HYPOVITAMINOSIS A (aVITAMINOSIS A) 597 



ported in the early days by Osborne and Mendel, '°^^ was urolithiasis, 

 which consists in the tendency to form calcium phosphate concretions in 

 the urinary tract. Van Leersum'"'*^ confirmed the results of Osborne and 

 Mendel. It was suggested that a morbid change of the epithehal cells in 

 the tubules takes place, which gives rise to the formation of calcium casts. 

 This suggestion was supported by the later work of van Leersum. ^"^^ 

 Lamming and co-workers ^^^^ reported that vitamin A deficiency did not re- 

 duce the formation of decidua in the rabbit, although it resulted in the pro- 

 duction of premature degeneration of ova, and reduced the number of 

 fertihzed ova present forty and ninety-six hours after mating. It was also 

 shown^''*^ that incipient vitamin A deficiency reduced, by 14%, the number 

 of animals which mated normally, while the number of animals which con- 

 ceived was reduced to the extent of 18% by the hypovitaminosis A. 

 Kahn^"^" noted an interrelation between vitamin A, estrogen, and the kera- 

 tinization of the vaginal epithehum. A dose of vitamin A as low as 0.6 

 I.U. significantly inhibits the cornification resulting from a total dose of 

 0.6 I.U. of a-estradiol. Thus, the effect of the lack of vitamin A on the 

 estrous cycle of animals can be correlated with its failure to react with the 

 estrogenic hormones. 



e'. Effect on the Skin: One of the most prominent symptoms of vitamin 

 A deficiency is the unthrifty appearance of the skin, and epithelial append- 

 ages such as hair, fur, and feathers. Hyperkeratosis of the hair follicles 

 has been reported in adult humans deficient in vitamin A,^"^^''"^''!"^- and 

 large amounts of vitamin A will undoubtedly restore the normal condition. 

 However, it apparently does not occur in rats and guinea pigs deprived of 

 vitamin A. Wolbach^"^^ reported that atrophy of the hair bulb and of the 

 external sheath cells occurs in newly-formed hair follicles, following the ap- 

 plication of keratinizing agents such as benzpyrene and methylcholanthrene. 

 Some hyperkeratinization of the epidermis and hair follicles has been pro- 

 log T. B. Osborne and L. B. Mendel, /. Am. Med. Assoc, 69, 32-33 (1917). 



io« E. C. van Leersum, J. Biol. Chem., 76, 137-142 (1928). 



^°" E. C. van Leersum, /. Biol. Chem., 79, 461-463 (1928). 



10^8 G. E. Lamming, G. W. Salisbury, R. L. Hays, and K. A. Kendall, /. Nutrition, 

 52, 217-225 (1954). 



10" G. E. Lamming, G. W. Salisburv, R. L. Hays, and K. A. Kendall, /. Nutrition, 52, 

 227-239 (1954). 



loso R. H. Kahn, Am. J. Anal., 95, 309-335 (1954). 



1051 C. N. Frazier and C.-K. Hu, Arch. Dermatol, and Syphilol, 33, 825-852 (1936). 



1052 Q ^ Bessey and S. B. Wolbach, Vitamin A, Physiology and Pathology, in The 

 Vitamins, Sympos. Council on Pharm. and Chem.; Council on Foods, Am. Med. Assoc, 

 Chap. II, Chicago, 1939, pp. 27-54. 



10" S. B. Wolbach, Ann. N. Y. Acad. Sci., 53, 517-536 (1951). 



