Distribution of S-100 protein and its subunits in bovine exocrine glands

 The distribution of S-100 protein and its α- and β-subunits in bovine exocrine glands was studied by indirect immunohistochemistry. The entire spectrum of salivary glands, glands of the respiratory tract, intestinal glands, male and female genital glands, and skin glands was examined. S-100 and its β-subunit were identified in most serous secretory cells of mixed salivary glands, although secretory acini in some serous glands remained unreactive for these antigens. Mucous cells were constantly negative; mucoid cells were positive in the lacrimal and Harderian gland. The α-subunit of S-100 protein was identified in serous cells but the staining reaction was faint. Subunits of S-100 showed a characteristic distribution along the excretory duct systems of compound glands: S-100 and the β-subunit were present in intercalated duct epithelium, while striated duct epithelium stained for S100-α. Therefore, it is suggested that S100-α is related to resorption and secretion in striated ducts, while S100-β may govern acinar exocytosis and probably regulates proliferation and differentiation of glandular cells. Differing staining intensities for S-100 and its subunits in secretory cells of exocrine glands most probably indicate functional differences with regard to secretory activity and the cell cycle. Accepted: 11 February 1997     

Immunoglobulin (Ig)-containing plasma cells in the Harderian gland in broiler and native chickens of Bangladesh

The distribution and frequency of immunoglobulin (Ig)-containing plasma cells, their variations due to sex, and the mode of secretion of Ig cells into the duct system of the Harderian gland was investigated in broiler and native chickens of both sexes in Bangladesh. The Harderian gland is covered by a capsule, and the connective tissue septa divide the gland into numerous unequal-sized numerous lobes and lobules. The Ig-containing plasma cells were located in the interstitial space, interacinar space, apical part of the lobule, and lumina of the lobules of the Harderian gland in both broiler and native chickens. The population of these Ig-containing plasma cells varied in between broiler and native chickens, and also between male and female broiler and native chickens. In the broiler, the number of IgM-containing plasma cells was higher; in contrast, in the native chickens, the population of IgA-containing plasma cells was larger. In the broiler, there were more IgA- and IgG-containing plasma cells in the male; in contrast, there were more IgM-containing plasma cells in female. In native chickens the frequency of IgA-containing plasma cells was greater in the female than male. When the data for broiler and native birds were compared, it was found that there were significantly more IgA- and IgG-containing plasma cells in the native male and female chickens than in the broiler males and females. The secretory Igs were located in the lumina of acini and the duct system of the Harderian gland. In the present study Ig-containing plasma cells were observed to be released in the lumina of the lobules of Harderian gland by the breakdown of acinar tissues in broilers, and by holocrine mode of secretion in the native chicken. These results suggested that the Harderian gland, even though it is not a lymphoid organ as a whole, but acts as an immunopotent organ in chickens, and that the gland in native chicken contains more Ig-containing plasma cells due to their scavenging.     

Morphology of the Harderian gland of the Gecko, Tarentola mauritanica

The Harderian gland of the gecko, Tarentola mauritanica, was studied at the histological, histochemical, and ultrastructural levels. It is a nonlobate compound acinar gland surrounded by a thin capsule of connective tissue. Numerous connective tissue-type mast cells, ultrastructurally similar to those described in other higher vertebrates, were identified in the interstitial tissue between the acini. Pyramidal or columnar-shaped secretory glandular cells were observed in the acini. In the glandular cells, two types of structures could be distinguished on the basis of their high or low electron density. Lipid droplets were found in the cytoplasm of the Harderian gland of both sexes. Histochemical tests showed that the Harderian gland of the gecko is a seromucous gland. The secretion is essentially merocrine, although an apocrine type of secretion is sometimes observed.     

Sexual differences and effects of castration on secretory mode and intracellular calcium ion dynamics of golden hamster Harderian gland

The aim of the present work was to study the sexual differences in secretory mechanisms and intracellular calcium ion dynamics in the Harderian gland of the golden hamster. In both sexes the Harderian gland consisted of small and large lobes. In the intact control male glands the secretory portions of both lobes showed wide lumina that contained secretory material and cytoplasmic fragments, suggestive of the occurrence of exocytosis and apocrine secretion. After perfusion with HEPES-buffered Ringer's solution containing 10 microM carbamylcholine (CCh), the glandular cells showed features of enhanced secretion and a rise in intracellular calcium concentration ([Ca2+]i). In the intact control female gland the lumina of most secretory portions in the large lobe contained porphyrin accretions, and exocytosis was the sole secretory mechanism. Stimulation of the large lobe with 10 microM CCh did not raise [Ca2+]i or cause enhanced secretion. The small lobe in females resembled the male gland in secretory functions, and CCh administration caused enhanced secretion and a rise in [Ca2+]i. Castration in males abolished apocrine secretion; exocytosis became the sole secretory mechanism, and stimulation of the glandular cells with CCh did not cause enhanced secretion or induce a rise in [Ca2+]i. To the contrary, in females, castration restored apocrine secretion and CCh administration caused enhanced secretion and a rise in [Ca2+]i. Castration did not affect the secretory mechanisms and the effect of CCh on the glandular cells in the small lobes of both male and female glands. The present study points to the possibility that sex hormones may control the functioning or expression of muscarinic receptors in the Harderian gland of the golden hamster.     

Microstructural Analysis of the Capture Thread Spinning Apparatus in Orb Web Spiders

The microstructural characteristics of the capture thread production from silk glands in the orb web spiders were analyzed using scanning and transmission electron microscopes. Sticky and gluey capture threads of the web are originated from the silks of two flagelliform glands and four aggregate glands. They supply precursors of the secretory silks to a pair of characteristic “triad” spinning units on the posterior spinnerets. The aggregate gland is composed of large and multi‐lobed secretory region and thick excretory duct surrounded by large irregular nodules. The excretory duct of this gland basically consists of three superposed types of cells which are inner columnar epithelium, nodule forming cells and outer connectives. The nodules contain numerous mitochondria and glycogen particles within their cytoplasm and they are surrounded by the same sheath of thin connective tissues. Secretory region of the aggregate gland which produce water‐soluble components of the capture thread comprises discrete secretory vesicles and extensive rough endoplasmic reticulum. Characteristically, secretory droplets are formed without involvement of the Golgi complexes, suggesting that they do not play an important role in the processing of the capture threads. However the electron densities and internal textures of the granules are observed with diverse according to their maturation level. Finally, the secretory products are released by the mechanism of apocrine secretion losing part of their cytoplasm during this process.     

Biological behavior of myoepithelial cells in the regeneration of rat atrophied sublingual glands following release from duct ligation

Summary The present study aimed to clarify how myoepithelial cells behave during regeneration of an atrophied sublingual gland by investigating cell proliferation and ultrastructure. Atrophy of rat sublingual glands was induced by unilateral ligation of the excretory duct near the hilum with metal clips, which were then removed after one week of ligation for regeneration. The sublingual glands 0–14 days after unligation were examined with single immunohistochemistry for actin as a marker of myoepithelial cells, double immunohistochemistry for actin and proliferating cell nuclear antigen (PCNA) as a marker of proliferating cells, and transmission electron microscopy (TEM). The single immunohistochemistry and TEM showed that myoepithelial cells surrounded residual ducts in the atrophied glands and immature and mature acini in the regenerating glands. Although PCNA-positive myoepithelial cells were identified during regeneration, PCNA labeling indices of myoepithelial cells were low at all time points except at day 7. Ultrastructurally, myoepithelial cells showing bizarre shaped structures in the atrophy changed with maturation of differentiating acinar cells and appeared normal in the regenerated glands. There was no differentiation of the remaining duct cells to myoepithelial cells. These observations suggest that proliferation of myoepithelial cells and differentiation to myoepithelial cells do not commonly participate in the regeneration of atrophied sublingual glands and that the bizarre shaped myoepithelial cells in the atrophied sublingual glands recover the original shapes with acinar cell regeneration.     

Acinar origin of CFTR-dependent airway submucosal gland fluid secretion

Cystic fibrosis (CF) airway disease arises from defective innate defenses, especially defective mucus clearance of microorganisms. Airway submucosal glands secrete most airway mucus, and CF airway glands do not secrete in response to VIP or forskolin. CFTR, the protein that is defective in CF, is expressed in glands, but immunocytochemistry finds the highest expression of CFTR in either the ciliated ducts or in the acini, depending on the antibodies used. CFTR is absolutely required for forskolin-mediated gland secretion; we used this finding to localize the origin of forskolin-stimulated, CFTR-dependent gland fluid secretion. We tested the hypothesis that secretion to forskolin might originate from the gland duct rather than or in addition to the acini. We ligated gland ducts at various points, stimulated the glands with forskolin, and monitored the regions of the glands that swelled. The results supported an acinar rather than ductal origin of secretion. We tracked particles in the mucus using Nomarski time-lapse imaging; particles originated in the acini and traveled toward the duct orifice. Estimated bulk flow accelerated in the acini and mucus tubules, consistent with fluid secretion in those regions, but was constant in the unbranched duct, consistent with a lack of fluid secretion or absorption by the ductal epithelium. We conclude that CFTR-dependent gland fluid secretion originates in the serous acini. The failure to observe either secretion or absorption from the CFTR and epithelial Na(+) channel (ENaC)-rich ciliated ducts is unexplained, but may indicate that this epithelium alters the composition rather than the volume of gland mucus.     

Development of the labial gland of the ponerine ant Pachycondyla obscuricornis (Hymenoptera, Formicidae) during the pupal stage

The labial gland of adult workers of the ant Pachycondyla obscuricornis is made up of many acini, each consisting of one central cell surrounded by approximately 10 parietal cells. Both cell types are associated with a system of ramified canaliculi that remove the secretion towards a ductule outside the acinus. These ductules, each associated with one acinus, fuse together and form a ramified system of ducts, ending in two paired ducts. These paired ducts widen to form a reservoir and anteriorly join into a common unpaired duct, which ends at the base of the labium. During development in the pupal stage, epithelial acini are formed first, consisting of a monolayered epithelium lining a central lumen. In these acini, one cell grows out to become the central cell, while the others will re-arrange around it to form the parietal cells. At the end of the pupal stage, the canaliculi are formed inside the acini by the central and parietal cells that secrete a lipidic substance and a cuticle. This gland type, which also occurs in some other Hymenoptera, is structurally different from the epithelial glands and the glands consisting of bicellular units, that have been traditionally distinguished until now.     

Age and food restriction alter the porphyrin concentration and mRNA levels for 5-aminolevulinate synthase in rat Harderian gland.

The effects of age and food restriction on the porphyrin concentration in Harderian glands were studied in male Fisher 344 rats. Harderian gland porphyrin concentrations increased with age; this was statistically significant in 20 month old animals compared with 3 month old animals. Food restriction (by 40%) prevented the age-associated rise in porphyrins; thus, in 20 month old food restricted rats had porphyrin concentrations similar to those found in young animals. In a second experiment, we correlated the age-associated rise in Harderian gland porphyrin concentrations with an increase in mRNA levels for 5-aminolevulinate synthase (ALV-S). Both the porphyrin concentration and ALV-S mRNA rose at 12 and 18 months of age, but decreased by 24 months of age. It is concluded that, a) porphyrin biosynthesis in the Harderian glands increases up to 20 months of age but decreases in rats that are 24 months old, and b) food restriction prevents the porphyrin rise associated with age in the Harderian gland of male Fisher 344 rats.     

Ultrastructural investigation of a salivary gland in a centipede: structure and origin of the maxilla I-gland of Scutigera coleoptrata (Chilopoda, Notostigmophora)

The maxilla I-gland of Scutigera coleoptrata was investigated using light and electron microscopy methods. This is the first ultrastructural investigation of a salivary gland in Chilopoda. The paired gland opens via the hypopharynx into the foregut and extends up to the third trunk segment. The gland is of irregular shape and consists of numerous acini consisting of several gland units. The secretion is released into an arborescent duct system. Each acinus consists of multiple of glandular units. The units are composed of three cell types: secretory cells, a single intermediary cell, and canal cells. The pear-shaped secretory cell is invaginated distally, forming an extracellular reservoir lined with microvilli, into which the secretion is released. The intermediary cell forms a conducting canal and connects the secretory cell with the canal cell. Proximally, the intermediary cell bears microvilli, whereas the distal part is covered with a distinct cuticle. The cuticle is a continuation of the cuticle of the canal cells. This investigation shows that the structure of the glandular units of the salivary maxilla I-gland is comparable to that of the glandular units of epidermal glands. Thus, it is likely that in Chilopoda salivary glands and epidermal glands share the same ground pattern. It is likely that in compound acinar glands a multiplication of secretory and duct cells has taken place, whereas the number of intermediary cells remains constant. The increase in the number of salivary acini leads to a shifting of the secretory elements away from the epidermis, deep into the head. Comparative investigations of the different head glands provide important characters for the reconstruction of myriapod phylogeny and the relationships of Myriapoda and Hexapoda.     

Papovaviral sialoadenitis in athymic nude rats

A wasting disease was found in 32 athymic nude rats. The rats had parotid sialoadenitis with intranuclear inclusion bodies in ductal and acinar epithelial cells. Other common lesions included bronchitis, bronchiolitis and secondary bacterial pneumonia. Less commonly, rhinitis and Harderian adenitis were seen. Intranuclear inclusions were also seen in bronchial epithelium of 1 rat, Harderian gland acini of 1 rat and laryngeal glands of 2 rats. Viral particles, averaging 45 nm in diameter, sometimes in crystalline arrays, were found in the nucleus of parotid epithelial cells. By the use of the avidin-biotin-peroxidase complex (ABC) immunoperoxidase technique, antibodies to disrupted SV40 virus (the group specific antigen of the polyomavirus (miopapovavirus) genus of the papovavirus family) reacted with intranuclear inclusions and cytoplasm of parotid epithelium and inclusions in lung and Harderian gland. The viral antigen did not cross react with antibodies to mouse polyoma, mouse K or disrupted bovine papilloma viruses.     

Active participation of apoptosis and mitosis in sublingual gland regeneration of the rat following release from duct ligation

Summary This study was designed to establish how mitotic cell proliferation and apoptotic cell death participate in the regeneration of atrophied rat sublingual glands. To induce atrophy to the sublingual gland of rats, the excretory duct was ligated unilaterally near the hilum, and after 1 week of ligation (day 0) the duct ligation was released to enable gland regeneration. The regenerating glands were examined with routine histology, immunohistochemistry for proliferating cell nuclear antigen (PCNA) as a marker of proliferating cells, terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick end labeling (TUNEL) as a marker of apoptotic cells, and transmission electron microscopy. At day 0, a few acini and many ducts remained in the atrophic sublingual glands, and newly formed immature acini were observed at day 3. Thereafter acinar cells progressively matured and increased in number, although the number of ducts decreased. Many PCNA- and some TUNEL-positive cells were seen in acini and ducts during regeneration. The labeling indices for both cell types were statistically significantly different from that of the control at several time points of the regeneration. Apoptotic and mitotic cells were also confirmed to be present in the experimental sublingual glands by electron microscopy. These observations suggest that apoptosis as well as mitosis of duct and acinar cells actively participate in and play important roles in sublingual gland regeneration.     

Histology and histochemistry of the parotid and the principal and accessory submandibular glands of the little brown bat

The parotid and the principal and accessory submandibular glands of the little brown bat. Myotis lucifugus (Vespertilionidae), were examined using light microscopy and staining methods for mucosubstances. The parotid gland is a compound tubuloacinar seromucous gland. Parotid gland secretory cells contain both neutral and nonsulfated acidic mucosubstances. The principal and accessory submandibular glands are compound tubuloacinar mucus-secreting glands. They contain somewhat atypical mucus-secreting demilunar cells that often appear to be interspersed between mucous tubule cells. The mucous tubule cells in both the principal and accessory submandibular glands contain sulfonmucins. Demilunar cells of the principal submandibular gland contain moderate amounts of nonsulfated acidic mucosubstances, but the corresponding cells of the accessory submandibular gland contain considerable neutral mucosubstance with very little acid mucosubstance. Intercalated ducts composed of cuboidal or low columnar epithelial cells are present in all three glands. Striated ducts in all glands are composed of columnar cells whose apices bulge into the ductal lumina. Excretory ducts are composed of simple columnar epithelium, with occasional basal cells that suggest a possible pseudostratified nature. The cells of the excretory ducts also have bulging apices. All duct types contain apical cytoplasmic secretory material that is a periodic acid-Schiff positive, neutral mucosubstance. Ductal apical secretory material is more evident in intercalated and striated ducts than in excretory ducts.     

Mandibular glands of male European beewolves, Philanthus triangulum (Hymenoptera, Crabronidae)

Males of a solitary digger wasp, the European beewolf, Philanthus triangulum, possess large mandibular glands that have been reported to produce a scent marking pheromone. We analysed the morphology and ultrastructure of these glands using light microscopy as well as scanning and transmission electron microscopy. The paired glands are located laterally in the head and each side consists of a larger and a smaller part. Both parts possess a collecting duct each with distinct openings at the mandible base. However, the collecting duct of the larger part is additionally connected to the pharynx through a lateral extension. The collecting ducts are bordered by a monolayered epithelium lined with cuticle that exhibits conspicuous ramified protuberances. About 1400 acini consisting of class 3 gland cells surround the ducts and are connected to them through conducting canals. The main components in the cytoplasm of these gland cells are mitochondria, well-developed smooth endoplasmatic reticulum, and electron lucent vesicles suggesting a high secretory activity. The connection between the large gland parts and the pharynx suggests that the secretion of the mandibular glands might not only be delivered directly onto the mandibles but might also be transported to and stored in the postpharyngeal gland.     

Effects of inhibition of thyroid function and of cold on melatonin synthesis and porphyrin content in the Harderian glands of male Syrian hamsters, Mesocricetus auratus

1. Indole metabolism and porphyrin content of the Harderian glands of the male Syrian hamster were measured as functions of drug-induced hypothyroidism and exposure to cold conditions. 2. Harderian gland N-acetyltransferase (NAT) activity was reduced from control levels by hypothyroidism induced by methimazole; exposure to cold had no effect on NAT activity. 3. Immunoreactive melatonin in the Harderian glands was unaffected by the state of thyroid secretion. However, immunoreactive melatonin content declined after 180 and 270 min, at 4 degrees C, suggesting that Harderian gland melatonin may be involved in thermoregulation. 4. Porphyrin content of the Harderian glands was not affected by either thyroid secretion or cold.     

Morphology of the Harderian gland of some Australian geckos

This study of the morphology, histology, histochemistry, and ultrastructure of the Harderian gland in Geckos (Squamata, Gekkota) revealed previously unreported variation. The gecko Harderian gland is unlike that of other squamates in that each cell of the secretory epithelium has both lipid and protein secretory granules. Lipid secretion has not been reported previously for the squamate Harderian gland. The structure of the protein granules resembles that described for a scincomorph lizard (Podarcis, Lacertidae). Differences between representatives of the subfamilies Gekkoninae and Diplodactylinae suggest possible phylogenetic constraints in the structure or function of Harderian glands within gekkotan lineages. The structural relationship between the Harderian gland and the lacrimal duct supports previous suggestions of a possible functional link between the Harderian gland and the vomeronasal organ. J Morphol 231:253–259, 1997. © 1997 Wiley-Liss, Inc.     

Morphology and innervation of the buccal glands of the Southern Hemisphere lamprey, Geotria australis.

The buccal glands of adults of the Southern Hemisphere lamprey Geotria australis consist of a pair of small, bean-shaped, hollow sacs, embedded within the basilaris muscle in the region below the eyes and to either side of the piston cartilage. Each gland, which is lined by a simple columnar epithelium and surrounded by an incomplete layer of skeletal muscle, discharges its contents into the oral cavity via a long, narrow duct. In downstream migrating young adults, the epithelial cells are low columnar, intermediate in electron density, and contain dark-staining inclusions and numerous lipid-like droplets. After saltwater acclimation, the epithelial cells become taller and the numbers of dark-staining inclusions increase whereas those of lipid-like droplets decline. By the end of the marine phase, the epithelium is more folded and now also contains dark and light cells. The ultrastructure of the epithelium shows the characteristics of both apocrine and merocrine secretion. Although intra-epithelial nerve endings were not observed, axons and occasional neurons are present in the lamina propria. Since the skeletal muscle capsule is also well innervated and contains neurons, a local feed-back mechanism may regulate the release of buccal gland fluid by monitoring the luminal pressure. Contractions of the skeletal muscle capsule and movements of the basilaris muscle during feeding would presumably assist the movement of secretion along the duct. The secretion possesses anticoagulating and haemolytic properties.     

Ultrastructure of the accessory gland in the parthenogenetic thrips heliothrips haemorrhoidalis (Bouché) (Thysanoptera : Thripidae)

The fine structure of the reproductive accessory gland of the parthenogenetic thrips Heliothrips haemorrhoidalis (Thysanoptera : Thripidae) is reported. It consists of an apical bulb and a fine gland duct. The former consists of an epithelium with secretory and duct-forming cells surrounding a large gland lumen lined with a thin cuticle and filled with dense secretion. Spent secretory cells degenerate and are eliminated from the epithelium. The gland duct is characterized by an irregular, branched lumen surrounded by a very flat epithelium. A valve controls the opening of the duct lumen. The proximal gland duct runs through a cuticular papilla that opens between the dorsal ovipositor valves. The secretions may serve for ovipositor valve lubrication and possibly to protect laid eggs. Observations of serial sections through the vagina exclude the presence of a spermatheca in this species.     

The structure of the salivary glands of the human soft palate

The glandular layer constitutes the greatest bulk of the human soft palate and is composed of individual compound tubulo-acinar salivary glands. Connective tissue partitions of the submucosa divide the glandular layer into lobules of irregular shapes and sizes. The glands are interwoven and bound firmly together by a connective tissue stroma rich in elastic fibers. The secretory units consist of elongated, branched, and sometimes convoluted tubules lined by a single layer of pyramidal mucous cells. Mucous secretion by acini is supplemented to some degree by mucous acinar cells, which were found as epithelial components of all ducts except the main excretory ducts, suggesting a diffuse distribution of progenitor cells. Some mucous acini communicate with highly convoluted intercalated ducts which occupy partially isolated positions within inter- and intralobular connective tissue septa. These ducts follow the connective tissue septa and eventually join the main duct system. The significance of this system of intercalated ducts is not known. A supplemental functional role is hypothesized.