684 



VII. VITAMINS A 



(5) Vitamin A in Mammalian Tissues Other Than the Retina 



Vitamin A also occurs in a number of other tissues, such as corpora lutea, 

 lungs, and kidneys,^^ as well as in the retina. Williams^'"' has summarized 

 data on the vitamin A content of a number of tissues of normal rats and 

 men (Table 4). 



TABLE 4 

 Vitamin A Content of Tissues Obtained from Normal Rats and Normal Man" 



° Adapted from R. J. Williams, Vitamins and Hormones, 1, 229-247 (1943), pp. 236, 

 237. 



TABLE 5 

 Vitamin A Content of Different Species" 



" R. J. Williams, Vitamins and Hormones, 1, 229-247 (1943), p. 240. 



There is a marked variation in the vitamin A content of different mam- 

 mals. ^"^ However, because of the wide variations noted in different 

 animals of the same species, it is difficult to ascribe significance to small 

 differences in the values. The results of Clausen and McCoord cited by 

 Williams ^°° are summarized in Table 5. These workers reported that in 

 some species certain tissues were devoid of vitamin A. These include lung 



'» T. Moore, Biochem. J., 25, 275-286 (1931). 

 ""> R. J. Williams, Vitamins and Hormones, 1, 229-247 (1943). 

 101 S. W. Clausen, Harvey Lectures, 38, 199-226 (1942-1943). 



