VITAMIN A DEFICIENCY AND METAPLASIA.

Of nineteen rats on a complete diet (Group III, Diet + C. L. O.), none showed foci of squamous keratinizing epithelium in abnormal situations. Of twenty-six rats on a diet deficient in vitamins A and D (Group I, Diet-A-D), twenty-three showed metaplastic changes of varying degree in one or more organs; the metaplasia was of columnar, cuboidal, and transitional epithelium to the squamous keratinizing type. Of eighteen rats on a diet deficient in vitamin A alone (Group II, Diet-A), seventeen showed epithelial metaplasia similar to that of Group I in one or more organs. In Groups I (Diet-A-D) and II (Diet-A) the changes occurred in one or more of the following organs: trachea, large bronchi, small bronchi or bronchioles in lung, posterior nares, accessory salivary glands of base of tongue, paraocular, submaxillary, sublingual, and parotid glands, renal pelvis, ureter, and bladder. The metaplastic changes were as extensive in the rats of Group II on a diet deficient in vitamin A alone as in those of Group I which received a diet deficient in vitamins A and D.