back to the cartilaginous or precartilaginous stage of the structures affected. The defects of ossification are secondary results, caused by the faulty development of the precursors of the bones.
Many cartilaginous structures show a lack of division in the longitudinal and transverse direction; this leads to a reduction in the number of the skeletal elements, and to syndactylism and brachydactylism in the paws.
The radius, ulna, tibia, and fibula are frequently shortened in the cartilaginous stage. Ossification is delayed and faulty, and eccentric centers of ossification lead to an abnormal arrangement of the bone trabeculae.