The thymus is a bilobed organ found in the space between the sternum (breastbone) and the aorta of the heart. The word thymus originated from the Greek word thymos, which means “soul” or “spirit”. In fact, for centuries it was believed that the soul was located in this part of the body. Within the thymus special cells called thymocytes are created which undergo maturation and differentiation into mature T lymphocytes. T lymphocytes are an essential component of our immune system.
The thymus is at its largest and most active during the neonatal and pre-adolescent periods. The organ then begins to gradually shrink over time; a process known as thymic involution. The rate of thymic T cell production is estimated to decline exponentially over time with a half-life of approximately 16 years. It is suggested that the total loss of thymic epithelial tissue and thymocytes would occur at about 120 years of age (Bodey et al. 2006). Therefore, it has been theorised that this is the absolute limit of a healthy human lifespan.
Reference:
Bodey, B., Siegel, S. and Kaiser, H. 2006. Immunological Aspects of Neoplasia – The Role of the Thymus. Berlin: Springer Science & Business Media.
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