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Comparative Anatomy, Physiology, and Biochemistry of Mammalian Skin
Published in David W. Hobson, Dermal and Ocular Toxicology, 2020
Five types of collagen fibers have been described in the human. The difference between the types is based on amino acid composition and sequence. Type I collagen is found in the dermis, bone, tendons, ligament, and dentin. Type II collagen is found predominantly in hyaline cartilage. Type III is found in the fetal dermis, uterus, and cardiovascular system, and immunofluorescent studies show it to be localized in the papillary dermis. Type IV is found in the basal lamina.202–204 Type V collagen, also known as AB, is found in the cornea, dermis, placental membranes, and lung. This type of collagen is thought to be important in cell movement.205
Fibrogenic Cytokines in Airway Fibrosis
Published in Alastair G. Stewart, AIRWAY WALL REMODELLING in ASTHMA, 2020
In the normal airway, there are several readily distinguishable layers by light microscopy, namely, surface epithelium, basement membrane, lamina propria, smooth muscle, submucosa, cartilage, and adventitia. Ultrastructurally, the basement membrane of the human airway consists of two distinct layers: a basal lamina and a reticular collagenous lamina (Figure 2).18,28 The basal lamina (true basement membrane) largely comprises type IV collagen, proteoglycans, laminin, and fibronectin. The reticular collagenous lamina or subepithelial collagen layer predominandy comprises types III and V collagen together with fibronectin.20 Beneath this is a bed of stromal tissue predominandy comprised of mesenchymal cells, fibroblasts, and smooth muscle cells, embedded in matrix. The matrix substance of normal airways, like other organs, is composed of a wide array of immunologically and biochemically distinct elements: collagens (collagens I, III, V), elastins, proteoglycans, fibronectins, and laminins (Plate 1* and Figure 3). The major components, collagens (types I and III) and elastin, are the primary determinants of the physical properties of bronchioles. In the upper airway there is the additional support to the cartilaginous structures composed predominantly of type II collagen.29
Endocrine, paracrine and intracrine mechanisms of growth regulation in normal and malignant endometrial epithelium
Published in A. R. Genazzani, Hormone Replacement Therapy and Cancer, 2020
The different endometrial cell types are surrounded by the extracellular matrix (ECM), which also shows cyclic changes during the menstrual cycle (Figure 1). The ECM can be separated into two types. The first is the interstitial matrix, which is a collagen-rich ground substance (contains collagen types I, II, III, V, VI and XI, glycosaminoglycans, proteoglycans and fibronectin), in which stromal fibroblasts are located. The components of the interstitial matrix are synthesized by stromal fibroblasts. The second is the basement membrane, which is the specialized matrix (contains collagen IV, the glycoproteins laminin and entactin, and heparan sulfate proteoglycans) underlying epithelial and endothelial cell layers. Epithelial cells may synthesize components of their own basal lamina. Basement membranes also surround muscle, fat and decidual cells, as well as vascular smooth muscle cells and endothelial cells.
Astrocytoma and glioblastoma IDH1-wildtype cells colonize tumor vessels and deploy vascular mimicry
Published in Ultrastructural Pathology, 2023
Haitham H. Maraqah, Mones S. Abu-Asab, Han Sung Lee, Orwa Aboud
The astrocytoma IDH1-mutant tumors showed similar abnormal features in the tumor vessels to that of IDH1-wildtype glioblastoma tumors. The tumor cells’ invasion of vessels’ was ubiquitous (Figure 2) and resulted in deformed and abnormal vessel shape and structure (Figure 2a-f). The VWs were thickened with redundant elastic layers of the basement membrane, morphologically distorted, and occupied with lipid and tumor cells (*, Figure 2a-c and e). The vessels’ lumina had lipid inclusions (L) and tumor cell (+). The basal lamina was abnormal and discontinuous as well as partially or totally lacking. Endothelial cells were absent and replaced by the tumor cells; however, this process is occasionally more prominent with more tumor cells forming a circle around on the luminal side, a sign of vascular mimicry (see discussion). The deformed and distorted structure is more prominent in the mutant type than in wildtype.
Effects of Trans-Cinnamaldehyde on Reperfused Ischemic Skeletal Muscle and the Relationship to Laminin
Published in Journal of Investigative Surgery, 2021
Esra Pekoglu, Belgin Buyukakilli, Cagatay Han Turkseven, Ebru Balli, Gulsen Bayrak, Burak Cimen, Senay Balci
Laminin is one of the main components of the basal lamina and a protein network for many cells and tissues [5]. Laminin proteins bind to cell membranes through plasma membrane proteins and integrin receptors [6]. The interaction within laminin and integrin and dystroglycan receptors allow the basement membrane and the actin cytoskeleton to be organized. This linkage stabilizes sarcolemma and protects muscle fiber from contractile damage [7]. In acute muscle ischemia, the extracellular matrix (ECM) of the myofibril basement membrane is remodified and this modification forms differences in type IV collagen and laminin [8]. Previous studies have reported that laminin is degraded as a result of myofibril degeneration and acute muscle ischemia [8,9]. A decrease in mitochondrial respiration and an increase in glycolysis were observed in muscle cells lacking the laminin α-chain [10]. As a result of inadequate mitochondrial respiration, ROS formation increases, causing increased muscle damage in dystrophic muscles [7]. A recent study showed that ROS levels were significantly enhanced in laminin deficiency mouse and patient skeletal muscle [7]. These findings suggest that there is a relationship between laminin and the formation of ROS.
Myoepithelioma of bone: ultrastructural, immunohistochemical and molecular study of three cases
Published in Ultrastructural Pathology, 2019
Paweł Kurzawa, Martin K. Selig, Patryk Kraiński, Michał Dopierała, G. Petur Nielsen
By electron microscopy (Table 4), the tumor was composed of, spindle and stellate shaped cells in a predominately collagenous matrix (Figure 2). The cells had long slender processes which did not intertwine (Figure 3) and were seen actively producing the collagen matrix (Figure 4). Cell junctions were not identified. Nuclei were irregular in contour and shape and lacked prominent nucleoli. The main cytoplasmic components were an abundance of intermediate filaments (Figure 5) without dense bodies, moderately dilated rough endoplasmic reticulum, moderate numbers of mitochondria, and glycogen. Some cells had innumerable pinocytotic vesicles. Irregular intermittent basal lamina was identified around many cells. Rare lipid droplets were present.