Histochemical Phenotypes of Von Ebner's Gland of Ferret and their Functional Implications

Von Ebner's gland of ferret was examined by means of light microscopy, protein, mucosubstance and enzyme histochemistry, and neurohistology. Acinar cells were replete with granules containing neutral mucosubstances and disulphides, and showed strong diffuse acid phosphatase activity and weak granular staining for peroxidase. Staining for cytochrome oxidase, succinate dehydrogenase, and NADH and NAD(P)H dehydrogenases was also seen. Basolateral plasmalemma of acinar cells showed weak, ouabain-sensitive Na⁺,K⁺-ATPase activity. Ductal cells were of a simple appearance, contained thiols and showed variable staining for acid phosphatase, dehydrogenases and cytochrome oxidase. Variable amounts of β-glucuronidase reaction product were localized in the glandular parenchyma, being marked in atrophic areas. Prominent stellate myoepithelial cells embracing acini and also basal ductal cells were demonstrated by alkaline phosphatase. Thiamine pyrophosphatase reaction product was concentrated in blood vessels around parenchyma, with little Golgi-like staining in acinar cells. Acetylcholinesterase activity was associated with an extensive network of nerve fibres embracing parenchyma, whereas catecholamine fluorescence was not seen. The results suggest that the acini of von Ebner's gland of ferret synthesise neutral secretory glycoproteins and peroxidase. Water mobilization is inconspicuous. Lysosomal activities feature in the parenchyma, possibly a consequence of processing secretory products in acini, absorption in ducts and/or adaptation atrophy. The gland receives a rich cholinergic-type innervation, and has extensive myoepithelial and microvascularbreak networks.     

Morphological phenotypes and functional capabilities of submandibular parenchymal cells of the ferret investigated by protein, mucosubstance and enzyme histochemistry

Submandibular glands obtained post-mortem from mature ferrets of both sexes were examined with the use of light microscopical histochemical methods for proteins, mucosubstances and enzymes associated with cell functions or organelles. Demilunar cells showed carboxylated mucosubstances that were mainly non-sulphated, and diffuse activity for peroxidase, E600-sensitive esterase and acid phosphatase. Thiol groups were also detected in these cells. Central acinar cells showed sulphated mucosubstances, disulphides and reticular staining for thiamine pyrophosphatase. Intercalary ducts showed diffuse activity for NADH and NAD(P)H dehydrogenases. Striated ducts contained protein, tryptophan, disulphides, neutral mucosubstances and E600-sensitive esterase periluminally. Basally, the striated ductal cells showed variable activity for peroxidase, cytochrome oxidase, succinate dehydrogenase and acid phosphatase. Basolateral plasma membranes of these cells exhibited ouabain-sensitive Na,K-ATPase activity. The collecting ducts were characterized by variable periluminal staining for acid phosphatase, -glucuronidase, acid -galactosidase and E600-resistant esterase. The results suggest that the histological appearances of the acini of the submandibular gland of the ferret are dependent on the synthesis of secretory acid glycoproteins, that the striated ducts are involved with the secretion of tryptophan-rich product comprising neutral glycoproteins and showing esterase activity and with marked transport of ions and that the collecting ducts are involved with absorption.     

Salivary glands of the cat: A histochemical study

Synopsis The submandibular, sublingual and parotid glands of the cat have been studied. Mucosubstance histochemistry demonstrated acidic mucosubstances with varying properties in the acini. Thiamine pyrophosphatase and nucleoside diphosphatase reaction products were seen with a Golgi-like appearance in acinar cells. Granules of acid phosphatase, -glucuronidase and E600-resistant esterase reaction products, presumably representing lysosomal enzyme activities, were seen in acinar and ductal cells. Diffuse acid phosphatase and -glucuronidase reaction products were seen in central cells of the submandibular acini, and diffuse non-specific esterase reaction product was seen in acinar and ductal cells. Arylamidase reaction product was associated with some acinar cells. Reaction product from a peroxidase technique was seen in demilunar cells of the submandibular acini, in parts of the sublingual acini, in parotid acini, and in ductal cells. Cytochrome oxidase and succinate dehydrogenase reaction products were seen most strongly in striated ducts, whereas NADH- and NADPH-diaphorase reaction products were seen at a high level throughout the ducts.     

Substance P immunoreactivity in rat von Ebner's gland

Summary The present immunohistochemical study revealed substance P-immunoreactive neuronal elements in the von Ebner's gland of rats. Immunoreactive ganglion cells were observed as single cells or groups of several immunoreactive ganglion cells among intra-lingual muscles, at the base of the vallate papillae and near the von Ebner's gland. Very numerous substance P-immunoreactive varicose nerve fibres ran closely associated with the serous cells and excretory duct cells, and were seen to run along blood vessels in the gland. Since substance P-immunoreactive ganglion cells were present near the glands, the immunoreactive varicose nerve fibres in the von Ebner's gland may be partly derived from the intra-lingual ganglion cells. These substance P-immunoreactive varicose nerve fibres may have an effect on the secretory activity of the serous cells and duct cells, and on the vasodilation of blood vessels of the von Ebner's gland. Actin immunoreactivity was seen in numerous myoepithelial cells embracing serous cells and duct cells, and in the smooth muscle cells of blood vessels of the gland. By using a double immunolabelling technique with anti-substance P and anti-actin sera, substance P-immunoreactive varicose nerve fibres were found to be in close contact with myoepithelial cells.     

Immunolocalization of myoepithelial cells in isolated acini of rat exorbital lacrimal gland: Cellular distribution of muscarinic receptors

The secretion of proteins and fluids from the exorbital lacrymal gland of rat is mainly controlled by muscarinic receptors. In a recent pharmacological study, Mauduit et al (Am J Physiol (1993) 264, C1550–C1560) identified a homogeneous population of M₃ muscarinic receptors in preparations of acini from these tissues. In order to define the cellular composition of these acini and localize the muscarinic receptors; we have performed an immunofluorescent labelling study combined with confocal scanning microscopy. Antibodies raised against components of the different cytoskeletal networks (α-smooth muscle actin, cytokeratin peptide 14 and α-tubulin) revealed the presence of two different cell types. Cells with a stellate form are identified as myoepithelial cells, whereas rounded cells are secretory acinar cells. Both cell types are reactive with an antibody specifically directed against the muscarinic receptor. However, myoepithelial cells appear more intensely labelled than acinar cells. The roles of myoepithelial cells and secretory cells in the physiological function of the gland are discussed in terms of the distribution of muscarinic receptors.     

Acid phosphatase and peroxidase in ‘resting’ acinar cells of the major salivary glands of cats and their possible movement into secretory granules

Synopsis After fixation by perarterial perfusion using an aldehyde mixture, salivary tissues were prepared for ultrastructural cytochemistry of acid phosphatase or peroxidase. Great variations in the distributions of the reaction products occurred, often within the same cell. Acid phosphatase staining occurred not only in lysosomes and sometimes in a GERL system, but a diffuse cytoplasmic component was also found in submandibular central acinar cells and to a lesser extent in parotid acini and variable staining occurred in the secretory granules of these cells. Peroxidase was variably associated with rough endoplasmic reticulum in submandibular demilunar cells, parotid acini, and more strongly in some sublingual cells. The secretory granules of the latter were darkly stained, but in parotid granules there was varibale staining and least staining occurred in the granules of submandibular demilunes.These results are thought to indicate that not all enzymes present in secretory granules have reached there by an elective secretory process. Sometimes they appear to have entered the granules haphazardly, possibly having been enzymes associated with intracellular cisternal channels for transport or metabolism of other secretory substances and ultimately to have passed into the cisternal channels by chance or as part of a natural removal of redundant material.     

Ultrastructural aspects of cat submandibular glands

Submandibular glands of five adult female cats were examined by conventional electron microscopic techniques. All gland acini are mucous secreting and each acinus is capped with mucous secreting demilunar cells. Secretory product of demilunar cells is more electron lucent than that of acinar cells. The demilunes show intercellular tissue spaces and intercellular canaliculi whereas similar specializations are absent between acinar cells. Mitochondria and arrays of granular endoplasmic reticulum are more numerous in demilunar cells than in acinar cells. In acinar and demilunar cells secretory droplets first appear as enlarged Golgi saccules which subsequently become closely related to cisternae of the granular endoplasmic reticulum. Filamentous structures, interpreted as mucin molecules, are present in secretory droplets of acinar cells. Intercalated ducts are short, consisting of several junctional cells between acini and striated ducts. Striated ducts are long and tortuous and contain light cells, dark cells and basal cells. Light cells contain numerous membrane bound granules in their distal ends whereas dark cells show electron lucent vesicles in the same position. Basal cells contain a paucity of organelles and membrane plications but exhibit hemidesmosomes along their basal plasma membranes. Myoepithelial cells are abundant in relation to acinar and demilunar cells. Nerve terminals are present in some instances between acinar cells or between acinar and myoepithelial cells.     

Morphologic diversity of the minor salivary glands of the rat: fertile ground for studies in gene function and proteomics

In this article the locations and histologic and ultrastructural features of all of the minor salivary glands of the rat are presented; similarities and differences among them are highlighted. These glands are almost as diverse morphologically as the major salivary glands of the rat. The acini of von Ebner's glands are serous; those of the anterior and posterior buccal glands and minor sublingual glands are mucous; and those of the glossopalatal, palatal, and Weber's glands are mucous with serous demilunes. The anterior buccal, minor sublingual and von Ebner's glands have striated and stratified columnar ducts, while only the minor sublingual and von Ebner's glands have intercalated ducts. The glossopalatal, palatal, posterior buccal and Weber's glands have none of these ducts; the tubulo-acini drain abruptly into short terminal ducts composed of stratified squamous epithelium. All of the mucous acini react with an antibody to a mucin (Muc19) of the rat major sublingual gland, but in some of the glands the reaction varies in intensity among the acinar cells. Ultrastructurally, the mucous secretory granules of the anterior buccal, glossopalatal, palatal and Weber's glands are biphasic, while those of the minor sublingual and posterior buccal glands are monophasic. Although there is a considerable body of literature concerning the development, innervation, physiology and proteomics of von Ebner's glands, investigation of the other minor salivary glands of the rat ranges from modest to nearly nonexistent.     

The effect of aging on the rat submandibular gland: an ultrastructural, cytochemical and biochemical study

The effect of aging on the rat submandibular gland was studied by using ultrastructural, ultrastructural cytochemical and biochemical techniques. There was an age-related clumping of the nucleolar-associated and peripheral chromatin in many of the acinar cells and a decrease in the number of cisternae of rough endoplasmic reticulum. Many aged acinar cells were binucleated. There was also an age-related increase in pigment granules throughout the gland. These membrane bound granules consisted of a lipid droplet and an associated dense cap which had a granular matrix and pigment droplets. The lead capture method for acid phosphatase activity demonstrated that activity was associated with the granular matrix of the dense cap. These results were correlated with the age-related increase in acid phosphatase activity as determined by colorimetric procedures. There was an age-related increase in the number of cells characterized by small secretory granules. These cells were found as part of the intercalated ducts or at the junction of the duct with the acini. Oncocytes were also found as part of the parenchyma of the aged submandibular gland. These cells were characterized by the pleomorphic mitochondria that fill their cytoplasm. Occasionally, cells that possessed extraordinary numbers of mitochondria and small secretory granules were also observed. The determinations of total DNA and RNA revealed and age-related decrease in RNA while there was no significant change in the concentration of DNA.     

Protein tyrosine phosphorylation in cardiovascular system

Treatment of rat parotid acinar cells with sodium orthovanadate (an inhibitor of protein tyrosine phosphatase) caused a dose-dependent inhibition of phosphatase activity as measured by the hydrolysis of para nitrophenylphosphate (pNPP). Inclusion of 50 M sodium orthovanadate inin vitro gland cultures prevented the amylase secretion from both untreated control and isoproterenol-stimulated parotid acinar cells. Four different tyrosine-phosphorylated proteins with M_r 40, 45, 70 and 95 kDa, respectively, were identified in secretory granule preparations from rat parotid glands by immunoblot using a monospecific antibody for phosphotyrosine. An increase in the phosphorylation levels of these phosphoproteins was noted in the presence of 50 M sodium orthovanadate, suggesting that a protein tyrosine phosphatase (PTPase) is involved in parotid gland protein dephosphorylation reactions. Using antibody to Syp (a PTPase belonging to class 1D), a major fraction of subcellular activity was found to be associated with secretory granule membranes. These results suggest the possible involvement of a PTPase (Syp) in parotid gland secretory mechanisms.     

Immunofluorescence-microscopic demonstration of myosin and actin in salivary glands and exocrine pancreas of the rat

Summary Actin and myosin were localized in various salivary glands (parotid, submandibular, sublingual, lingual and Harderian gland) and the exocrine pancreas of rats by indirect immunofluorescence microscopy using specific rabbit antibodies against chicken gizzard myosin and actin. A bright immunofluorescent staining with both antibodies was observed at three main sites: (1) In myoepithelial cells of all salivary glands, (2) in secretory gland cells underneath the cell membrane bordering the acinar lumen (except Harderian and mucous lingual gland), and (3) in epithelial cells of the various secretory ducts (of all glands) in similar distribution as in acinar cells. The present immunohistochemical findings in acinar cells could lend further support to a concept suggesting that myosin and actin are involved in the process of transport and exocytosis of secretory granules.Supported by grants form Deutsche Forschungsgemeinschaft (Dr. 91/1, Ste. 105/19 and U. 34/4). We thank Mrs. Ursula König, Mrs. Christine Mahlmeister and Miss Renate Steffens for excellent technical assistance.     

Light microscopic detection of sugar residues in glycoconjugates of salivary glands and the pancreas with lectin-horseradish peroxidase conjugates. I. Mouse

Summary Mouse salivary glands and pancreases were stained with a battery of ten horseradish peroxidase-conjugated lectins. Lectin staining revealed striking differences in the structure of oligosaccharides of stored intracellular secretory glycoproteins and glycoconjugates associated with the surface of epithelial cells lining excretory ducts. The percentage of acinar cells containing terminal -N-acetylgalactosamine residues varied greatly in submandibular glands of 30 male mice, but all submandibular acinar cells contained oligosaccharides with terminal sialic acid and penultimate -galactose residues. The last named dimer was abundant in secretory glycoprotein of all mucous acinar cells in murine sublingual glands and an additional 20–50% of these cells in all glands contained terminalN-acetylglucosamine residues. In contrast, terminal -N-acetylgalactosamine was abundant in sublingual serous demilune secretions. Serous acinar cells in the exorbital lacrimal gland, posterior lingual gland, parotid gland and pancreas exhibited a staining pattern unique to each organ. In contrast, the apical cytoplasm and surface of striated duct epithelial cells in the submandibular, sublingual, parotid and exorbital lacrimal gland stained similarly. A comparison of staining with conjugated lectins reported biochemically to have very similar carbohydrate binding specificity has revealed some remarkable differences in their reactivity, suggesting different binding specificity for the same terminal sugars having different glycosidic linkages or with different penultimate sugar residues.     

Ultrastructural localization of endogenous mammary gland peroxidase during lactogenesis in the rat results after tannic acid-formaldehyde-glutaraldehyde fixation.

Endogenous mannary gland peroxidase in acinar cells of prelactating and lactating rats is revealed in tannic acid-formaldehyde-glutaraldehyde-fixed tissue by means of the standard diaminobenzidine procedure. Diaminobenzidine cytochemical reaction product is present in perinuclear cisternae, in the granular endoplasmic reticulum and in Golgi apparatus of functionally differentiated secretory cells. The mammary gland peroxidase is thought to represent lactoperoxidase. Peroxidase staining is diminished or absent in acinar cells of hypophysectomized and ovariectomized rats, in normal rats during early pregnancy and in nonpregnant mature females. Endogenous peroxidase or a heme protein with peroxidatic activity may be considered an ultracytochemical marker enzyme for acinar cells actively engaged in lactogenesis.     

Stereologic and fine-structural studies of prostatic acinar basal cells in the dog

Summary There are two distinct types of epithelial cells in the lining of the glandular acini of the prostate in adult male Beagle dogs, i.e., the columnar secretory epithelial cells and the basal cells. In contrast to the secretory epithelial cells, basal cells exhibit an abundance of micropinocytotic vesicles on their basal surface. Blood capillaries are often found in the stromal tissue in close proximity to these cells and their walls frequently display chains of fenestrations bridged by diaphragms.Stereological analysis shows that the volume density of the basal cells in the reference volume of acinar parenchyma is 0.056, and there are approximately 132.14 million cells per cm³ of prostatic tissue. An average basal cell has a volume of 373.5 m³, and the volume densities of its nucleus, rough endoplasmic reticulum, Golgi apparatus, mitochondria and micropinocytotic vesicles, are 0.49, 0.04, 0.04, 0.094 and 0.013, respectively. These data are distinctly different from those that have been reported for the prostatic secretory epithelial cells of the same animals.Visiting scientist to the Institut für Pathologie, Universität Basel (Prof. Dr. med. Hanspeter Rohr), and a recipient of the Aichi Medical University Grant for overseas investigations (1983)     

Ultrastructure of the salivary glands of the planthopper,peregrinus maidis (ashmead) (Homoptera : Delphacidae)

The principal salivary gland of the planthopper, Peregrinus maidis (Ashmead) (Homoptera : Delphacidae), comprises 8 acini of only 6 ultrastructurally different acinar types. In these acini, secretory cells contain elongated vacuoles partly lined by microvilli and by microtubule bundles. These vacuoles are apparently connected with extracellular canaliculi deeply invaginated into secretory cells. Canaliculi of each acinus lead to a ductule lumen, which is lined with spiral cuticular intima, surrounded by duct cells. Striated muscle fibers, supplied with small nerve axons and tracheoles, are found in various acini of the principal gland, usually around secretory and duct cells.In the accessory salivary gland, the 2 large secretory cells contain no elongated vacuoles or canaliculi invaginations. However, in their central region, apically, these cells border a large microvilli-lined canal with its own canal cells. This canal is apparently connected with the cuticle-lined accessory duct, formed by duct cells. Nerve axons, but no muscle fibers, are found in the accessory gland and its duct. It is suggested that the system for transporting secretory material within acini of the principal gland, is basically different from that within the accessory gland.     

The presence of carbonic anhydrase in orbital glands. An enzyme-histochemical study in cynomolgus monkeys and rabbits

The distribution of carbonic anhydrase (CA) was studied in the lacrimal gland of the cynomolgus monkey as well as in the lacrimal, infra-orbital and harderian glands of the rabbit. In the lacrimal gland of the cynomolgus monkey, a number of acini with positive staining were found; however, another group of acini did not stain. In the positively stained acinar cells, large amounts of reaction product were located in the cytoplasm, but only weak staining was observed in the membranes. In the endothelial cells of capillaries a strong staining reaction was only seen in those vessels which were adjacent to the acinar cells containing CA. In the lacrimal and infra-orbital glands of the rabbit, there was intense staining of the cell membranes in all acinar cells and weak staining of the cytoplasm in a few acinar cells. Stained capillaries were also found here, but these were not as numerous as in the lacrimal gland of the cynomolgus monkey. In the harderian gland of the rabbit, there was no staining in the white lobe. In the red lobe the acinar cells displayed distinct staining exclusively in the basolateral membranes. There was no staining of capillaries in the harderian gland. In none of the glands studied was there staining of the epithelial cells of the excretory ducts. The functional significance of these findings is discussed.     

Immunocytochemical localization of seminal proteins in salivary and lacrimal glands of the rat

Antibodies against 10 different secretory proteins from the accessory sex glands of the male rat were used for immunohistochemical studies of salivary and lacrimal glands from intact and castrated rats, at the light- and electron-microscopic levels. In the parotid gland, secretory acinar cells showed immunoreactivity with antibodies against prostatic binding protein, cystatin-related peptide and acid phosphatase (isoenzyme pI 8.0; 5.6) typical of ventral prostate, and seminal vesicle secretion VI. Western blotting analysis indicated that immunoreactivity against prostatic binding protein was attributable to a subunit, presumably C3. Acid phosphatase pI 5.6 showed a molecular weight of 66 kDa, which is at variance with the prostatic form. Immunoreactivity for secretory transglutaminase, derived from the coagulating gland, was restricted to myoepithelial and stromal cells. In castrated animals, the immunoreactivity of acinar cells was reduced to the background level, whereas stromal transglutaminase immunoreactivity was unaltered. The distribution pattern of immunoreactivity for the proteins mentioned was almost identical in the lacrimal gland. Significant differences were however observed in the immunoreactivity of the inframandibular gland, where serous glandular cells were non-immunoreactive for seminal proteins, with the exception of acid phosphatase isoenzyme pI 8.0. Granules present in the convoluted granular ducts were immunoreactive particularly for acid phosphatase (isoenzyme pI 5.6)but much less for cystatin-related peptide; immunoreactivity was reduced after castration. The straight portion of the inframandibular duct system was immunoreactive for transglutaminase, but no influence of castration was visible. The distribution of immunoreactivity for seminal proteins present in the salivary and lacrimal glands and the pronounced androgen-dependence of their expression point to functional relationships of the respective proteins at both glandular sites.     

Effects of double ligation of Stensen's duct on the rabbit parotid gland

Salivary gland duct ligation is an alternative to gland excision for treating sialorrhea or reducing salivary gland size prior to tumor excision. Duct ligation also is used as an approach to study salivary gland aging, regeneration, radiotherapy, sialolithiasis and sialadenitis. Reports conflict about the contribution of each salivary cell population to gland size reduction after ductal ligation. Certain cell populations, especially acini, reportedly undergo atrophy, apoptosis and proliferation during reduction of gland size. Acini also have been reported to de-differentiate into ducts. These contradictory results have been attributed to different animal or salivary gland models, or to methods of ligation. We report here a bilateral double ligature technique for rabbit parotid glands with histologic observations at 1, 7, 14, 30, 60 days after ligation. A large battery of special stains and immunohistochemical procedures was employed to define the cell populations. Four stages with overlapping features were observed that led to progressive shutdown of gland activities: 1) marked atrophy of the acinar cells occurred by 14 days, 2) response to and removal of the secretory material trapped in the acinar and ductal lumens mainly between 30 and 60 days, 3) reduction in the number of parenchymal (mostly acinar) cells by apoptosis that occurred mainly between 14–30 days, and 4) maintenance of steady-state at 60 days with a low rate of fluid, protein, and glycoprotein secretion, which greatly decreased the number of leukocytes engaged in the removal of the luminal contents. The main post- ligation characteristics were dilation of ductal and acinar lumens, massive transient infiltration of mostly heterophils (rabbit polymorphonuclear leukocytes), acinar atrophy, and apoptosis of both acinar and ductal cells. Proliferation was uncommon except in the larger ducts. By 30 days, the distribution of myoepithelial cells had spread from exclusively investing the intercalated ducts pre-ligation to surrounding a majority of the residual duct-like structures, many of which clearly were atrophic acini. Thus, both atrophy and apoptosis made major contributions to the post-ligation reduction in gland size. Structures also occurred with both ductal and acinar markers that suggested acini differentiating into ducts. Overall, the reaction to duct ligation proceeded at a considerably slower pace in the rabbit parotid glands than has been reported for the salivary glands of the rat.     

A high resolution sem study of human minor salivary glands

By SEM we have investigated the human minor salivary glands using the NaOH method for the visualization of endpieces and myoepithelial cells, and the osmium maceration technique that reveals membranous intracellular structures. With the former method all minor glands, including the posterior deep (Ebner's) lingual glands, consist of tubules sometimes dilated into alveoli, while true acini of the kind observed in human major salivary glands, are absent. Tubules of the posterior deep lingual gland exhibit stellate myoepitelial cells that leave a substantial part of the secretory cells uncovered. The latter cells, at variance with serous cells of major glands, do not show basal folds. In contrast, tubules of the other minor glands, like the mucous ones of major glands, are covered almost completely by band-like myoepithelial cells. The osmium maceration method clearly demonstrates that posterior deep lingual glands are serous in character and that all the other minor glands, together with the predominant mucous cells, possess a variable number of seromucous cells that, despite variations among individuals, increase in order from palatine and posterior superficial lingual (Weber's), to minor sublingual, labial, anterior lingual (Blandin and Nuhn's), and buccal glands.     

Vergleichende histologische,histochemische und elektronenmikroskopische Untersuchungen an Tränendrüsen

Zusammenfassung Vergleichende histologische, histochemische und elektronenmikroskopische Untersuchungen an der Tränendrüse erwachsener Kaninchen und Katzen beiderlei Geschlechts ergaben sowohl hinsichtlich des Baues als auch der Substrat- und Enzymausstattung des Drüsengewebes deutliche Unterschiede. Folgende Befunde wurden erhoben:Der Kaninchen-Tränendrüse fehlt eine deutlich ausgeprägte Kapsel. Die Glandula lacrimalis des Kaninchens ist eine tubulo-acinöse Drüse, deren sezernierende Endstücke ohne Einschiebung enger Schaltstücke direkt in intralobuläre Ausführungsgänge münden. Sekretorische Tubuli und Streifenstücke fehlen. Die Endstücke werden von einem zylindrischen oder kegelförmigen Epithel ausgekleidet. Die Lumina sind eng. Interzelluläre Sekretkapillaren kommen nicht vor. Die Drüsenzellen reagieren schwach PAS-positiv. Vereinzelte Acini, teilweise nur einzelne Drüsenzellen enthalten jedoch Astrablau- und Alcianblaupositive Granula (saure Mucopolysaccharide). Die Gangephithelien sind kubisch bis zylindrisch und enthalten apical PAS-positives und alcianophiles Material.Nach der Enzymverteilung ist in der Tränendrüse des Kaninchens ein anaerober, ein aerober und ein direkter (Pentosephosphat-Zyklus) Glukoseabbau möglich. Drüsenendstücke und Ausführungsgänge besitzen hohe Aktivitäten der Enzyme NADH-Tetratzolium-Reduktase, NADPH-Tetrazolium-Reduktase und Cytochromoxydase. Einer stark positiven Reaktion auf alkalische Phosphatase und Esterase im Gangepithel steht ein schwächerer Ausfall in den Drüsenendstücken gegenüber. Im elektronenmikroskopischen Bild fällt die vielfältige cytoplasmatische Organisation der Drüsenzellen auf. Die Zellen verjüngen sich zum Lumen zu, das Sekretmassen mittlerer elektronenmikroskopischer Dichte enthält. Die basalen Zellabschnitte enthalten ergastoplasmatische Lamellen und Mitochondrien. Supranukleär liegt der Golgi-Apparat. Die oberen zwei Drittel der Drüsenzellen sind von zahlreichen hellen und dunklen, z.T. kontrastreichen Sekretvakuolen erfüllt. Benachbarte Sekretvakuolen können konfluieren. In manchen Drüsenzellen scheint die Sekretbildung unter einer nahezu vollkommenen Destruktion des Cytoplasmas zu erfolgen. Die Ausführungsgangepithelien weisen außer den gewöhnlichen cytoplasmatischen Bestandteilen osmiophile Sekretgranula auf.Die Tränendrüse der Katze ist ebenfalls eine tubulo-acinöse Drüse, die außen von einer dicken bindegewebigen Kapsel umhüllt ist. Bindegewebssepten unterteilen das Drüsenparenchym in zahlreiche kleine Läppchen. In Tränendrüsen erwachsener Tiere werden zahlreiche Lymphozytenansammlungen beobachtet. Zwischen Drüsenzellen und Basalmembran kommen Myoepithelzellen vor. Die Drüsenendstücke enthalten zwei qualitativ verschiedene Zelltypen: große helle und kleine dunkle Zellen. Die hellen Zellen enthalten nur neutrale, die dunklen dagegen ein Gemisch neutraler und saurer Mucopolysaccharide. Intra- und interlobuläre Ausführungsgänge sind von einem kubischen bis zylindrischen Epithel ausgekleidet, das sich apical PAS-positiv verhält. Streifenstücke fehlen. Drüsenzellen und Ausführungsgänge zeigen eine kräftige Reaktion auf LDH, GDH, G-6-PDH, NADH-T-Red, NADPH-T-Red und Cytochromoxydase. Die Drüsenendstücke sind reich an -D-Glucuronidase.Die Feinstruktur zeigt den typischen Bau sekretorischer Zellen. Auch im elektronenmikroskopischen Bild lassen sich helle und dunkle Zellen unterscheiden, die einer Basalmembran aufsitzen. Das umgebende Bindegewebe (Lamina propria) enthält zahlreiche Fibrozyten. Das supranukleäre Cytoplasma ist mit Sekretvakuolen unterschiedlicher Dichte angefüllt. Kurze, stummelförmige Mikrovilli ragen in die Drüsenlichtung. Mitochondrien und ergastoplasmatische Lamellen sind spärlich. Zwischen den Sekretvakoulen kommen zahlreiche freie Ribosomen vor. Die Interzellularräume sind eng und durch kontrastreiche Desmosomen abgedichtet.Die Ausführungsgänge sind von einem zylindrischen Epithel ausgekleidet. Das Cytoplasma ist von mittlerer elektronenoptischer Dichte und enthält nur wenig Mitochondrien. In den mittleren und apicalen Zellabschnitten liegen osmiophile, teils homogene, teils feingranulierte Sekretgranula. Die Zelloberflächen sind durch kurze Mirkovilli differenziert. Die seitlichen Zellwände verlaufen streckenweise völlig glatt, teilweise aber auch leicht geschlängelt.

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Summary Comparative histological, histochemical and electronmicroscopical investigations of the lacrimal gland of adult rabbits and cats of both sexes reveal a distinct difference of the glandular acini. Observations also were made in respect of reactions for glycogen, mucopolysaccharides and lipids as well as for numerous dehydrogenases and hydrolytic enzymes. The results are as follows.The lacrimal gland of the rabbit is a tubulo-acinar gland. There are no secretory and intercalated ducts. The serous acini are lined with pyramidal epithelial cells, resting upon a basement membrane and surrounding a narrow lumen. By employing the various techniques, fine intercellular secretory canaliculi may not be seen in the serous acini. The acinar cells contain very little PAS-reactive material. In other cells the cyptoplasm is filled with a number of small Astrablue and Alcianblue reactive granules. The cuboidal cells of the ducts are slightly stained by the Alcianblue- and PAS-methods for polysaccharides. The distribution of enzymes shows that in the lacrimal gland of the rabbit an anaerobic, an aerobic and a direct (Pentose-phosphate-cycle) glucose breakdown is possible. The enzyme pattern of acini and ducts is characterized by high activities of NADH-, NADPH-tetrazolium reductase and cytochrome oxydase. A marked positive reaction for alkaline phosphatase and esterase in the cuboidal epithelium of the ducts is in contrast with a much weaker reaction in the acini. Electronmicroscopic examination of the lacrimal gland of the rabbit shows the different cytoplasmic organization of the gland cells. Tubuli and acini are composed of pyramidal cells. The apices of the cells converge toward a central lumen, filled with a secretory product of medium density. The acinar cell has a large nucleus, and the basal part of the cells is characterized by a wealth of rough-surfaced endoplasmic reticulum in which mitochondria can be identified. The apical two-thirds of the cells are occupied by a large Golgi-complex and numerous light and dark secretory vacuoles in various stages of maturation. The cells of the ducts also contain secretory granules besides the common cytoplasmic components.The lacrimal gland of the cat is a compound tubulo-acinar gland. The stroma consists of loose connective tissue which blends peripherally with the surrounding structures. In the adult, considerable lymphoid tissue occurs in the stroma. Between the acinar cells and the basement membrane are numerous basal or basket cells. There are two types of acinar cells: the light cells contain neutral polysaccharides, the small dark cells are filled with granules consisting of acid mucopolysaccharides. The intra- and interlobular ducts are lined by a single layer of cuboidal or sometimes pyramidal cells. The enzyme pattern of acini and ducts is characterized by high activities of LDH, GDH, G-6-PDH, NADH-T-Red, NADPH-T-Red and cytochrome oxydase. The terminal acini are rich in -D-glucuronidase.The ultrastructure of the epithelial cell of the lacrimal gland of the cat clearly indicates the typical secretory cell. The acini are lined by light and dark cells surrounded by a thin basement membrane, which borders on a lamina propria containing numerous fibroblasts. The cytoplasm is rich in secretory vacuoles, which display all gradations of density. All the cells are in a secretory phase with numerous vacuoles accumulating toward the lumen of the gland in which a secretion of medium densitiy is present. Short microvilli project into the lumen. Mitochondria are few in number, as are the profiles of the roughsurfaced endoplasmic reticulum. The cytoplasm contains numerous ribosomes. The Golgi complex is located at the apical portion of the nucleus. The intercellular space is small and becomes sometimes wider in the basal region of the acinar cells. Desmosomes may be found at the apical parts of the lateral cell surfaces. The ducts are lined by columnar cells. These cells have a cytoplasm of medium density with few mitochondria and apically located secretory granules. A few protrusions like microvilli characterize the luminal surface. The lateral sides of the duct cells are flat or irregular.

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Gekürzter Teil einer Arbeit, die der Medizinischen Fakultät der Philipps-Universität Marburg als Habilitationsschrift vorlag.

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Mit dankenswerter Unterstützung durch die Deutsche Forschungsgemeinschaft.