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Ageing and its effect on the functional capacity of the thymus
Abstract
Background: Thymus gland is the only primary lymphoid organ in mammals, the first organ to become lymphoid and influences the development of other lymphoid organs in the body. It develops from the 3rd pharyngeal pouch in 5th week of intra uterine life and is located in the anterior and superior mediastinum of the thorax. Survival of an organism is influenced by an adequate immune system, and the thymus is a dependable lymphoid organ responsible for cell mediated immunity via T-cell training and maturation. It also produces hormones that play a role in immune mediation. However, the gland is said to increase in size from birth onwards but undergo involution after puberty and may disappear by middle age as reported in other parts of the world. Hence the need to establish what happens in Ugandans, with an aim to determine the functional capacity of the gland as one grows or if T-cell production does continue. The objective of this study was to determine the structural changes and functional ability of the thymus gland with age among Ugandans.
Methods: This was a descriptive cross-sectional study. The study was carried out at Makerere University and the associated Mulago teaching hospital. Autopsy cases at Mulago hospital and Kampala city mortuaries were used for the study.
Results: A total of 41 cases were dissected comprising of 71% male and 29% female specimens. Of them, 34% were pre-puberty and 66% were post- pubertal individuals. The age range was six months to seventy years with a mean age of 22.3, median 34.75 and mode 25. Seventy five percent of all cases were 30years and below, only 5% were more than 45years. It should be noted that only The thymus tissue was found in 39 cases and absent in two aged 40 and 43 years respectively.
Conclusions/Recommendation: The relative size of the cortex and proportion of lymphoblasts decreased with age while the medulla and lymphocytes increased. The fat content of the gland increased with age. The study showed a positive correlation of weight of the glands with age from birth to puberty, later the correlation becomes negative. There is a decrease in the activity of the gland as shown by the reduced ratio of lymphoblasts to lymphocytes.
Methods: This was a descriptive cross-sectional study. The study was carried out at Makerere University and the associated Mulago teaching hospital. Autopsy cases at Mulago hospital and Kampala city mortuaries were used for the study.
Results: A total of 41 cases were dissected comprising of 71% male and 29% female specimens. Of them, 34% were pre-puberty and 66% were post- pubertal individuals. The age range was six months to seventy years with a mean age of 22.3, median 34.75 and mode 25. Seventy five percent of all cases were 30years and below, only 5% were more than 45years. It should be noted that only The thymus tissue was found in 39 cases and absent in two aged 40 and 43 years respectively.
Conclusions/Recommendation: The relative size of the cortex and proportion of lymphoblasts decreased with age while the medulla and lymphocytes increased. The fat content of the gland increased with age. The study showed a positive correlation of weight of the glands with age from birth to puberty, later the correlation becomes negative. There is a decrease in the activity of the gland as shown by the reduced ratio of lymphoblasts to lymphocytes.
