See also
 | This disambiguation page lists articles associated with the title Follicular cell. If an internal link led you here, you may wish to change the link to point directly to the intended article. |
Several types of cell in the body are referred to as follicular cell. These include:
| | This disambiguation page lists articles associated with the title Follicular cell. If an internal link led you here, you may wish to change the link to point directly to the intended article. |
The thyroid, or thyroid gland, is an endocrine gland in the neck consisting of two connected lobes. The lower two thirds of the lobes are connected by a thin band of tissue called the thyroid isthmus. The thyroid is located at the front of the neck, below the Adam's apple. Microscopically, the functional unit of the thyroid gland is the spherical thyroid follicle, lined with follicular cells (thyrocytes), and occasional parafollicular cells that surround a lumen containing colloid. The thyroid gland secretes three hormones: the two thyroid hormones – triiodothyronine (T3) and thyroxine (T4) – and a peptide hormone, calcitonin. The thyroid hormones influence the metabolic rate and protein synthesis, and in children, growth and development. Calcitonin plays a role in calcium homeostasis. Secretion of the two thyroid hormones is regulated by thyroid-stimulating hormone (TSH), which is secreted from the anterior pituitary gland. TSH is regulated by thyrotropin-releasing hormone (TRH), which is produced by the hypothalamus.
A lymph node, or lymph gland is a kidney-shaped organ of the lymphatic system, and the adaptive immune system. A large number of lymph nodes are linked throughout the body by the lymphatic vessels. They are major sites of lymphocytes that include B and T cells. Lymph nodes are important for the proper functioning of the immune system, acting as filters for foreign particles including cancer cells, but have no detoxification function.
Triiodothyronine, also known as T3, is a thyroid hormone. It affects almost every physiological process in the body, including growth and development, metabolism, body temperature, and heart rate.
Tumors of the hematopoietic and lymphoid tissues or tumours of the haematopoietic and lymphoid malignancies are tumors that affect the blood, bone marrow, lymph, and lymphatic system. Because these tissues are all intimately connected through both the circulatory system and the immune system, a disease affecting one will often affect the others as well, making myeloproliferation and lymphoproliferation closely related and often overlapping problems.
Thyroid follicular cells are the major cell type in the thyroid gland, and are responsible for the production and secretion of the thyroid hormones thyroxine (T4) and triiodothyronine (T3). They form the single layer of cuboidal epithelium that makes up the outer structure of the almost spherical thyroid follicle.
Parafollicular cells, also called C cells, are neuroendocrine cells in the thyroid. The primary function of these cells is to secrete calcitonin. They are located adjacent to the thyroid follicles and reside in the connective tissue. These cells are large and have a pale stain compared with the follicular cells. In teleost and avian species these cells occupy a structure outside the thyroid gland named the ultimobranchial body.
Peyer's patches are organized lymphoid follicles, named after the 17th-century Swiss anatomist Johann Conrad Peyer. They are an important part of gut associated lymphoid tissue usually found in humans in the lowest portion of the small intestine, mainly in the distal jejunum and the ileum, but also could be detected in the duodenum.
Follicular lymphoma (FL) is a cancer that involves certain types of white blood cells known as lymphocytes. The cancer originates from the uncontrolled division of specific types of B-cells known as centrocytes and centroblasts. These cells normally occupy the follicles in the germinal centers of lymphoid tissues such as lymph nodes. The cancerous cells in FL typically form follicular or follicle-like structures in the tissues they invade. These structures are usually the dominant histological feature of this cancer.
Germinal centers or germinal centres (GCs) are sites within secondary lymphoid organs – lymph nodes and the spleen where mature B cells proliferate, differentiate, and mutate their antibody genes during a normal immune response to an infection. These develop dynamically after the activation of follicular B cells by T-dependent antigen.
Follicular dendritic cells (FDCs) are cells of the immune system found in primary and secondary lymph follicles of the B cell areas of the lymphoid tissue. Unlike DCs, FDCs are not derived from the bone-marrow hematopoietic stem cell, but are of mesenchymal origin.
chemokine ligand 13 (CXCL13), also known as B lymphocyte chemoattractant (BLC) or B cell-attracting chemokine 1 (BCA-1), is a protein ligand that in humans is encoded by the CXCL13 gene.
C-X-C chemokine receptor type 5 (CXC-R5) also known as CD185 or Burkitt lymphoma receptor 1 (BLR1) is a G protein-coupled seven transmembrane receptor for chemokine CXCL13 and belongs to the CXC chemokine receptor family. It enables T cells to migrate to lymph node and the B cell zones. In humans, the CXC-R5 protein is encoded by the CXCR5 gene.
Lymphoid hyperplasia is the rapid growth proliferation of normal cells that resemble lymph tissue.
Follicular thyroid cancer accounts for 15% of thyroid cancer and occurs more commonly in women over 50 years of age. Thyroglobulin (Tg) can be used as a tumor marker for well-differentiated follicular thyroid cancer. Thyroid follicular cells are the thyroid cells responsible for the production and secretion of thyroid hormones.
Follicular B cells are a type of B cell that reside in primary and secondary lymphoid follicles of secondary and tertiary lymphoid organs, including spleen and lymph nodes. Antibody responses against proteins are believed to involve follicular B cell pathways in secondary lymphoid organs.
The ocular immune system protects the eye from infection and regulates healing processes following injuries. The interior of the eye lacks lymph vessels but is highly vascularized, and many immune cells reside in the uvea, including mostly macrophages, dendritic cells, and mast cells. These cells fight off intraocular infections, and intraocular inflammation can manifest as uveitis or retinitis. The cornea of the eye is immunologically a very special tissue. Its constant exposure to the exterior world means that it is vulnerable to a wide range of microorganisms while its moist mucosal surface makes the cornea particularly susceptible to attack. At the same time, its lack of vasculature and relative immune separation from the rest of the body makes immune defense difficult. Lastly, the cornea is a multifunctional tissue. It provides a large part of the eye's refractive power, meaning it has to maintain remarkable transparency, but must also serve as a barrier to keep pathogens from reaching the rest of the eye, similar to function of the dermis and epidermis in keeping underlying tissues protected. Immune reactions within the cornea come from surrounding vascularized tissues as well as innate immune responsive cells that reside within the cornea.
Thyroid lymphoma is a rare cancer constituting 1% to 2% of all thyroid cancers and less than 2% of lymphomas. Thyroid lymphomas are classified as non–Hodgkin's B-cell lymphomas in a majority of cases, although Hodgkin's lymphoma of the thyroid has also been identified.
The follicular lumen is the fluid-filled space within a follicle of the thyroid gland. There are hundreds of follicles within the thyroid gland. A follicle is formed by a spherical arrangement of follicular cells. The follicular lumen is filled with colloid, a concentrated solution of thyroglobulin and is the site of synthesis of the thyroid hormones thyroxine (T4) and triiodothyronine (T3).
In situ lymphoid neoplasia is a precancerous condition newly classified by the World Health Organization in 2016. The Organization recognized two subtypes of ISLN: in situ follicular neoplasia (ISFN) and in situ mantle cell neoplasia (ISMCL). ISFN and ISMCL are pathological accumulations of lymphocytes in the germinal centers and mantle zones, respectively, of the follicles that populate lymphoid organs such as lymph nodes. These lymphocytes are monoclonal B-cells that may develop into follicular (FL) and mantle cell (MCL) lymphomas, respectively.
Pediatric-type follicular lymphoma (PTFL) is a disease in which malignant B-cells accumulate in, overcrowd, and cause the expansion of the lymphoid follicles in, and thereby enlargement of the lymph nodes in the head and neck regions and, less commonly, groin and armpit regions. The disease accounts for 1.5% to 2% of all the lymphomas that occur in the pediatric age group.