Summary
The early development of an organism is a critical stage which many factors may influence unfavourably. Maternal nutritional deficiencies, especially vitamin deficiencies, can disturb the development and bring about the most diverse malformations, affecting the nervous system, eye, vascular system, kidneys, limbs, etc. The teratological effects of deficiencies in vitamin A, vitamin B2, pantothenic acid and folic acid are firmly established.
Deficiencies not only produce malformations in the embryo. They may merely retard development, but they can also cause various lesions, and among others lesions which are analogous to those brought about in the adult by nutritional deficiencies.
The gravity of the result of deficiencies varies greatly. It may be negligible or it may end in the death of the embryo or sterility of the mother. The effect is a function of the intensity of the deficiency, as shown by chemical estimations of the vitamin in question.
A slight deficiency may produce a malformation. It may therefore occur readily, the more so as it may result from various causes, such as an insufficient exogenous or endogenous supply, a disequilibrium of the ration, imperfect utilization, etc.
Deficiencies act on the embryo as on the adult, by a disturbance of metabolism, for it is known that many vitamins are essential constituents of enzymatic systems. The results of the deficiencies depend upon the tissues or cells with which these systems are specially concerned. At an early stage such metabolic disturbances may affect organizers and so cause anomalies in development, that is, deformities.
Here, as elsewhere, genetical factors may intervene in restraining or facilitating the effect of a deficiency.
It is probable that these phenomena, observed in several types of birds and mammals, are of general occurrence, to be found also in man and in domestic animals.
From the practical point of view it follows that maternal nutrition should be closely supervised.
