[Show abstract][Hide abstract] ABSTRACT: The therapeutic effect of tonsillectomy for immunoglobulin A nephropathy (IgAN) has been widely recognized, but the mechanism by which tonsillar immunity leads to glomerulonephritis has been unclear. We investigated subtypes and localization of dendritic cells (DCs) in tonsils and looked for relationships between the tonsillar DCs and the clinical features and renal histological changes of patients with IgAN.
We examined tonsils from 33 IgAN patients, using as control tonsillar specimens from subjects without glomerulonephritis. Five distinct markers of DCs (CD303, CD1c, CD209, CD208 and CD1a) were analyzed by immunohistochemistry and flow cytometry. The mRNA levels of these DC markers were evaluated using real-time polymerase chain reaction. The clinical data and histological results obtained evaluating renal biopsy tissues were statistically compared with immunological data.
Of the five subtypes of DCs, CD208(+) DCs were significantly increased in the tonsils of IgAN patients compared with that of controls. Furthermore, the number of CD208(+) DCs in the tonsils was positively and linearly correlated with the proportion of crescentic glomeruli in renal biopsy tissues and with the urinary protein level. Only few CD208(+) cells, however, were found in the kidney biopsy specimens of IgAN patients.
These observations suggest that increased CD208(+) DCs in tonsils may play a directive role in the pathogenesis of IgAN. The present results support the therapeutic significance of tonsillectomy for IgAN patients.
[Show abstract][Hide abstract] ABSTRACT: Fibroblast activation protein (FAP)/seprase and dipeptidylpeptidase-IV (DPP-IV)/CD26 are serine integral membrane proteases. They are involved in tissue remodelling, cancer invasion and metastases, mechanisms that are controversial. The aim was to identify cell types that express FAP and DPP-IV in human bone and soft tissue tumours, and to determine whether there are any correlations between the expression of FAP and DPP-IV and the malignant potential of tumours.
This study analysed in situ expression in 25 malignant and 13 benign human bone and soft tissue tumours. Reverse transcriptase-polymerase chain reaction analyses confirmed mRNA expression of FAP and DPP-IV in all individuals. Immunohistochemistry using pre-fixed frozen sections revealed that FAP was positive in low-grade myofibroblastic sarcoma, the fibroblastic component of osteosarcomas, and malignant fibrous histiocytomas, but negative in Ewing's sarcomas and rhabdomyosarcomas. DPP-IV showed similar immunohistochemical results. Among benign tumours, non-ossifying fibromas, desmoid tumours and chondroblastomas expressed both FAP and DPP-IV. Giant cells expressed DPP-IV in giant cell tumours.
Our data suggest that FAP and DPP-IV are consistently expressed in bone and soft tissue tumour cells that are histogenetically related to activated fibroblasts and/or myofibroblasts, irrespective of their malignancy. DPP-IV is also expressed in monocyte-macrophage lineage cells.
[Show abstract][Hide abstract] ABSTRACT: An autopsy case of malignant mesothelioma with asbestosis caused by asbestos exposure for 17 years is reported. Autopsy revealed that mesothelioma spread extensively in all serosal tissues including pleura, pericardium, diaphragm, peritoneum and tunica vaginalis testis. Histopathologically, most of the tumor showed an epithelial form, but sarcomatous and microcystic patterns were also observed. The tumor cells had abundant glycogen and hyaluronic acid and, immunohistochemically, they were positive for cytokeratin, vimentin and epithelial membrane antigen (EMA). Long, slender microvilli were characteristically observed in these tumor cells. All of these data were compatible with malignant mesothelioma. Procollagen type I (procol.l) immunostaining was performed to reveal the mesenchymal character of mesothelioma. Both epithelial-type cells and sarcomatous-type cells showed positive staining for procol.l, although the latter showed stronger immunoreactivity. Immunostaining for procol.l was found to be one of the useful tools for distinguishing mesothelioma from adenocarcinoma. Using an extraction method for asbestos fibers, asbestos bodies were found in many tissues including lymph nodes, liver, small intestine, spleen, kidney, testis and pleura, in addition to lung parenchyma. Although multiple tumor metastases from an undetermined primary site is not ruled out, 'multifocal tumorigenesis' is suspected from the widespread deposit of asbestos fibers.
No preview · Article · Oct 2008 · Pathology International
[Show abstract][Hide abstract] ABSTRACT: The pathophysiological significance of matrix metalloproteinases (MMPs) in aortic dissection remains poorly understood. The purpose of the present study is to clarify the significance of MMPs in aortic dissection. The activities and distributions of MMP-2, membrane-type 1-MMP (MT1-MMP), and MMP-9 were evaluated by gelatin zymography, immunohistochemistry, and in situ hybridization in 29 patients and seven autopsy cases. To assess if these MMPs are related to a tissue remodeling process, we compared the expression of these MMPs with that of type I procollagen and platelet-derived growth factor receptor beta chain (PDGF Rbeta). Patients were divided into three groups based on histological findings: acute, intermediate, and healed groups. The most remarkable changes were observed in the intermediate group, in which MMP-2 activity peaked and tissue expression of mRNAs for MMP-2 and MT1-MMP were observed in spindle-shaped cells in the neointima, organizing thrombus, and the adventitia. These expression patterns were essentially coupled with those of type I procollagen mRNA and PDGF-Rbeta protein. The association of MMP-2, MT1-MMP, type I procollagen, and PDGF-Rbeta suggests that MMP-2 and MT1-MMP could be involved not only in the degradation of aortic tissue but also in tissue remodeling, which may be associated with the healing process.
No preview · Article · Jul 2006 · Archiv für Pathologische Anatomie und Physiologie und für Klinische Medicin
[Show abstract][Hide abstract] ABSTRACT: The ultrastructural sites of secretory component (SC) in the intestinal epithelium of severely immunoglobulin-deficient and immunologically intact persons were compared. SC was found in the same sites in the immunoglobulin-deficient and normal epithelium: perinuclear spaces, rough endoplasmic reticulum, Golgi completes, external surfaces and endocytic invaginations of the basolateral plasmalemma, and in membranous vesicles throughout the cytoplasm. These observations suggest that the synthesis, external expression and transcellular migration of SC occur independent of the presence of immunoglobulins. The migration of SC from the basolateral cell surfaces to apical surfaces may be an inherent property of epithelial cells and the primary event in the translocation of polymeric immunoglobulins across the cells to external body fluids.
No preview · Article · Jun 2006 · Scandinavian Journal of Immunology
[Show abstract][Hide abstract] ABSTRACT: Abnormalities in humoral immunity are implicated in the pathogenesis of ulcerative colitis. However, the detailed mechanisms of B-cell activation in the locale remain unaccounted for. We analyzed ulcerative colitis from the standpoint of lymphocytic expansion in the loco. Intestinal specimens obtained at surgery from 30 patients with ulcerative colitis treated with corticosteroids and 15 with Crohn's disease were analyzed by immunohistochemistry and flow cytometry. Ulcerative colitis was characterized by a diffuse distribution of Ki-67(+) small round cells particularly in the ulcer base (that were CD19(+) and CD20(-)), with a significant number of them also CD138(+). Immunoelectron microscopy for CD19 revealed an abundance of rough endoplasmic reticulum in the cytoplasm. These indicated that they are of immature plasma lineage cells. By contrast, plasma cells in Crohn's disease were negative for CD19, and the labeling for Ki-67 was infrequent, showing mature phenotype. Flow cytometry revealed an occurrence of CD19(+) and CD20(-) cells in ulcerative colitis but not in Crohn's disease. The labeling index of Ki-67 among CD19(+) plasma cells was positively correlated with the clinical activity of ulcerative colitis. High labeling of Ki-67 in CD19(+) plasma cells is specific for active ulcerative colitis that was resistant to medical treatment by corticosteroids.
No preview · Article · May 2006 · Archiv für Pathologische Anatomie und Physiologie und für Klinische Medicin
[Show abstract][Hide abstract] ABSTRACT: T cell infiltration in colorectal cancer is associated with a favorable prognosis, suggesting an occurrence of a certain degree of anti-tumor immunity. T helper type 1 (Th1) and Th2 cells are now known to selectively express CC-chemokine receptor 5 (CCR5)/CXC-chemokine receptor 3 (CXCR3) and CCR4, respectively. To clarify the mechanism of T cell infiltration, we examined in situ expression of these chemokine receptors and their respective chemokine ligands in 40 cases of human colorectal cancer. Immunohistochemistry showed a predominant accumulation of T cells expressing CCR5 and CXCR3 mainly along the invasive margin, whereas those expressing CCR4 were rare. Flow cytometric analysis showed that more than half of CD8(+) T cells and a fraction of CD4(+) cells isolated from fresh tumor tissues co-expressed CCR5 and CXCR3, and CD8(+) T cells and CD4(+) cells predominantly produced interferon-gamma (IFN-gamma) over interleukin-4 (IL-4) after in vitro stimulation. RANTES/CCL5, a ligand of CCR5, was localized within infiltrating CD8(+) T cells in a granular pattern, whereas IP-10/CXCL10, a ligand of CXCR3, was localized in cancer cells and macrophages along the invasive margin. These data were consistent with an active recruitment of T cells expressing CCR5 or CXCR3 into the invasive margin of colorectal cancer. With the previous clinicopathological studies showing a favorable prognostic impact of T cell infiltration in colorectal cancer, our study supports the occurrence of a certain level of Th1-shifted cellular immune responses in human colorectal cancer.
Full-text · Article · Oct 2005 · International Journal of Cancer
[Show abstract][Hide abstract] ABSTRACT: In adults, epithelial cell proliferation and apoptosis of the gastric mucosa are induced by Helicobacter pylori infection and are associated with gastric atrophy or gastric carcinoma. In children, there are few studies about such epithelial changes. To elucidate the role of H. pylori infection in gastric mucosal inflammation, we immunohistochemically examined gastric mucosa of Japanese children.
Biopsy specimens obtained from the gastric antrum and corpus of H. pylori-infected (n = 13) and noninfected children (n = 15) were studied for immunolocalization of Ki-67, single-strand DNA, manganese superoxide dismutase (Mn-SOD), and CD68, and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling. In 10 patients with successful eradication, pre- and posttreatment results were compared.
In both gastric antrum and corpus, neutrophil and mononuclear cell infiltration, epithelial cell proliferation, and apoptosis significantly increased in H. pylori-infected patients, predominantly in the antrum. In the antrum of H. pylori-infected patients, there was positive correlation between the degrees of neutrophil infiltration and cell proliferation (P < 0.05) or apoptosis (P < 0.05). H. pylori eradication improved mucosal inflammation, cell proliferation (P < 0.001), and apoptosis (P < 0.01) in the antrum. Mn-SOD immunoreactivity and CD68-positive macrophages in the antrum, which significantly increased in H. pylori-infected patients, decreased after the eradication.
H. pylori infection induced gastric mucosal inflammation and epithelial cell turnover in children. Moreover, gastric mucosal defense mechanism against H. pylori infection was activated. H. pylori eradication in childhood might prevent the accumulation of gastric epithelial cell damage.
No preview · Article · Mar 2005 · Journal of Gastroenterology
[Show abstract][Hide abstract] ABSTRACT: Immunological abnormalities are implicated in the pathogenesis of inflammatory bowel disease (IBD), that is, Crohn's disease and ulcerative colitis. In particular, Crohn's disease is considered to be a T helper type 1 (Th1)-shifted disease. Chemokines and their receptors are involved in various immune responses including Th1- and Th2 responses. In this study, we analyzed chemokines and their receptors by immunohistochemistry, using frozen sections derived from 33 patients with Crohn's disease and 24 with ulcerative colitis. In inflamed mucosa, small mononuclear cells predominantly expressed CCR5 and CXCR3, the receptors selectively expressed on Th1 cells, without significant differences between Crohn's disease and ulcerative colitis. We then focused on the noncaseating granulomas that are characteristic of Crohn's disease. Granuloma cells, observed in all the layers of intestinal tissues, were positive for RANTES/CCL5 protein along their cell membranes. Lymphocytes surrounding granulomas were mostly CCR5+ and CXCR3+ T cells with CD4+ and CD8+ cells at similar frequencies. Granuloma cells were positive for RANTES mRNA by in situ hybridization. By contrast, lymphoid aggregates in Crohn's disease and lymphoid follicles in the normal intestinal mucosa were characterized by abundant B cells, a predominance of CD4+ T cells over CD8+ T cells, and low frequencies of cells expressing CCR5 or CXCR3. Together with the notion that granuloma cells are possible antigen-presenting cells, our results suggest that the noncaseating granulomas could be one of the crucial sites of Th1-shifted immune responses in Crohn's disease.
Full-text · Article · Feb 2005 · Laboratory Investigation
[Show abstract][Hide abstract] ABSTRACT: T-cell infiltration into human cancer tissues can be a manifestation of host immune responses to cancer cells. The present study was undertaken to explore the clinicopathological significance of intraepithelial CD8(+) T cells using 371 consecutively sampled human colorectal carcinomas. By univariate analysis, we noted that the survival curves by intraepithelial CD8(+) T cells became separated only after 1 to 2 years postoperation. Multivariate analyses revealed that the beneficial effect of this factor becomes significant only after a longer (more than 2 year), but not after a shorter (less than 2 year) follow-up period. Furthermore, the number of intraepithelial CD8(+) T cells was significantly higher in patients alive for more than 5 years than in patients who either died of cancer after a curative operation or patients who underwent a noncurative operation. Patients' cancer-specific death long after a curative operation is thought to be caused by the growth of micrometastases in other organs or near the primary sites. The effects of intraepithelial CD8(+) T cells, therefore, may be mediated by suppression of micrometastasis, rather than suppression of growth in the primary tumour. In conclusion, our data support a hypothesis on the presence of systemic immunosurveillance against micrometastasis of cancer cells.
Full-text · Article · Dec 2004 · British Journal of Cancer
[Show abstract][Hide abstract] ABSTRACT: This study calls attention to a new syndrome presenting with gastrointestinal symptoms including abdominal pain, vomiting, and/or hematemesis and endoscopic multiple lesions predominantly in the descending duodenum, without the skin rash observed in Henoch-Schonlein purpura. We examined the gastrointestinal mucosa for IgA deposits in nine children and compared the results with those for three patients with Henoch-Schönlein purpura. In addition, gastroduodenal biopsy specimens of 11 patients with various diseases were studied as controls for IgA staining. Intestinal histology showed nonspecific mucosal inflammation without vasculitis. In six patients without rash (67%), IgA deposition was observed in the capillary wall with the same staining pattern as seen in two patients with Henoch-Schonlein purpura. Compared with the controls (9%), the positive rate of IgA deposition was significantly higher in nonrash patients (P < 0.01). Deposited IgA showed immunoreactivities of polymeric IgAl containing J chain. IgA deposits were ultrastructually seen along the plasma membranes of the endothelial cells. Overall, the data suggest that IgA deposition played a pathogenetic role in the gastrointestinal damage in this group of patients presenting primarily with gastrointestinal complaints. Further studies are needed to clarify whether this patient population has a variant of Henoch-Schönlein purpura or a distinct "IgA enteropathy."
No preview · Article · Nov 2004 · Digestive Diseases and Sciences
[Show abstract][Hide abstract] ABSTRACT: Chronic gastritis is frequently associated with infection of Helicobacter pylori and characterized by tissue infiltration of neutrophils, lymphocytes, and plasma cells. To address the mechanism of lymphocyte infiltration in chronic gastritis, we examined the expression of chemokines and their receptors using frozen sections of chronic gastritis, obtained from 23 patients who underwent gastrectomy for gastric cancer. By immunohistochemistry, lymphocytes in inflamed gastric mucosa expressed CCR5 abundantly, CXCR3 less frequently, and CCR4 sparsely. The numbers of CCR5(+) cells, which were composed of mainly CD8(+) and partly CD4(+) T cells, were positively correlated with the degree of neutrophil infiltration, and decreased in areas with intestinal metaplasia or mucosal atrophy. RANTES/CCL5, one of the ligands of CCR5, was localized mainly in CD8(+) and partly CD4(+) T cells with a characteristic dotted pattern, and such lymphocytes were most densely distributed around the neck region of gastric glands. In situ hybridization confirmed the expression of CCL5 mRNA in these cells, and immunoelectron microscopy revealed localization of CCL5 in the membrane-bound granules, which most probably corresponded to the cytolytic granules of cytotoxic T cells. The numbers of CCL5(+) lymphocytes showed a close correlation with the degree of neutrophil infiltration and markedly decreased in intestinal metaplasia. In conclusion, our data suggest that, together with neutrophils, CCL5(+) T cells, presumably activated cytotoxic T cells, would play important roles in the active inflammatory process of chronic gastritis. Our data also suggest a self-recruiting mechanism involving CCR5 and CCL5 for tissue accumulation of such T cells.
No preview · Article · Apr 2004 · Laboratory Investigation
[Show abstract][Hide abstract] ABSTRACT: The interaction of mucosal addressin cell adhesion molecule 1 (MAdCAM-1) with integrin alpha4beta7 mediates lymphocyte recruitment into mucosa-associated lymphoid tissue (MALT). Nodular gastritis is characterized by a unique military pattern on endoscopy representing increased numbers of lymphoid follicles with germinal center, strongly associated with H pylori infection. The purpose of this study was to address the implication of the MAdCAM-1/integrin beta7 pathway in NG.
We studied 17 patients with NG and H pylori infection and 19 H pylori-positive and 14 H pylori-negative controls. A biopsy sample was taken from the antrum and snap-frozen for immunohistochemical analysis of MAdCAM-1 and integrin beta7. In simultaneous viewing of serial sections, the percentage of MAdCAM-1-positive to von Willebrand factor-positive vessels was calculated. We also performed immunostaining with anti-CD20, CD4, CD8 and CD68 antibodies to determine the lymphocyte subsets co-expressing integrin beta7.
Vascular endothelial MAdCAM-1 expression was more enhanced in gastric mucosa with than without H pylori infection. Of note, the percentages of MAdCAM-1-positive vessels were significantly higher in the lamina propria of NG patients than in H pylori-positive controls. Strong expression of MAdCAM-1 was identified adjacent to lymphoid follicles and dense lymphoid aggregates. Integrin beta7-expressing mononuclear cells, mainly composed of CD20 and CD4 lymphocytes, were associated with vessels lined with MAdCAM-1-expressing endothelium.
Our results suggest that the MAdCAM-1/integrin alpha4beta7 homing system may participate in gastric inflammation in response to H pylori-infection and contributes to MALT formation, typically leading to the development of NG.
Full-text · Article · Jan 2004 · World Journal of Gastroenterology
[Show abstract][Hide abstract] ABSTRACT: The mucosal immune system forms a unique barrier system that handles a myriad of infectious and food antigens exposed to the mucosal surface, in order to prevent their invading into the tissue and producing an excessive immune response. The mucosal immune system interacts with the neuro-endocrine system through hormones in the hypothalamic-pituitary-adrenalaxis and cytokines and with energy metabolism through leptin and its receptor by the mutual expression of receptors and mutual usage of mediators. Thus, it plays an important role for the homeostasis of various gastrointestinal functions and immunologic and metabolic changes.
[Show abstract][Hide abstract] ABSTRACT: Lichen planus is a chronic inflammatory disease of the skin and oral mucosa in which the cell-mediated cytotoxicity is regarded as a major mechanism of pathogenesis. To understand its pathophysiology further, the present study examined the in situ expression of chemokines and chemokine receptors in oral lichen planus. Immunohistochemical analysis of 15 cases has consistently revealed that infiltrating CD4(+) and CD8(+) T cells in the submucosa predominantly expressed CCR5 and CXCR3. Furthermore, infiltrating T cells, particularly CD8(+) T cells, were positive for RANTES/CCL5 and IP-10/CXCL10, the ligands of CCR5 and CXCR3, respectively. By immunoelectron microscopy, these chemokines were localized in the cytolytic granules of CD8(+) T cells. Lesional keratinocytes also overexpressed the ligands of CXCR3, namely, MIG/CXCL9, CXCL10, and I-TAC/CXCL11. Our data suggest that the chemokines signaling via CCR5 and CXCR3, which are known to be selectively expressed by type 1 T cells, are predominantly involved in T-cell infiltration of oral lichen planus. Furthermore, the presence of CCL5 and CXCL10 in the cytolytic granules of tissue-infiltrating CD8(+) T cells expressing CCR5 and CXCR3 reveals a potential self-recruiting mechanism involving activated effector cytotoxic T cells.
Full-text · Article · Aug 2003 · American Journal Of Pathology
[Show abstract][Hide abstract] ABSTRACT: Skin flaps have routinely been used as substitutes for oral mucosa after extensive resection of oral tissues. However, it remains unknown how the transplanted skin flaps perform as a host defence in the new environment of the oral cavity.
To evaluate the expression of cornified cell envelope (CCE) precursors in pretransplanted (normal) skin, intraorally transplanted skin and normal oral mucosa, because CCEs are highly responsible for a protective barrier in each type of epithelium.
We used immunohistochemistry and immunoelectron microscopy to examine the expression of CCE precursors, small proline-rich protein (SPR) 2 and 3 and loricrin, in biopsy specimens of normal skin, transplanted skin and normal oral mucosa, including buccal and lingual (non-keratinized) mucosae, and palatal (keratinized) mucosa.
Transplanted skin flaps were classified into two groups. About two-thirds of the transplanted skin flaps displayed a reddish appearance and were devoid of the stratum corneum (SC) together with a psoriasiform inflammatory tissue reaction. Others showed a native appearance, retaining the SC. While SPR2 expression was limited to the stratum granulosum (SG) in both normal and transplanted skin retaining the SC, it extended to the stratum spinosum (SS) of the transplanted skin lacking the SC and that of the normal oral mucosa. Although SPR3 expression was not found in normal skin or in the transplanted skin retaining the SC, it was strongly expressed in the SS of the transplanted skin lacking the SC and the non-keratinized oral mucosa, and in the SS and SG of the keratinized oral mucosa. Loricrin, which was expressed in the SG of normal skin, the transplanted skin retaining the SC and the keratinized oral mucosa, was not detected in the transplanted skin lacking the SC or in the non-keratinized oral mucosa. Immunoelectron microscopy confirmed the ultrastructural localization of SPR3 directly under the cytoplasmic membrane of keratinocytes of the transplanted skin lacking the SC and that of the oral mucosa.
The altered expression of SPR2, SPR3 and loricrin reflects the possible adaptation of epidermal keratinocytes in the new environment of the oral cavity.
No preview · Article · Jun 2003 · British Journal of Dermatology
[Show abstract][Hide abstract] ABSTRACT: De novo formation of lymphoid tissue is one of the characteristic features of chronic inflammation. The formation of T cell-mature dendritic cell (DC) clusters has been previously demonstrated in chronically inflamed skin infected with Candida albicans. A functional similarity was also found between chronic inflammation and the T-cell zone of lymph nodes (LNs), since a substantial fraction of phenotypically mature DCs in both tissues expressed CCL22 (macrophage-derived chemokine; MDC) and were closely surrounded by memory-type T cells expressing its receptor, CCR4. To analyse the nature of T cell-mature DC interactions further in chronically inflamed skin and LNs, the present study focuses on another chemokine system, namely CCL19 (EBI1 ligand chemokine; ELC), CCL21 (secondary lymphoid tissue chemokine; SLC) and their shared receptor, CCR7. RT-PCR analysis revealed expression of CCL19, CCL21, and CCR7 at high levels in LNs and at low levels in inflamed skin. Using immunohistochemistry, the majority of DC-Lamp(+) mature DCs in the T-cell area of LNs expressed CCL19 and were surrounded by CCR7(+) naïve-type lymphocytes, while CCL21 was expressed in reticular stromal cells and vascular endothelial cells. Very few mature DCs in LNs were found to express CCR7. In contrast, the majority of DC-Lamp(+) mature DCs in inflamed skin were totally negative for CCL19 and were surrounded by CCR7(-) memory-type T cells. Furthermore, CCL21 expression in the inflamed skin was detected in dermal lymphatic endothelial cells and rare CCR7(+) mature DCs were mostly seen within the lymphatic vessels. In normal skin, on the other hand, no cells immunoreactive for CCL19, CCL21, or CCR7 were found. The present study thus reveals a striking difference in the function of mature DCs between LNs and chronically inflamed skin.
No preview · Article · Jan 2003 · The Journal of Pathology
[Show abstract][Hide abstract] ABSTRACT: Mutual communication among the immune, neuroendocrine and metabolic systems is essential for the maintenance of gastrointestinal mucosal function. A unique barrier system by the mucosal immune system handles a myriad of infectious and food antigens, while the neuroendocrine system interplays with the immune system in the intestinal mucosa. The close relation between these two systems is associated with the pronounced effects of stress and metabolic changes.
No preview · Article · Jan 2003 · Acta histochemica et cytochemica official journal of the Japan Society of Histochemistry and Cytochemistry