Histological and immunohistochemical assessment of the immunological aspect of certain cells in human palatine tonsils

Tonsils contain four specialized lymphoid compartments that together are involved in immune functions. The capacity of tonsillar lymphocytes to counter infections may be altered during one's lifetime. The classification of lymphocytes by CD antigen expression is now widely used in clinical medicine and experimental immunology. The present work was designed to study the distribution of CD4 and CD8 antigen expression in T lymphocytes in human tonsils at different periods of life. Sixty-two tonsillar specimens were obtained from still birth infants and from children aged 1-9 years. Paraffin sections were prepared and stained with H and E and with immunohistochemical stains to demonstrate CD4 and CD8 T lymphocytes. The distribution of these cells in the different components of the tonsils was evaluated with an image analyzer. The obtained data were statistically analyzed using SPSS. There was a significant increase in the distribution of stained CD4 and CD8 T lymphocytes in the interfollicular areas, mantle zones of lymphoid follicles, and partially in the germinal centers of the examined tonsils with the advancement of age. Activated T lymphocytes differentiate into several subtypes, among which are CD4 and CD8 cells. These types of T lymphocytes express surface antigens, which can interact with different foreign pathogens

overview of the histochemistry of the retinal matrix

The constituents of the retinal matrix may be involved in the transport of nutrients from the choroidal circulation to the retina, its molecules may provide trophic support to retinal pigmented epithelium. Relatively little is known about the molecular structure of the retinal matrix. The aim of this work was to clarify the histochemical nature of the constituents of the matrix of the different layers of two types of retinae; vascular and avascular. The retinae were obtained from two groups of animals, retinae of cats and rats [vascular retinae] and retinae of rabbits and Guinea pigs [avascular retinae]. The prepared retinal sections were subjected to these techniques: Hx and E, alcian blue, PAS, silver impregnation, and to modified Landers technique [1991][10]. Quantitative morphometric study was applied through the use of the image analyzer computer system. The obtained results revealed that Muller cells were clearly demonstrated in all examined retinae, their presence was discussed from the fact that they are similar to neuroglia of CNS. They provide structural support to all layers of the retina. They also mediate the transfer of essential metabolites to the retinal neurones. Acid mucopolysaccharides were clearly demonstrated in the matrix of rods and cones, inner nuclear layer and around the neurones of the ganglion cell layer of the vascular retinae more than in the avascular retinae. Neutral mucopolysaccharides were highly demonstrated in the matrix of the rods and cones, plexiform layer as well as in the ganglion cell layer of both vascular and avascular retinae. Chondroitin sulphate proteoglycans were clearly demonstrated in the superficial and deep parts of the matrix of rods and cones, plexiform layer and around the neurones of ganglion cell layer. The obtained results were discussed in relation to the role of the molecular components of this matrix in trophic support of the retinal layers. The matrix fills the small amounts of spaces between the retinal pigmented epithelium and the photoreceptors. The molecular components of the matrix may exert a survival influence upon the normal adhesion between the photoreceptors and the pigmented retinal epithelium. Pathological changes in the molecular components of retinal matrix may be one of the factors which may lead to retinal detachment