The distribution and structure of cells in the tracheal epithelium of the mouse

Summary The tracheal epithelium of the mouse is a single layer of columnar cells resting on a basement membrane. Many of the cell types resemble those of other species. However, goblet cells are rare and ciliated cells occur only in scattered patches. Submucosal glands are absent from all but the highest reaches of the airway.The major proportion of the epithelial cells are non-ciliated. These usually project into the lumen of the trachea. Large amounts of smooth endoplasmic reticulum and many secretory vesicles occur within the cytoplasm. Secretory activity of these cells may be either apocrine or merocrine and these cells may transform into other cell types.It is suggested that these non-ciliated cells are Clara cells and that the mouse tracheal epithelium may make a useful model for the study of this type of cell.     

Tracheobronchial epithelium in the adult rhesus monkey: a quantitative histochemical and ultrastructural study

Previous studies of the intrapulmonary conducting airways of sheep and rabbit have demonstrated marked diversity in the epithelial populations lining them. Because studies of trachea and centriacinar regions of macaque monkeys suggested that primates may be even more diverse, the present study was designed to characterize the epithelial population throughout the airway tree of one primate species, the rhesus monkey. Trachea and intrapulmonary airways of the right cranial and middle lobes of glutaraldehyde/paraformaldehyde-infused lungs of five adult rhesus monkeys were microdissected following the axial pathway. Each branch was assigned a binary number indicating its specific location within the tree. The trachea and six generations of intrapulmonary airway from the right cranial lobe were evaluated for ultrastructure and quantitative histology as were those of the right middle lobe for quantitative carbohydrate histochemistry. Four cell types were identified throughout the tree: ciliated, mucous goblet, small mucous granule, and basal. The tallest epithelium lined the trachea; the shortest, the respiratory bronchiole. The most cells per unit length of basement membrane were in proximal intrapulmonary bronchi; the least, in the respiratory bronchiole. The nonciliated bronchiolar epithelial or Clara cell was restricted to respiratory bronchioles. Sulfomucins were present in the vast majority of surface goblet cells in the trachea and proximal bronchi. In proximal bronchi, neutral glycoconjugates predominated in glands and acidic glycoconjugates in surface epithelium. In terminal and respiratory bronchioles the ratio of acidic glycoconjugate to neutral glycoconjugate equaled that in proximal bronchi, although glands were not present. Sulfomucins were minimal in terminal airways. We conclude that the characteristics of the epithelial lining of the mammalian tracheobronchial airway tree are very species-specific. The lining of the rhesus monkey does not have the diversity in cell types in different airway generations observed in sheep and rabbit. Also, the populations lining these airways in the rhesus are very different from either the sheep or rabbit in number, proportions of different cell types, glycoconjugate content, and distribution of specific cell types.     

Differentiation of tracheal epithelium during fetal lung maturation in the rhesus monkey Macaca mulatta

Of the eight categories of epithelial cells identified in pulmonary conducting airways, four are found in the trachea of adult primates: basal, mucous goblet, intermediate, and ciliated cells. While their ultrastructure is well characterized, little is understood about their origin or differentiation. This study describes the pattern of differentiation of the tracheal luminal epithelium in a species of nonhuman primate, the rhesus monkey, Macaca mulatta. Tracheas of 57 fetal and postnatal rhesus were fixed with glutaraldehyde/paraformaldehyde: ten at 29-54 days gestational age (GA), ten at 59-80 days GA (pseudoglandular stage), sixteen at 82-130 days GA (canalicular stage), ten at 141-168 days GA (saccular stage), eight at 1-134 days postnatal, and three adults (2 yr 11 months to 11 yr 11 months). Slices taken proximal to the carina were processed for electron microscopy by a selective embedding procedure. In the youngest fetuses, essentially one population of cells lined the tracheal epithelial surface. These cells were columnar in shape with a central nucleus, few organelles, and large amounts of cytoplasmic glycogen. At 46 days GA, ciliated cells were observed on the membranous side of the trachea. Some nonciliated cells had concentrations of organelles in the most apical portion of their cytoplasm. At 59 days GA, membrane-bound cored granules were intermixed with organelles in the apices of some glycogen-filled cells. They were observed first on the cartilaginous side. Between 59 and 100 days GA, a large number of cell forms which appeared to be transitional between ciliated, secretory, basal, and undifferentiated cells were present. These included ciliated cells with electron-lucent inclusions resembling mucous granules. Mucous secretory cells were more numerous and had more granules and less glycogen in older fetuses. By 105 days GA, few of the secretory cells had significant amounts of glycogen and the cytoplasm was condensed. Secretory granules were very abundant in some cells and minimal in others. The Golgi apparatus was prominent. In animals 120 days GA and older, small mucous granule cells and basal cells resembling these cells in adults were present. By 134 days postnatal age, the epithelium resembled that in adults. We conclude that most of the differentiation of tracheal epithelium in the rhesus monkey occurs prior to birth; the cells differentiate in the following sequences: ciliated, mucous goblet, small mucous granule, basal; and basal and small mucous granule cells do not play a role in ciliated and mucous cell formation in the fetus.     

Ultrastructure of cell types of the olfactory epithelium in a catfish,Heteropneustesfossilis (Bloch)

Transmission electron microscopical study of olfactory epithelium of a mud-dwelling catfish,Heteropneustes fossilis (Bloch) shows receptor, supporting, goblet and basal cells. The receptor cells are of ciliated and microvillous type. Both ciliated and microvillous receptor cells are provided with olfactory knob. The dendrite of all the receptor cells bears many longitudinally arranged microtubules. Occurrence of the rod cell and its function is quite debatable. Specialized juctional complexes between the receptor and adjacent cells are clearly noted. The supporting cells are both ciliated and nonciliated. The ciliated supporting cells are responsible for water ventilation in the olfactory chamber as well as in the inter-lamellar spaces. This facilitates better perception of odours by the receptor cells. In addition to providing mechanical support to other cells, the nonciliated supporting cells also have a secretory function which is evident from the present study. The different stages of maturity of goblet cells are well documented. The presence of white cells in the olfactory epithelium is a very rare finding.     

Histamine-induced changes in rat tracheal goblet cell mucin store and mucosal edema

The pathology of chronic asthma in human and mouse is characterized by inflammation and remodeling of airway tissues. As a result of repeated inflammatory insults to the lower airways, smooth muscle thickening, mucin secretion and airway hyperreactivity may develop. In ovalbumin (OVA)-sensitized mice with repeated challenges with OVA to the lower airways, the trachea and bronchi are characterized by goblet cell hyperplasia and mucus hypersecretion from goblet cells. Previous study reports that intravenous (i.v.) application of a high dose of capsaicin releases tachykinin from capsaicin-sensitive nerves, producing acute plasma leakage and mucosal edema formation and causing depletion of mucin granules in goblet cells that results in a reduction in the number and size of Alcian blue (AB)-positive goblet cells in the rat trachea within a few minute after capsaicin application. Histamine is an important non-neural mediator of asthma from mast cells. The present study investigated whether i.v. application of a high dose of histamine (18 μmol/ml/kg) could result in these acute changes and the similar time-course changes in rat trachea. The tracheal whole mounts stained with chloroacetate esterase reagent and AB and tracheal methacrylate sections stained with AB and periodic acid-Schiff reagent were used for evaluation of histological and cellular changes. At 5 min after histamine application, mucosal leaky venules were numerous and subepithelial edema ratio (% of length of edema along the mucosal epithelial circumference of tracheal cross section) was found to be 48.2 ± 4.9, which was greater (P < 0.01) than saline-treated rats. But, the number of AB-positive goblet cells, 2,030 ± 170/mm² of mucosal surface epithelium, was similar to saline-treated group (P > 0.05). One day later, edema ratio remained large and the number of AB-positive goblet cells was 1,140 ± 150/mm² epithelium, reduced to half the number of the group at 5 min after histamine (P < 0.01). It is suggested that mucus hypersecretion occurred at this time point. At 3 or 5 days after histamine, edema ratio gradually decreased. The number of AB-positive goblet cells continued to remain small on day 3. On day 5 after histamine, the number of AB-positive goblet cells restored to the level of rat group at 5 min after histamine application. At 7 days after histamine, edema ratio returned to the level of saline-treated group. It is concluded that degranulation and thinning of tracheal goblet cells and mucus hypersecretion lagged behind histamine-induced acute plasma leakage and edema, and restoration of mucin store in goblet cells was associated with remission of mucosal edema.     

Histochemical localization of carbonic anhydrase in the trachea of the guinea pig

 Tissue specimens from guinea pigs were examined using an enzyme-histochemical reaction to explore the presence of carbonic anhydrase (CA) activity in the trachea. CA activity was detected in a group of morphologically distinct epithelial cells, in goblet cells, and in glands of the tracheal mucosa. The epithelial cells showing CA activity were distributed singly and sparsely throughout the entire trachea. These cells showed a wide morphological variability and were clearly different from those forming the pseudostratified ciliated epithelium. Their number was higher in sections closer to the tracheal bifurcation than in those near the larynx. Although the nature of these cells is unknown, based on their morphological and histochemical characteristics and their distribution, they may represent a specialized chemoreceptor. To our knowledge, this is the first report of CA localized in tracheal epithelial cells. Accepted: 6 March 1996     

Electron microscopic observations on ciliated epithelium of tracheal organ cultures infected with Bordetella bronchiseptica

Using mouse tracheal organ cultures, the pathogenic effect of Bordetella bronchiseptica to epithelial cells was studied by electron microscopy. The ultrastructure of epithelial cells in uninfected tracheal rings was preserved well for longer than 3 days. In mouse tracheal rings infected with graded doses (3 x 10(5) to 10(7) CFU/ml) of phase I B. bronchiseptica, the colonization in the interciliary spaces of ciliated epithelial cells was observed after a 20-hr infection period. The infected tracheal rings showed swelling of nonciliated cells as well as ciliated cells, rupture of cell membrane of cilia, swelling and disappearance of cilia, and atrophic cytomorphosis of epithelial cells. The severity of these changes occurred depending on the infection doses. These changes were essentially similar to those observed previously in the tracheal epithelia of the B. bronchiseptica-infected mice. The usefulness of this in vitro model was suggested for studying the pathogenesis of Bordetella infection.     

Surface architecture of the mucosal epithelium of the cat trachea: II. Structure and dynamics of the membranous portion

Bronchoscopic examination of anesthetized cats revealed that the trachea is capable of considerable change in caliber via lateral expansion of the membranous trachea. The morphological basis for this expansile capacity was determined by correlated light microscopy and scanning and transmission electron microscopy. The organization of the membranous trachea differs from that of the cartilaginous trachea. The mucosa is arranged in a series of longitudinal folds that open like an accordion when stretched laterally. These fold are not random, but appear to depend on rows of nonciliated, microvillus-rich cells that form flexure lines in the surface epithelium. The mitochondria in such cell have a condensed configuration, indicating a high level of oxidative metabolism and suggesting that they may participate in transport processes that modify the luminal contents. Goblet cells, which are relatively sparse in the membranous trachea, have mitochondria in which the prominence of matrix granules and degree of mucus storage are inversely related. Mitochondrial morphology allows goblet cells that have discharged their mucin content to be readily distinguished from the microvillus-rich cells, even when their luminal surfaces lie outside the thickness of a section.     

Morphology and quantitation of ciliated outgrowths from cultured rabbit tracheal explants

Ciliated outgrowths from cultured rabbit tracheal epithelium have been characterized with scanning and transmission electron microscopy and the ciliary frequencies measured. Outgrowth surface cells change in morphology from columnar to cuboidal to squamous shapes in their progression away from the explant. The ciliated cells retain the organization of their cilia in a cluster usually centrally on the apical cell surface. Closest to the explant the nonciliated surface of ciliated cells develops extensive microvilli. Ciliary frequencies are comparable to those observed in fresh tracheal epithelium with means of 50 cells per explant ranging from 11 to 23 beats per second. For most cultures examined no correlation exists between ciliary frequency and cell distance from the explant. The goblet cells loose their ability to synthesize the characteristic mucus granules and can only be identified by the absence of cilia. Surface cells are supported by an underlying layer of discontinuous cells and connective tissue fibers. The characteristics of an outgrowth suggest that development occurs through migration of differentiated cells from the explant rather than differentiation of cell types from migrating basal cells.     

Microscopic and ultrastructural anatomy of the trachea and bronchi of Melopsittacus undulatus (Aves,Psittaciformes)

Summary The normal microscopic pattern and ultrastructure of the lower trachea and the primary and secondary bronchi of the budgerigar (Melopsittacus undulatus) are described. The trachea is lined by mucociliary pseudostratified columnar epithelium with simple acinar mucous glands; epithelium in primary and secondary bronchi becomes progressively lower and less pseudostratified, and mucous cells less aggregated. The wall structure shows a parallel simplification; tracheal elements are comprised of osseous metaplastic cartilage with bone marrow between cancellous trabeculae, whereas distal secondary bronchial walls are principally comprised of smooth muscle. Mucous cells are similar to those described in mammalian, and other avian respiratory mucosae. Ciliated cells are similar to those known in other avian airways. No brush cells or Clara cells are observed.     

Transitional epithelial zone of the bovine nasal mucosa

To determine the extent and ultrastructure of epithelium lining the transitional nasal mucosa of the neonate, gnotobiotic calf tissues were prepared for scanning and transmission electron microscopy. Stratified cuboid epithelium of the rostral 40% of the nasal cavity contained few ciliated cells; the next caudal 10-15%, although ciliated, had extensive nonciliated areas. The predominant type of surface cell was nonciliated, had short microvilli, and contained a multilobate nucleus and numerous pinocytotic vesicles. In some areas the surface of these cells presented a cobblestone appearance. Basal cells contained numerous bundles of filaments, ribosomes, and basal vesicles. Caudally, nonciliated columnar cells included a cell type similar to the more rostral cuboid cell, as well as brush cells and immature secretory and ciliated cells. Goblet cells were infrequently observed. Intraepithelial nerve terminals were abundant. Other intraepithelial cells, often difficult to identify owing to varying characteristics, included lymphocytes. Based upon comparisons of this neonatal epithelium with mature epithelium, observed in earlier studies of other mammalian species, the transitional mucosa is believed normally to occupy an extensive area of the nasal cavity.     

The Recovery Process of Mice Tracheal Epithelium Injured by 5-FU and Its Microarray Analysis

Although the research on the localization of trachea stem cells has made a rapid progress, the mechanism of proliferation and differentiation of trachea stem cells remains unclear. The objective of this study is to observe and analyze the recovery process of mice tracheal epithelium injured by 5-FU, and to investigate the mechanism involved in the regulation of tracheal stem cells proliferation and differentiation through morphological, immunofluorescence, and microarray analysis. After treatment with 5-FU, the mature cells were dead and desquamated. Only a few G₀ phase cells remained on the basement membrane. When supplied with normal culture media, the cells eventually became flat, cubic, and restored as pseudostratified epithelium. These G₀ phase cells were ABCG2 positive. It suggested that these cells could differentiate into cilia cells or Clara cells, and had the multi-differentiation ability of stem cells. We examinated the expression profile of genes involved in the stem cell differentiation in normal tracheal epithelial cells and the regenerated epithelial cells at 24 and 48 h after injured by 5-FU using gene microarray. After 24 h treatment, 8 genes were up-regulated and 31 genes were down-regulated. After 48 h treatment, 5 genes were up-regulated and 42 genes were down-regulated. The differential gene expressions in gene microarray analysis focused on cell cycle regulation, intercellular junction, fibroblast growth factors, bone morphogenetic protein, Notch and Wnt-signaling pathways, which suggested that the differential gene expressions might be closely associated with the proliferation and differentiation of tracheal stem cells.     

Nonolfactory surface epithelium of the nasal cavity of the bonnet monkey: a morphologic and morphometric study of the transitional and respiratory epithelium

The purpose of the present study was to characterize ultrastructurally the nonolfactory nasal epithelium of a nonhuman primate, the bonnet monkey. Nasal cavities from eight subadult bonnet monkeys were processed for light microscopy, and scanning and transmission electron microscopy. Nonolfactory epithelium covered the majority of the nasal cavity and consisted of squamous (SE), transitional (TE), and respiratory epithelium (RE). Stratified SE covered septal and lateral walls of the nasal vestibule, while ciliated pseudostratified RE covered most of the remaining nasal cavity. Stratified, nonciliated TE was present between SE and RE in the anterior nasal cavity. This epithelium was distinct from the other epithelial populations in abundance and types of cells present. TE was composed of lumenal nonciliated cuboidal cells, goblet cells, small mucous granule (SMG) cells, and basal cells, while RE contained ciliated cells, goblet cells, SMG cells, basal cells, and cells with intracytoplasmic lumina lined by cilia and microvilli. TE and RE contained similar numbers of total epithelial cells and basal cells per millimeter of basal lamina. TE was composed of more SMG cells but fewer goblet cells compared to RE. We conclude that nonolfactory nasal epithelium in the bonnet monkey is complex with distinct regional epithelial populations which must be recognized before pathologic changes within this tissue can be assessed adequately.     

Murine nasal septa for respiratory epithelial air-liquid interface cultures

Air-liquid interface models using murine tracheal respiratory epithelium have revolutionized the in vitro study of pulmonary diseases. This model is often impractical because of the small number of respiratory epithelial cells that can be isolated from the mouse trachea. We describe a simple technique to harvest the murine nasal septum and grow the epithelial cells in an air-liquid interface. The degree of ciliation of mouse trachea, nasal septum, and their respective cultured epithelium at an air-liquid interface were compared by scanning electron microscopy (SEM). Immunocytochemistry for type IV beta-tubulin and zona occludens-1 (Zo-1) are performed to determine differentiation and confluence, respectively. To rule out contamination with olfactory epithelium (OE), immunocytochemistry for olfactory marker protein (OMP) was performed. Transepithelial resistance and potential measurements were determined using a modified vertical Ussing chamber SEM reveals approximately 90% ciliated respiratory epithelium in the nasal septum as compared with 35% in the mouse trachea. The septal air-liquid interface culture demonstrates comparable ciliated respiratory epithelium to the nasal septum. Immunocytochemistry demonstrates an intact monolayer and diffuse differentiated ciliated epithelium. These cultures exhibit a transepithelial resistance and potential confirming a confluent monolayer with electrically active airway epitheliumn containing both a sodium-absorptive pathway and a chloride-secretory pathway. To increase the yield of respiratory epithelial cells harvested from mice, we have found the nasal septum is a superior source when compared with the trachea. The nasal septum increases the yield of respiratory epithelial cells up to 8-fold.     

Mast Cells Present Protrusions into Blood Vessels upon Tracheal Allergen Challenge in Mice

Mast cells (MC) and myeloid dendritic cells (DC) act proximally in detecting and processing antigens and immune insults. We sought to understand their comparative dynamic behavior with respect to the airway epithelium in the steady state and in response to an allergic stimulus in mouse trachea. We devised methods to label MC in living trachea and to demonstrate that MC and DC occupy distinct layers of the tracheal mucosa, with DC being closer to the lumen. DC numbers doubled after allergen challenge, but MC numbers remained stable. MC and DC migrated minimally in either steady state or allergen-challenge conditions, and their interactions with one another appeared to be stochastic and relatively infrequent. While DC, unlike MC, exhibited probing behaviors involving dendrites, these projections did not cross the epithelium into the airway lumen. MC typically were located too far from the epithelial surface to contact the tracheal lumen. However, MC had protrusions toward and into blood vessels, likely to load with IgE. Thus, DC and MC occupy distinct niches and engage in sessile surveillance in the mouse trachea. Little or no access of these cell types to the airway lumen suggests that trans-epithelial transport of proteins in the steady state would be required for them to access luminal antigens.     

Light and electron microscopic cytochemistry of glycoconjugates in the rectosigmoid colonic epithelium of the mouse and rat

The several cell types in mouse and rat rectosigmoid colon have been examined with light and electron microscopic methods for localizing and characterizing complex carbohydrates. Mucous cells, also termed vacuolated cells, and goblet cells comprised most of the deep crypt epithelium in both species, and absorptive columnar cells and goblet cells mainly populated the more superficial epithelium of the upper crypts and main lumen. Occasional tuft cells and enteroendocrine cells were also encountered. Transitional cells structurally intermediate between mucous cells and absorptive cells contained granules characteristic of mucous cells and vesicles like those of columnar absorptive cells. These intermediate cells supported the concept of replacement of mucous by absorptive cells through transformation of mucous into absorptive cells. The intermediate cells also contained numerous lysosomes often in apparent fusion with mucous granules, indicating crinophagic disposal of mucous granules as a mechanism in the cell transformation. Glycoconjugate in absorptive cell vesicles resembled that coating the apical plasmalemma and appeared to represent the source of the glycocalyx of the brush border. Complex carbohydrate in these vesicles differed cytochemically from that of the mucous cell granules, which release their content into the crypt lumen. The absorptive cell vesicles, therefore, constitute an organelle distinct from the mucous cell granules rather than an atrophic form of the latter in a more mature cell. Goblet cells differed in failing to transform morphologically with age but changed in the cytochemical characteristic of their secretion during migration up the crypts. Terminal N-acetylglucosamine residues diminished, while terminal sialic acid-galactose dimers increased during the upward migration, indicating activation of glycosyl transferase synthesis in relation to goblet cell maturation. Glycoconjugate in secretion of mucous cell granules differed markedly from that in goblet cell granules, and content of both organelles differed from that of absorptive cell vesicles. However, secretion in mucous cell granules appeared generally similar for mice and rats with minor exceptions, and secretion in goblets of mice generally resembled that in goblets of rats. Cells interpreted tentatively as Kulchitsky cells stained for high content of fucose with the Ulex europeus I lectin. Globoid leukocytes infiltrating the epithelium of the rat but not the mouse rectosigmoid colon resembled globoid leukocytes in rat tracheal epithelium and, like the latter, appeared to derive from mast cells.     

Growth and differentiation of mouse tracheal epithelial cells: selection of a proliferative population

Highly regulated programs for airway epithelial cell proliferation and differentiation during development and repair are often disrupted in disease. These processes have been studied in mouse models; however, it is difficult to isolate and identify epithelial cell-specific responses in vivo. To investigate these processes in vitro, we characterized a model for primary culture of mouse tracheal epithelial cells. Small numbers of cells seeded at low density (7.5 x 10(4) cells/cm2) rapidly proliferated and became polarized. Subsequently, supplemented media and air-liquid interface conditions resulted in development of highly differentiated epithelia composed of ciliated and nonciliated cells with gene expression characteristic of native airways. Genetically altered or injured mouse tracheal epithelial cells also reflected in vivo patterns of airway epithelial cell gene expression. Passage of cells resulted in continued proliferation but limited differentiation after the first passage, suggesting that transit-amplifying cell populations were present but with independent programs for proliferation and differentiation. This approach provides a high-fidelity in vitro model for evaluation of gene regulation and expression in mouse airway epithelial cells.     

Histochemical methods for characterizing secretory and cell surface sialoglycoconjugates

Paraffin sections of trachea, sublingual gland, and pancreas from rats, mice, and hamsters were stained with peanut agglutinin (PNA) or Dolichos biflorus agglutinin (DBA) conjugated to horseradish peroxidase before or after enzymatic removal of sialic acid. Adjacent sections were oxidized with periodate prior to incubation with sialidase and staining with PNA and DBA. PNA binding demonstrated terminal beta-galactose in secretions, at the basolateral plasmalemma of mouse tracheal serous cells, in or at the surface of zymogen granules, and at the apical and basolateral surface of mouse and hamster pancreatic acinar cells. Sialidase digestion revealed PNA binding, demonstrative of penultimate beta-galactose, in secretions of mucous cells in tracheal and sublingual glands and at the apical glycocalyx of ciliated and secretory cells in the tracheal surface epithelium of all the rodents studied. Sialidase also imparted PNA affinity to endothelium in all three species and to secretions and the basolateral plasmalemma of tracheal serous cells and pancreatic acinar cells in the rat. Periodate oxidation blocked the enzymatic removal of N-acetylneuraminic acid as judged by prevention of staining with the sialidase-PNA procedure. Sites in which periodate prevented sialidase-PNA staining included pancreatic islet cells and at the luminal glycocalyx of ciliated and secretory cells in tracheal surface epithelium in all three rodents, most sublingual mucous cells in the hamster, pancreatic acinar cells in the rat, and endothelium, except that of the rat. Glycoconjugate in other sites remained positive with the periodate-sialidase-PNA sequence. Resistance to periodate was interpreted as evidence for the presence of terminal sialic acid with an O-acetylated polyhydroxyl side chain. DBA binding demonstrated terminal alpha-N-acetylgalactosamine in the secretion of all mucous cells in the hamster trachea and 50-90% of those in the rat, secretion and the basolateral plasmalemma of all glandular serous cells in the mouse trachea, at the apical surface of most secretory cells lining the lumen of the rat and hamster trachea, and cilia of 5-10% of ciliated cells in the rat trachea. Periodate oxidation and sialidase digestion demonstrated N-acetylneuraminic acid and penultimate alpha-N-acetylgalactosamine in cilia in the mouse trachea and sialic acid containing O-acetylated polyhydroxyl side chains subtended by N-acetylgalactosamine in the secretion of all mucous cells in the rat and hamster trachea and of 80-90% of mucous cells in the hamster sublingual gland.(ABSTRACT TRUNCATED AT 400 WORDS)     

Ultrastructure and fluorescence histochemistry of endocrine (APUD-type) cells in tracheal mucosa of human and various animal species

This study describes distrinctive cells with ultrastructural and histochemical features of APUD-type endocrine cells within the tracheal epithelium of human fetuses, newborns and children as well as different animal species. These cells referred to as Kultschitzky cells (K cells) were found to be argyrophilic, but not argentaffin, and are considered analogous to the same type of cells in lung and gastro-intestinal tract. Fluorescence histochemistry demonstrated the presence of intracellular amine within tracheal K cells, but only after in-vitro or in-vivo administration of amine precursor (L-DOPA). Ultrastructurally, these cells are characterized by the presence of numerous cytoplasmic granules (dense core vesicles) which show species related morphologic variations. Two different types of K cells were found in trachea of lamb and armadillo, each type possessing morphologically different dense core vesicles. In human and rabbit tracheas, only one type of K cell was identified. K cells in the trachea are distributed as single cells between other epithelial cells; neuroepithelial bodies such as those found in bronchial mucosa were not identified. Well differentiated K cells were found in tracheas of early human fetuses and throughout gestation, infancy, and childhood. Preservation of K cells in human autopsy material and widespread occurence of these cells in various laboratory animals will permit further studies into the nature and function of tracheobronchial endocrine cells.