The Tissue Mast Cell

Electron Microscopy Observations on a Spontaneous Mastocytoma in a Dog

The ultrastructure of a dog mastocytoma examined with the electron microscope after fixation in glutaraldehyde, post-fixation in osmiumtetroxide and butyl-methyl methacrylate embedding is described. The ultrastructural characteristics with particular regard to the submicroscopic morphology of specific granules were studied in details, also with the aid of comparative observations on thick sections stained by Giemsa and toluidine blue. On the basis of their observations, the authors describe the following characteristics of neoplastic mastcells: microvilli, a well-developed Golgi region, centrioles, mithocondria, ribosomes, endoplasmic reticulum and 4 different types of granules. Other mastcells, with various degree of regressive phoenomena, had almost no microvilli, multiple interruptions of plasma membrane, mithocondrial swelling as well as vacuolar and fibrillar aspect of the cytoplasm. The morphology of different types of intracytoplasmic granules is discussed also in the light of parallel observations made by other authors. Expulsions of granules were not observed. The hypothesis of the phospholipidic nature of the lamellar component of granules is suggested.

Distribution of Mast Cells and Locations, Depths, and Sizes of the Putative Acupoints CV 8 and KI 16

The anatomical locations and sizes of acupuncture points (APs) are identified in traditional Chinese medicine by using the cun measurement method. More precise knowledge of those locations and sizes to submillimeter precision, along with their cytological characterizations, would provide significant contributions both to scientific investigations and to precise control of the practice of acupuncture. Over recent decades, researchers have come to realize that APs in the skin of rats and humans have more mast cells (MCs) than neighboring nonacupoints. In this work, the distribution of MCs in the ventral skin of mice was studied so that it could be used to infer the locations, depths from the epidermis, and sizes of three putative APs. The umbilicus was taken as the reference point, and a transversal cross section through it was studied. The harvested skins from 8-week-old mice were stained with toluidine blue, and the MCs were recognized by their red-purple stains and their metachromatic granules. The three putative APs, CV 8 and the left and the right KI 16 APs, were identified based on their high densities of MCs. These findings also imply that acupuncture may stimulate, through MCs, an immune response to allergic inflammation.

Canine Mastocytoma

Utilizing a modified capillary tube technique, analysis revealed a significantly higher mean blood coagulation time in a group of 14 dogs with mastocytoma when compared to the mean coagulation time of 70 non-mastocytoma dogs. In dogs with mastocytoma, approximately one third had intermediate size tumors and a prolonged mean coagulation time and two thirds had a mean coagulation time that did not differ significantly from the mean of the non-mastocytoma dogs. Evidence for heparin release and possible heparin inactivating mechanisms is reviewed.

Dose-response studies of depletion and repopulation of rat intestinal mucosal mast cells after irradiation

The effects of radiation on gut mucosal mast cells (MMC) and tissue eosinophils were examined. Groups of rat were given single doses of whole-body irradiation from 0.5 to 5 Gy. Serum rat mast cell protease II (RMCPII) concentration showed a significant dose-dependent fall after 1 Gy on day 3 and 1.5 Gy on day 7. MMC counts and tissue RMCPII values on day 7 decreased significantly by 70% after 1 Gy and were undetectable with larger doses. Rat with normal and expanded MMC populations were irradiated or given anaphylaxis. Serum RMCPII concentrations did not change after irradiation, but there was a 10-fold increase in RMCPII after anaphylaxis. Tissue eosinophils in jejunum were 50% of control at 7 days after 2 Gy, and this effect was progressively more marked with higher doses. Similar effects on MMC and eosinophils were demonstrated in ileum, ascending colon and rectum. After 4.5 Gy, repopulation of the gut with MMC did not occur until week 3-4 postirradiation and MMC counts were still 50% below those of controls at 5 weeks postirradiation. Counts of tissue eosinophils 5 weeks after 4.5 Gy irradiation had returned to control levels in jejunum but were still significantly depleted in colon. These experiments show that the high radiosensitivity of rat intestinal MMC is dose dependent, similar at four different levels in the gastrointestinal tract and does not lead to immediate release of granule protease; repopulation with MMC does not begin until at 3 weeks postirradiation.

Radiation effects on mast cells: secretory ability, histamine release and recovery, and cell number

We studied the effects of irradiation with a single fraction of high-energy electrons, in the absorbed dose range used in radiotherapy, on features related to the rat mesenteric mast-cell (MC) population. Such features were energy dispersive X-ray microanalysis for zinc, light and transmission electron microscopic changes, histamine content, and secretory ability of MCs when exposed to the potent secretagogue 48/80. The observation period was 14 days. Also studied were the effects of radiation on the number and histamine content of free peritoneal MCs. Irradiation-induced decrease in histamine content was delayed for at least two days and the rate of subsequent recovery of mesenteric histamine was approximately 70% below normal. This was corroborated by the findings of necrotic and fragmented mesenteric MCs during the entire experimental period. Fibroblasts and macrophages phagocytosed groups of MC granules as well as individual MC granules. A fraction of the extruded MC granules retained an almost normal appearance. This suggests that they were solubilized unduly slow presumably because the irradiation destroyed the mechanisms and enzymes which normally degrade the heparin-protein granule matrix and its heparin. Moreover, the irradiation suppressed the secretory ability of mesenteric MCs and significantly reduced the number of free peritoneal MCs. The findings indicate that the MC is a remarkably radiosensitive connective-tissue cell.

The mast cell: IV. An ultrastructural and autoradiographic study of the distribution and maturation of peritoneal mast cells in the rat

Ultrastructural studies of peritoneal mast cells in adult and young rats showed that results are comparable to those obtained by light microscopic and histochemical studies as far as their maturation and distribution are concerned. It was also evident that mast cells possess cytoplasmic structures common to other cells including microtubules and microfilaments in addition to their distinctive cytoplasmic granules. Granules appear to develop from the vicinity of the Golgi apparatus as progranules in a structured sequence to full maturity rather than from mitochondria or from the cytoplasm de novo. In newborn and young rats mast cells are mostly immature and exhibit frequent mitotic activity. Autoradiographic studies showed that young Stages 1 and 2 peritoneal mast cells are primarily responsible for mitotic and therefore proliferative activity. It was concluded that the final density of mast cells is achieved in the early stages by proliferation and possibly by heteroplastic differentiation of precursor cells.

The mast cells of the mammalian central nervous system. V. The effect of compound 48/80 on the neurolipomastocytoid cells and related areas of the CNS: early changes

The response of the neurolipomastocytoid cells (NLMs) and elements in their vicinity within the central nervous system of various animal species was studied following injection of the animals with the specific mast cell (MC)-discharger compound 48/80. The observed alterations were grouped into those occurring early (0--21 days) and later (up to 18 months). In the present report, only the acute changes are described, light and electron microscopically. Most experimental animals developed prostration, scratching, acral-type reaction, signs of respiratory distress and salivation, and, in the monkey, uncontrollable somnolence. Within about 2 weeks after the injection some animals (especially guinea pigs) manifested various degrees of limb paralysis. The NLMs, like MCs outside the CNS, responded to injection by various degrees of degranulation, vacuolation, marked variation in granule size, apparent cell loss and sometimes an increase in number. Electron microscopically, particulate breakdown products of the granules of the NLMs appeared in the cytoplasm; occasionally there was suggestive evidence that they had passed inward across the vessel wall to reach the lumen, and also outward through the outermost basal lamina. Perivascular astrocytic feet showed swelling and vacuolation shortly after the injection, which was followed by evidence of gliosis and later scarring; occasionally, alterations in the mitochondria were observed. In the spinal cord of the guinea pig, capillary neoformation was observed with endothelial cells and adjacent NLMs taking up tritiated thymidine. The discussion centers on the partial similarity of response to compound 48/80 of the NLMs to that of MCs outside the CNS, and the probable involvement of NLM-damage in the parenchymal changes.

Demonstration of probes in human periodontal pockets

Twenty-two anterior and bicuspid teeth that previously had been designated for extraction, were removed from 11 male patients. Two teeth were extracted from each patient and each tooth had a periodontal pocket of at least 4 mm and a Gingival Index of 2 or 3. One tooth in each patient was subjected to scaling, root planing, and plaque control in an effort to reduce gingival inflammation. By means of an orthodontic tube and composite resin bonding material a periodontal probe under 15 to 20 gm of pressure was fixed in the periodontal pocket of each tooth. The specimens were removed en bloc and histologic specimens prepared. The conclusions were that when the gingiva is inflamed, the tip of the periodontal probe tends to extend to the apical base of the junctional epithelium or slightly beyond but there is great variation in this position. Further, it was concluded that the position of the probe tip during probing is not affected by the depth of the sulcus or periodontal pocket.

Mast cell population density, blood vessel density and histamine content in normal human skin

Mast cell population density was determined in normal skin from two regions of the arm of several healthy men and compared with blood vessel density and histamine concentration in the same sites. Mast cell and blood vessel counts were made in 1--1.5 micrometer thick plastic sections, by light microscopy and tissue-histamine concentrations were determined by automated fluorimetric analysis. Statistically significant correlations were found between mast cell counts, blood vessel counts and histamine content in skin from the upper arm but no similar correlations were obtained in the forearm. Anatomical differences between the two sites may have been the cause of this discrepancy. Wide variations in mast cell counts and blood vessel density were found in different sections from the same biopsy samples which confirms the notion that dermal mast cells are unevenly distributed. Analysis of variance of the mast cell counts showed that the variance between sections from different blocks from the same biopsy samples was greater than the variance between adjacent biopsies. There was also a marked variation in the histamine content between biopsy samples from sites only 2 cm apart in the same subject.

Frequency of mast cells in the olfactory mucosa of rhesus monkeys

During studies of the olfactory mucosa and its response to the different levels of circulating sex hormones, considerable numbers of mast cells have been observed in its epithelia and subepithelial regions. The number of these cells in the olfactory mucosa of male monkeys differs greatly from that found in females. The frequency of these cells in the olfactory mucosa of females fluctuates significantly during the menstrual cycle. These fluctations stimultaneously correspond to the well known changes in olfactory sensitivity: around ovulation, when the olfactory sensitivity for certain odorants is high, the number of mast cells in the olfactory mucosa also increases.

Intraepithelial mast cells in gingival lichen planus: an ultrastructural study

Intraepithelial mast cells, identified by ultrastructural criteria, were seen in lesions of gingival lichen planus. The mast cells were found either singly, interspersed among keratinocytes, or in combination with other mononuclear cell types, especially lymphocytes. The mast cells were seen in regions with relatively normal intercellular spaces, as well as in regions of more severely disrupted keratinocytes. They had cytologic features indicative of active synthesis and release of granules. Moreover, the finding of centrioles in several intraepithelial mast cells, in combination with certain other cytologic features, suggested that these cells might be in an early stage of differentiation. It is speculated that intraepithelial mast cells have a role in the pathogenesis of gingival lichen planus.

Os basófilos do líquido cefalorraqueano

Os autores antigos e atuais não deram a devida consideração aos basófilos do líquido céfalorraqueano (LCR) apenas havendo referências isoladas e imprecisas na literatura. Alguns pesquizadores referem-se a estas células simplesmente como basófilos; outros afirmam que só há basófilo de tecido (mastócito) no LCR. O propósito do presente trabalho foi o de relatar os resultados dos estudos sobre os basófilos do LCR. O material é constituído pelas observações de 300 pacientes neurológicos com moléstias ou condições mórbidas diversas em cujo LCR foi assinalada a presença destas células basófilas. Os resultados destes estudos permitiram a seguintes conclusões: 1) os basófilos do LCR são morfologicamente identificáveis com os basófilos sangüíneos; 2) a falta de correlação percentual entre as células do LCR e sangue sugere que estes basófilos têm a sua origem nas leptomeninges e, neste sentido, são basófilos de tecido; 3) deve ser considerada a hipótese da presença simultânea de basófilo e de mastócito no LCR; 4) os basófilos foram encontrados no LCR de numerosos pacientes com processos inflamatórios agudos do sistema nervoso central, particularmente nas meningites linfocitárias, meningo-encefalites e meningo-mielites, em percentagem que variou de 0.1 a 18%; 5) em muitos casos em que existe um quadro agudo de alterações do LCR conseqüentes à reação a corpo extranho, tais como casos de parasitoses do sistema nervoso central, de hemorragia e de Insuflação de ar no espaço sub-aracnóide, os basófilos foram observados em percentagem que variou de 0.1 a 11%; 6) em muitos destes pacientes, nos quais é provável haver uma reação imuno-alérgica, os eosinófilos e as células plasmocitárias estavam presentes em associação com os basófilos; 7) a presença dos basófilos no LCR é de duração efêmera durante o curso da moléstia ou condição mórbida; 8) habitualmente os basófilos aparecem em casos com pleocitose, mas não é excepcional o achado destas células com contagem global normal; 9) ainda nada se sabe sobre a significação dos basófilos no LCR em relação com as moléstias do sistema nervoso central, assunto que constitui campo aberto para pesquisa clínica e investigação experimental; 10) seria tentador sugerir que a presença dos basófilos no LCR faça parte das alterações citológicas indicadoras de reação imuno-alérgica em sua fase aguda.

Further characterization of a factor from endotoxin-treated serum which releases histamine and heparin from mast cells

Upon incubation of hamster serum with bacterial endotoxin, a factor is produced which releases histamine and heparin from hamster mast cells and increases capillary permeability in guinea pig skin. The major histamine-releasing activity derived from hamster serum was characterized by gel filtration, found to have a molecular weight of approximately 60,000, and shown by electrophoresis to migrate with alpha-2- or beta-1-globulins. The ability to increase vascular permeability was not reversed by antihistamine. On the basis of these properties, the histamine-liberating factor generated by endotoxin in hamster serum differed significantly from known anaphylatoxins.

Ribonucleic acid in canine mast cell granules and the possible interrelationship of mast cells and plasma cells

RNase-sensitive pyroninophilia has been demonstrated in neoplastic and non-neoplastic canine mast cell granules and it was concluded that these granules contain RNA. When combined with (1) the observed morphologic similarities between mast cells and plasma cells, (2) the presence of common distinctive ultrastructures, (3) the differentiation of both cells from a common precursor and (4) the participation in a common reaction, the presence of RNA in mast cell granules is offered as additional evidence for a mast cell-plasma cell relationship. A proposed functional relationship between these two cells is discussed and the “plasma mast cell” is proposed as a possible transitional form between mast cells and plasma cells.