X. EFFECTS OF DEFICIENCY 383 



hv ril)o(la\in than hy I'olic; acid. There was a hyperplasia of hone marrow 

 in the riboHavin-cleficieiit rats which was indistinguishable from that seen 

 in rats with folic acid deficiency. There was also an atrophy of the lymph- 

 oid tissue and no evidence of blood formation in the spleen. Fiuiher study 

 of these observations has led to the assumption that riboflavin deiiciency^^"^* 

 can cause anemia in the rat. 



The importance of riboflavin in the reproductive cycle has been quite 

 apparent to animal breeders. Its absence from the diet of rats may result 

 in anestrus, and if riboflavin is not restored within 10 weeks, the damage 

 becomes irreparable."^ Female rats bred on a deficient diet by Warkany*^- " 

 gave birth to litters one-third of which had congenital skeletal malfor- 

 mations including shortening of the mandible, tibia, fibula, radius, and 

 ulna, fusion of the ribs, sternal centers of ossification, fingers, and toes, 

 and cleft palate. There were no abnormal young when riboflavin was added 

 to the diet.^'* Nelson et al}^ did not observe skeletal abnormalities at birth 

 in the fitters of their riboflavin-deficient rats. The principal changes which 

 appeared in their deficient animals were retarded development of the 

 epiphyses, progressive decrease in the width of the epiphyseal cartilage, 

 increased hyalinization of its matrix, and calcification and separation of the 

 epiphyseal cartilage from the marrow cavity by a thin layer of bone. Hema- 

 topoietic tissue was replaced by fat in all the rats after they had been on 

 the deficient diet for 144 days. 



Riboflavin has been found to be protective to the rat against the rickett- 

 siae of murine tj'phus.^'' Chronic riboflavin deficiency is often accompanied 

 by a type of pediculosis against which riboflavin seems to have a specific 

 effect." 



It has been shown that there is no appreciable loss of appetite during 

 riboflavin deficiency. On the contrary, there is a relatively increased food 

 intake during the final stages of riboflavin deficiency.''*' ^^ Pair-fed control 

 rats grew much faster than the riboflavin-depleted rats. Consequently, 

 riboflavin has been associated with an increased economy of food utiliza- 

 tion. 



" W. H. Sebrell, Federation Proc. 8, 568 (1949). 



" C. F. Shukers and P. L. Day, /. Nutrition 25, 511 (1943). 



" A. Kornberg, H. Tabor, and W. H. Sebrell, Am. J. Physiol. 145, 54 (1945). 



" K. H. Coward, B. G. E. Morgan, and L. Waller, /. Physiol. 100, 423 (1942). 



" J. Warkany and R. C. Nelson, Science 92, 383 (1940). 



" J. Warkany, Vitamins and Hormones 3, 73 (1945). 



*« J. Warkany and E. Schraffenberger, Proc. Soc. Exptl. Biol. Med. 54, 92 (1943). 



" M. ^r. Nelson, E. Sulon, H. Becks, and H. M. Evans, Proc. Soc. Exptl. Biol. Med. 



66, 631 (1947). 

 «« H. Pinkcrton and O. A. Bessey, Science 89, 368 (1939). 

 " P. Gyorgy, Proc. Soc. Exptl. Biol. .Med. 38, .383 (1938). 

 «- B. Sure and M. Dichek, J. Xutrition 21, 4.53 (1941). 



