Histological studies on the ontogeny of bovine palatine and pharyngeal tonsil: germinal center formation, IgG, and IgA mRNA expression.

The development and distribution of lymphocyte subsets in calf palatine and pharyngeal tonsil were examined. During prenatal development, B cells were distributed in the subepithelial area, and T cells and MHC class II(+) cells were found in the deep layer of B-cell area, respectively, in both tonsils. At neonatal stage, lymphoid follicle containing a few CD4(+) cells have been formed in both tonsils. IgG(+) and IgA(+) cells were found in the parafollicular and epithelial area. At 3 months old, many germinal centers were recognized in both tonsils. CD4(+) cells and IgG mRNA expression were detected in light zone of germinal centers. Many IgG, and IgA mRNA expressions also could be detected in the parafollicular and subepithelial area of both tonsils. The data suggest that both tonsils have an important role of local immune defense against invading antigen after birth. The comparison of the histological characteristics of tonsil and Peyer's patch during ontogeny is also discussed.

[Embryogenesis of the human pharyngeal tonsil]. / Embryogenez glotochnoi mindaliny cheloveka.

By means of histological, histochemical, immunological and morphometric methods 78 pharyngeal tonsils of human embryos at the age of 12-40 weeks have been investigated. The character of the organ's anlage at 12-14 weeks of development as longitudinal folds on the dorsal wall of the rhinopharynx and changes in correlation of the lymphoid and epithelial tissues are presented in the process of the tonsil embryogenesis. Occupation of the organ with lymphocytes takes place on the 16th week of development. The embryos possess already two classes of T- and B-lymphocytes and their subclasses: auto-E-RFC, EAC-RFC, IgM and IgG positive cells; their kinetics is demonstrated in the process of the organ's development. A comparison on lymphocyte quantity, participating in cell-dependent immunity of the tonsil in fetuses, children and mature persons is presented.

The embryogenesis and anatomy of Waldeyer's ring.

The developmental history of the embryonic germ disk is briefly traced through the bilaminar, trilaminar, and bodyfold stages with emphasis on the pharyngeal arches, pouches, and clefts. This is followed by a discussion of the genesis and adult anatomy of the tonsillar tissues.