China
Africa
Explore chapters and articles related to this topic
Summation of Basic Endocrine Data
Published in George H. Gass, Harold M. Kaplan, Handbook of Endocrinology, 2020
The effects vary with the specific hormone that is circulating to the cells of the body. The material stored in colloid as thyroglobulin is translocated to the lumen of each thyroid follicle. T4, which is necessary for life, is the dominant circulatory form and gives rise to most of T3 and just about all of rT3. The hormones circulate almost totally bound to proteins. Thyroxine-binding globulin is the major binding protein; it is a glycoprotein-a-globulin. Other binding proteins are albumin and a thyroid-binding albumin.
Principles of Radioiodination and Iodine-Labeled Tracers in Biomedical Investigation †
Published in Garimella V. S. Rayudu, Lelio G. Colombetti, Radiotracers for Medical Applications, 2019
Mrinal K. Dewanjee, Shyam A. Rao
Iodide ion is concentrated in the thyroid gland by an energy-dependent active transport mechanism (pump). This trapping mechanism maintains an intrathyroidal iodide level 20 to 40 times that in the plasma level. This trapped iodide is rapidly oxidized to iodine by peroxidase enzyme and H2O2, as in in vitro enzymatic iodination, and iodine binds to tyrosine residues of thyroglobulin molecule in the thyroid follicle. The tyrosine residue might contain one atom (monoiodotyrosine, M.I.T.) or two atoms (diiodoty-rosine, D.I.T.) of iodine. The species difference of iodine uptake is shown in Figure 19.
Defects in Tg Gene Expression and Tg Secretion
Published in Geraldo Medeiros-Neto, John Bruton Stanbury, Inherited Disorders of the Thyroid System, 2019
Geraldo Medeiros-Neto, John Bruton Stanbury
Thyroid hormone synthesis is intimately bound up with thyroglobulin (Tg). Indeed, after the active transport of iodide into the thyroid cell, every subsequent step of triiodothyronine (T3) and thyroxine (T4) formation occurs within the Tg molecule. Thus, synthesis of T3 and T4 follows a metabolic pathway that depends on the integrity of the Tg structure. This large glycoprotein, a dimer of 660,000 Da, is synthesized and secreted by the thyroid cells into the lumen of the thyroid follicle. Thyroglobulin serves two main purposes in the function of the thyroid gland. The first is related to the process of hormone production. Thus, Tg provides for the efficient coupling of the hormone precursors mono- and diiodotyrosine to form T3 and T4. The second function is that of a repository within the gland of a large supply of iodine and of hormone for secretion at a steady rate or upon demand.1 These two properties of Tg seem to permit the organism to operate in an environment that is usually deficient in iodine and to accommodate to wide variations in iodine supply. The efficiency of hormone synthesis in Tg depends on structural factors intrinsic to the protein matrix that favors the coupling reaction. We may assume that genetic mutations that would result in a structurally defective protein would severely impair the functional ability of Tg to serve as matrix for T3 and T4 generation.
The possible ameliorative role of Lycopene on Tributyltin induced thyroid damage in adult male albino rats (histological, immunohistochemical and biochemical study)
Published in Ultrastructural Pathology, 2023
Ghada A Elsammak, Aliaa Talaat, Samar Reda
Electron micrograph of ultrathin sections in the thyroid gland of control rat showed thyroid follicular cells with apical microvilli, oval euchromatic nucleus, rough endoplasmic reticulum and mitochondria. Follicle was surrounded by thin regular basal lamina and blood capillary. Junctional complexes between adjacent cells appeared intact. Homogenous colloid was noticed (Figure 6). Tributyltin treated group showed follicular cells with irregular shrunken nuclei and atrophied apical microvilli. The cytoplasm contained vacuoles, multiple lysosomal granules and extensively dilated rough endoplasmic reticulum (Figure 7a,b,c). A congested blood capillary was seen (Figure 7a). There were mitochondria with destructed cristae (Figue 7b,c). The interfollicular space contained fibroblast with heterochromatic nucleus and collagen fibers deposition (Figure 7c). Tributyltin & Lycopene group showed thyroid follicle lined by more than one layer of follicular cells, one cell had rounded euchromatic nucleus and other exhibited irregular nucleus. Follicular cells had apical microvilli border, rough endoplasmic reticulum, electron dense lysosomes and numerous mitochondria. Junctional complexes between adjacent cells, regular basal lamina and homogenous colloid were noticed (Figure 8).
Extracellular vesicles from endothelial progenitor cells promote thyroid follicle formation
Published in Journal of Extracellular Vesicles, 2018
Jonathan Degosserie, Charlotte Heymans, Catherine Spourquet, Mathias Halbout, Ludovic D’Auria, Patrick Van Der Smissen, Didier Vertommen, Pierre J. Courtoy, Donatienne Tyteca, Christophe E. Pierreux
The thyroid is an endocrine gland composed of three main cell types: thyrocytes, C cells and endothelial cells. Thyrocytes are polarised epithelial cells organised as monolayers into follicles enclosing packed iodothyroglobulin in the colloid, and responsible for the production of thyroglobulin-derived hormones, T3 and T4. C cells are epithelial cells, closely associated with follicles, which produce calcitonin. A dense network of endothelial cells surrounds each thyroid follicle. The close juxtaposition between follicles and blood capillaries is essential for bidirectional exchange supporting thyroid function. Iodide is captured from bloodstream into thyrocytes, and incorporated into thyroglobulin as T3 and T4 hormonogenic peptides. When T3 and T4 blood levels are low, thyrocytes capture iodothyroglobulin and release by proteolysis T3 and T4 hormones that are excreted into the blood flow. The functional couple between follicles and blood capillaries, often called the angio-follicular unit, forms during embryonic development [1,2].
Exploring of the Unpredicted Effects of Olfactory Network Injuries on Mammary Gland Degeneration: A Preliminary Experimental Study
Published in Journal of Investigative Surgery, 2019
Erdem Karadeniz, Mehmet Nuri Kocak, Ali Ahiskalioglu, Kemal Alp Nalci, Sevilay Ozmen, Mufide Nuran Akcay, Nazan Aydin, Mehmet Dumlu Aydin, Ahmet Hacimuftuoglu
To detect the olfactory nerve lesion, brain materials were sectioned parallel to the long axis of these nerves in order to examine the olfactory nerve histology. Brain materials were also stained with same dyes. In order to estimate the total thyroid follicle numbers and volumes, the brain materials were embedded in parafin blocks. They were stained with H&E dyes. The advantages of this method are: particle number was estimated easily, it could be readily performed, it was intuitively simple, it was free from assumptions about particle shape, size, and orientation, and it was unaffected by overprotection and truncation.