The mast cell: Distribution and maturation in the rat

This paper reports preliminary studies in the rat of the connective tissue mast cell — its origin, distribution in various tissues, regeneration and function, as well as its relationship with basophil leucocytes and mucosal mast cells. Connective tissue mast cells and basophil leucocytes exhibit a reciprocity of incidence in animals such as the rat and rabbit, and with mucosal mast cells comprise a family of cells that share the common feature of having a cytoplasm packed with granules that stain metachromatically. At least in connective tissue mast cells, these granules represent miniature pharmacological storehouses.The relative insolubility in aqueous solutions of the granules of connective tissue mast cells in the rat has made this species a popular one for laboratory investigations of the mast cell. Progressive sulphation of the granules of rat mast cells is demonstrable by staining with Alcian blue and safranin. Coupled with morphological features, such staining permits the identification of four stages in the maturation of mast cells. The maturation and distribution of these cells is illustrated for mesentery, omentum and peritoneal fluid. Although it has long been accepted that mast cells are particularly associated with the blood vessels of the vascular arcades of the mesentery, our own work inneonatal rats has indicated clearly that the association is with lymphatic rather than blood vessels. However, this association with lymphatic vessels seems restricted to the mesentery and omentum.In further work in the newborn rat, mast cells have been observed in substantial numbers inskin andthymus, the population of mast cells in these organs being maintained during the next 3 months. In theliver andspleen of the newborn rat, mast cells are reasonably numerous in the foci of haemopoiesis, but progressively decline in number during the initial 4 weeks, in step with the disappearance of extramedullary haemopoiesis. On the other hand, thebone marrow becomes populated by mast cells, particularly during the 2nd and 3rd weeks of life. In theconnective tissue ofheart, lung, stomach andportal tract of the rat, mast cells are practically absent at birth but progressively increase in number during the initial postnatal month. Thereafter, their number remains fairly steady.The presence at birth of mast cells in extramedullary and subsequently in medullary foci of haemopoiesis, suggests that the process of mastopoiesis may be analogous to that of granulopoiesis in haemopoietic tissues. This possibility is discussed in relation to other evidence concerning the origin of mast cells.     

Rat ovarian mast cells: distribution and cyclic changes

Numerous tissue mast cells are present in the ovarian medulla and hilus and in the oviduct of rats. In the medulla, most of these mast cells are in the connective tissue of the stroma near blood and lymphatic vessels. During proestrus, many of the medullary mast cells totally degranulate and thus are not visible histochemically; they then regranulate during estrus. In contrast, the number of stainable mast cells in the ovarian hilus and oviduct does not change during the estrous cycle. Histofluorometric methods demonstrate that mast cells in the ovarian medulla and hilus, as well as the oviduct, contain histamine. In addition, the lining of small blood vessels in the ovarian medulla contains histamine. Thus, mast cell and blood vessel histamine secretion may play a role in ovarian function.     

Intraepithelial migration of mucosal mast cells in hay fever: ultrastructural observations

Evidence has been presented suggesting that a migration of nasal mast cells from the mucosal connective tissue stroma into the epithelium is part of the mucosal response in birch pollen allergy. In a previous study, the identification of these intraepithelial cells as tissue mast cells rather than blood basophils was based on light microscopical morphology and histochemistry. We have now studied the ultrastructure of these cells in mucosal biopsies taken before and during the birch pollen season. Intraepithelial cells with basophil or metachromatic granules were only observed in biopsies taken during the season. Some of these cells had the ultrastructural appearance of tissue mast cells, including cytoplasmic lipid droplets and a granular substructure composed of multilamellar arrays and scrolls, serving to distinguish human mast cells from blood basophils. The ultrastructural traits of the remaining cells were heterogeneous, some reminiscent of human blood basophils, others of globule leucocytes of other species, but entirely typical blood basophils could not be identified. The results thus support our previous suggestion that a migration of mucosal mast cells from the connective tissue stroma into the epithelium is part of the human allergic mucosal response. It cannot be determined whether the ultrastructural heterogeneity of these cells is the result of an adaptation to the intraepithelial environment of one single mast cell type or to the existence of an ultrastructurally distinct mucosal mast cell.     

Expression of epithelial adhesion proteins and integrins in chronic inflammation.

Epithelial cell behavior in chronic inflammation is poorly characterized. During inflammation of tooth-supporting structures (periodontal disease), increased proliferation of epithelial cells into the inflamed connective tissue stroma is commonly seen. In some areas ulceration and degeneration take place. We studied alterations in the expression of adhesion molecules and integrins during chronic periodontal inflammation. In inflamed tissue, laminin-1 and type IV collagen were still present in the basement membrane and surrounding blood vessels, but they were also found extravascularly in inflamed connective tissue stroma. Type VII collagen and laminin-5 (also known as kalinin, epiligrin, or nicein) were poorly preserved in the basement membrane zone, but both were found in unusual streak-like distributions in the subepithelial connective tissue stroma in inflamed tissue. Both fibronectin and tenascin were substantially decreased in chronically inflamed connective tissue, showing only punctate staining at the basement membrane zone. Integrins of the beta 1 family showed two distinct staining patterns in epithelial cells during chronic inflammation; focal losses of beta 1 integrins (alpha 2 beta 1 and alpha 3 beta 1) were found in most areas, while in other areas the entire pocket epithelium was found to be strongly positive for beta 1 integrins. No members of the alpha v integrin family were found in any epithelia studied. Expression of the alpha 6 beta 4 integrin was high in basal cells of healthy tissue, but weak in epithelium associated with chronic inflammation. Chronic inflammation therefore involves alterations in both adhesion proteins and integrins expressed by epithelial cells. Basement membrane components found at abnormal sites in stroma in chronic inflammation might serve as new adhesive ligands for various cell types in inflamed stroma.     

Expression of Platelet-Derived Growth Factor Receptors is Induced on Connective Tissue Cells During Chronic Synovial Inflammation

The tissue distribution of the receptor for platelet-derived growth factor (PDGF) was investigated by immunohistochemistry on frozen sections from normal and inflamed synovial tissue using monoclonal antibodies to the receptor. Non-inflamed synovial tissue showed no staining, indicating that PDGF receptor expression is low or absent in normal tissue. In contrast, tissue from synovitis with prominent neovascularization showed a strong staining in the tunica media of the proliferating blood vessels as well as on connective tissue cells in the stroma. Tissue from synovitis with prominent proliferation of synovial lining showed intense staining for PDGF receptors in fibroblast-like cells of the lining and a less intense staining on vascular and connective tissue cells deeper in the stroma. Staining for PDGF receptors was also intense in the pannus tissue close to infiltrated bone and cartilage. In all these forms of synovitis, PDGF receptor staining was associated with increased HLA-DR staining and infiltration of macrophages and T lymphocytes. The finding that PDGF receptor expression is induced in conjunction with the chronic synovial inflammation associated with rheumatoid arthritis and some other forms of arthritides suggests that PDGF may play a role in the stimulation of mesenchymal cell proliferation that often accompanies chronic inflammatory disease.     

Ultrastructure of the tracheal muscle in developing, adult and ageing guinea-pigs

Summary The musculature of the trachea of adult guinea-pigs is ultrastructurally similar to other visceral muscles. However, tracheal muscle cells have irregular outlines, large accumulations of glycogen, a small number of gap junctions, and many small elastic fibres and collagen fibrils (50 nm in diameter). Fibroblasts, mast cells, Schwann cells and axons are found within the muscle, but no interstitial cells. Capillaries run in the connective tissue septa.The tracheal muscle is well differentiated at the end of the fetal life. At this time, muscle cells have an appearance similar to that of a mature muscle. However, the cells are smaller, especially in length, and their orientation is less regular. There are no undifferentiated cells; a few muscle cells are seen in mitosis. There is a limited amount of stroma, mainly small collagen fibrils not exceeding 30 nm in diameter. Within the muscle there are many nerves, but no fibroblasts or mast cells. Many structural contacts link together the muscle cells, but there are no gap junctions. Gap junctions develop in the first few days after birth and are distinct in 5-day-old animals.In ageing guinea-pigs (30–36 months old) the muscle cells are slightly larger than in the young adult. They display deep invaginations of the cell membrane and a very irregular profile. There is an increase in the number of glycogen granule clusters, and the basal lamina is particularly prominent. The amount of stroma has increased, and is made of large elastic fibres and collagen fibrils up to 105 nm in diameter.     

Intraepithelial migration of nasal mucosal mast cells in hay fever

Mast cells were studied by light microscopy in mucosal imprints and in biopsies of nasal mucosa of 12 birch pollen allergic individuals before and during the pollen season, using techniques optimized for the demonstration of mucosal mast cells. We also measured the histamine content of nasal mucosa, whole blood and plasma, and counted the numbers of circulating blood basophils. Before the pollen season the nasal mucosa was found to contain many mast cells located in the mucosal connective tissue stroma, and very few cells with basophilic and metachromatic granules were found in mucosal imprints. During the pollen season there was a redistribution of mast cells into the epithelium, many such cells now being recovered in mucosal imprints. The total number of mucosal mast cells counted in tissue sections did not change significantly with the onset of the pollen season, suggesting a redistribution of mucosal mast cells by migration. Judged by morphologic appearance and naphthol-AS-D chloroacetate esterase activity, the intraepithelial mast cells found in tissue sections had rather the properties of tissue mast cells than of blood basophils, and only a few of the basophilic cells of the imprints had a morphology compatible with blood basophils. The histamine content of the mucosa, as well as histamine levels of whole blood and plasma, and circulating blood basophil numbers did not change significantly in relation to the pollen season. These findings suggest that an intraepithelial migration of mucosal mast cells is part of the allergic mucosal response.(ABSTRACT TRUNCATED AT 250 WORDS)     

Mast cells in acute hepatitis

The prevalence and morphological characteristics of mast cells were studied in 41 liver biopsies from patients with acute hepatitis of different causes. In 17 of these biopsies mast cells were found both in portal tracts and sinusoids. They were mainly found in the classical and periportal types of hepatitis, and were more abundant in the later stages of the disease. Their presence was established both by staining for mast cells at light microscopic level and by electron microscopy. Two types of mast cells were found. Those in the portal tracts had the characteristics of connective tissue mast cells in other organs. The second type was the sinusoidal mast cell. These were closely associated with a variety of myeloid cells, and ultrastructural evidence suggests that they may be derived from the latter. Mast cells are considered to participate in the inflammatory response in acute hepatitis.     

Development of different mast cell types in the opossum<Emphasis Type="Italic"> Didelphis albiventris</Emphasis>

Previous studies have disclosed three types of mast cell in opossums: connective tissue (CTMC), mucosal (MMC), and lymphatic sinus (LSMC). In contrast to most opossum lymph nodes, the mesenteric lymph node is virtually devoid of LSMC, displaying medullary cord CTMC. The present study aimed to describe the development of these mast cell populations. Toluidine blue staining and a histochemical method for demonstrating heparin allowed the identification of immature and mature mast cells. Immature CTMC devoid of detectable heparin were rare until postnatal day 10. Mature CTMC filled with heparin-containing granules became numerous by day 30 to day 40. In the ileum, despite the presence of mature CTMC in the submucosa and mucosa (villus base), immature mast cells first appeared in the villus core by day 65 and adult features were apparent by day 100. In LSMC-containing lymph nodes, immature mast cells were found in lymphatic sinuses by day 10. Clear signs of LSMC differentiation were observed from day 20. Compared with the 10-day value, the mean diameter of cytoplasmic granules at day 40 had doubled and that at day 110 had tripled. In the mesenteric lymph nodes, immature mast cells differentiated into lymphatic sinus CTMC-like cells. After day 80, most of them were located in medullary cords. Weaning and complete maturation of mucosa preceded the differentiation of MMC. In lymph nodes, LSMC differentiation occurred in parallel with the development of the medullary region and deep cortex units.     

Development of different mast cell types in the opossum Didelphis albiventris

Previous studies have disclosed three types of mast cell in opossums: connective tissue (CTMC), mucosal (MMC), and lymphatic sinus (LSMC). In contrast to most opossum lymph nodes, the mesenteric lymph node is virtually devoid of LSMC, displaying medullary cord CTMC. The present study aimed to describe the development of these mast cell populations. Toluidine blue staining and a histochemical method for demonstrating heparin allowed the identification of immature and mature mast cells. Immature CTMC devoid of detectable heparin were rare until postnatal day 10. Mature CTMC filled with heparin-containing granules became numerous by day 30 to day 40. In the ileum, despite the presence of mature CTMC in the submucosa and mucosa (villus base), immature mast cells first appeared in the villus core by day 65 and adult features were apparent by day 100. In LSMC-containing lymph nodes, immature mast cells were found in lymphatic sinuses by day 10. Clear signs of LSMC differentiation were observed from day 20. Compared with the 10-day value, the mean diameter of cytoplasmic granules at day 40 had doubled and that at day 110 had tripled. In the mesenteric lymph nodes, immature mast cells differentiated into lymphatic sinus CTMC-like cells. After day 80, most of them were located in medullary cords. Weaning and complete maturation of mucosa preceded the differentiation of MMC. In lymph nodes, LSMC differentiation occurred in parallel with the development of the medullary region and deep cortex units.     

Morphofunctional characteristics of connective tissue in emotionally stressed august and wistar rats

August rats, which are predisposed to emotional stress, are shown to differ from Wistar rats, which are not so predisposed, in the morphofunctional organization of lymphoid and connective tissues. In August as compared to Wistar rats, the lymphoid tissue of the spleen, trachea, bronchi, intestine, and lymph nodes is less abundant, the pancreatic insular apparatus is developed much better, and loose connective tissue contains more mast cells without signs of degranulation. Emotional stress leads, in both strains, to strong connective tissue congestion, massive hemorrhages, edema of loose connective tissue in the renal medullary substance and in the liver, focal or focal/confluent connective tissue metachromasia, and progressive mast cell degranulation. These changes are all more pronounced in August rats. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 119, N ^o 6, pp. 571–573, June, 1995     

Tenascin-C protein expression and mRNA splice variants in thyroid carcinoma

Tenascin-C (Tn-C) is a matricellular protein involved in the initial and intermediate stages of cell adhesion. The present study is the first undertaken to comparatively investigate Tn-C in neoplastic, non-neoplastic thyroid lesions and normal thyroid tissues. Forty-eight thyroid specimens were studied immunohistochemically using a monoclonal antibody against Tn-C. Immunohistochemistry was supplemented by RT-PCR analysis of the two Tn-C mRNA splice variants in 13 thyroid cancer cell lines. Normal and non-neoplastic tissues were devoid of Tn-C, as well as follicular neoplasms, Huerthle-cell and anaplastic carcinomas. Most papillary carcinomas showed a focally intensive extracellular staining, localized in the connective tissue stroma, whereas most medullary carcinomas showed a staining in the connective tissue but also in intracellular location mainly. RT-PCR analysis detected Tn-C mRNA in all thyroid cancer cell lines with prevalence of the large splice variant in all but the medullary line, characterized by a higher Tn-Csmall:Tn-Clarge ratio. In conclusion, Tn-C re-expression has been observed in papillary and medullary thyroid carcinomas with different staining patterns accompanied by the prevalence of different mRNA splice variants in cell cultures. It seems possible that Tn-C is rather synthesized by tumor cells than by activated stromal cells.     

Structural and Functional Peculiarities of Mast Cells in Undifferentiated Connective Tissue Dysplasia

We performed an immunomorphological study of mast cells from undamaged skin in women with phenotypical evidence of undifferentiated connective tissue dysplasia syndrome, patients of cosmetological clinics. It was found that the numerical density of mast cells containing chymase granules in this condition 1.7-fold surpassed the corresponding parameter in patients without signs of connective tissue dysplasia syndrome, which probably was a result of compensatory and adaptive reaction aimed at activation of the synthesis of the connective tissue extracellular matrix components. It was hypothesized that increased content of chymase-positive mast cells in the skin of patients with connective tissue dysplasia syndrome contributed to the formation of associated arterial hypertension.     

Alterations in mast cell frequency and relationship to angiogenesis in the rat mammary gland during windows of physiologic tissue remodeling

Background: The mammary epithelium undergoes proliferation and regression accompanied by remodeling of the fibrocellular and vascular stroma. Mast cells are abundant in these compartments and have been implicated in remodeling during wound healing and cancer progression. The purpose of this study was to test the hypothesis that mast cell abundance correlates with physiologic mammary tissue remodeling during estrous cycling, lactogenesis (pregnancy and lactation) and involution. Results: Mast cell and capillary frequency were quantified in the stroma surrounding ducts and lobules from mammary glands of rats. During estrous cycling, periductal mast cell numbers were unchanged, but lobule‐associated mast cells significantly increased in the regressive phase of diestrus II. During lactogenesis, lobular stroma mast cells peaked early in pregnancy, at D2, followed by a significant decrease throughout lactation. Involution was associated with a rapid return in mast cell numbers, similar to diestrus II. Lobular vascularization peaked during the state of metestrus, when limited secretory differentiation occurs. Lobular angiogenesis peaked at D7 of pregnancy, regressed, and then returned to high levels during lactation and early involution, when secretory differentiation is high. Conclusions: These results suggest mast cells are predominantly associated with regressive lobular remodeling during cycling and involution, whereas angiogenesis is predominantly associated with secretory differentiation. Developmental Dynamics 241:890–900, 2012. © 2012 Wiley Periodicals, Inc.     

Extrafollicular antibody responses

Summary: In adaptive antibody responses, B cells are induced to grow either in follicles where they form germinal centers or in extrafollicular foci as plasmablasts. Extrafollicular growth typically occurs in the medullary cords of lymph nodes and in foci in the red pulp of the spleen. It is not a feature of secondary lymphoid tissue associated with the internal epithelia of the body. All types of naïve and memory B cells can be recruited into extrafollicular responses. These responses are associated with immunoglobulin class switching but, at the most, only low‐level hypermutation.     

Postnatal maturation of mast cell subpopulations in the rat respiratory tract.

The distribution and enumeration of mast cell subpopulations within the respiratory tract of a high- and low-Ige responder rat strain was determined during postnatal development. Mast cells were identified in adjacent sections by the alcian blue (AB)/safranin (SAF) staining sequence, or using immunoperoxidase to detect the rat mast cell proteinases I (RMCPI) or II (RMCPII). At birth both mucosal mast cells (MMC) and connective tissue mast cells (CTMC) were represented in very low numbers at distinct locations throughout the respiratory tract. The total number of mast cells increased with age. MMC (AB+/RMCPII+ mast cells) were the predominant phenotype in the epithelium and lamina propria of the trachea and the major conducting airways of the lung in all age groups. In contrast, CTMC (AB+/RPMCPI+ and SAF+/RMCPI+ mast cells) predominated in the submucosa of the trachea and major conducting airways as well as in the parenchyma and visceral pleura of the peripheral lung. Both phenotypes co-exist in similar proportions in peribronchial adventitial tissue and adventitia surrounding large blood vessels in neonates as well as adults. In rats the tracheal epithelium is densely populated by MMC from around the time of weaning (3 weeks) and a small but generalized increase in the number of MMC at all sites within the respiratory tract is noted from this time. This increase in MMC frequency in tissue sections with increasing age is mirrored by the levels of circulating serum RMCPII. The number of bone marrow-derived MMC also increased with increasing age prior to weaning, with a significant drop (P less than 0.01) at 4 weeks of age before returning to the peak numbers in 3-week-old rats. The high-IgE responder Brown Norwegian (BN) rat strain constitutively produces significantly more IgE than the low-IgE responder White albino Glaxo (WAG) strain (P less than 0.001) at all ages studied. In contrast, only minor differences between the number and distribution of mast cells in the two strains were observed.     

奶牛乳腺肥大细胞的粘膜免疫学特征

应用改良甲苯胺蓝染色法 (MTB )和阿尔辛蓝 番红鉴别染色法 (AB S )对静止期和活动期奶牛乳腺肥大细胞的粘膜免疫学性质进行了研究。MTB染色结果显示 ,静止期乳腺中的肥大细胞主要分布于各级输乳管上皮基膜区 ,小血管周围也有肥大细胞分布。在活动期 ,肥大细胞主要分布于腺泡上皮基膜附近 ,上皮内也有极少数肥大细胞分布 ,小叶间结缔组织中的肥大细胞则分布于小叶间导管或输乳管上皮基膜区。AB S染色证实 ,乳腺肥大细胞只被阿尔辛蓝染成蓝色 ,而不被结缔组织型肥大细胞的标志性染料番红着染。这表明 ,乳腺肥大细胞是一种典型的粘膜型肥大细胞 (MMC ) ,并参与构成乳腺粘膜免疫的第一道防线。     

Angiocentric invasion by lentigo maligna melanoma.

A case of angiocentric invasion by a lentigo maligna melanoma is reported. Pericapillary cuffing and permeative intimal expansion of veins by melanoma without luminal tumour cell emboli, thrombosis, or vascular destruction were associated with a lentigo maligna melanoma on the face of a 93 year old woman. This unusual infiltrative pattern suggests a specific interaction between melanoma cells and perivascular connective tissue elements, and may imply expression by tumour cells of receptors for molecules in the intima of blood vessels and in pericapillary stroma.     

Occurrence of large groups of mast cells in subcutaneous connective tissue in the mouse

Skin from the mouse trunk together with panniculus adiposus and panniculus carnosus and, separately, trunk muscles, were fixed, stained with Astra blue at pH 1.0, made translucent in methyl salicylate and whole-mounted. In the connective tissue on the surface of panniculus carnosus directed towards the trunk muscles or on the surface of trunk muscles rounded and oval mast cells occurred singly or in groups from two to several dozen cells. These groups had no association with blood vessels or hair follicles. Mast cell groups were scarse in 1-month-old, clearly recognizable in 2-months-old and conspicuous in 4-months-old mice of both sexes. The number of mast cells and their number per group was larger in CFW/Ll and C3H than in Balb/c mice. Accumulation of mast cells in subcutaneous connective tissue was noted in animals from two separate breeding centers. The animals were free of ectoparasites and dermatophytes but contained some pinworms and protozoa. Elimination of these parasites, change of diet and drinking water as well as cage lining did not prevent the appearance of mast cell accumulations. These accumulations occurred in all studied mice (over 100) at the age of 2 months or older, and were also found in 1 out of 6 four-month-old hamsters and in 2 out of 6 four-month-old rats. It is suggested that mast cells accumulate in subcutaneous connective tissue in response to some undefined noxious agent. Whatever the reason of their presence, large groups of mast cells could considerably influence the results of tests performed in the skin-hypodermis area.