ABSTRACT
The megaloblastic development of erythrocytes is an abnormal process and results in abnormal and insufcient production of red cells, decreased hematocrit, and a lowered level of hemoglobin, thereby producing anemia (and in some instances, a reduced number of granulocytes and platelets in the circulating blood) (Figure 25a,b). Wills and Bilimoria (1932) and Wills and Stewart (1935) were the rst to report that a megaloblastic bone marrow could be experimentally produced in macaque monkeys on the basis of decient diets. Subsequent extensive rigorously controlled investigations employing Macaca mulatta were conducted demonstrating that a vitamin C-decient diet was capable of routinely inducing a megaloblastic anemia (without the use of drugs or vitamin antagonists) (May et al. 1950a, 1951; Sundberg et al. 1952). Immature rhesus monkeys were placed on ad libitum milk diets that were decient in ascorbic acid (vitamin C) while control monkeys were placed on the same diet plus an additional 50 mg of vitamin C per day. The latter subjects thrived and none developed megaloblastic anemia during control periods of 5 months to 1.5 years. On the other hand, megaloblastic anemia developed in all the monkeys if vitamin C was not given.
