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

Immunohistochemical identification of the pacemaker cajal cells in normal human colon

The Interstitial Cells of Cajal [ICC] are C-Kit immunoreactive cells in the gastrointestinal tract. They are suggested to have a role in the control of gut motility. The present study was aimed to identify the morphology and the pattern of distribution of the ICC in the different parts of the human colonic segments. This study included sixteen normal colonic specimens obtained from the safety margins of the surgically excised colonic carcinoma. The prepared colonic longitudinal sections -were subjected to: haematoxylin and eosin, Masson's trichrome stain and to C-Kit immunohistochemistry. Statistical analysis was performed on the obtained data through the use of Leica Owin software of the image analyzer computer system to evaluate the degrees of locations of ICC [area percent] in the different colonic segments. The results revealed the following: ICC were demonstrated either as groups or as sporadic cells. The groups of ICC were surrounded with concentric connective tissue cells. The sporadic cells were usually in close relation to blood vessels and to the circular smooth muscle layers. ICC were of different sizes and different shapes. Statistical analysis through the use of the image analyzer was performed on the data obtained after examination of ten fields from each colonic segment. The area and area percent of the stained ICC were recorded in relation to a standard measuring frames. The obtained results revealed that great numbers of ICC were present at the coeco-colonic junction. The ascending, transverse and descending colonic segments showed moderate number of ICC. The greatest numbers of ICC were recorded in the region of sigmoid colon. ICC were located in the level of myenteric plexus, between the circular and longitudinal smooth muscle layers or within the circular muscle layer itself as reported in the sigmoid colon. The obtained results were discussed from the fact that ICC are considered to be generators of spontaneous pacemaker activity in the smooth muscle layers of the colon. They mediate or transduce inputs from enteric motor nerves to the smooth muscle syncytium