Histomorphology of the Harderian gland in the Angora rabbit

Morphometric and Histochemical Features of the Harderian Gland in Rabbits with Different Types of Autonomous Regulation

The tonus of autonomous centers reflected in the morpho-functional features of the organs in mammals. The study aimed to establish the influence of the autonomous regulation and its’ typological peculiarities on the structural features of the rabbits’ Harderian gland. Clinically healthy male rabbits, four months old, weighing 3.6-3.9 kg, were selected for the research. Based on the study of heart rate variability, three types of autonomous regulation were outlined, according to which three groups of rabbits were formed: ST rabbits (sympathetic dominant regulation), PS rabbits (parasympathetic dominant regulation), and NT rabbits (combined sympathetic and parasympathetic regulation). After euthanasia, the Harderian gland was dissected in all animals. Histological specimens were prepared and a morphometric examination was performed. ST rabbits corresponded to the minimal indicators in the tubular alveoli in both parts of the gland, as well as the maximum indicators of capsule thickness. NT rabbits corresponded to the maximum values of the acini area in the pink lobe, and in the white lobe - the maximal values of the cross-sectional area of the tubular alveoli, its wall area, and the epithelium height. The maximum acini area corresponded to PS rabbits in the white lobe, and in the pink lobe - the maximum indicators of the tubular alveoli cross-sectional area, and epithelial height. The pink and white lobes’ structure of the rabbit’s Harderian gland was affected by the combined tonus of the sympathetic and parasympathetic centers. The findings elucidate the regulatory and trophic effects on the Harderian gland in rabbits.

International Harmonization of Nomenclature and Diagnostic Criteria (INHAND): Nonproliferative and Proliferative Lesions of the Rabbit

The INHAND (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions Project (www.toxpath.org/inhand.asp) is a joint initiative of the Societies of Toxicologic Pathology from Europe (ESTP), Great Britain (BSTP), Japan (JSTP) and North America (STP) to develop an internationally accepted nomenclature for proliferative and non-proliferative lesions in laboratory animals. The purpose of this publication is to provide a standardized nomenclature for classifying microscopic lesions observed in most tissues and organs from the laboratory rabbit used in nonclinical safety studies. Some of the lesions are illustrated by color photomicrographs. The standardized nomenclature presented in this document is also available electronically on the internet (http://www.goreni.org/). Sources of material included histopathology databases from government, academia, and industrial laboratories throughout the world. Content includes spontaneous lesions as well as lesions induced by exposure to test materials. Relevant infectious and parasitic lesions are included as well. A widely accepted and utilized international harmonization of nomenclature for lesions in laboratory animals will provide a common language among regulatory and scientific research organizations in different countries and increase and enrich international exchanges of information among toxicologists and pathologists.

Structural study and expression of the androgen receptors during the reproductive cycle in the Harderian gland of the male Meriones libycus

The goal of this study was to evaluate for the first time the expression of the androgen receptors (AR) in Harderian glands (HG) of the male Meriones lybicus in relation to the reproductive cycle. Six male Harderian glands of the resting period and 6 of the breeding period were collected. The animals were trapped in the desert of Béni Abbès (Algeria). The morphology of the Harderian glands was studied by light microscopy and morphometry, whereas the expression of the androgen receptors was assessed and quantified based on immunohistochemistry techniques. We have shown that the Harderian glands of Meriones libycus are tubuloalveolar glands with wide lumen. The glandular epithelium is composed of two types of cells (types I and II) in the resting season and three types of cells (types I, II and III) in the breeding season. These three types of cells differ in size and shape. Type-I cells have a prismatic shape, an acidophilic cytoplasm, and small lipidic vacuoles, whereas type-II ones are pyramidal in shape, with basophilic cytoplasm. Type-III cells resemble those of type I, and so they are prismatic in shape and have an acidophilic cytoplasm with larger lipidic vacuoles. The immunoreactivity of type-I and type-III cells was mainly cytoplasmic and the intensity of the immunostaining was significantly higher during the breeding season. Among other functions, the Harderian gland seems to be involved in the production of pheromones under the effect of androgens.

Pilot Study of a "Large-Eye," Surgically Induced Dry Eye Rabbit Model by Selective Removal of the Harderian, Lacrimal, and Meibomian Glands

Background/Aims

Establish a reliable rabbit dry eye (DE) model.

Methods

An interventional cohort study surgically removing glands contributing to the tear film. Eight rabbits were studied after removal of left lacrimal, Harderian, or both glands. Additional rabbits had Meibomian glands in the left eye thermally obstructed. All were followed for 10 weeks with phenol red thread (PRT) and slit-lamp examination with 2% fluorescein. We assessed corneal sensitivity using a Cochet-Bonnet esthesiometer. Outcome measures were severity/duration of reduced PRT, punctate epithelial erosions (PEE), and histologic evidence of corneal pannus.

Results

Fluorescein staining demonstrated signs of dryness including PEE in all of the interventional eyes. The subjective measurement of epithelial erosions correlated with decreased tear production. PRT measurements in the control eyes averaged 31.54 mm (±1.83) and 22.71 mm (±1.60) in the eight left eyes, without loss of corneal sensitivity.

Conclusions

Surgical removal of either the Harderian or lacrimal gland results in statistically significant decreases in tear volume and the development of severe DE. Removal of both glands results in the occurrence of a DE of comparable severity/duration to removal of either the lacrimal or Harderian gland alone. Meibomian gland obstruction contributes less to the DE model.

Ultrasonography of the Harderian gland in the rabbit, guinea pig, and chinchilla

OBJECTIVE

To evaluate the Harderian gland in rabbits, guinea pigs, and chinchillas using B-mode ultrasound and to determine normal size and changes in size and/or location in normal and diseased eyes and orbits by ultrasonographic measurements.

PROCEDURE

Normal Harderian glands were evaluated ultrasonographically in 20 rabbits, 10 guinea pigs, and eight chinchillas. The Harderian gland was measured ultrasonographically in horizontal and vertical planes. Normal Harderian gland sizes were then compared with sizes in 27 rabbits, 13 guinea pigs, and three chinchillas that had exophthalmos.

RESULTS

Harderian glands in normal rabbits were 0.69 ± 0.07 cm (mean value ± SD) horizontally and 1.33 ± 0.14 cm vertically. Harderian glands in normal guinea pigs were 0.58 ± 0.05 cm horizontally and 0.61 ± 0.10 vertically. In normal chinchillas, the Harderian glands were 0.53 ± 0.04 cm horizontally and 0.53 ± 0.03 cm vertically. Harderian glands were significantly larger in the vertical plane in rabbits with exophthalmos (P = 0.001) and in the horizontal plane in guinea pigs with exophthalmos (P = 0.018). Harderian glands of rabbits with exophthalmos were significantly larger in both diseased and healthy glands in both planes compared with those of normal rabbits. Guinea pigs and chinchillas with exophthalmos had larger Harderian glands bilaterally in only the vertical plane.

CONCLUSIONS

Ultrasonography is a valuable diagnostic imaging technique to evaluate the Harderian gland in the rabbit, guinea pig, and chinchilla. Retrobulbar pathologic processes cause enlargement of the Harderian gland, which may be attributable to inflammation or possible obstruction of the excretory ducts.

Establishment of the mild, moderate and severe dry eye models using three methods in rabbits

BACKGROUND

Dry eye (DE) is a common eye disease, and appropriate animal models are essential to explore the pathogenesis and therapy of DE. In this study, we aimed to establish rabbit models by three methods.

METHODS

In group A, the lacrimal gland, Harderian gland, and nictitating membrane of the left eyes were surgically removed. In group B, the bulbar conjunctiva of the left eyes was burned with 50% trichloroacetic acid. In group C, both methods above were used. The right eyes served as normal controls. The Schirmer I test (SIt), fluorescein staining, and impression cytology were evaluated at baseline and on days 28, 42, and 56.

RESULTS

Both the SIt and goblet cell density were significantly lower in operated eyes compared to the control eyes, while the corneal fluorescein staining scores in the operated eyes were significantly higher than in the control eyes on days 28, 42, and 56 (p < 0.05, p < 0.01 or p < 0.001). The SIt and goblet cell densities in groups B and C were significantly lower than group A on days 28, 42, and 56 (p < 0.05, p < 0.01 or p < 0.001). In addition, the corneal fluorescein staining scores in group C were significantly higher than either group A or group B on days 28, 42, and 56, while fluorescein staining scores were higher in group B than group A on days 42 and 56 days (p < 0.05, p < 0.01 or p < 0.001), with mean score 3.8 ± 1.30 (group A), 7.4 ± 1.14 (group B) and 10.8 ± 1.30 (group C) on day 56.

CONCLUSIONS

Results suggest that three separate DE models, with mild, moderate, and severe manifestations of DE, could be stably established, in which conjunctival goblet cells took an important role.