SELECTION FOR HIGH AND LOW ADRENAL WEIGHT IN MICE

Abstract

SUMMARY Four strains of mice were used to found a heterogeneous stock from which one line was selected for high adrenal weight/100 g body weight and another line for low adrenal weight/100 g body weight. By the eighth generation of selection, two stocks of mice were produced, one with adrenals whose absolute weight was greater than any of the parental strains. The realized heritability estimates were 75% for females and 67% for males during the period of selection, showing that a large component of variation in adrenal weight was genetic in origin. Asymmetry in response to selection was also noticed and attributed to possible variation in adrenal structure between sexes. Estimates of variances in each generation, particularly the eighth, did not show any decline which suggested that further responses to selection would be possible with further selection.