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.     

Exophthalmos in ageing rats with Harderian gland disease

Exophthalmos was found in aged rats in several longevity studies. Four cases were due to malignant Harderian gland neoplasia whilst others were associated with severe Harderian gland inflammation, less severe inflammation being found in rats without exophthalmos.     

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.     

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.     

Guanidinoacetate-N-methyltransferase: location in mammalian retina and rat Harderian gland]

Homogenates of retinal external segments of rat, rabbit, beef and hen and of rat Harderian gland were found to possess a considerable activity of guanidineacetate-N-methyltransferase (GAMT, E.C. 2.1.1.2), comparable with the enzyme activity in liver, pancreas and testis. Permanent UV-illumination of rats (from 1 day to 1 week) resulted in the decrease of GAMT activity in retina and especially in Harderian gland. Caffeine (10(-4) M) and papaverine (10(-7) M) activated GAMT in retina and rat Harderian gland, while cycloheximide, a protein synthesis inhibitor (0.5-2 mkg/ml), eliminated caffeine-stimulated GAMT activity. Histamine (0.3 mkg/ml) inhibited GAMT activity both in retina and Harderian gland. A decrease of GAMT activity in retina, liver and testis of rat and an increase of the enzyme activity in rat pancreas and Harderian gland were observed in the presence of Mg2+ (5 mM). Physiological importance of GAMT and creatine in mammalian retina and rat Harderian gland is discussed.     

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.     

Effects of diazepam and its metabolites on nocturnal melatonin secretion in the rat pineal and Harderian glands. A comparative in vivo and in vitro study

We investigated the effects of diazepam (DZP) and its three metabolites: nordiazepam (NZP), oxazepam (OZP), and temazepam (TZP) on pineal gland nocturnal melatonin secretion. We looked at the effects of benzodiazepines on pineal gland melatonin secretion both in vitro (using organ perifusion) and in vivo in male Wistar rats sacrificed in the middle of the dark phase. We also examined the effects of these benzodiazepines on in vivo melatonin secretion in the Harderian glands. Neither DZP (10^-5-10^-6 M) nor its metabolites (10^-4-10^-5 M) affected melatonin secretion by perifused rat pineal glands in vitro. In contrast, a 10^-4 M suprapharmacological concentration of DZP increased melatonin secretion of perifused pineal glands by 70%. In vivo, a single acute subcutaneous administration of DZP (3 mg/kg body weight) significantly affected pineal melatonin synthesis and plasma melatonin levels, while administration of the metabolites under the same conditions did not. DZP reduced pineal melatonin content (-40%), N-acetyltransferase activity (-70%), and plasma melatonin levels (-40%), but had no affects on pineal hydroxyindole-O-methyltransferase activity. Neither DZP nor its metabolites affected Harderian gland melatonin content. Our results indicate that the in vivo inhibitory effect of DZP on melatonin synthesis is not due to the metabolism of DZP. The results also show that the control of melatonin production in the Harderian glands differs from that observed in the pineal gland.     

Experimental nasal dermatitis in the Mongolian gerbil: effect of bilateral harderian gland adenectomy on development of facial lesions

Two groups of adult Mongolian gerbils (Meriones unguiculatus) of mixed ages and sex were used to study the effect of bilateral Harderian gland adenectomy on development of nasal dermatitis. One group of gerbils underwent bilateral Harderian gland adenectomies, while the other group underwent sham surgeries, leaving the Harderian gland intact. All animals in both groups were fitted with Elizabethian collars to prevent self-grooming, allowing a buildup of nasolacrimal or Harderian gland secretions near the medial canthus of the eye and at the external nares. Twenty-six of 27 animals with intact Harderian glands developed nasal and facial lesions within 20 days. None of the 27 Harderian gland adenectomized animals developed nasal or facial lesions. Apparently, accumulation of Harderian gland secretions is involved in the pathogenesis of nasal dermatitis in the Mongolian gerbil.     

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.     

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.     

Alligator tears: a reevaluation of the lacrimal apparatus of the crocodilians

The Harderian gland is a poorly understood anterior ocular gland that occurs in most terrestrial vertebrates. Numerous extraorbital functions have been ascribed to the Harderian gland, principally based on its association with the nasolacrimal duct. Few studies have centered on archosaurs and the majority of those available focused solely on the Harderian gland of birds. Little is known about the lacrimal apparatus of the crocodilians. We examined the lacrimal apparatus of several specimens of Alligator mississippiensis anatomically, histologically, and histochemically and studied the embryogenesis of this system. The nasolacrimal duct possesses a distal secretory area, which is more convoluted than that of typical mammals or lepidosaurs. The alligator Harderian gland possesses a unique combination of characteristics found in lepidosaurs, birds, and mammals. Like that of both mammals and lepidosaurs, it is a large, tuboloacinar gland that appears to secrete both mucoprotein and lipids. However, the presence of blood vessels and immune cells is reminiscent of that of the avian Harderian gland. The immunogenesis of the alligator Harderian gland appears to be tied to the development of the vascular system. The presence of a distinct palpebral gland in the anterior aspect of the ventral eyelid is a feature unique to alligators. Based on position, this gland does not appear to be homologous to the anterior lacrimal gland of lepidosaurs. Lymphatic aggregations were also found in the palpebral gland. The presence of interstitial immune cells in the orbital glands of alligators suggests that the alligator lacrimal apparatus, like that of birds, may play a role in the head-associated lymphatic tissue system.     

Microscopic anatomy of the orbital Harderian gland in the common tree shrew (Tupaia glis)

The orbital Harderian gland of the common tree shrew (Tupaia glis) was investigated at the macroscopic and microscopic levels. In the glands of both sexes only one acinar cell type was found. The cell is characterized by the presence of numerous lipid vacuoles of variable size and by a small number of PAS-positive, electron-dense granules distributed throughout the cytoplasm, which are predominant at the basal portion of each acinar cell. The duct system is well developed within the gland. The content of lipid vacuoles within the acinar cells is secreted from the apical portions by exocytosis, indicating the exocrine function of the organ. Apart from the lipid vacuoles, both acinar and ductal luminal contents of the Harderian gland also contain accretion of electron-dense materials. The vascularization within the Harderian gland is unique in that two capillary types (small fenestrated and irregular sinusoidal capillaries) could be demonstrated. The presence of fenestrated capillaries together with other morphological features (such as accumulation of the small electron-dense granules at the basal pole and the presence of basolateral microvilli) near the basal portion of the acinar cells suggest that the Harderian gland in T. glis might also be involved in an endocrine function.     

Harderian gland: regulation of sexual "type" by gonads and pineal gland

The sexual dimorphism of the Harderian glands of golden hamsters is regulated by a complex interaction of the gonads and pineal gland. Ovariectomy was shown to prevent the conversion to male-type gland which normally follows blinding. Testosterone administration in combination with blinding and ovariectomy promoted the male type. Ovariectomy after 8 wk of blinding was ineffective in reversing the effects of blinding on the Harderian glands, but ovariectomy and pinealectomy caused complete reconversion to the female type. To our knowledge, this is the first report to demonstrate an influence of the ovaries on the Harderian gland of the hamster. In males, administration of testosterone for 7 days after 8 wk of castration was shown to have little effect on the conversion to the female type which normally attends castration, whereas testosterone injection followed by a period of blinding completely reversed the effects of castration on the Harderian gland. These studies, along with previously published reports, strongly suggest that the male-type Harderian gland is expressed whenever significant androgen levels are present, or when the glands are exposed to androgen priming during or just prior to a period of blinding-induced pineal activation. The probable role of ovarian androgens in mediating conversion to the male-type gland is discussed.     

Androgen receptor in rat Harderian and submandibular glands

Summary Androgens regulate the development and sexual dimorphism of rodent Harderian and submandibular glands. This effect is believed to be mediated by the androgen receptor. Immunohistochemistry and immunoblotting were carried out to study the receptor in normal, castrated and dihydrotestosterone-supplemented rat Harderian and submandibular glands. Immunohistochemically, the most intense nuclear staining was observed in the acinar cells of the submandibular glands, followed by intercalated duct cells. The granular convoluted tubules showed weak immunostaining and the striated ducts were negative. In the Harderian gland, nuclear staining was seen in both type I and II secretory cells. Castration and treatment had no effect on the expression of the androgen receptor protein in either gland. A 110 K androgen receptor signal was detected by immunoblotting in the Harderian gland but not in the submandibular gland. An experiment was designed to explore the possible effect of proteinases on the receptor protein in the homogenate of submandibular gland. Our results demonstrate the cell-specific location of the receptor in Harderian and submandibular glands, and show that the expression of the receptor protein is androgen-independent.     

N-Acetyltransferase activity of the rat Harderian gland.

Harderian gland extracts from male rats catalyze the conversion of serotonin to N-acetylserotonin and of tryptamine to N-acetyltryptamine. The reaction is linear up to 14 mg tissue and departs from linearity after 10 min. The pH otpimum with tryptamine as substrate is between 8 and 9. Enzymic activity of the gland in vivo does not show diurnal variations. Enzymic activity of tissue in organ culture is not stimulated by 10 micrometer isoproterenol or 100 micrometer dibutyryl cyclic AMP. Harderian gland tissue in culture can acetylate tryptamine and serotonin and can O-methylate the N-acetylserotonin to form melatonin.     

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.     

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.