Further Gross Observations on the B12-Deficient Chick Embryo

Abstract
The characteristics of the B12-deficient embryo as described by Olcese et al. (′50) have been confirmed. In addition, embryos produced from hens fed a diet low in vitamin B12 were found to have an enlarged thyroid, hemorrhages in the yolk sac, a thin-walled digestive tract, and to be edematous. The muscles examined were small and tendinous. Of 291 embryos examined on the 17th day of incubation, 23% exhibited the typical B12-deficiency symptoms as described by Olcese et al. (′50). A fatty liver or a pale, dilated, irregularshaped heart or both occurred in 55% of the cases and fatty kidneys were also observed. Parenteral injections of vitamin B12 into hens maintained on the low-B12 diet, or injections of vitamin B12 into the eggs from these hens prior to incubation prevented the anomalies described.