Etude du nerf phrenique chez le cobaye (Cavia porcellus, L., 1756)

The aim of the present study to ascertain the mode of origin of the phrenic nerve and to provide a morphological basis for experimental studies of this nerve in the guinea pig. In sketches made of the dissections, in 10 male and 10 female guinea pigs adults, the modes of origin of the phrenic roots were demonstrated to arise from the fourth to the seventh cervical nerves. Four types of origin could be distinguished. The phrenic nerve of the guinea pig has three or four roots.

Mammary benign neoplasm diagnosed by fine needle aspiration biopsy in a guinea pig (Cavia porcellus)

Cytology is a well established research technique in human and veterinary medicine, but it is rarely used in small rodents. Spontaneous tumors are relatively uncommon in guinea pigs and those described in literature include a variety of organs like skin and subcutis, respiratory and reproductive tract, endocrine and hematopoietic system, and mammary gland. The objective of this article was to describe the use of the fine needle aspiration biopsy technique (FNAB) on evaluation of a mammary neoplasm in a guinea pig and describe the main cytological findings for the first time in literature.

Morfologia do epidídimo de cobaio (Cavia porcellus) em diferentes fases do desenvolvimento pós-natal

The morphological evolution of the epididymal duct of guinea pigs (Cavia porcellus, L.) was studied on 10, 20, 30, 45, 60, 70, 90 and 100 days of age, being complex, which is due to the proper differentiation postnatal in the epididymal epithelium. Thus, it was observed that the initial segment of the epididymis reveals an increase of epithelial height corresponding to the average height of the main tubular epithelium cells, generally progressive after 45 days of age. The epithelial height in the middle segment were higher in younger stages (10 to 45 days) than in the prepubertal age (60 days), and have a decrease among 70 to 100 days of age. The ductular terminal segment starts a gradual decrease of the epithelial heights from puberal age (70 days), until adult age (90 to 100 days). In addition, this segment showed epithelial waviness that disappeared after 70 days of age, when the lumen fills it with sperm and cellular exfoliation. The cell types of the epididymal tubular epithelium, principal cells, basal cells and apical cells, were observed in all ages. In the epididymis of very young animals, there was a predominance of undifferentiated columnar cells. After 20 days of age, there was natural prevalence of the principal cells on other cell types, what is a feature similar to other mammals.

Tibial osteosynthesis in a guinea pig (Cavia porcellus)

A guinea pig was presented with left pelvic limb lameness after unknown trauma. Radiographs revealed complete oblique diaphyseal fracture of the distal third of the left tibia and fibula. The guinea pig was treated surgically with an intramedullary pin. The day after surgery the guinea pig was using the limb comfortably (grade 1/5 lameness). Callus formation was obtained 21 days after surgery without complications.

Alterações epiteliais e cartilaginosas em cirurgia traqueal: estudo experimental em cobaias

FORMA DE ESTUDO: Experimental. MATERIAL E MÉTODO: Transplante homógeno de traquéia foi realizado em 51 cobaias (Cavia Porcellus). RESULTADO: Observamos reepitelização do enxerto a partir da traquéia receptora da cobaia, evoluindo de epitélio escamoso de 1 a 3 células nos animais com 3, 7 e 14 dias de observação para epitélio ciliado após 60 a 120 dias do transplante. A viabilidade do enxerto traqueal era boa, com reabsorção parcial da cartilagem e formação de estenose traqueal parcial, mas sem sinais clínicos evidentes de obstrução respiratória durante o tempo de observação dos animais.

Life cycle and host specificity of Amblyomma triste (Acari : Ixodidae) under laboratory conditions

We report biological data of two generations of Amblyomma triste in laboratory and compared the suitability of different host species. Infestations by larval and nymphal stages were performed on guinea pigs (Cavia porcellus), chickens (Gallus gallus), rats (Rattus norvegicus), rabbits (Oryctolagus cuniculus), wild mice (Calomys callosus), dogs (Canis familiaris) and capybaras (Hydrochaeris hydrochaeris). Infestations by adult ticks were performed on dogs, capybaras and rabbits. Tick developmental periods were observed in an incubator at 27degreesC and RH 90%. Guinea pigs were the most suitable hosts for larvae and nymphs, followed by chickens. The remaining host species were less suitable for immature ticks as fewer engorged ticks were recovered from them. Mean larval feeding periods varied from 3.8 to 4.7 d between different host species. Mean larval premolt periods ranged from 8.9 to 10.4 d. Nymphal mean feeding periods varied from 4.2 to 6.2 d for ticks fed on different host species. Premolt period of male nymphs (mean: 15.4 d) was significantly longer than that of female nymphs (14.7 d). Female nymphs were significantly heavier than male nymphs. The overall sex ratio of the adult ticks emerged from nymphs was 0.9:1 (M:F). Capybaras were the most suitable host for the tick adult stage as significantly more engorged females were recovered from them and these females were significantly heavier than those recovered from dogs or rabbits. The life cycle of A. triste in laboratory could be completed in an average period of 155 d. The potential role of guinea pigs, birds and capybaras, as hosts for A. triste in nature, is discussed.

Immunisation of dogs, hamsters and guinea pigs against Rhipicephalus sanguineus using crude unfed adult tick extracts

Naive experimental groups of dogs, hamsters and guinea pigs were inoculated three times subcutaneously with unfed adult extract of the tick Rhipicephalus sanguineus and challenged with adult R. sanguineus to evaluate resistance. The acquisition of resistance was based on alterations of some reproductive and feeding performance parameters of female ticks such as female and egg mass weights, engorgement, pre-oviposition and incubation periods, larval hatchability rate and efficiency rates of female ticks in converting their food reservoir to eggs and larvae. Dogs did not develop resistance under these experimental conditions; guinea pigs and hamsters, to a lesser extent, acquired an effective immunity to ticks as demonstrated by the impairment of the reproductive and feeding performance. However, the resistance induced by inoculation of the extract in the rodents seemed not to be as efficient as that induced by successive infestations.

Western blot analysis of tick antigens from a Rhipicephalus sanguineus unfed larval extract and identification of antigenic sites in tick sections using immunohistochemistry. A comparative study between resistant and susceptible host species

Most parasite-host relationships are characterized by the development of resistance by the host, thus limiting the number of parasites. However, some cases are very unusual. In the relationship of the domestic dog with the brown dog-tick Rhipicephalus sanguineus this does not occur, whereas guinea pigs develop efficient resistance. Sera from domestic dogs, crab-eating foxes and guinea pigs collected before and after infestation with R. sanguineus ticks, and after immunization with a whole tick adult or larval homogenate, were used in Western blot analysis to compare and identify potential important antigens from a tick larval homogenate. The same sera were tested in an indirect immunohistochemistry assay in an attempt to compare relevant antigenic sites on histological tick sections. The immunoblotting displayed antigens recognized only by the guinea pigs, as well as several shared antigens between host species, depending on the kind of immunization. Immunohistochemistry revealed probable antigenic sites on the cells and tissues of ticks, which varied depending on the kind of immunization (infestation or vaccination) and the animal species involved.

Evaluation of Paracoccidioides brasiliensis exoantigen in the detection of delayed dermal hypersensitivity in experimental and human paracoccidioidomycosis

The exoantigen of Paracoccidioides brasiliensis standardized by Camargo et al. [1] (AgR) was used to evaluate the in vivo and in vitro cell immune response of experimental animals and of patients with paracoccidioidomycosis (PBM). Fava Netto antigen (AgF) was tested in parallel as a control antigen. The study was conducted with mice and guinea pigs infected with P. brasiliensis or immunized with its fungal antigens, on patients with PBM and on their respective control groups. The cell immune response was analysed by skin tests, and by the macrophage and leucocyte migration inhibition tests (MMIT and LMIT) in the animals and in the patients, respectively. The skin test with AgR as paracoccidioidin was positive in infected or immunized mice and guinea pigs and negative in control animals. The skin tests with AgR (24 h) showed 96.7% positivity in patients with PBM and were negative in control individuals. Histopathological study of the in vivo tests in the different experimental models was consistent with a delayed hypersensitivity response (DHR). Immunohistochemical study of the skin tests of PBM patients demonstrated a predominance of T lymphocytes, confirming the nature of a DHR to the fungal antigens. The in vitro cell immune response showed variable results for the various experimental models, i.e. significant rates of MMIT in immunized mice, a tendency to positivity in infected guinea pigs, and the absence of migration inhibition in PBM patients. Taken together, the data indicate that the AgR is efficient as paracoccidioidin in the evaluation of DHR in PBM, with an optimum time of reading the test of 24 h.

The ultrastructure of the guinea pig rete testis

The chambers of the rete testis (RT) of guinea pig are lined by a simple epithelium, whose cells are squamous, cubical and columnar in shape. The epithelial cells with distinct shapes were counted and the quantitative analysis of the number of these cells showed relative predominance of cubical cells. The ultrastructural observations showed predominance of membrane interdigitations among the epithelial cells. These cells present common cytoplasmic organelles. The Golgi complex polarity is typical with observation of electronlucent vesicles on the Golgi cis face closely related to rough endoplasmic reticulum (ER) lamellae, mitochondria and large number of polysomes on the Golgi trans face. These related structures present in Golgi area of RT cells suggest secretory activity which maybe occurs in the RT epithelium. Endocytotic process also occurs in the RT and this function probably concerns the uptake of substances and resorption of seminiferous fluid. Apical cilia present in RT epithelium cells are related with fluid transport and perhaps with chemoreception. Presence of spermatozoa portions enclosed into the cytoplasm of some epithelium cells has been refferred to as spermatophagy. The RT complex is mainly supported by loose connective tissue, with collagen fibres and some Leydig cells. Leydig cells are adjacent to the network channels of the septal part of the RT and apparently are able to secrete inside the RT lumen.

Intraepithelial alterations in the Guinea pig lateral prostate at different ages after estradiol treatment

The prostate is an accessory gland of the mammal reproductive system with great volume and high functional importance. Many works infer that, in addition to the androgenic ones, the estrogen can be associated with benign prostatic hyperplasia and prostatic cancer, but no conclusive evidence exists on the role of estrogen in normal prostatic and neoplastic tissue. The objective of this work was to evaluate the effects of chronic administration of estradiol benzoate on the lateral prostate of guinea pigs in the pre-pubescent, pubescent, post-pubescent and adult phases, with emphasis on the modifications provoked by this hormone on the glandular epithelium. The analyses of the estradiol-treated and control groups were investigated using histological procedures and transmission electron microscopy. The histopathological analysis of the lateral prostate in the treated group revealed areas where epithelial dysplasia was observed, assuming at some places a pattern of epithelial stratification characteristic of prostatic intraepithelial neoplasia. After ultrastructural analysis, the following were observed: enlargement of the internal membranes, heterogeneity in the cellular types, hypertrophy of the basal cells and apparent decrease of cytoplasmic organelles in some cells of the prostatic intraepithelial neoplasia. Still, a loss of cellular polarity was observed, along with nuclei of various forms, sizes and heights - as well as irregular chromatin distribution patterns. Such alterations were found mainly in pubescent, post-pubescent and adult animals subject to the chronic administration of estradiol. These findings reinforce the already existent data in understanding the role of estrogen in the etiology of prostatic diseases.

Evaluation of homologous, heterologous, and affinity conjugates for the serodiagnosis of Toxoplasma gondii and Neospora caninum in maned wolves (Chrysocyon brachyurus)

Use of serological tests in the diagnosis of infectious diseases in wild animals has several limitations, primarily the difficulty of obtaining species-specific reagents. Wild canids, such as maned wolves (Chrysocyon brachyurus), are highly predisposed to infection by Toxoplasma gondii and, to a lesser extent, to Neospora caninum. The aim of the present study was to evaluate homologous, heterologous, and affinity conjugates in enzyme-linked immunosorbent assays (ELISAs) and indirect fluorescent antibody tests (IFATs) for detecting immunoglobulin (Ig) G antibodies against T. gondii and N. caninum in maned wolves. Serum samples were obtained from 59 captive animals in Brazil and tested by ELISA for T. gondii serology and IFAT for N. caninum serology using 3 different enzymatic and fluorescent conjugates: homologous (guinea pig anti-maned wolf IgG-peroxidase and -fluorescein isothiocyanate [FITC]), heterologous (rabbit anti-dog IgG-peroxidase and -FITC), and affinity (protein A-peroxidase and -FITC). Seropositivity to T. gondii was comparable among the homologous (69.5%), heterologous (74.6%), and affinity (71.2%) enzymatic conjugates. A significant positive correlation was found between the antibody levels determined by the 3 enzymatic conjugates. The highest mean antibody levels (ELISA index = 4.5) were observed with the protein A-peroxidase conjugate. The same seropositivity to N. caninum (8.5%) was found with the homologous and heterologous fluorescent conjugates, but protein A-FITC was not able to detect or confirm any positive samples with homologous or heterologous conjugates. Our results demonstrate that homologous, heterologous, and affinity conjugates might be used in ELISA for serological assays of T. gondii in wild canids, whereas for N. caninum infection, only the homologous or heterologous fluorescent conjugates have been shown to be useful. © American Society of Parasitologists 2005.

Bone morphology of the hind limbs in two caviomorph rodents

In order to evaluate the hind limbs of caviomorph rodents a descriptive analysis of the Cuniculus paca (Linnaeus, 1766) and Hydrochoerus hydrochaeris (Linnaeus, 1766) was performed using anatomical specimens, radiography, computed tomography (CT) and full-coloured prototype models to generate bone anatomy data. The appendicular skeleton of the two largest rodents of Neotropical America was compared with the previously reported anatomical features of Rattus norvegicus (Berkenhout, 1769) and domestic Cavia porcellus (Linnaeus, 1758). The structures were analyzed macroscopically and particular findings of each species reported. Features including the presence of articular fibular projection and lunulae were observed in the stifle joint of all rodents. Imaging aided in anatomical description and, specifically in the identification of bone structures in Cuniculus paca and Hydrochoerus hydrochaeris. The imaging findings were correlated with the anatomical structures observed. The data may be used in future studies comparing these animals to other rodents and mammalian species. © 2012 Blackwell Verlag GmbH.

Ocorrência de crryptosporidium spp, em animais exóticos de companhia no Brasil: Milena Sato de Souza. -

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)