Involution patterns of the human thymus. I Size of the cortical area as a function of age
Tosi, P.; Kraft, R.; Luzi, P.; Cintorino, M.; Fankhauser, G.; Hess, M.W.; Cottier, H.
Clinical and Experimental Immunology 47(2): 497-504
1982
ISSN/ISBN: 0009-9104 PMID: 7075032 Document Number: 192414
Thymic tissue obtained at autopsy from 123 victims of sudden death, ranging from neonates to individuals > 80 yr and predominantly male, was studied with histometric techniques, i.e., a combination of test point analysis and planimetry on unit optical fields. The pattern of natural age-dependent involution of the thymic cortex was examined using computerized mathematical models. The range of variations of results was greatest in children and young adults, followed by the very old, then the middle age group. In a 1st approximation, regression for thymic cortical volume in individuals > 15 yr corresponded better to a negative exponential than to a negative linear function of age. Best fits for the data suggest at least a 2-component negative exponential function of age, with a steeper slope of the regression for individuals > 30 yr of age. Extrapolation on a log-normal plot of regression lines for thymic cortical involution points to near-zero values at an age range below the estimated maximum human life span, corresponding to the steepest slope of survival curves in Western Europe.