Granulated mast cells in mouse tongue.
Mast cells, anatomy and appearance[1].
Mast cells are oval to round cells 20-30µm in diameter, whose cytoplasm is richly filled with basophilic granules. The central, round nucleus is often hidden behind the granules when studied in a light microscope. In a coupe made of paraffin, the individual granules and cell nucleus are often less visible. In a coupe made of plastic such as Technovit or Epon, the coupe thickness is so thin that the mast cell can usually be made clearly visible with granules and nucleus. See images on the website (Red).
Mast cells are fairly long-lived cells and, unlike other solid connective tissue cells, are probably derived from a stem cell[2] in the bone marrow[2]. The cell is found throughout the body, but especially in the dermis[2] (around blood vessels), intestinal tract and respiratory tract. The cells can be visualized by a metachromatic color reaction[3], in which toluidine blue colors the granules reddish purple, as they contain sulfated glycosaminoglycans[2].
Mast cells, function[1].
Mast cells have a function in the formation, storage and release of mediators, which play an immediate role in inflammatory and hypersensitivity reactions. One of these compounds is heparin, which can inhibit blood clotting. In addition, granules of mast cells contain other biologically active substances, such as histamine (vasodilatation) and neutral proteases[2].Mast cells show great similarities to the much smaller basophilic granulocytes of the blood. However, they originate from a different stem cell in the bone marrow.
Mast cells in a mouse tongue sample.
The image shows drawn mast cells as recorded by Professor Doctor Max Clara[4]. Clearly visible here are the large nuclei that are almost always located centrally in the cell body. Almost the entire cytoplasm is filled with granules. The metachromatic staining, described above, relates to this granules. The red purple staining is not always clearly visible in plastic sections. Often it also remains blue or only vaguely purple and the reason for this is not known (Red). In a section of Technovit 7100, the granule does turn purple but in LR White it remains quite blue. However, the morphology of the mast cell is so specific that there can be no mistaken determination.
Pathology of mast cells in a mouse tongue.
Mastocytosis involves a benign accumulation of mast cells, usually in the skin[2].
Mastocytosis, in medicine, is the presence of too many mast cells, usually in the skin. This can occur scattered through the skin, or as a tumor due to local accumulation. When tumor formation occurs, it is referred to as a mastocytoma[2].Mastocytosis is a rare abnormality, which can also occur in the wall of the intestine and in other tissues such as the lungs, liver, spleen or bone marrow. Cause of onset of the disease is unknown[2].
In the sections of a mouse tongue shown here, no mast cell accumulations can be seen but mast cells are present in large quantities. In human tissue, for example, there are far fewer mast cells[Red].
In "A practical guide to the histology of the mouse," it is stated that in rodents this large amount is completely normal and thus is not a disease.
Quote, "Heavily granulated mast cells are commonly seen in normal rodent tongues and can be demonstrated with toluidine blue staining."[5]
Bronvermelding:
[1] Junqueira L.C. en Carneiro J. (2004, tiende druk), Functionele histologie, Maarssen. Uitgeverij Elsevier. Hoofdstuk 5, 'Bindweefsel' blz 126 t/m 128.
[2] Wikipedia, the free encyclopedia, https://en.wikipedia.org/wiki/Main_Page[3] Romeis, Dr. Habil. Maria Mulisch und Prof. Dr. Peter Böck, Spektrum Akademischer Verlag Heidelberg 2010, Mikroskopische Technik (2010, achttiende druk), Hoofdstuk 3, pag. 185, 'Farbstoffe', par. 3.2.6, Färbevokabular, ISBN 3-541-11227-1
[4] Prof. Dr. med. Max Clara (1974), Atlas der normalen mikroskopischen Anatomie des Menschen, Uitgeverij Urban&Schwarzenberg, Hoofdstuk 'Sanguis', pag. 272, 'Drei Mastzellen im lockeren faserigen Bindegewebe aus der Haut'.
[5] Cheryl L. Scudamore, A practical guide to the histology of the mouse, ISBN: 978-1-119-94120-0, Pag 45, 3.2.4 Antomy and histology of tongue.