8.15A). Other approaches include surface decoration with polysaccharides such as dextran, heparin, or polysialic acid derivatives. 17.14B). Monocytes and macrophages are motile, yet become highly adherent upon phagocytic activity. Reticular cells are stellate with processes that extend along reticular fibers in order to make contact with neighboring cells. In dogs, Bruch’s membrane appears trilaminar, with the inner and outer membranes separated by a single layer of collagen [221]. Loose connective tissue is found around every blood vessel, helping to keep the vessel in place. After the initial antigenic encounter, they proceed to the T cell area near the follicle, where they hook up with antigen-specific helper T cells and become immunologically activated. Histology Learning System [ Connective Tissue, reticular fibers] The sinus pore size can vary between species, and the morphology and degree of fenestration can change in certain disease processes, such as cirrhosis. Conventional thought is that the tapetum reflects light that has passed through the retina back to the photoreceptors to increase stimulation, enhancing vision under scotopic conditions. Visit & Look Up Quick Results Now On celebrandoleonardo500.com! Reticular connective tissue consists of reticular cells and the network of reticular fibres formed by them. Fisher, ... N.A. Due to their function as exchange villi, sometimes more than 50% of the stromal cross section is dominated by vessels (capillaries and sinusoids). The capsule is deeply indented in one part of the spleen to form the hilus where blood vessels, lymphatic vessels and nerves enter and exit. The function of terminal villi is the direct exchange between mother and fetus across the placental barrier. Terminal villi show a length of about 200 μm with diameters between 50 and 100 μm. Initial evidence that distinct subsets of pre-cDCs may exist came from analysis of CD24 expression which subdivided pre-cDCs into three populations based on CD24 expression (CD24hi, CD24int, and CD24lo), with CD24hi and CD24lo cells preferentially generating cDC1s and cDC2s, respectively, while CD24int cells maintained the potential to generate both subsets (Naik et al., 2007, 2006). Categorized under loose connective tissues, reticular connective tissues are also named as reticular fibers, which are an essential part of the body’s tissue framework. In cases with maternal hypoxia (chronic anemia or pregnancy at high altitude) less oxygen reaches the placenta. However, RPE (peripheral-lining, nonsensory, epithelial support cells to the retina) tight junctions prevent leakage into the retina of the healthy eye, and create osmotic pressure that assists in drawing fluid out of the retina through cellular mechanisms. Figure 17.16. The eye may be rendered vulnerable to systemic drug exposure with compromise of the blood–ocular barrier such as occurs with systemic vascular diseases, particularly those that may have ocular components in their pathologies. A few arterial capillaries may connect with the venous sinuses, but many of them open directly in the reticular meshwork of the cellular cords. The endometrial cycle is divided into the proliferative, secretory, and menstrual phases (Figs. The myometrium is composed of an inner circular layer and outer longitudinal layer of smooth muscle fibers separated by loose, highly vascular connective tissue, the stratum vasculosum. At term about 25% of the villous volume can be attributed to mature intermediate villi. The villous stroma is filled with only few fibroblasts and Hofbauer cells but lots of fibers such as collagen type I and other matrix components to stabilize this type of villi. Bruce M. Carlson MD, PhD, in The Human Body, 2019. The uterine horns in rodents and the uterine fundus in humans both consist of the endometrium, an inner epithelial-lined mucosa, which covers the myometrium (muscular layer) of the uterus (Fig. The white pulp of the spleen is lymphoid tissue consisting of lymphocytes, macrophages and other free cells lying in a reticular meshwork and surrounding arterial vessels to form the PALS (Figure 2). (A) From Male et al. Particle clearance from the blood usually involves localization in an organ or tissue associated with the reticuloendothelial system (RES). Collagen is a strong protein and is a main component of ligaments and tendon. As fibroblasts are the most common cells in areolar tissue, the majority of the nuclei seen here are probably fibroblast nuclei. The cytoplasm of these reticular cells stains lightly and is reduced or occupies a small space but their nuclei stain weakly. Within the sinuses, fine fibers of reticular connective tissue form a very loose meshwork that both slows down the flow of lymph and serves as attachment sites for the resident macrophages. Reticular connective tissue is characterized by a cellular framework and does not run in bundles but rather as delicate and thin network of fibers and is mostly seen in lymphatic tissues and bone marrow. A basement membrane complex resides between the choriocapillaris and the RPE known as Bruch’s membrane, an exterior lining of the RPE, extending anterior to the ora serrata, and penetrated posteriorly by the optic nerve. The CDPs further differentiate in the bone marrow into pre-cDCs or pDCs. Endothelial cells are elongated and lie parallel to the long axis of the vessel. The central artery runs out into the red pulp and usually terminates in the cords (‘open’ circulation) or into the sinuses (‘closed’ circulation) of the red pulp. B-lymphocytes (resting and immunologically naïve) form dense aggregates known as primary lymphoid follicles within the cortex, whereas T cells migrate into a paracortical region closer to the medulla, where they also form dense aggregates alongside the B cells of the lymphoid nodules (see Fig. Specialized pigmented macrophages, melanocytes, are distributed in this layer and have a role in absorption of excess radiation. Connective Tissue - Introduction. Most connective tissues contain reticular fibres, but only in reticular connective tissue are they the dominant fibre type. (B) Human menstrual cycle. Stem villi develop from further differentiation of immature intermediate villi or directly differentiate from mesenchymal villi. 17.11 and 17.12). Reticular connective tissue. It consists of a series of flattened vascular spaces that lie between the white pulp and the marginal zone. Lymphatics are found in the capsule and trabeculae but not in the pulp. The human endometrium is composed of glands and specialized stroma. A tapetum is not present in the primate, rabbit, or rodent. Blood from the choriocapillaris support the metabolic demands of the outer portion of the retina, extending to the inner nuclear layer. Tight junctions (zonulae occludens) of the retinal endothelium provide a barrier to macromolecule diffusion from blood vessels that is additionally supported by a discontinuous layer of surrounding cells with smooth-muscle characteristics—pericytes—and by basement membrane of Müller cells and astrocytes. Specialized macrophages include Kupffer cells in the liver, Langerhans cells in skin, and glial cells in the central nervous system. A rich branching network of trabeculae from the internal capsular surface subdivides the organ into communicating compartments. The vaginal fornix (VF) is shown. Germinal center activity increases the overall size of the lymphoid nodule and contributes to the swelling of lymph nodes that occurs during an infection. Figure 2. They are surrounded by fibroblasts but lack any relation to endothelial cells. Both cDC subsets develop from hematopoietic stem cells in a stepwise manner through a number of intermediary progenitor cells before ultimately deriving from distinct precursors (Liu et al., 2009; Schlitzer et al., 2015; Grajales-Reyes et al., 2015; Naik et al., 2006). Reticular Connective Tissue is a type of loose connective tissue that is made up of a delicate 3-dimensional network of type III collagen that helps to support cells and other tissues. Rabbits possess an extended region comparable to the area centralis known as the visual streak, a horizontal band in the posterior retina inferior to the optic disc (positioned in the dorsal posterior pole). The lymphoid tissue is separated from the red pulp by the marginal zone. After antigenic stimulation, lymphoid follicles, now called secondary lymphoid follicles, develop a lighter staining germinal center that consists predominantly of activated B cells with increased amounts of cytoplasm (Fig. At the next stage of cDC differentiation, the MDP generates CD117lo CX3CR1+ CD135+ CD115+ DC committed progenitors, termed common DC progenitors (CDPs) (Onai et al., 2007) or pro-DCs (Naik et al., 2007). The CDPs generated from MDPs have lost their potential to generate cells of the monocyte/mϕ lineage and next differentiate into either CD117−CX3CR1– CD135+CD115−CCR9+CD11cintB220+Ly6C+ pDCs through a CCR9− pre-pDC intermediate (Schlitzer et al., 2011, 2012) or into CD117−CX3CR1+CD135+CD115−CD11cint SIRPαint precursors of cDCs (pre-cDCs) (Naik et al., 2007). collagen fibers. Their stromal core shows a loose reticular connective tissue with little extracellular matrix, small blood vessels and large numbers of Hofbauer cells. Endometrial morphology also varies with cycle, although not as dramatically as in humans. Components of Connective Tissue Matrix The matrix of connective tissue can composed of fibers which are produced by fibroblasts such as-collegen -elastic -reticular The matrix of connective tissue can also be composed of a substance called, ground substance. Circulation, the uterine wall is not present in the bone marrow entering. Of terminal villi often show extension of their diameters and are the largest villi with diameters of 100 μm video. Supply is derived from the choriocapillaris and the marginal zone enter peripheral through! Kelli L. Boyd,... Katherine N. Gibson-Corley, in Encyclopedia of Immunology ( Second Edition,. Is surrounded by a single layer of reflective tissue, and leukocyte infiltration and regenerative changes are in. Labeled `` art '' ( bubbles are one type of villi viral infections not in. 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