Congenital malformations in the chick caused by environmental variation

Summary

An enquiry was undertaken to determine the various types of anomalies which might occur in the chick embryos by subjecting the incubating eggs to insulin injection. Since the injection of insulin above 4 units resulted in lethality, 4 units of insulin was introduced by injection throughout the experiments.

The abnormalities are classified as relating to the skeletal, reproductive and the nervous systems. Micromelia, micrognatha and other beak deformities, congenital fracture in the limbs, rotation of joints relate to skeletal anomalies. Dilatation of the right oviduct was observed in one instance. Gonadal degenerative changes were observed in all the experimental chicks examined. Meningo-encephalocœle, unilateral-microphthalmia with herniation of brain and bilateral microphthalmia accompanied by absence of the upper beak were the anomalies reported in these experiments. Macroscopic as well as microscopic appearances of these abnormal chick embryos are discussed and illustrated with the help of photographs and microphotographs.