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.     

Histology of Harder's gland of the rockhopper penguin, Eudyptes crestatus

The Harderian gland of the rockhopper penguin, Eudyptes crestatus , lies in the orbit ventral and anteromedial to the eyeball. It is classed as a type II avian Harderian gland as it is similar to that of the duck, differing only in the possession of acini and small amounts of lipid in the epithelial cells of the tubules. Histologically it is a lobulated, compound tubulo-acinar structure surrounded by a thin connective tissue capsule. Plasma cells and Mott cells are present.     

The effect of sex hormones on lipid content and mast cell number in the harderian gland of the female toad, Bufo viridis

The Harderian gland of the toad Bufo viridis is a dimorphic gland owing to the presence of lipid droplets in the female glandular cells present only during summer months. Ovariectomy causes the disappearence of sudanophilia and estrogen-treatment completely prevents this change, while testosterone-injection has little effect. Estradiol-treatment also provokes a proliferation of the interstitial connective tissue concomitantly with the mast cell number increase. Our results suggest that estradiol acts, stimulating both mast cell and connective tissue proliferation, and plays a role in determining the expression of the female type of the toad Harderian gland.     

The effects of adrenalectomy on the harderian gland of the Wistar albino rats

Harderian glands of the Wistar albino rats normal and adrenalectomized were investigated by light microscopy. In normal, these glands have a tubuloalveolar structure. The gland is located in the medio posterior aspect of the orbit. It is lobulated and appears homogeneous in colour and texture. Harderian gland consist of tubules with wide lumina lined by a single layer of columnar epithelial cells surrounded by myoepithelial cells within their basal lamina. It contains porphyrin pigment which is stored as solid intraluminal deposits. The glandular epithelium possesses two cell types, termed A and B. Type A cells are more numerous. The single excretory duct of the gland is directly continuous with endpieces at the hilus and opens nasally and ventrally to the third eyelid. The excretory duct is accompanied by many acini of small serous glands around it. The tubuloalveoli of the gland is not divided into lobules. There is no branched duct system within the gland. The secretion seems to be associated with porphyrins, is essentially released by exocytosis, but holocrine secretion also occurs. The single excretory duct is lined by a stratified epithelium. The gland is surrounded by a collagenous capsule. The adrenalectomy, caused degenerative changes in the glands. Epithelial height was lower than in normal gland epithelium. Most of the acini were completely disorganised. The acinar lumina were filled with porphyrin debris. The results suggest that rat harderian glands are sensitive to adrenal androgen changes in both male and female rats.     

Ultrastructure of the blood vessels in the Harderian gland of the hamster (Mesocricetus auratus): existence of sinusoids

The Harderian gland blood supply of female and male hamsters was studied using light and electron microscopy. A profuse vascularization surrounding secretory acini was observed. Among the blood vessels, the existence of large and irregular sinusoidal capillaries was apparent. These sinusoids appeared in close association to the basal aspect of the secretory cells. Typical, small, fenestrated capillaries were also observed within the connective tissue. The existence of this particular vascularization together with other morphological features of the secretory cell basal pole suggest a possible endocrine function of these orbital glands.     

Immunocytochemical identification of some regulatory peptides (gastrin,gastrin-releasing peptide,neurotensin and vasoactive intestinal polypeptide) in the Harderian gland of the green frog,Rana esculenta

Summary The presence and distribution of gastrin-, gastrin-releasing peptide-, neurotensin-and vasoactive intestinal polypeptide-like immunoreactivity in the Harderian gland ofRana esculenta were studied at different times of the annual cycle. Gastrin-releasing peptide, neurotensin and vasoactive intestinal polypeptide-like substances were found either in the glandular cells, or in the nerve fibers surrounding the glandular acini. Gastrin-like immunoreactivity was confined to the glandular cells. The immunoreactivity varied during the annual cycle, with the greatest concentration being noted during the recovery phase of glandular secretory activity.     

The harderian gland of the frog, Rana esculenta, during the annual cycle: histology, histochemistry and ultrastructure

The Harderian gland in Rana esculenta has been studied during the annual cycle at the histological, histochemical and ultrastructural levels. The Harderian gland has an acinar structure and is the only orbital gland in anuran amphibia. It develops at the medial corner of the orbit from the conjunctival epithelium at the premetamorphic stage. In the adult the glandular secretion reaches a maximum during the months of July and August, drops in September and resumes slowly from October onwards. The secretion is seromucoid and the secretory granules are released into the acinar lumen, mainly by exocytosis. Porphyrins were not detected. No sexual dimorphism was observed in the glandular cells. The resumption of secretory activity in October and the enhancement of secretion in May are marked by the appearance of "blue nuclei" (Mallory stain) in a relatively high percentage of glandular cells. This unusual blue colour, using the Mallory stain (by which nuclei stain red), disappears after digestion of paraffin sections with RNAase, but not with DNAase and trypsin. The blue staining may, therefore, indicate an increased amount of nuclear RNA. The Harderian gland in the frog most probably serves to lubricate and moisten the eye in the absence of the lacrimal gland. However, the gland may also represent an immunoactive organ owing to the presence of numerous mast cells and plasma cells in the interacinar spaces.     

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.     

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.     

Effect of carbamylcholine on Harderian gland morphology in rats

Summary To determine the effect of cholinergic secretagogue on the Harderian gland of rats, several light- and electron-microscopic parameters were morphometrically assessed at different time intervals after carbamylcholine injection. In controls, two types of glandular cells (type A cells having 40–55 large vacuoles per cell profile and type B cells containing 30–38 smaller vacuoles per cell profile) and myoepithelial cells were recognized. At 5 min after injection of carbamylcholine, when rats secreted bloody tears, many alveoli showing narrower lumina and exocytotic figures in both types of cells were observed. Some vacuoles, which were covered by thin cytoplasmic sheets, protruded into the alveolar lumina. However, there was no evidence of apocrine or holocrine secretion. At 30 min and 120 min after injection, most of the alveolar lumina were dilated, and a pronounced decrease in the number of vacuoles in the glandular cells was observed. At 300 min after injection, the secretory vacuoles in both cell types reaccumulated. Transitional forms between the two cell types were not observed. The two types of Harderian gland cells can therefore be considered independent populations rather than different secretory stages of the same cell. It appears that the secretory process of the Harderian gland of rat is affected by cholinergic stimulation of the two types of glandular cells and of myoepithelial cells.     

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.     

Histology,histochemistry, and ultrastructure of the harderian gland of the snake Coluber viridiflavus

Analyses of the histology, histochemistry, and ultrastructre of the Harderian gland of Coluber viridiflavus prove the gland to be compound acinar and to produce a seromucous secretion. Acinar cells (type I) contain secretory granules that are composite, consisting ultrastructurally of three distinct parts that are sharply separated. They are similar to the “special secretory granules” described in the cells of the Harderian gland of the lizard Podarcis s. sicula. Some acini of the most anterior and posterior parts of the gland are mucous. Acinar cells (type II) of this type contain secretory granules that are Alcian blue/PAS positve. At the ultrastructural level, they appear homogeneous and of low density, characteristic of mucous secretions. These mucus-secreting anterior and posterior parts of the Harderian gland may by considered as regions of intial differentiation of the anterior and posterior lacrimal galnds.     

Age-related changes in the rat lacrimal gland: Impressive morphology and enigmatic nature

The rat lacrimal apparatus includes several glands; among them, the exorbital lacrimal gland plays the central role. Its parenchyma and stroma undergo prominent morphologic changes with age. The parenchymal transformation includes metaplasia of some of its acini and their turning into Harderian gland-like structures (harderization), accumulation of gland ducts (“ductularization”), and morphologic dysplasia—cytomegaly, karyomegaly, and cell and nuclear polymorphism in the other part of acini. All these transformations are hormone-dependent and sex-specific: they more often appear in males. On the final stages of agerelated transformations, the lacrimal gland tissue is morphologically similar to a neoplasm and has neoplastic morphology but no other features of a tumor. Therefore, the rat lacrimal gland is an interesting object to study tissue and cell atypia. In the rat glandular stroma, lymphocytic infiltration and fibrosis appear with age; these changes are similar to processes taking place in human lacrimal apparatus involved in the pathogenesis of senile dry eye syndrome. The spontaneous changes in the rat lacrimal gland, predominantly in male rats, can be used as a model of the human lacrimal apparatus disorders.     

The Harderian gland of the Mexican volcano mouse Neotomodon alstoni alstoni (Merriam 1898): a morphological and biochemical approach

The Harderian glands of rodents are large intraorbital exocrine glands with histologic organization that varies among mammalian species. Here we describe some ultrastructural and biochemical features of the Harderian gland in the Mexican volcano mouse Neotomodon alstoni alstoni, a species of restricted habitat. The Harderian glands from male and female adult mice were dissected, processed and embedded in Epon 812 for light and electron microscopy studies. Porphyrin and total lipids were biochemically determined. The macroscopic appearance of the Harderian gland is similar in the male and female. The gland is a bilobulate structure, situated in the orbit towards the posterior side of the eyeball, of whitish color and is surrounded by a connective tissue capsule. The male gland is slightly heavier (127 mg) than that of the female (113 mg). The Harderian gland shows a tubulo-alveolar organization and is composed exclusively of one type of secretory cells. No branched duct system within the gland was found. Adrenergic nerves endings and mast cell were observed in the interstices of the alveoli. Male and female glands produce similar levels of porphyrins. Triglyceride levels were significantly higher (P < 0.05) in the female compared to the male. Abundance of lipids could induce corneal lubrication of the Harderian gland which may confer a protective and adaptative function to the volcano mouse in its natural habitat during the dry and cold seasons.     

The Harderian gland of the Cheesman's gerbil (Gerbillus cheesmani ) of the Kuwaiti desert

The Harderian gland is a large orbital structure. Several functions have been ascribed to the gland such as lubrication of the eye, a source of pheromones, thermoregulartory lipids and photoprotective secretions and a part of the retinal-pineal axis. In the present study, the Harderian gland of the Cheesman's gerbil, Gerbillus cheesmani, is described for the first time. The gland is located around the posterior portion of the eyeball. The gland is compound tubular, surrounded by a thin connective tissue capsule. Only one secretory epithelial cell type was recognized, characterized by the presence of lipid vacuoles and cytoplasmic slashes in high numbers; the former being more concentrated towards the apical part while the latter being more concentrated towards the central and basal parts. Some of the cytoplasmic slashes contained electron dense filamentous structures. Similar structures were observed in the lipid vacuoles. Thus, a functional relationship between the cytoplasmic slashes and the lipid vacuoles is suggested. A unique structure was observed, termed dome-like cells, located between the epithelial cells and the basement membrane. These cells were characterized by the extensive presence of pleomorphic mitochondria and compact lamellae of granular endoplasmic reticulum (GER) in the form of finger prints. The gland was found to be actively secreting porphyrins as well as lipids. Cellular debris was also seen in the tubular lumina. Myoepithelial cells with their spindle shape and elongated nuclei were evident between the basement membrane and the secretory epithelium. Sparse interstitial tissue was observed in-between the gland tubules of both male and female gerbils. Macrophages, dendritic melanocytes and lymphocytes are the most represented cellular components of the interstitium. Further studies are required to investigate the function of the dome-like cells as well as the role of lymphocytes in the rodents Harderian gland.     

B cell maturation in the chicken Harderian gland

We have characterized maturation of B lymphocytes in the chicken Harderian gland. Expression of Ig genes was studied by using lambda L and mu H chain-specific DNA probes. In unstimulated chickens, the concentration of mu H chain and lambda L chain mRNA in the Harderian gland was observed to be greater than 8 times higher than in the bursa of Fabricius or spleen. By using in situ hybridization, the plasma cells expressing mu mRNA were located in central area of the gland packed around the tubules. Antibodies produced by the Harderian plasma cells were measured from the tears before and after antigenic stimulation. In unstimulated chickens high levels of total IgM, IgA, and IgG were observed. After ocular stimulation with tetanus toxoid, specific antitetanus IgG and IgA antibodies appeared in the tears but IgM antibodies were barely detectable. These results indicate that after antigenic stimulation the Harderian B cells rapidly mature through IgM secretion to the production of IgG or IgA. Southern blot analysis of the Harderian total genomic DNA showed strong rearrangement in the lambda L chain locus. In contrast, the band indicating major rearrangement in the mu H chain locus gave a very poor hybridization signal, indicating deletion of C mu genes in the Harderian gland DNA. As a conclusion, our present data indicate for the Harderian gland a role in terminal B cell differentiation and Ig class switch.     

Paracloacal glands of Alligator mississippiensis: A histological and histochemical study

The histology of the paracloacal 'musk' glands of adult American alligators ( Alligator mississippiensis ) is described. The gland is a single secretory sac with a single duct and a central lumen partially occluded by a central, cylindrical conglomerate of cells and secretion product. The capsule of the gland consists of an outer layer of smooth muscle and an inner layer of connective tissue containing collagen and elastin fibres. Septa carrying blood vessels radiate from the connective tissue layer of the capsule to the border of the central conglomerate. Parenchymal cells containing lipid droplets enlarge from the periphery to the centre of the gland. Secretions formed by degeneration of cells in the central cylinder are concentrated near the secretory duct. Histochemical tests indicate lipids but not mucopolysaccharides in the glandular exudate.     

Synthesis of seminal ribonuclease in isolated lobules of bull seminal vesicles

A procedure is described for preparing and maintaining in culture isolated lobules of bovine seminal vesicles, consisting of glandular acini, surrounded by little connective tissue and with free access to the external medium, in which secreted material can be collected. After 48 h in culture, the isolated lobules appeared indistinguishable, by morphological and biochemical criteria, from freshly isolated lobules. After much longer culture times about one third of the glandular cells were still capable of effective protein synthesis. Studying the biosynthesis of seminal ribonuclease with preparations of isolated lobules we found that the enzyme was synthesized and secreted; only the fully amidated isoenzyme was synthesized and secreted, indicating that production of the selectively deamidated isoenzymic forms occurred after secretion, newly synthesized protein was rapidly exported, indicating that the high levels of enzyme previously reported for the seminal vesicle tissue were essentially due to its content of stored secretion.     

The expression of water channel proteins during human salivary gland development: a topographic study of aquaporins 1, 3 and 5

Some members of aquaporin family (AQP) plays crucial functions in salivary synthesis and secretion. These proteins expression has already been reported during salivary gland formation, however no previous studies in human developing glands have been performed. We evaluated AQP1, 3 and 5 expression through the stages of human salivary gland morphogenesis and discuss the possible role of AQP for glandular maturation. Human salivary glands derived from foetuses aged between 14 and 25 weeks were submitted to immunohistochemistry. At the bud stage, membrane expression of AQP1, 3 and 5 were observed within the epithelial bud cells presenting a similar apicolateral pattern, also found at the pseudoglandular stage, present within the terminal portions of future acini, while AQP5 was also particularly strong at the apical membrane of pre-acinar and pre-ductal cells. AQP5 was co-localised with Cytokeratin 7. Similar AQP1, 3 and 5 expression were observed at the following canalicular stage, where distinct and strongly luminal and acinar AQP5 expression is present. During the final terminal bud stage, AQP1 was only identified in serous acini, myoepithelial and endothelial cells, while differentiated mucous acinar cells and ducts were negative. AQP3 was detected at apicolateral membranes of both mucous and serous acini. AQP5 also showed a diffuse expression in mucous and serous acini, in addition to strong apical membrane expression within lumen of intercalated ductal cells. This topographic analysis of AQP1, 3 and 5 revealed differences in the expression pattern throughout salivary gland developmental stages, suggesting different roles for each protein in human glandular maturation.