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Mucosal B cells and their function
Published in Phillip D. Smith, Richard S. Blumberg, Thomas T. MacDonald, Principles of Mucosal Immunology, 2020
Jo Spencer, Edward N. Janoff, Per Brandtzaeg
Mucosal tissue can be subdivided into structures and cells associated with the inductive or the effector arms of the mucosal immune response. The inductive compartment consists of mucosa-associated lymphoid tissue (MALT), classically Peyer's patches in the intestinal mucosa (gut-associated lymphoid tissue [GALT]) and bronchus-associated lymphoid tissue (BALT) (Chapter 23), which resemble lymph nodes and are highly organized and dynamic in terms of lymphocyte traffic and proliferation. However, because MALT is constantly exposed to antigens coming directly from mucosal surfaces, MALT structures are uniquely adapted to generate diverse precursors of mucosal effector cells. In contrast, the GALT effector compartment is diffusely located in the subepithelial lamina propria. The lamina propria contains plasma cells and their immediate precursors, together with effector T cells, macrophages, dendritic cells, granulocytes, and mast cells. The most abundant effector molecule produced in the lamina propria is IgA, which is among the best understood mediators of mucosal protection.
The gastrointestinal system
Published in C. Simon Herrington, Muir's Textbook of Pathology, 2020
Sharon J. White, Francis A. Carey
The mucosa of the large bowel differs from that of the small in the following important respects: It is flat with no villi.It contains straight crypts lined by absorptive and mucus-producing goblet cells.The endocrine cells and Paneth cells are less numerous, the latter normally being found only on the right side of the colon and in very small numbers.The lamina propria is less prominent and contains very few lymphatics; thus, malignancy confined to the mucosa has very limited metastatic potential.
Exposure
Published in Frank A. Barile, Barile’s Clinical Toxicology, 2019
Oral administration of drugs and toxins is by far the most popular route of exposure. Oral administration involves the presence of several physiological barriers, which must be penetrated or circumvented if an adequate blood concentration of the compound is to be achieved. The mucosal layers of the oral cavity, pharynx, and esophagus consist of stratified squamous epithelium, which serves to protect the upper gastrointestinal (GI) lining from the effects of contact with physical and chemical agents. Simple columnar epithelium lines the stomach and intestinal tracts, which function in digestion, secretion, and some absorption. Immediately underlying the epithelium is the lamina propria, a mucosal layer rich in blood vessels and nerves. Mucosa-associated lymphoid tissue (MALT) is layered within this level, where prominent lymphatic nodules sustain the presence of phagocytic macrophages and granulocytes. Salivary and intestinal glands contribute to the digestive process by secreting saliva and digestive juices. The submucosa, muscularis, and serosa complete the strata that form the anatomical envelope of the GI tract. Enteroendocrine and exocrine cells in the GI tract secrete hormones and in the stomach, secrete acid and gastric lipase. Tables 5.1 and 5.2 illustrate select toxic substances and routes of exposure, including dermal and ocular routes, and their suspected clinical effects.
The possible effect of lycopene in ameliorating experimentally induced ulcerative colitis in adult male albino rats (A histological, immunohistochemical, and ultrastructural study)
Published in Ultrastructural Pathology, 2023
Shaimaa Mostafa Kashef, Rania Ibrahim Yassien, Dalia El-Sayed El-Ghazouly
H&E-stained sections of control group (group-I) revealed the normal well-known histological structure of the colon. From inside outwards, the colon wall was formed of mucosa, submucosa, musculosa, and serosa. The mucosa appeared folded, continuous, and intact (Figure 1a). The mucosa was formed of tightly packed and evenly spaced crypts occupying the entire mucosal thickness to the muscularis mucosa. The luminal surface and crypts were lined with simple columnar cells and goblet cells (Figure 1b). On the other hand, the UC group (group-III) revealed severe alterations in the mucosa. There was destruction of crypts architecture with the loss of the surface epithelium. The goblet cells revealed decrease in their number. The lamina propria showed heavy infiltration with inflammatory cells. Also, hemorrhage and congested blood vessels were observed in the lamina propria. Cell remnants were seen in the lumen (Figures 1c & 1d). Interestingly, sections from LYC+UC group (group-IV) exhibited pictures almost similar to those of the control group except for some inflammatory cells and dilated blood vessels in the mucosa of few colonic sections (Figure 1e).
Preliminary dynamic observation of wound healing after low-temperature plasma radiofrequency ablation for laryngeal leukoplakia
Published in Acta Oto-Laryngologica, 2022
Fang Hao, Liyan Yue, Xiaoyan Yin, Chunguang Shan
The vocal folds are composed of epithelium, lamina propria, and muscularis. The lamina propria is rich in extracellular matrix. The abundance and distribution of proteins and glycans in this extracellular matrix maintain the biomechanical properties of vocal folds vocalization, while injury to the extracellular matrix often affects postoperative pronunciation [17]. The arrangement and content of fibronectin and other components in the extracellular matrix of the wound after vocal fold surgery determine the formation of vocal fold lamina propria scars. Damage to the adult skin can lead to scar formation, which increases as the depth of the injury increases [18]. Although the skin and vocal folds tissue structures are different, there are similarities, and the vocal folds mucosa is a special tissue with unique repair and regeneration requirements [19]. The scars of the vocal folds are not evident after the LTPA treatment of LL wounds. Because the wound was in the mucosal layer, the lamina propria was not damaged or slightly damaged, and did not reach the muscle layer, which is consistent with the observation of postoperative wound healing in the later stage of scar formation. Similarly, Zhang et al. [20] summarized the healing of the vocal folds after treatment with LTPA in patients with early glottic laryngeal cancer and found that postoperative vocal folds scar formation was not apparent.
The concept revolution of gut barrier: from epithelium to endothelium
Published in International Reviews of Immunology, 2021
Song Liu, Peng Song, Feng Sun, Shichao Ai, Qiongyuan Hu, Wenxian Guan, Meng Wang
The gut barrier is traditionally recognized to be consisted of mechanical, immunological and microbial barriers [1, 2, ]. The mechanical barrier includes intestinal epithelium and associated cells and structures, such as goblet cells, Paneth cells, glial cells as well as tight and adherens junctions. These structures and cells form a physical firewall to separate lumen from internal space that prevents the invasion of dangerous antigens. The immunological barrier is mainly constituted by various innate and adaptive immune cells in lamina propria. Dendritic cells, macrophages, lymphocytes and other cells interactively survey, capture and process harmful agents. The microbial barrier includes pro- and anti-inflammatory commensals that inhibit pathogenic microbes to maintain gut homeostasis. These three barriers collaborate to achieve food tolerance and host defense reinforcement.