[Development of the mucosa and differentiation of the lymphocytes of the vermiform appendix of the human fetus].

One hundred and twenty-two appendices have been obtained from 12-30-week-old human fetuses and studied histologically (90) and immune-morphologically (32). Lymphoid follicles in the organ appear on the 17th week. Character of the epithelial and the reticular tissue structure in the area of the cupola including the lymphoid follicle have been studied. T- and B-lymphocytes have been stated to be present in the appendix of a 17-week-old fetus. As the fetus is further developing, the number of lymphocytes in the appendix increases: the amount of T-lymphocytes is practically constant, and that of B-lymphocytes increases. Direction of the lymphocytes migration out of the follicle is demonstrated. The lymphoid formations of the appendix are necessary for certain local protective reactions and already in the fetus they begin to participate in the general system of the organism's immunogenesis.