Myofibroblasts, cells sharing characteristics with fibroblasts and smooth muscle cells, may have a very heterogeneous origin. The myofibroblasts may be derived from a variety of sources including resident mesenchymal cells, epithelial to mesenchymal transition, as well as from circulating fibroblast-like cells called fibrocytes that are derived from bone-marrow stem cells, or derived from bone marrow precursors. In normal conditions, fibroblastic cells exhibit a low extracellular matrix production ability. After tissue injury, they become activated by cytokines locally released from inflammatory and resident cells to migrate into the damaged tissue and to synthesize extracellular matrix components. The investigation of cytoskeletal and cell surface markers showed a certain degree of heterogeneity of these cells. The reason for this is that markers these cells express to a large extent depend on the type of animal, age and stage of development of fibrosis. A better knowledge of the molecular mechanisms involved in the appearance of differentiated myofibroblasts in different pathological situations will be useful for understanding the development of fibrosis, its prevention and therapy
Milan Aničić, Vladimir Kukolj and Darko Marinković
Equine glanders is a severe bacterial disease known since ancient times. Although eradicated in the most part of the world it is now considered re-emerging. Considering very scarce literature data, we used from formalin fixed collection material: nasal septum, lung and skin specimens from naturally infected horses. Tissues were grossly examined and photographed. Tissue samples, after standard processing, were stained with HE, Congo red and Groccot and microscopically examined. Gross changes include nodules and ulcers in the nasal mucosa with granulation and scarring, pyogranulomas in the lung tissue and nodules and ulcers of the skin. Microscopically marked inflammation of affected tissues with neutrophilic and mononuclear infiltration and fibrous tissue proliferation were seen. As a potent zoonotic agent it has been already used as a biological weapon in the past.
Ivana Vučićević, Darko Marinković, Vladimir Kukolj, Miloš Vučićević, Milorad Mirilović, Slađan Nešić and Sanja Aleksić-Kovačević
Histopathological examination, grading, immunohistochemical staining and molecular genetic examinations are the proposed criteria that should be used for cutaneous mast cell tumors (CMCTs) classification. The presence of aberrant CD117 expression and mutations of the c-kit proto-oncogene could be an indicative parameter for final histological grading. Determination of the connection between the localization of KIT receptor expression and the histological grade of CMCTs without c-kit proto-oncogene mutations was the main goal of this study. The study included twenty four CMCTs and six control skin samples from 30 dogs of different ages, breed and sex. Formalinfixed and paraffin-embedded tissue samples were stained with hematoxylin-eosin and toluidine blue and immunohistochemically tested for CD117 expression. DNA was extracted from the same paraffin blocks and subsequent polymerase chain reaction amplification was performed using PE1 and PE2 primers. Degree of malignancy was determined based on the presence of mitotic figures, multinucleated cells, bizarre nuclei and karyomegaly in 10 high power fields. Based on histological features, fourteen of 24 CMCTs were of a high histological grade, while ten were classified as a lowgrade malignancy. CD117 cytoplasmic expression was observed in nine of fourteen high-grade malignancy CMCTs, which confirms the link between the aberrant CD117 expression and increased cell proliferation.
Ivana Vučićević, Darko Marinković, Vladimir Kukolj, Slađan Nešić, Milan Aničić, Biljana Đurđević and Sanja Aleksić-Kovačević
Peripheral nerve sheath tumors (PNSTs) comprise a heterogeneous group of neoplasms originating from the elements of the nerve sheath. They are divided into two forms: benign and malignant PNST. Both benign and malignant PNSTs are not very common in domestic animals but they are reported in different animal species. Histologically, PNSTs are composed predominantly of spindle cells arranged in bundles, whorls and sheets, with a different number of pleomorphic cells and mitotic figures.
The aim of this study was a reclassification of 17 dog tumor samples initially diagnosed with peripheral nerve sheath tumors using histopathological analysis. The main criterion for reclassification was immunohistochemical positivity for various antigens.
PNSTs are often histologically very similar to other spindle cell tumors and immunohistochemistry is required for differential diagnosis. PNSTs generally express vimentin, S-100 protein, glial fibrillary acidic protein (GFAP), collagen IV and laminin.
Four tumor samples were positive to muscular marker α-SMA and vimentin and negative for S-100 protein and desmin. The spindle cells whirling around some blood vessels were observed in these tumors so they were reclassified as perivascular wall tumors (PWTs). The other 13 tumors were S-100 protein and vimentin positive and α-SMA and desmin negative, thus classified as PNST.
The use of the immunohistochemical panel is necessary for distinguishing PNSTs from PWTs in routine diagnostics.
Darko Marinković, Jòzsef Özvegy, Milan Aničić, Ivana Vučićević, Slađan Nešić and Vladimir Kukolj
Gastric dilatation and volvulus is a life-threatening condition characterized by rapid accumulation of food and gases that cause displacement and distension of the stomach. The large and giant, deep-chested breeds of dogs are at higher risk for developing the gastric dilatation and volvulus. Uncommonly, it can also develop in cats, but it is also described in free-range polar bears.
A case of gastric dilatation and volvulus in a brown bear (Ursus arctos) is described in this paper. This case was characterized by lack of any previous symptoms, sudden death, as well as macroscopic findings during necropsy - twisted distended stomach, congested displaced spleen and necrotic gastric wall. According to the available data this is the first described case report of the gastric dilatation and volvulus in brown bear (Ursus arctos).