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The Inducible Defense System: The Induction and Development of the Inducible Defence
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
Michael A. Hickey, Diane Wallace Taylor
Morphologically, the lymphocyte usually appears in the peripheral blood as a small, round uninucleate cell approximately 7 to 8 μm in diameter. The nucleus occupies the bulk of the cell, with a small amount of basic cytoplasm surrounding it (Figure 8.1). The lymphocyte that is commonly observed in blood films is in the resting stage (G0) of the cell cycle. The cytoplasm contains a few mitochondria, a smali number of ribosomes, little or no endoplasmic reticulum, and an interphase nucleus. Upon activation by antigen, however, lymphocytes increase in size (≈ 12 μm) and differentiate into lymphoblasts (or blasts). Because lymphoblasts ultimately secrete products (for example, antibodies or cytokines) or transport in tra cellulari y produced molecules to cell surfaces (for example, the interleukin-2 receptor), lymphoblasts have many of the morphologic characteristics of secretory cells. The Golgi apparatus becomes prominent and there are large amounts of rough endoplasmic reticulum and polyribosomes. Activated cells usually undergo cell division, during which chromosomes and spindle fibers are evident. Electron micrographs of resting, dividing, and activated lymphocytes with these attributes are shown in Figure 8.1
Introduction: Background Material
Published in Nassir H. Sabah, Neuromuscular Fundamentals, 2020
The endoplasmic reticulum (ER) is an elaborate network of vesicles, tubules, and cisternae. It can take the form of a rough endoplasmic reticulum (RER) because of the presence of ribosomes, which are granular structures that are the sites of protein synthesis. Ribosomes can also be free in the cytosol in addition to being membrane-bound in the RER. The RER is thus involved in the synthesis of integral membrane proteins and proteins that are to be secreted outside the cell, including hormones. The smooth endoplasmic reticulum (SER) is almost devoid of ribosomes and is involved in the synthesis of lipids and steroids and in Ca2+homeostasis, that is, regulation of Ca2+ concentration in the cytosol, by acting as the principal store of Ca2+ in the cell. A type of SER, the sarcoplasmic reticulum (SR), is found in muscle cells (Section 9.1.2) and is specialized for the uptake and release of Ca2+.
Comparative Anatomy, Physiology, and Biochemistry of Mammalian Skin
Published in David W. Hobson, Dermal and Ocular Toxicology, 2020
The plasma cell is usually found in loose connective tissue and in great numbers in lymphatic tissue. It is derived from B-lymphocytes which differentiate in the connective tissue after antigenic stimulation. Antibody production is the function of the plasma cell (see Chapter 5). In routine staining for light microscopy, plasma cells can be seen to contain a large amount of cytoplasm relative to the size of the nucleus. The nuclear chromatin is distributed in clumps around the periphery of the cell. The nucleolus is prominent. The plasma cell can sometimes contain acidophilic granules termed Russel bodies. Ultrastructurally, plasma cells have an abundance of rough endoplasmic reticulum and prominent organelles such as a large Golgi region, mitochondria, polyribosomes, and finger-like extensions of the plasma membrane. The abundance of rough endoplasmic reticulum suggests protein secretion, a finding consist with their role of producing antibodies for release into the blood.204
Bazi Bushen capsule attenuates cognitive deficits by inhibiting microglia activation and cellular senescence
Published in Pharmaceutical Biology, 2022
Chuanyuan Ji, Cong Wei, Mengnan Li, Shuang Shen, Shixiong Zhang, Yunlong Hou, Yiling Wu
Neurons are the main components of brain tissue, which exchange information by receiving, integrating, conducting and outputting information. Nissl bodies are plaque-like or granular substances present in neurons. They are composed of a large number of rough endoplasmic reticulum and free ribosomes, which mainly synthesize proteins required for the renewal of organelles. Nissl bodies can be used as a marker of neuronal functional status. The Nissl bodies undergo decrease, loss and dissolution in an injured neuron. Nissl bodies can increase and return to normal levels in the recovery from neuronal injury (Kaufmann et al. 2012). The current study showed that BZBS can protect against neuronal damage and ameliorate the cognitive deficits in d-gal-induced ageing mice (Figure 4(C,D)).
Covid-19: a comprehensive review of a formidable foe and the road ahead
Published in Expert Review of Respiratory Medicine, 2020
Arafat Hussain, Suniti Yadav, Vijay Hadda, Tejas M Suri, Pawan Tiwari, Saurabh Mittal, Karan Madan, Anant Mohan
Similar to SARS-CoV, the S glycoprotein of SARS-CoV-2 mediates binding to the human angiotensin-converting enzyme 2 (ACE2) receptor and membrane fusion with host cells of the target organ [27]. The receptor-binding domain (RBD) of S-glycoprotein facilitates interaction with the host-cell receptor. Upon binding, conformational changes within the S-glycoprotein render it susceptible to cleavage by nearby protease [28]. Its cleavage and subsequent activation release the spike fusion peptide to promote membrane fusion and the virus releases its RNA into the host-cell cytoplasm. The viral RNA then uncoats and translation of two polyproteins and structural proteins, transcription of the sub-genomic RNAs and replication of viral genome take place. The newly synthesized S, M, and E structural proteins are then transported to the rough endoplasmic reticulum (RER) or Golgi membranes. The nucleocapsid is formed by combination of genomic RNA with nucleocapsid proteins. Finally, the structural proteins are packaged into the nucleocapsid and the viral envelope at the ER-Golgi intermediate compartment (ERGIC) followed by fusion of the virion-containing vesicles with the host-cell plasma membrane and release of the virus [8]. The whole process of viral entry into host cells and its replication are schematically presented in Figure 2.
Lithium effects on vesicular trafficking in hepatocellular carcinoma cells
Published in Ultrastructural Pathology, 2019
Iuliia Taskaeva, Nataliya Bgatova, Izabella Gogaeva
Histologically, tumors arising from HCC-29 cells exhibited hepatocyte-like cellular morphologies (Figure 1a) while their nuclei had a typical morphology with irregular shapes and numerous clusters of heterochromatin. The membranes of the rough endoplasmic reticulum were not abundant and both multiple polysomes and ribosomes were distributed throughout the cytoplasm. Structural abnormalities in mitochondria, such as homogenous mitochondrial matrices with cristae fragmentation, were also found. Multivesicular bodies and lysosomes were not numerous and were only occasionally distributed throughout the cytoplasm (Figure 1b). These bodies had typical morphological features such as central, round vacuoles with a few intraluminal vesicles and no connections to the vacuolar membrane. Lysosomes, on the other hand, appeared as spherical organelles which contained relatively homogeneous, electron-dense content. We could therefore confirm that the cytoplasm of HCC-29 cells contained multiple tubular and vesicular structures (Figure 2). These vesicles are referred to as endosomes due to their location at the cellular periphery and included predominantly electron-transparent content with accidental intraluminal vesicles. Endosomes in HCC-29 cells were abundant, with various shapes and sizes, and were occasionally associated with short tubules.