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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.
SBA Answers and Explanations
Published in Vivian A. Elwell, Jonathan M. Fishman, Rajat Chowdhury, SBAs for the MRCS Part A, 2018
Vivian A. Elwell, Jonathan M. Fishman, Rajat Chowdhury
Stratified squamous epithelium consists of several layers of epithelial cells arranged upon a layer of basement membrane. The layers can be sloughed off and replaced constantly; hence it is suited for areas with constant insults and abrasions. Stratified squamous epithelium can be divided into keratinised and non-keratinised types, depending on the presence of keratin on its surface. Examples of keratinised types include the skin, tongue, and outer lips. Examples of non-keratinised types are cornea, oesophagus, rectum, and vagina. The epididymis and trachea have pseudo-stratified columnar epithelium, whereas the colon and uterus are lined by simple columnar epithelium.
Introduction
Published in Shayne C. Gad, Toxicology of the Gastrointestinal Tract, 2018
The epithelium in the mouth, pharynx, esophagus, and anal canal is mainly nonkeratinized stratified squamous epithelium that serves a protective function. Simple columnar epithelium, which functions in secretion and absorption, lines the stomach and intestines. Neighboring simple columnar epithelial cells are firmly sealed to each other by tight junctions that restrict leakage between the cells. The rate of renewal of GI tract epithelial cells is rapid (5 to 7 days.) Located among the absorptive epithelial cells are exocrine cells that secrete mucus and fluid into the lumen of the tract, and several types of endocrine cells, collectively called enteroendocrine cells, that secrete hormones into the bloodstream.
An overview of the latest in state-of-the-art murine models for prostate cancer
Published in Expert Opinion on Drug Discovery, 2021
Elisabete Nascimento-Gonçalves, Fernanda Seixas, Rita Ferreira, Bruno Colaço, Belmiro Parada, Paula A. Oliveira
The mouse prostate is composed of four lobes located around the urethra and caudal to urinary bladder: anterior lobe, dorsal lobe, lateral lobe and ventral lobe [56–58] (Figure 2 and Figure 3). The anterior prostate lobe, also known as the coagulating gland, follows the curvature of seminal vesicles and is attached to it. The anterior prostate has a simple columnar epithelium, with variable degrees of infolding with a cribriform pattern. The dorsal prostate lobe is located dorsally and bilaterally at the base of the seminal vesicles, and exhibits a simple columnar epithelium [10,11,13]. The lateral prostate lobe is located around the urethra centrally and bilaterally and has a simple columnar epithelium with very little infolding. The two ventral prostate lobes wrap the urethra ventrally and exhibit simple and columnar epithelium with little infolding [11] (Figure 4).
Chemopreventive effect of α-hederin/carboplatin combination against experimental colon hyperplasia and impact on JNK signaling
Published in Toxicology Mechanisms and Methods, 2021
Hoda I. Bahr, Afaf T. Ibrahiem, Attia M. Gabr, Alaaeldeen M. Elbahaie, Hoda S. Elmahdi, Nema Soliman, Amal M. Youssef, Mohamed El-Sherbiny, Sawsan A. Zaitone
In Hx&E sections, colon of saline group showed the normal histological architecture of the mice colon. The wall of the colon was formed of mucosa, submucosa, musculosa, and serosa. The mucosa of colon showed intact surface lined by simple columnar epithelium with acidophilic cytoplasm and basal basophilic nuclei. Crypts appeared straight tubular in shape with narrow openings. The crypts were lined by simple columnar epithelium that had basal oval vesicular nuclei. Goblet cells are flask shaped with vacuolated cytoplasm and basal flattened nuclei (Figure 3(A)). The colon sections of the hyperplasia group showed severe dysplasia as the mucosa form irregular shape and elevated, distorted with crowded hyperchromatic nuclei, loss of crypt architecture, disintegration of goblet cells, and cellular infiltration in the lamina propria (stroma) (Figure 3(B)). Carboplatin group showed diffuse moderate dysplasia (grade 3) with fusion of some crypts and appearance of more goblet cells. Cellular infiltrate were seen (Figure 3(C)). α-Hederin group showed moderate degree of dysplasia (grade 2) with much more goblet cells and less cellular infiltration in lamina propria is shown in Figure 3(D). On the other side, carboplatin + α-hederin group revealed marked improvement of the pathological changes and showed mild crowed crypts with near normal cytological features and normal goblet cells except few foci still with mild degree of dysplasia (Figure 3(E)).
The effect of antioxidants on angiogenesis in uterine transplantation
Published in Journal of Obstetrics and Gynaecology, 2018
Tugba Ugurlu, Candan Ozogul, Gulistan Sanem Saribas, Seren Gulsen Gurgen, Seda Nur Akyol, Bahar Kartal
According to our histological results, the endometrium, myometrium and serous layers of uteri were clearly seen in normal histological structure in the uteri stored in HTK solution at +4 °C for 4 h (Group 1). The connections between ciliated simple columnar epithelium of the uterus and the underlying basement membrane were normal. Stromal tissue, uterine glands and blood vessels were observed in the endometrium. Myometrium, which is composed of smooth muscle of the uterine and adventitia layer that surrounds the myometrium of uterus were clearly seen in Group 1 (Figure 1(a). We observed the cells and structures making up the histological layers of the uteri that were stored in HTK solution combined with Acetyl L-carnitine at +4 °C for 4 h (Group 2) were similar to Group 1 (Figure 1(b)).