The thyroid lobes: The different twins

Although differences in size of the right and left thyroid lobes are well defined, differences in morphology, follicles structure, cAMP production, thyrotropin receptor, and protein involved in cell signalling have not previously been reported. This study provides morpho-functional data of right and left thyroid lobes by biochemical, immunohistochemistry, immunoblotting and immunofluorescence analysis. We demonstrate that, in comparison with the left lobe, the right lobe has a higher activation index, is more sensitive to thyrotropin treatment, is rich in thyrotropin receptor and caveolin 1 involved in thyroid hormone synthesis as well as in epithelial thyroid cell homeostasis, is characterised by a high content of molecules involved in cell signalling such as stat3, raf1, sphingomyelinase and sphingomyelin-synthase whose activity ratio is necessary for epithelial cell activity and finally has more areas calcitonin-dependent. The relation between structure/function of right lobe and its susceptibility to the higher risk of pathological modifications with respect the left lobe is discussed.

► Right and left lobes of mouse thyroid have structural differences.
► The right lobe is more sensitive to thyrotropin treatment than the left lobe.
► The sphingomyelin metabolism enzymes have a specific localization in the right lobe.
► STAT3 and raf1 are more expressed in the right lobe than in the left lobe.
► Our results could explain the particular susceptibility of the right lobe to diseases.