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

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.

Exocrine gland structure-function relationships

Fluid secretion by exocrine glandular organs is essential to the survival of mammals. Each glandular unit within the body is uniquely organized to carry out its own specific functions, with failure to establish these specialized structures resulting in impaired organ function. Here, we review glandular organs in terms of shared and divergent architecture. We first describe the structural organization of the diverse glandular secretory units (the end-pieces) and their fluid transporting systems (the ducts) within the mammalian system, focusing on how tissue architecture corresponds to functional output. We then highlight how defects in development of end-piece and ductal architecture impacts secretory function. Finally, we discuss how knowledge of exocrine gland structure-function relationships can be applied to the development of new diagnostics, regenerative approaches and tissue regeneration.

Correlation between computed tomography, magnetic resonance imaging and cross-sectional anatomy of the head of the guinea pig (Cavia porcellus, Linnaeus 1758)

The current work aimed to study the anatomical features of the guinea pig's head by two medical imaging techniques: computed tomography (CT) and magnetic resonance imaging (MRI), and their correlation with the anatomical cross-sectional images. Six adult healthy guinea pigs were used in the present study. Two heads were imaged by CT scanner and then by MRI. The examined heads were cut sagittally and transversely, and two skulls were macerated. The anatomical features were identified on the anatomical sections and compared with the tomographic and MRI images obtained. Data were presented as three-dimensional reconstructed images of the head. In addition, representative combinations of the sagittal and transverse anatomical sections and the corresponding CT scans and MRI images were also presented. Reconstruction of CT images enabled the visualization of different bony structures and airways of the guinea pig head. In addition, skull bones were easily visualized on CT scans, while different parts of the brain were identified on MRI images. Air cavities could be identified by their different contrast on the CT scans and their low intensity on MRI images. The study showed that guinea pig had poorly developed paranasal sinus system represented by rostral and caudal maxillary sinuses. On the contrary, the guinea pig had two tympanic bullae: a small dorsal and a large ventral bulla. In conclusion, this study provides one of the first investigations that uses the multislice CT scans and MRI to study the guinea pig's head and their correlation with the corresponding anatomical sections.

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.

Ophthalmologic Diseases of Small Mammals

Ophthalmic examination of small mammals follows the same principles as in other species. Reference values for tear production and intraocular pressure are provided. Conjunctivitis and epiphora is common in rabbits. Numerous infectious organisms have been isolated from rabbits with conjunctivitis. Dental disease can be a cause for conjunctivitis in rabbits. Treatment consists of topical and oral antimicrobial agents and irrigation of the nasolacrimal system. Underlying dental disease needs to be addressed. Ulcerative keratitis, corneal dystrophy, membranous occlusion of the cornea and eosinophilic keratitis are described. Encephalitozoon cuniculi can cause phacoclastic uveitis in rabbits. A break in the anterior lens capsule exposes lens protein with subsequent anterior uveitis and cataract formation. Cataract surgery can be performed to remove the affected lens. Glaucoma is inherited as an autosomal recessive trait in rabbits. Orbital disease in rabbits may be associated with dental disease. Treatment is often difficult due to the caseous nature of the abscessed material. The most common ophthalmic diseases seen in ferrets include conjunctivitis, corneal endothelial cell degeneration, cataract formation, retinal degeneration and orbital disease. Ophthalmic diseases in guinea pigs include conjunctivitis, dermoids, cataract and osseous metaplasia of the mesectodermal trabecular meshwork. Exophthalmos may be related to dental disease in guinea pigs and chinchillas. Chromodacryorrhea is seen in rats and mice associated with inflammation of the Harderian gland. Sialodacryoadenitis virus is a highly contagious virus that may cause exophthalmos, epiphora and keratoconjunctivitis. Ammonia vapors from soiled bedding can cause keratoconjunctivitis in hamsters.

Reference Values for the Ophthalmic Schirmer Tear Test and the Intraocular Pressure in Healthy Chinchillas

The objective of this study was to measure the intraocular pressure (IOP) and tear production before and after topical anaesthesia in healthy chinchillas (Chinchilla lanigera). Thirteen healthy non-sedated chinchillas (eight males and five females) were used in this study. The tear production was measured by the novel endodontic paper point tear test (PPTT) using Roeko Colour No. 30 Paper points. Following the PPTT, one drop of 0.4 % oxybuprokainium chloride was added to the eye to anaesthetise the cornea and the IOP was measured using the Tono-Pen Avia®Vet. Excess anaesthetic was removed from the conjunctival fornix using a sterile cotton tipped applicator and the PPTT II was performed. The PPTT I and II were measured in 26 eyes, mean ± standard deviations (SD) were 7.98 ± 1.95 mm.min−1, and 9.71 ± 3.52 mm.min−1 respectively. The IOP was measured in 20 eyes, and the mean ± SD was 28.52 ± 12.48 mmHg (35.50 ± 9.31 mmHg in males and 21.53 ± 11.57 mmHg in females). There was no significant difference in the PPTT results between the left and right eyes or between the male and female groups. The males were found to have a significantly higher IOP than females and the PPTT II was significantly greater than the PPTT I. The PPTT test proved to be effective, easy to use, and reliable, causing little apparent discomfort to the chinchillas and could prove to be a much more effective tool than the Schirmer tear test for the evaluation of the tear production in animals with small eyes and/or low aqueous tear production. The mean intraocular pressure proved to be much higher in this population of chinchillas than those previously studied and so further investigation is warranted before a reliable reference range may be produced.

Structure of the secretory cells of male and female adult guinea pigs Harderian gland

The main objective of this study was to investigate the structure of the Harderian gland (HG) in male and female guinea pigs. A total number of sixteen animals of 4 months age were divided according to sex into two groups; eight animals each. Unfixed glands were weighed and their length and width were measured. Specimens from fixed glands were processed and examined using light, transmission electron microscopy and immunohistochemistry for the detection of the presence of chromogranin A (CgA). The gland consisted of a well-developed duct system which included both intra and extra parenchymal ducts and secretory end pieces lined by many types of cells of variable morphological features and modes of secretion. However, the holocrine mode of secretion was rare as mitotic figures were occasionally present. The interstitial cells included fibroblasts and immune cells (mast cells, lymphocyte, plasma cells and macrophages). The secretion produced by the gland included lipid, protein, neutral mucin and CgA which may be a newly identified constituent of biologically potent proteins stored in the cells of the guinea pig HG. Neutral mucin and CgA may function in photoprotection. The gland revealed sexual dimorphism in mast cells and blood capillaries number and chromogranin secretory activity.