FACTORS WHICH DETERMINE RENAL WEIGHT

Abstract

I. A description is given of the means used to approximate constant conditions in a colony of albino rats and of the methods employed in making anatomical measurements. II. The relation at different ages of kidney weight to 3 measurements of body size[long dash]weight, length and surface[long dash]was determined in 548 normal [male] rats of known age (35-760 days). In relation to body weight, kidney weight decreased with increasing age, reaching a minimum value at about 200 days of age; in relation to body length it increased with age, attaining a maximum value at about the same age. On the other hand, kidney weight has practically the same relation to body surface at all ages. The relationship of kidney weight to body surface is less variable than to either body weight or body length. III. Measurements of kidney weight and body size were made on 382 normal [female] rats of known age (35-400 days). The relation at different ages of kidney weight to the 3 measurements of body size[long dash]weight, length and surface[long dash]are compared to the above data from d rats. The variation of these relationships with age and the order of their variability is similar to that found for d. The 9 rat is shown to have 15% less renal tissue per unit of body surface than the cf.