Effect of Fixation on the Light Microscopical Visualization of Mast Cells in the Mucosa and Connective Tissue of the Human Duodenum

Abstract

Mast cells have been studied in the mucosa and connective tissue of 28 biopsies of human duodenum. They were collected from individuals who for various reasons had to undergo upper intestinal endoscopy. Tissues were fixed in both standard formalin and a formalin-acetic acid (FA) fixative developed for visualization of mucosal mast cells. With both fixatives connective tissue mast cells (CTMC) were equally well recognized. Only with the FA fixative, an additional population of mast cells was observed both in the mucosa and the connective tissue. This population consisted of round cells, always smaller than CTMC, with a number of granules staining violet with toluidine blue. These mast cells comprised two cell types, differing in size, the larger being present in both the mucosa and the connective tissue, the smaller ones in a subepithelial position in the crypts of Lieberkühn and in the adjacent submucosa. It was suggested that this first mentioned additional population was similar to the mucosal mast cells (MMC) observed in rats and mice. The subepithelially located metachromatic cells differed in morphology from the globule leukocytes found in rats and mice. It was concluded that in the human duodenum a population of cells with MMC staining characteristics is present, which can only be visualized under special fixation conditions. Their further characterization and role in various disease conditions remains to be elucidated.

Identification of chondroitin sulfate E proteoglycans and heparin proteoglycans in the secretory granules of human lung mast cells.

“…Although fixation properties of the mast cells in human skin differ from those in the intestine (26,27), all mast cells in the human are alcian blue+/safranin-. In contrast, rat and mouse MMC are alcian blue + /safranin -, and their CTMC are alcian blue+/safranin+.…”

“…These in vitro-differentiated BMMC preferentially synthesize chondroitin sulfate E proteoglycans (2,6). Although the rodent MMC and CTMC were generally believed to be separately derived populations of mast cells, we recently demonstrated that when IL-3-dependent mouse MMC-like mast cells were cocultured for [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] days with mouse skin-derived 3T3 fibroblasts, they became histochemically and morphologically similar to CTMC, increased their content of histamine and carboxypeptidase A, and augmented their synthesis of [35S]heparin proteoglycans (7)(8)(9)(10). In addition, when mast cell-deficient WBB6F1 W/W' mice were reconstituted with BMMC from WBB6F1 +/+ mice, the mast cells recovered from the serosal cavity synthesized heparin proteoglycans in preference to chondroitin sulfate E proteoglycans (11 A small fraction of each mast cell extract was chromatographed on 10-ml Sephadex G25/PD10 columns (Pharmacia) to determine the total incorporation of [35S]sulfate into macromolecules (2).…”

Two types of human mast cells that have distinct neutral protease compositions.

“…Both types have high-affinity plasma membrane receptors for IgE and show coupled activation-secretion on cross-linkage of these receptors. An analogous heterogeneity has been suspected in humans based on the presence of formalin nonfixable and fixable mast cells in human gastrointestinal mucosa and submucosa, respectively (6)(7)(8), even though convincing histochemical, functional, or compositional differences between such mast cells is lacking (4,5,(9)(10)(11).…”

Origin, morphology, histochemistry and function of the mucosal mast cell and the globule leukocyte. A review

“…Al- Rangifer,11 (1): 3-11 though comparison of the properties of MMC and GL has led to the assumption that GL are derived from MMC (Miller & al., 1968), there are several indications that GL are an independent cell type (Ruitenberg & Elgersma, 1976, 1982. This question is reviewed in the light of facts on the morphology, histogenesis, histochemistry, and function of MMC and GL.…”