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Anatomy and Physiology of Head and Neck Endocrine Glands
Published in R James A England, Eamon Shamil, Rajeev Mathew, Manohar Bance, Pavol Surda, Jemy Jose, Omar Hilmi, Adam J Donne, Scott-Brown's Essential Otorhinolaryngology, 2022
Thyroid cells are organised into functional lobules surrounding a lobular artery. Lobules contain 20–40 spherical follicles lined by a single layer of follicular cells around a collection of colloid. The basal and apical layers of the follicular cells are bound by tight junctions to allow control of the release of thyroid hormones. In response to thyroid-stimulating hormone (TSH), follicular cells adopt a columnar shape, and their apical surfaces protrude microvilli to facilitate reabsorption of colloid.
Thyroid nodules
Published in Nadia Barghouthi, Jessica Perini, Endocrine Diseases in Pregnancy and the Postpartum Period, 2021
Estrogen and ProgesteroneThyroid cancer incidence is more common in women during the years between puberty and menopause suggesting the potential role of estrogen and/or progesterone in the etiology of thyroid nodule formation and tumorigenesis.Estrogen and progesterone in vitro have a role in thyroid growth; however, clinical trials to date have not shown any consistent associations.Estrogen (ER)-α and progesterone receptors are expressed in some thyroid tumor tissues.11 Thyroid follicular cells in vitro are stimulated by estradiol through estrogen-dependent genomic and nongenomic signaling.12 Progesterone has been shown to increase the mRNA expression of genes involved in thyroid cell function and proliferation.13
Thyroid
Published in Pat Price, Karol Sikora, Treatment of Cancer, 2020
Although thyroid follicular cells can give rise to both benign and malignant tumors, the evidence to support an adenoma to carcinoma multi-step pathogenesis is not universally accepted. Malignant transformation is due to the activation of proto-oncogenes or the inactivation of tumor suppressor genes in combination with environmental factors. Defects to the tyrosine kinase receptor genes are commonly found in thyroid cancer. The interaction of these receptors with growth factors leads to the activation of the mitogen-activated protein kinase (MAPK) pathway through RAS and BRAF proteins, resulting in uncontrolled cell division. A pan-cancer study using The Cancer Genome Atlas (TCGA) showed that PTC is a tumor with one of the lowest tumor mutational burdens, usually with only a single driver gene alteration.12 This provides some explanation of the indolent nature of thyroid cancer compared with other solid tumors. The fact that the development of thyroid cancer occurs following single gene alterations suggests that these could be potential therapeutic targets to provide effective disease control.13
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
H&E stained sections of the thyroid gland of the control group showed thyroid follicles lined by cuboidal follicular cells with central rounded nuclei. There was acidophilic and homogenous colloid filling in the luminae of the follicles. The parafollicular cells were small oval with dark stained nuclei and situated between the follicular cells on the basement membrane (Figure 1a). The TBT-treated group showed some follicles lined by cuboidal cells with rounded nuclei and others lined by flat cells with flat nuclei. Numerous follicular cells showed vacuolated cytoplasm. In some follicles, multiple layers of follicular cells were seen on one side. There were large interstitial spaces between some follicles. Some follicles were dilated while others were involuted. There was a large congested blood vessel. There were numerous darkly stained nuclei. The capsule was noted. Some follicles had no colloid (Figure 1b). The protective (TBT-Lycopene) group showed nearly normal thyroid architecture. Thyroid follicles were of variable sizes. Almost all the follicles were filled with colloid and showed peripheral vacuolations. Most of thyroid follicles were lined by cuboidal cells with large rounded central nuclei while some follicles were lined by flat cells with flat nuclei. Few follicles showed vacuolated cytoplasm and dark nuclei. Groups of interfollicular cells were present in between follicles. Two fused follicles were seen (Figure 1c).
Insights into the possible impact of COVID-19 on the endocrine system
Published in Archives of Physiology and Biochemistry, 2023
Adel Abdel-Moneim, Ahmed Hosni
A study performed during the 2003 SARS-outbreak recorded lower levels of serum T3 and tetraiodothyronine (T4) in patients with SARS compared with controls (Wang et al.2003). In addition, intensive care cases of SARS with sick-euthyroid syndrome seemed to have a lower thyroid weight related to decreasing follicular thyroid size along with colloid depletion (De Jongh et al.2001). Multiple pathways have been proposed for the progression of sick-euthyroid syndrome, including changes in iodothyronine deiodinases and TSH secretion, thyroid hormone binding to plasma protein, thyroid hormone delivery in peripheral tissues, and thyroid hormone inhibitory effects (DeGroot 2000). Moreover, Sun et al. (2005) identified follicular cell dystrophy, deformation, and decrease levels of thyroglobulin in four patients with SARS who died. Furthermore, autopsy investigations of five patients with SARS showed considerable degradation of the thyroid follicular and parafollicular cells with significant numbers of cells undergoing apoptosis (Wei et al. 2007). Destruction of the thyroid follicular cells can be manifested by low T3 and T4 levels.
The possible protective role of vitamin C versus melatonin on potassium dichromate induced changes in rat thyroid gland: light and electron microscopic study
Published in Ultrastructural Pathology, 2023
Eman Saeed, Ahmed A. El-Mansy, Shireen A Mazroa, Amal M. Moustafa
The thyroid gland of the control group showed the same structure in the different subgroups (Іa, Іb and Іc). The stroma was formed of a thin capsule and septa dividing the gland into incomplete lobules. The thyroid parenchyma was composed of thyroid follicles and separated by interfollicular tissue. The thyroid follicles were variable in shape and size. The central follicles had a smaller diameter than the peripheral ones. The thyroid follicles were lined mainly with follicular cells and a small number of parafollicular cells. The central follicles were lined by cubical follicular cells with large, rounded nuclei, whereas the peripheral ones were lined with low cubical or flat follicular cells with flat nuclei. The thyroid follicles exhibited a central acidophilic homogenous colloid that revealed marginal vacuoles (Figure 1(a,b,c)). Parafollicular cells were rarely seen in the section. They were resting on the basement membrane and did not reach the luminal surface. They were few in number, large in size, rounded or oval in shape with vesicular nuclei and pale stained cytoplasm (Figure 1(a,b)). The interfollicular tissue was composed of a scanty amount of C.T. containing blood vessels, fibroblast and interfollicular cells, which were seen among the thyroid follicles (Figure 1c).