Quantitative histologic effects on mouse thymus of controlled dietary restriction.

Specific volume fractions (VF) of cellular populations of 6-month-old mouse thymus are altered in animals dietarily restricted since weaning. The VF ratios of cortex:medulla are 2:1 for restricted animals and 1:1 for controls. Thymic cortex of restricted mice exhibits a greater VF of lymphoid cells. Dietary restriction did not alter the VF of medullary lymphoid cells. The VF of non-lymphoid cellular elements tended to decrease throughout the thymus with dietary restriction. No dietary effect on the VF of thymic vascular and connective tissues was observed. VF ratios of cortical lymphoid cells:medullary lymphoid cells show a tendency to increase in restricted mice as does the VF ratio of cortical lymphoid cells:cortical non-lymphoid cells. The VF ratio of thymic medullary lymphoid cells:medullary non-lymphoid cells also increases in restricted mice. VF ratios of cortical non-lymphoid cells:medullary non-lymphoid cells were not altered by diet.