Connective tissue of the human fallopian tube mucosa--polarization microscopic detection of collagen using Solaminrot 4B

The Picrosirius-polarization method was applied to the selective morphological collagen detection in the human uterine tube. Solaminrot 4B (VEB Chemiekombinat Bitterfeld) was used as dyestuff which enhances the normal birefringency of collagen fibrous material in tissue sections. The results show that the connective tissue of the lamina propria mucosae consists of collagen fibres, namely considerably. The mucosal folds of uterine tubes of younger individuals contain delicate, weaker birefringent fibres stained yellowish-red and red-orange. The folds of oviducts of ageing individuals composed of compact, strong birefringent collagen fibrous material stained intensely red, red-orange, and yellow. This is characteristic of organs in the pre- and postmenopausal periods and in the senium. The findings suggest that the fibrous structures detected selectively in the oviductal mucosa by combinative method of Picrosolamin-staining and polarization microscopy are distinct collagen fibres. The delicate, weaker birefringent fibres could correspond with collagen type III and the thicker, stronger birefringent ones could represent collagen type I.     

Light and electron microscopic study of the eyelids,conjunctiva-associated lymphoid tissue and lacrimal gland in Bilgorajska Goose (Anser <Emphasis Type="Italic">anser</Emphasis>)

Normal structure of the accessory organs of the eye is essential for normal eye physiology. Among the most important accessory organs of the eye are the eyelids, the conjunctiva-associated lymphoid tissue (CALT) and the lacrimal gland (LG). The aim of this study was to demonstrate the histological structure of the eyelids and LG by histochemical and ultrastructural analysis. The study was performed on 13 adult female Bilgorajska geese. Eyelid samples were stained with the Alcian blue (AB pH 2.5) and periodic acid-Schiff (PAS) methods. Staining methods used for LG were AB pH 2.5, aldehyde fuchsin (AF), PAS and Hale’s dialysed iron (HDI). Within the connective tissue of the eyelids, well-developed, diffuse, CALT follicles were observed, mostly under the conjunctival epithelium. Numerous lymphocytes were present within loose connective tissue. Staining of the eyelids with the PAS method demonstrated the presence of goblet cells of a mucous nature, and AB pH 2.5 staining indicated the presence of sulfated acid mucopolysaccharides. PAS staining of LG revealed the presence of secretory cells containing weakly PAS-positive granules. All epithelial cells of the corpus glandulae and the duct systems reacted positively to AB pH 2.5. HDI staining detected the presence of carboxylated acid mucopolysaccharides. Transmission electron microscopy investigations revealed two types of secretory epithelial cells in LG. Both types of LG cells contained drop-like secretory vesicles of different sizes with low or high electron density in cytoplasm, as well as small and large lipid vacuoles, and numerous small primary lysosomes.     

Morphological changes in oral mucosae and their connective tissue cores regarding oral submucous fibrosis

Oral submucous fibrosis (OSF) is a chronic disease of the oral cavity characterized by an inflammatory reaction followed by severe fibro-elastic changes. The aim of the present study was to investigate the three-dimensional morphological changes in the connective tissue cores (CTCs) of the oral mucosa in OSF. The sample consisted of buccal mucosal biopsies from ten human subjects ranging in age from 40-45 years; five of them were clinically diagnosed as having moderate to severe OSF, and the remaining five served as unaffected controls. Half of each biopsy was formalin-fixed and paraffin-embedded for light microscopy, while the other half was fixed in a Karnovsky's solution, treated with HCl to exfoliate the epithelium, and processed for examination under a scanning electron microscope (SEM). Oral submucous fibrosis biopsies exhibited heavily packed aldehyde fuchsin-positive fibers (i.e. elastic fibers) in the submucosa under the light microscope. Broad bundles of collagen fibers were seen in a concentrated manner in the deeper layers. Scanning electron microscopy of the buccal mucosa in OSF showed the finger-shaped CTCs to be attenuated beneath the epithelium at the initial stages of the disease. Patchy degenerative areas lacking the CTCs were observed in advanced cases. These degenerative areas increased gradually with the progression of the disease. Highly fibrosed cases showed severe degeneration of the CTCs, resulting in a smoothening of the connective tissue surface in the buccal mucosa.     

Ultrastructural changes in the cervical epithelium during the estrous cycle of the marsupial Monodelphis domestica (grey short-tailed opossum)

Ultrastructural changes in the cervical epithelium related to the estrous cycle have been studied in the South American marsupial Monodelphis domestica. The two cervices protrude with prominent papillae into the sinus vaginalis. At times of simple columnar at others of more pseudostratified character consists of two types of cells, ciliated and secretory cells. The mucosal epithelium is uniform in its entire length and shows no division into an endo- and ectocervix. The mucosa of the cervix differs from the uterine endometrium. There are no glandular structures, but the luminal epithelium shows deep invaginations underlined by dense connective tissue. The most conspicuous changes include the height and the differentiation of the cervical epithelium which attains its maximum development during estrus, where secretory cells are fully packed with large secretory granules and ciliated cells are well developed. After extruding their granules, secretory cells may transform into ciliated cells, while ciliated cells show the phenomenon of deciliation in which cilia packets are shed into the cervical lumen. This transformation process takes place mainly during post- and metestrus. The presence of solitary cilia is only noticeable during pro-estrus, being in contrast to the uterine epithelium where they appear during the whole estrous cycle.     

利用醛复红染色法制作家兔皮下疏松结缔组织铺片标本

目的 探讨适用于家兔皮下疏松结缔组织铺片标本的制片方法。方法 家兔3只,分别经腹腔注射10g/L锥虫蓝生理盐水溶液10～12ml。每天1次,连续注射3d后,于第4天取皮下疏松结缔组织进行铺片。待铺片晾干后,用福尔马林-酒精固定液固定约6h。然后,分别入醛复红、核固红和伊红染色液进行染色。每步之间用自来水冲洗。最后,常规脱水、透明、封片。 结果 巨噬细胞呈不规则形,分布在纤维中间,胞质中可见粗大的锥虫蓝颗粒。细胞核呈红色。醛复红染色30～40min时,弹性纤维呈紫色或蓝紫色,胶原纤维呈浅红色。结论 该法操作步骤简单,结果稳定可靠,是制作家兔皮下疏松结缔组织铺片标本适宜的方法。     

Microanatomy of the major airway mucosa of the bowhead whale, Balaena mysticetus

In the bowhead whale, Balaena mysticetus, the mucosa of the major airways from the blowholes through the rostral portion of the larynx is lined with parakeratotic, pigmented, stratified squamous epithelium. Scattered enlarged connective tissue papillae of the lamina propria of the nasal vestibules and the palatopharyngeal sphincter contain encapsulated nerve endings. Abundant papillae in the mucosa covering the epiglottic and arytenoid cartilages contain similar nerve endings. The remainder of the laryngeal cavity and laryngeal sac is lined by a variably pigmented, stratified squamous epithelium, which is not keratinized. At the laryngotracheal junction the lining changes to ciliated pseudostratified columnar epithelium which continues through the trachea and principal bronchi. Scanning electron microscopy (SEM) indicates that this epithelium is typically mammalian, with approximately half of the surface cells bearing cilia and slender microvilli. The remaining cells are mucus producing and have thicker microvilli. The valvular mass regulating the external nares consists of irregular, dense white fibrous connective tissue with numerous adipose cells and is penetrated by skeletal muscle cords ranging from 2-4 mm in diameter. The septal mass between the blowholes is composed of irregular, dense white fibrous connective tissue containing large tendinous bundles, clusters of adipose cells, and several large arteries and thick-walled veins. The lamina propria of the nasal vestibules is irregular, dense white fibrous connective tissue. That of the larynx is not as dense and contains proportionately more elastic fibers. The laryngeal sac does not contain elastic laminae, but does have a tunica muscularis of skeletal muscle bundles. Within the trachea and principal bronchi, the lamina propria possesses laminae of longitudinally oriented elastic fibers and simple, branched tubuloalveolar mucous glands. The nasal, laryngeal, tracheal, and bronchial cartilages are hyaline with vascular channels.     

Morphology of the copulatory apparatus of the spotted tinamou Nothura maculosa (Aves: Tinamiformes).

The components of the copulatory apparatus of Nothura maculosa were identified and studied by means of dissections, parenteral latex injections and standard histological and histochemical techniques. N. maculosa possesses an intromittent phallus with a tubular cavity, within which a fixed base and a tubular portion can be distinguished. An ejaculatory groove, which is supported by a fibrous body, runs dorsally at the base of the phallus. The tubular portion of the phallus inserts into the fibrous body, the former possessing two continuous but morphologically distinct parts, one of which is eversible and is extruded during erection while the other is a fixed non-eversible glandular portion. The walls of both parts are formed by the mucosa, an intermediate layer of connective tissue containing a wide lymphatic space which surrounds the whole perimeter of the tube, and an external layer of dense connective tissue. The mucosa of the eversible portion, which lodges the phallic groove, is lined by a non-keratinized stratified squamous epithelium. In the fixed tubular portion, the tubular lumen is reduced in size, the phallic groove disappears, the mucosa becomes folded and there occurs an abrupt change to a pseudostratified columnar secretory epithelium. The copulatory apparatus of N. maculosa includes the vascular bodies of the phallus, which show morphofunctional continuity with the phallic structures, thus forming a single system involved in erection. On erection, the eversible portion of the phallus evaginates and emerges from the cloacal opening as a spiral shaped structure directed towards the left.     

Increase of mucosal mast cells in the jejunum of patients infected with Trichinella spiralis

The mast cell response in the mucosa and connective tissue of 36 jejunal biopsies of patients with clinically diagnosed trichinellosis, teniasis and lambliasis has been studied. Biopsy material was fixed in standard formalin or Carnoy's fixative, enabling differentiation between mucosal mast cells (MMC) and connective tissue mast cells (CTMC). With both fixatives CTMC could equally well be recognized. With Carnoy's fixative an additional population of mast cells (MMC) could be visualized both in the mucosa and the connective tissue. In the mucosa small mucosal mast cells were observed as well. Compared to the numbers of mast cells in the mucosa and the connective tissue of teniasis and lambliasis patients, the number of mast cells in trichinellosis patients only visualized using Carnoy's fixative was markedly higher. It was concluded that also in man trichinellosis is accompanied by an increase of cells with MMC characteristics. Further studies are needed to clarify the morphological and histochemical features of these cells and their possible role in this parasitic infection.     

Histomorphological and histochemical study of mucosa of fallopian tube of ageing goat.

The mucosa of infundibulum, ampulla and isthmus of fallopian tubes from 24 female goats aged from 2 months 24 days to 5 years 2 months and 18 days have been studied. The transition of mucosal folds, the lining epithelium and its cell types from Infundibulum towards uterine end, and changes in relation to the age and phases of estrous cycle have been reported. The most striking findings were: a) in goat the fallopian tube like that of sheep was lined chiefly by nonciliated type of cells in infundibulum, whereas the ciliated cells increased caudally, almost all being nonsecretory type in the isthmus; b) the presence of smooth muscle cells as identified with Gomori's one step trichrome stain was observed in the goat fallopian tube in case of mucosal folds specifically at the sites of branchings which anastomose with the adjacent ones; c) the PAS positive secretory material was found to be associated with glycogen acid mucopolysaccharides and mucoproteins as demonstrated by Best's carmine, Alcian blue-PAS and Bismark brown reactions, respectively.     

Ultrastructural heterogeneity of the basophilic cells in the allergic nasal mucosa

Basophilic cells in scrapings and pieces of nasal mucosa removed from the inferior turbinates of adult patients with house dust nasal allergy plus pieces of the oral mucosa from normal persons were examined electron microscopically. Three distinct types of basophilic cells, ie, blood basophil leukocytes (predominantly in the subepithelium), mucosal mast cells (predominantly in the epithelium), and connective tissue mast cells (predominantly in the deeper lamina propria) were identified in the nose.     

Fibrous structure of connective tissue in the vocal fold of the Japanese monkey (Macaca fuscata).

Fibrous structures in the vocal fold were studied in 8 adult Japanese monkeys. Their vocal folds were fixed with formalin and longitudinal and cross-sections were prepared. Some of the samples were treated with 10% NaOH to digest cellular components and elastic fibers, and some of them were treated with 90% formic acid to digest cellular components and collagen fibers. Each sample was then fixed with OsO4, dehydrated, dried at the critical point, ion-coated, and studied under a scanning electron microscope. The lamina propria mucosae in Japanese monkeys was thinner than that in humans and consisted of a superficial layer rich in connective tissue and a deep layer poor in this tissue. Both collagen fibers and elastic fibers mostly ran straight, and the fiber distribution and morphology slightly differed according to the depth of the layer. Their density was higher in upper layers. In the muscle layer, connective tissue surrounding muscle fibers was scarce. The fibrous structure of the monkey vocal fold is simpler than that of human vocal fold, and these findings reflect the short and monotonous phonation of monkeys.     

Morphologic studies of the extrahepatic bile ducts in infancy, childhood and youth

Morphology of the extrahepatic bile ducts was examined with light microscopic methods in 55 human cases from the age of 28 gestational weeks up to 19 years. We found that barrel-shaped cells, rod-shaped cells and goblet cells are obligatory components of the bile duct epithelium in infancy. Tunica fibromuscularis of extrahepatic bile ducts consists of connective tissue. Increase of collagen fibers and fibers stained by resorcin fuchsin was observed during development. Neither in hepatic bile duct nor in common bile duct a muscle layer exists. A third of all bile ducts was free of muscles. Sparse muscle bundles in the other cases seem not able to generate bile duct motility. A morphological correlate to the sphincter of Mirizzi and Bernhard we did not find. Tunica adventitia and surrounding connective tissue contain many spacious lymphatic vessels.     

Yak (Bos grunniens) Tonsils: Morphological Description and Expression of IgA and IgG

This study aimed to describe the morphology, expression of IgA and IgG in adult yak tonsils. The 12 clinically healthy yak tonsils [3- to 6-year old, n = 12] were examined for morphology using light, and transmission electron microscopes. Expression of IgA and IgG was measured by qRT-PCR, ELISA, and immunohistochemistry. The results showed that the palatine tonsil, the tonsil of the soft palate, and the lingual tonsil were oropharyngeal tonsils. The stratified squamous epithelia covering them had a thick underlying layer of connective tissue and their crypts were heavily infiltrated by lymphocytes. The pharyngeal tonsil and the tubal tonsil were nasopharyngeal tonsils. The epithelia of them was predominantly pseudostratified columnar ciliary epithelium, which were loosely arranged with a number of desmosomes or intermediate junctions variably connecting them. The expression levels of IgA and IgG mRNA and protein from high to low was in the pharyngeal tonsil, palatine tonsil, tonsil of the soft palate, lingual tonsil, and tubal tonsil, respectively. Interestingly, the expression of IgG was very significantly higher than that of IgA in yak tonsils (P < 0.01). Both the IgA and IgG ASCs were distributed in the subepithelial areas of the non-reticular crypt epithelium, especially areas of pseudostratified columnar ciliary epithelium, the reticular crypt epithelium, lymphoid follicles, interfollicular areas, and with some of the positive cells aggregating around the glands. The results indicated that the tonsils were not only typical secondary lymphoid organs but also lymphoepithelial structures. IgG could be a significant component of mucosal immune responses in yak tonsils. Anat Rec, 302:999–1009, 2019. © 2018 Wiley Periodicals, Inc.     

Endometrial pathomorphology in bacterial vaginosis associated with chronic endometritis

A complex morphological and morphometric study was used to examine endometrial biopsy specimens from 133 patients with bacterial vaginosis (BV). Chronic endometritis (CE) was detected in 100% of them. The morphological components of CE in BV were significant dystrophic changes in integumentary endotheliocytes and glandular cells, differently pronounced polymorphocellular infiltration of the uterine mucosa with signs of tissue lymphopenia, as well as stromal and vascular fibroblastic changes with the decreased volume density of the endometrial integumentary endothelium, lower relative volumes of glands, and increased relative volume of connective tissue. The characteristic structural changes for CE and BV are intensive processes of apoptosis of the uterine mucosal epithelium in the presence of its slight proliferative activity, which determines progressive endometrial atrophy and may contribute to non-developing pregnancy. As this takes place, discrinism occurs in the uterine mucosa, mainly as inadequate progesterone reception of endometrial target cells, which leads to uterine gland dysfunction and may also cause fetal depletion syndrome.     

Collagenase-3 (matrix metalloproteinase-13) expression is induced in oral mucosal epithelium during chronic inflammation.

Increased proliferation of mucosal epithelium during inflammation is associated with degradation of subepithelial connective tissue matrix and local invasion of the epithelial cells. Here we have studied, whether collagenase-3 (MMP-13), a collagenolytic matrix metalloproteinase with an exceptionally wide substrate specificity, is expressed in the epithelium of chronically inflamed mucosa. Examination of human gingival tissue sections from subjects with chronic adult periodontitis with in situ hybridization revealed marked expression of MMP-13 in basal cells of some epithelial rete ridges expanding into connective tissue. Immunohistochemical staining demonstrated that these cells also expressed strongly laminin-5, suggesting that they are actively migrating cells. A strong signal for MMP-13 mRNA was occasionally also noted in the suprabasal epithelial cells facing the gingival pocket, whereas no collagenase-1 (MMP-1) mRNA was detected in any areas of the epithelium. MMP-13 expression was also detected in fibroblast-like cells associated with collagen fibers of the inflamed subepithelial connective tissue. In organ culture of human oral mucosa, MMP-13 mRNA expression was observed in epithelial cells growing into connective tissue of the specimens. Regulation of MMP-13 expression was examined in cultured normal nonkeratinizing epithelial cells isolated from porcine periodontal ligament. In these cells, MMP-13 expression at the mRNA and protein level was potently enhanced (up to sixfold) by tumor necrosis factor-alpha, transforming growth factor-beta(1), and transforming growth factor-alpha and by keratinocyte growth factor in the presence of heparin. In addition, plating periodontal ligament epithelial cells on type I collagen stimulated MMP-13 expression (sevenfold) as compared with cells grown on tissue culture plastic. The results of this study show, that expression of MMP-13 is specifically induced in undifferentiated epithelial cells during chronic inflammation due to exposure to cytokines and collagen. Thus, it is likely that MMP-13 expression is instrumental in the subepithelial collagenolysis and local invasion of the activated mucosal epithelium into the connective tissue.     

The connective tissue and glial framework in the optic nerve head of the normal human eye: light and scanning electron microscopic studies

The arrangement of connective tissue components (i.e., collagen, reticular, and elastic fibers) and glial elements in the optic nerve head of the human eye was investigated by the combined use of light microscopy and scanning electron microscopy (SEM). Light-microscopically, the optic nerve head could be subdivided into four parts from the different arrangements of the connective tissue framework: a surface nerve fiber layer, and prelaminar, laminar, and postlaminar regions. The surface nerve fiber layer only possessed connective tissue elements around blood vessels. In the prelaminar region, collagen fibrils, together with delicate elastic fibers, formed thin interrupted sheaths for accommodating small nerve bundles. Immunohistochemistry for the glial fibrillary acidic protein (GFAP) showed that GFAP-positive cells formed columnar structures (i.e., glial columns), with round cell bodies piled up into layers. These glial columns were located in the fibrous sheaths of collagen fibrils and elastic fibers. In the laminar region, collagen fibrils and elastic fibers ran transversely to the optic nerve axis to form a thick membranous layer - the lamina cribrosa - which had numerous round openings for accommodating optic nerve fiber bundles. GFAP-positive cellular processes also ran transversely in association with collagen and elastin components. The postlaminar region had connective tissues which linked the lamina cribrosa with fibrous sheaths for accommodating nerve bundles in the extraocular optic nerve, where GFAP-positive cells acquired characteristics typical of fibrous astrocytes. These findings indicate that collagen fibrils, as a whole, form a continuous network which serves as a skeletal framework of the optic nerve head for protecting optic nerve fibers from mechanical stress as well as for sustaining blood vessels in the optic nerve. The lamina cribrosa containing elastic fibers are considered to be plastic against the mechanical force affected by elevation of the intraocular pressure. The present study has also indicated that glial cells with an astrocytic character play an important role in constructing the connective tissue framework characteristic of the optic nerve head.     

大鼠胸腺实质中的肥大细胞—异染性,嗜银性,粘多糖和酶组织化学的研究

从异染，嗜银性，粘多糖和酶组织化学方面探讨了大鼠胸腺实质中的肥大细胞的异质性。结果表明；肥大细胞分布于皮，髓交界区或散在于皮质和髓质中。甲苯胺蓝染色和多糖组织化示；至少存在两种类型的肥大细胞，结缔组织在细胞和粘膜大细胞。在酶组织化学方面其也存在着异质性，尤其发现肥大细胞内含有ＡｃｈＥ阳性反应颗粒存在。此外，还发现肥大伴随ＡｃｈＥ阳性神经纤维分布，两者紧密接触，互相联接。     

Characterization of the peri-implant epithelium in hamster palatine mucosa: behavior of Merkel cells and nerve endings

The purpose of this study was to investigate the relationship between Merkel cells and nerve elements during tissue regeneration after receiving dental implants. Golden hamsters were divided into 3 groups and titanium alloy implants were fixed in their left-side maxilla through the third palatine rug. Animals were sacrificed at 1, 2, 3, 4, 5, 6, and 7 days after the implantation and tissues were characterized at the immunohistochemical and morphological levels. CK 20 and PGP 9.5 antibodies which react with Merkel cells and nerve fibers were used. Immunohistochemically, no CK 20-positive Merkel cells were seen in the peri-implant epithelium throughout the 7 days. However, starting at day 4, PGP 9.5-positive nerve fibers appeared in the connective tissue, and by day 7, nerve fibers had invaded the more superficial layer of the peri-implant epithelium compared to the mucosa removal control group. At the electron microscopic level, the intercellular spaces of the regenerating epithelium in the mucosa removal control group were small. In contrast, intercellular spaces of the peri-implant epithelium tended to be wide and regenerating nerve fibers invaded those intercellular spaces. In both the mucosa removal control group and the implantation group, the basal lamina and connective tissues regenerated completely. However, clear Merkel cells containing neurosecretory granules were not observed. Taken together, our results indicate that Merkel cells in the hamster palatine mucosa do not regenerate in the peri-implant epithelium. However, regenerative nerve fibers seem to play essential roles as part of the defense and sensory systems around the peri-implant epithelium to compensate for the weakened defense mechanism.     

人胰结缔组织纤维的细微和超微构筑及其意义--NaOH消蚀法SEM观察

目的探讨胰结缔组织纤维的细微和超微构筑及其意义.方法采用NaOH消蚀和超声波(USW)清洗技术,制备只保留结缔组织纤维成分的人胰组织样品,进行扫描电镜(SEM)观察和分析.结果经NaOH消蚀和USW清洗处理的胰组织,其细胞和基质成分全被消蚀掉,只留有结缔组织纤维,仍保持原有构筑特征.胰腺小叶、小叶间结缔组织和胰岛的轮廓清晰可见.穿行于小叶间结缔组织内的胰腺导管、动脉和静脉血管、淋巴管以及神经纤维束,易被辨认和区别.结缔组织纤维织成的束或网,均由胶原蛋白聚合而成的纳米(10-100mm)纤维,或称胶原细纤维所组成.结论活体上充满组织液的胰结缔组织纤维网,构成了该器官的组织支架和通道,为胰内、外分泌细胞的支持与保护、营养与代谢、分泌与通讯、再生与修复等,提供了适宜的微环境.     

Globule leukocytes and mast cells in the rat trachea: their number, distribution, and response to compound 48/80 and dexamethasone

Summary Globule leukocytes in the epithelium of the rat trachea may be counterparts of mucosal mast cells that are located in the gastrointestinal tract. If they are indeed similar to mucosal mast cells, globule leukocytes would be expected to decrease in number in rats treated with dexamethasone but not in rats treated with compound 48/80, an agent which causes non-antigenic degranulation of connective tissue mast cells. In this study, we determined the number and compared the distribution of globule leukocytes and connective tissue mast cells in the tracheas of pathogen-free rats. We then determined whether the number of these two types of cells changes in rats treated for 5 days with compound 48/80, dexamethasone, a combination of compound 48/80 and dexamethasone, or saline. We identified globule leukocytes and mast cells in whole mounts and histological sections of rat tracheas by using a histochemical reaction that demonstrates the chymotrypsin-like protease (chloroacetate esterase) present in mast cell granules. Using this method, we found that aproximately 225000 globule leukocytes were present in the epithelium of the trachea. These cells were most abundant in the rostral trachea. Rats treated with dexamethasone had a 91% reduction in the number of globule leukocytes with protease-containing granules, but rats treated with compound 48/80 had a normal number of these cells. We found some 55000 connective tissue mast cells in the same tracheas. Mast cells were most abundant in the posterior membrane of the caudal trachea and in the lamina propria between cartilaginous rings. Rats treated with compound 48/80 had a 96% reduction in mast cells with protease-containing granules, but rats treated with dexamethasone had a normal complement of mast cells. We conclude that globule leukocytes are abundant in the tracheas of healthy rats, are similar in morphology and pharmacological responses to mucosal mast cells located in other organs of rats, and are more numerous than and have a different distribution than connective tissue mast cells. Globule leukocytes in the tracheal epithelium may have a role in respiratory defenses similar to that of mucosal mast cells in other organs. Funded in part by National Institutes of Health Pulmonary Program Project Grant HL-24136. Dr. Tam is a fellow of the Parker B. Francis Foundation