Abstract: The mucosal, luminal and lymphoid follicle diameters of the vermiform appendix were measured in micrometers from the basal, middle and terminal segments and their relationships analyzed and plotted. There is a strong relationship between these diameters, especially between lymphoid follicle diameter and the thickness on one hand and that between the luminal diameter and the lymphoid follicle diameter on the other. The lumen decreases when either the thickness or the lymphoid follicle diameter increases in size, suggesting that obstruction can occur at such sites with the resulting microscopic and macroscopic changes that come to bear on normal subjects. This segmental profile shows that, histomorphological and histomorphometric changes in the appendix are capable of explaining the basis and indeed the likely sites of obstruction in appendicitis.