Expression of bone morphogenetic protein-6 and bone morphogenetic protein receptors in myoepithelial cells of canine mammary gland tumors

To study the ectopic chondrogenesis in canine mammary mixed tumors, the expression of bone morphogenetic protein-6 (BMP-6) and specific BMP receptors (BMPRs), BMPR-IA, BMPR-IB, and BMPR-II, was examined using immunohistochemical and immunoblot analysis in 39 canine mammary gland tumors. Immunohistochemically, BMP-6 and all three types of BMPRs were coexpressed in the myoepithelial cells and chondrocytes in six of eight benign mixed tumors. In complex adenomas, myoepithelial cells showed an expression pattern of BMP-6, BMPR-IA, and BMPR-II similar to those in benign mixed tumors, whereas immunoreactivity for BMPR-IB was very mild. The myoepithelial cells proliferating within the basement membrane showed more intense immunoreactivity for BMP-6 and all BMPRs as compared with those proliferating in the interstitial areas. Western blotting analysis revealed immunopositive bands at 40-45 kDa for BMP-6 in the samples from simple and complex adenomas and benign mixed tumors. The BMPR-IB-specific bands at 45 kDa were most detected in benign mixed tumors. Because among BMPRs, BMPR-IB is thought to be the major receptor for BMP-6 for primary chondrogenesis, these findings suggest that the expression of BMP and its receptors on the myoepithelial cells might play a role in the ectopic cartilage formation in canine mammary gland tumors, especially in benign mixed tumors.     

Co-localization of chondromodulin-I (ChM-I) and bone morphogenetic protein-6 (BMP-6) in myoepithelial cells of canine mammary tumors

To compare the roles of chondromodulin-I (ChM-I) and bone morphogenetic protein-6 (BMP-6) in ectopic mesenchymal tissue formation in canine mammary gland tumors, 33 tumors and 2 normal mammary glands were examined. Immunohistochemical analysis revealed co-expression of ChM-I and BMP-6 in canine mammary tumors. In mixed tumors, newly formed woven bone with ossified cartilage matrix was observed in 4/9 cases. The osteoblasts lining the woven bone showed moderate immunoreactivity to ChM-I and BMP-6. Almost all chondrocytes and proliferative myoepithelial cells within the basement membrane showed intense immunoreactivity to both, and the myoepithelial cells adjacent to the mature cartilage showed the most intense immunoreactivity. The immunoreactivity to ChM-I and BMP-6 of the interstitial myoepithelial cells in the myxomatous stroma varied in each focus of mixed tumors. Similar findings were found in complex adenomas. In simple adenomas, hyperplasic myoepithelial cells within the basement membrane showed moderate immunoreactivity to both markers. Western blot analysis detected a 25 kDa band of ChM-I in fresh tissue samples from three mixed tumors. Our results support the hypothesis that proliferating myoepithelial cells with ChM-I and BMP-6 expression play important roles in mesenchymal metaplasia in canine mammary tumors.     

Expression of class II beta-tubulin by proliferative myoepithelial cells in canine mammary mixed tumors

Benign mammary mixed tumors in dogs resemble human salivary pleomorphic adenomas with regard to their histogenesis, including the occurrence of cartilaginous or bony metaplasia as well as the expression pattern of cytoskeletal proteins in proliferative myoepithelial cells. Recently, a monoclonal antibody specific for class II beta-tubulin has been developed. The epitope it recognizes was determined to be the heptapeptide Glu-Glu-Glu-Glu-Gly-Glu-Asp, which is the common sequence found among the canine, rat, mouse, and human class II beta-tubulin-specific regions. We carried out immunohistochemical studies on mammary mixed tumors obtained from three female dogs using this the monoclonal antibody. The antibody to class II beta-tubulin reacted intensely with proliferative myoepithelial cells in canine mammary mixed tumors, whereas staining was barely detectable in normal myoepithelial cells surrounding alveoli and alveolar ducts within the tumor and adjacent normal tissue. Proliferative myoepithelial cells also expressed vimentin, but alpha-smooth muscle actin (alphaSMA) staining was barely detectable. Immunoblot analysis showed that class II beta-tubulin and vimentin were expressed in myoepithelial cell lines prepared from the three mammary mixed tumors. On the other hand, only one cell line, which was negative for alphaSMA, produced cartilage-specific type II collagen. These results suggest that class II beta-tubulin could be a new molecular marker of proliferating myoepithelial cells in canine mammary mixed tumors and that differential expression of cytoskeletal components is associated with cartilaginous metaplasia of proliferative myoepithelial cells in mixed mammary tumors.     

Alkaline phosphatase reaction of canine mammary mixed tumours: a light and electron microscopic study

Alkaline phosphatase (ALK-P) reactions at the light and electron microscopic levels were performed on eight canine mammary mixed tumours. In the morphologically normal gland next to the tumours, the myoepithelial cells and the stromal tissues near the acinar basement membranes both showed a positive ALK-P reaction by light microscopy. At the electron microscopic level, those parts of the myoepithelial cell membrane that were in contact with other cells--myoepithelial or lumenal epithelial--showed an ALK-P-positive reaction, as did the adjacent stromal tissue. The characteristic tumour cells, at sites of early proliferation, were ALK-P-positive, while in the mucoid and chondroid areas of the mixed tumours they were largely ALK-P-negative by light microscopy. By electron microscopy, those neoplastic cells which were in contact with other cells typically showed a positive ALK-P reaction, while those cells which were in contact with mucoid or chondroid matrix were largely negative. Although the cytoplasmic filaments of the neoplastic cells were 10 nm thick, and those of normal myoepithelial cells were 6 to 8 nm thick, the observations reported provide further evidence for the view that the essential cells of the canine mammary mixed tumour are derived from myoepithelial cells.     

The expression of intermediate filaments in canine mammary glands and their tumors

Monoclonal antibodies specific for different types of intermediate filaments (cytokeratin, vimentin, desmin and neurofilaments) were used to study the histogenesis of canine mammary glands and 57 canine mammary tumors by immunocytochemistry. The intra- and interlobular duct epithelium, acinar, and intralobular myoepithelial cells stained positively for cytokeratin. Peripheral ductal and acinar cells, as well as interstitial cells, stained positively for vimentin. A similar staining pattern was seen in adenomas, complex adenomas, benign mixed tumors, ductular carcinomas, and one myoepithelioma-like tumor. Additionally, cytokeratin positive cells were scattered interstitially in one single adenoma, most complex adenomas, some benign mixed tumors, complex carcinomas, and in the malignant mixed tumors. All stromal cells stained positively for vimentin. The fibrosarcomas were positive only for vimentin, while the following expressed both desmin and cytokeratin: epithelial-like cells in one adenoma, three complex adenomas, the myoepithelioma-like tumor, the single comedo carcinoma, two complex carcinomas, the single lobular carcinoma, one malignant mixed tumor, and three osteosarcomas. Epithelial-like cells in one adenoma, six complex adenomas, two benign mixed tumors, two complex carcinomas, the lobular carcinoma, and the malignant schwannoma stained for neurofilaments. Three tumors, one adenoma, one complex adenoma, and the lobular carcinoma expressed both desmin and neurofilaments in addition to cytokeratin and vimentin. The results show the expression of different types of intermediate filaments and indicate that there might be a stem cell origin in most of the canine mammary tumors.     

DNA measurement and immunohistochemical characterization of epithelial and mesenchymal cells in canine mixed mammary tumours: putative evidence for a common histogenesis.

DNA measurement by image cytometry, and a detailed immunohistochemical study using monoclonal antibodies directed against different human cytokeratin types, muscle-specific actin, vimentin and S100 protein were carried out on normal canine mammary tissue (n =4), benign canine mammary mixed tumours (n =20) and malignant canine mammary mixed tumours (n =13). The results showed that ductal and alveolar luminal cells in normal and neoplastic tissue were immunoreactive with CAM5.2 and AE1/AE3 antibodies recognizing human keratins.Basal/myoepithelial cells were clearly differentiated from ductal and alveolar epithelial cells, since the latter only expressed cytokeratins, whereas the former also expressed vimentin and muscle-specific actin. This immunohistochemical study showed that there is loss of expression of muscle-specific actin and cytokeratins in areas of myoepithelial proliferation, and enhanced expression of vimentin and S100 protein in proliferative areas with osseous and/or chondroid metaplasia. The ploidy studies revealed that 20% (4/20) of benign and 54% (7/13) of malignant mixed tumours of canine mammary gland were aneuploid and that the epithelial and myoepithelial components of the mixed tumours had identical DNA content.Our results reinforce the role of myoepithelial cells in mesenchymal metaplasia in mixed mammary tumours and suggest the possibility of a common origin of both components from a totipotential stem cell with capacity for divergent differentiation.     

Immunolocalization of the smooth muscle-specific protein calponin in complex and mixed tumors of the mammary gland of the dog: assessment of the morphogenetic role of the myoepithelium

The immunohistochemical expression of the smooth muscle-specific protein calponin was studied to assess the contribution of myoepithelial cells to the histogenesis of spindle cells of complex and mixed tumors of the mammary gland of the dog and the origin of cartilage and bone in mixed tumors. Formalin-fixed tissues from 55 benign and malignant tumors (49 also containing surrounding normal mammary gland) were evaluated. Periacinar and periductal myoepithelial cells of all the 49 normal mammary glands were diffusely stained by the anti-human calponin monoclonal antibody. Calponin was found in 53 (98%) of the tumors studied, reacting with the myoepithelium-like cells of 86% of benign tumors and their remnants in 85% of malignant tumors. Five different types of calponin-immunoreactive myoepithelial cells were identified: hypertrophic myoepithelial cells. fusiform cells, stellate myoepithelial cells, rounded (myoepithelial) cells, and chondroblasts. Differences in staining intensity and staining pattern among these five types of cells suggested a transition of myoepithelial cells to chondroblasts. Stromal myofibroblasts also showed calponin immunoreactivity, but they did not react with a cytokeratin 14 monoclonal antibody, which recognizes myoepithelial cells in mammary gland. Calponin appears to be a very sensitive marker of normal and neoplastic myoepithelium in the canine mammary gland, and its identification in different cell types of complex and mixed tumors of the mammary gland of the dog suggests a major histogenetic role for myoepithelial cells.     

The expression of p63 and cytokeratin 5 in mixed tumors of the canine mammary gland provides new insights into the histogenesis of these neoplasms

Cytokeratin 5 and p63 have been described as basal and myoepithelial cell markers in human breast. Mixed tumors of the canine mammary gland have been associated with a myoepithelial origin. Cytokeratin 5 expression has not been evaluated in these tumors. We investigated the relation between cytokeratin 5 and p63 double-immunohistochemical expression in 23 mixed tumors of the canine mammary gland (10 benign mixed tumors and 13 carcinomas arising from benign mixed tumors) and their origin. Cytokeratin 5 and p63 co-expression was observed in myoepithelial cells of benign mixed tumors, as well as in squamous differentiation of carcinoma arising from benign mixed tumors. Though a few interstitial spindle cells of the mesenchymal components expressed both p63 and cytokeratin 5, the basal epithelial cells were labeled only by cytokeratin 5. The co-expression of p63 and cytokeratin 5 in myoepithelial cells and squamous differentiation suggest that, like in human breast, cytokeratin 5 can also be considered a myoepithelial- and squamous-cell differentiating marker in canine tumors. The presence of some interstitial spindle cells stained for p63 and cytokeratin 5 might be associated with a myoepithelial origin of the mesenchymal component of mixed tumors of the canine mammary gland. Moreover, contrary to p63, basal epithelial cells were labeled by cytokeratin 5, indicating that cytokeratin 5 may not represent an exclusive myoepithelial cell marker but also a basal epithelial cell marker in canine mixed tumors. According to these data, basal epithelial cells may be related to the origin of the epithelial component of mixed tumors of the canine mammary gland.     

p63: a novel myoepithelial cell marker in canine mammary tissues

Several immunohistochemical markers have been used to demonstrate the presence of myoepithelial cells in order to determine their role in the histogenesis of mammary tumors. p63, a recently characterized p53 homologue, is consistently expressed in myoepithelial cells of the human breast; however, no assessment of its immunoreactivity has been reported so far in canine mammary tissues. We investigated p63 immunohistochemical expression, as a novel myoepithelial cell nuclear marker, in 81 samples of normal (n = 2), hyperplastic (n = 11), and neoplastic (n = 68) canine mammary tissues. Myoepithelial phenotype was confirmed by using complementary monoclonal antibodies: alpha-smooth muscle actin, cytokeratin 14, cytokeratin AE1/AE3, and vimentin. p63 expression was observed in 91.4% (74/81) of the samples evaluated. Normal mammary glands, mammary hyperplasias, and benign tumors showed 100% immunoreactivity, with p63 expression restricted to myoepithelial cell nuclei. In general, benign mixed tumors showed a basal cell compartment immunoreactive to p63, with a gradual decrease of its expression during myoepithelial transformation. p63 expression was found in 72% of malignant tumors, allowing myoepithelial or basal cell identification in spindle-cell carcinomas (2/2), tubulopapillary carcinomas (8/9), solid carcinomas (7/10), and carcinosarcomas (1/3). The osteosarcoma analyzed was p63 negative. In our series, stromal components were consistently nonreactive to p63. In conclusion, the present study reveals p63 as a sensitive and highly specific marker of myoepithelial cells in canine mammary tissues, and the authors suggest p63 as an additional marker for defining myoepithelial histogenesis.     

Electron microscopic observations on canine mixed mammary tumors, with special reference to cytoplasmic filamentous components

Three chief cell types were studied in 8 canine mixed mammary tumors--luminal epithelial cells, myoepithelial cells, and filament cells, the last being the "stellate" cells recognized by light microscopists. Most cytoplasmic filaments in the myoepithelial cells were 5 to 8 nm thick, whereas another type of filaments were scattered, 8 to 10 nm thick. Almost all cytoplasmic filaments in the filament cells were 8 to 10 nm thick. In the adenomatous parts of the tumors, myoepithelial cells were chiefly seen, along with luminal epithelial cells. Filament cells were rarely observed without intercellular accumulation of mucoid. The filament cells were largely confined to the myxomatous and chondromatous parts of the tumors. The presence of cells of transitional forms in adenomatous areas suggested that the filament cells were derived from the myoepithelial cells.     

Alpha basic crystallin expression in canine mammary tumors

The aim of this study was to evaluate prognostic and/or diagnostic factors of canine mammary tumors by immunohistochemically analyzing the expression of alpha basic crystallin (αB-c). For this, formalin-fixed, paraffin-embedded blocks of 51 naturally-occurring canine mammary tumors (11 benign and 40 malignant) were used. Tissue from eight normal canine mammary glands were served as a control. Immunohistochemically, in the control mammary tissues, a few luminal epithelial cells were αB-c positive but myoepithelial cells were negative. In benign or simple type malignant tumors, αB-c expression was observed in luminal epithelial cells while the myoepithelial basal cells were negative. In benign or complex type malign tumors, positive staining was predominantly found in the cytoplasm of epithelial cells. Immunoreactivity of αB-c was also observed in neoplastic myoepithelial cells. Statistically, the number of cells immunolabeled with αB-c was found to be significantly different among tissues from normal canine mammary glands, benign lesions, and malignant tumors (p < 0.05). αB-c immunoreactivity was higher in malignant tumors than the control mammary tissues (p < 0.001). Data obtained in the current study revealed a strong association between high expression levels of αB-c and primary mammary gland tumors in canines.     

E-cadherin immunoreactivity in canine mammary tumors.

The reduction or loss of E-cadherin (E-cad), a calcium-dependent epithelial cell adhesion molecule, has been associated with tumor dedifferentiation and invasiveness. The immunohistochemical pattern of E-cad expression was evaluated in formalin-fixed and paraffin-embedded sections of 6 normal mammary glands, 3 dysplasias, 12 benign tumors (8 benign mixed tumors, 4 adenomas), and 60 malignant tumors (12 stage 0, 29 stage I, 19 stage II) of the canine mammary gland. E-cadherin expression was classified as membranous, when on cell-cell boundaries, or as cytoplasmic, when in the form of a diffuse cytoplasmic staining. In addition, the percentage of E-cad-positive epithelial neoplastic cells was graded by a semiquantitative method, categorizing cases into a reduced (or -) type group, when showing less than 25% positivity, a reduced (or +/-) type group, when showing 25-75% positivity, and a preserved (or +) type group, when more than 75% positive cells were present. In the normal mammary gland, E-cad expression was evident in epithelial luminal cells. A stronger positivity was revealed in ductular than in alveolar luminal cells. The myoepithelial cells showed inconsistent, weak cytoplasmic positivity in the normal gland as well as in mammary tumors. In normal glands and benign and malignant noninvasive tumors, E-cad expression was mainly membranous and preserved in most of the epithelial cells. In stage I tumors, both membranous (38%) and cytoplasmic (62%) positivity were well represented, as well as preserved type (55%) and reduced type (45%) tumors. All stage II malignant tumors showed the highest frequency of cytoplasmic positivity (79%) and reduced type (62%) tumors.     

Cellular proliferative and telomerase activity in canine mammary gland tumors

In canine mammary tumors, we examined the telomerase activity, proliferative activity by proliferative cell nuclear antigen (PCNA) immunohistochemistry, and percentage of apoptotic cells by the deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling (TUNEL) method. The relationship between these measures and histopathologic malignancy was also investigated. PCNA index was highest in malignant tumors (adenocarcinoma: 27.0%; malignant mixed tumor: 15.7%), followed by benign tumors (adenoma: 4.4%; benign mixed tumor: 5.3%), hyperplasia (2.1%), and normal mammary gland (0.9%). In adenoma and adenocarcinoma, papillary and solid types showing higher cellularity tended to have higher PCNA indices than did cystic and tubular types. Although the TUNEL index was <1% in all cases, the relationship between this measure and histopathologic diagnosis showed the same tendency as observed in PCNA immunostaining. Telomerase activity was detectable in all adenomas, benign mixed tumors, and adenocarcinomas examined. In contrast, all normal mammary glands, hyperplasias, and malignant mixed tumors were negative for telomerase. Relative telomerase activity (RTA) of adenocarcinoma (56.5) was significantly higher than that of adenoma (27.8) and benign mixed tumor (33.9), and a significant positive correlation (P < 0.001) was noted between RTA and PCNA index. No significant correlations were noted between either PCNA or TUNEL index and clinical features such as metastasis and tumor diameter. PCNA index and telomerase activity may be useful markers for judging malignancy of canine mammary tumors.     

Immunohistochemistry with keratin,vimentin, desmin,and α‐smooth muscle actin monoclonal antibodies in canine mammary gland: Benign mammary tumours and duct ectasias

Summary

Duct ectasias (n=2) and different types of benign canine mammary tumours (n=19) were studied immunohistochemically with monoclonal antibodies (MoAbs) directed against various human keratin types (K), α‐smooth muscle actin, vimentin, and desmin. In the duct ectasias and in most tumours the epithelial structures revealed an inner and outer cell layer. The inner cell layer was characterized by labelling with K 7, 8, 18, 19 and mostly also with K 4 and/or K 10 MoAbs. The outer cell layer was almost invariably labelled by K 14, K 14 and 17, and a‐smooth muscle actin MoAbs. The labelling patterns of both duct ectasias and tumours corresponded largely to the patterns observed in normal mammary gland tissue, although a more distinct heterogeneity was seen. Tumours histomorphologically assumed to be of a myoepithelial origin did not show immunohistochemical features of myoepithelial cells. The myoepithelial nature of the vast majority of spindle‐shaped cells present in the adenomas of the complex type and in the fibroadenomas of the benign mixed type could not be confirmed immunohistochemically. These cells, however, unequivocally expressed vimentin, suggesting proliferation of stromal cells in these tumours, which in the fibroadenomas of the benign mixed type may show metaplasia to bone or cartilage.

In the duct ectasias and in some tumours, a fraction of elongated stromal cells, probably representing myofibroblasts, was labelled with the α‐smooth muscle actin MoAb.     

Computerized morphometry of mean nuclear diameter and nuclear roundness in canine mammary gland tumors on cytologic smears

BACKGROUND: The use of computer-based image analysis systems in veterinary oncology has increased. Computerized morphometry is a part of image analysis that describes geometric figures of cellular structures in any dimension. Most investigators have performed morphometric analysis on histologic specimens. Computer-assisted nuclear cytomorphometry can provide important preoperative information on neoplastic lesions in animals. OBJECTIVES: The aim of this study was to define whether the morphometric parameters of mean nuclear diameter and nuclear roundness could be used to differentiate benign from malignant canine mammary gland tumors on cytologic specimens. METHODS: Mean nuclear diameter and nuclear roundness were determined by computer-assisted morphometry of epithelial cells in Hemacolor-stained cytologic smears from normal canine mammary gland (n = 7) and from canine mammary adenomas (n = 8), tubulopapillary carcinomas (n = 9), and solid carcinomas (n = 6). Data were analyzed by the Mann-Whitney U test. RESULTS: Significant differences (P <.001) were found in mean nuclear diameter and nuclear roundness among all tumor types and in comparison with normal canine mammary gland epithelial cells (except for nuclear roundness between tubulopapillary carcinomas and solid carcinomas). CONCLUSIONS: The morphometric parameters of mean nuclear diameter and nuclear roundness can be used in the preoperative differentiation of benign from malignant canine mammary gland tumors.     

Immunohistochemical analysis of c-yes and c-erbB-2 oncogene products and p53 tumor suppressor protein in canine mammary tumors

In order to evaluate the involvement of c-yes and c-erbB-2 oncogene products, and p53 tumor suppressor protein in canine mammary neoplastic lesions, sections of archived paraffin-embedded samples of 79 mammary tumors were analyzed immunohistochemically using antibodies against human c-yes p62 and c-erbB-2 products and p53. These 79 tumors were divided into 2 groups: 32 benign (2 adenosis, 7 simple adenomas, 14 complex adenomas, and 9 benign mixed mammary tumors) and 47 malignant tumors (26 simple adenocarcinomas, 7 complex adenocarcinomas, 5 solid carcinomas, 2 sclerosing carcinomas, 6 malignant mixed mammary tumors, and 1 malignant myoepithelioma). As a result of immunostaining, 40.6% (13/32) of the benign tumors and 21.3% (10/47) of the malignant tumors expressed the c-Yes oncogene product, ErbB-2 expression was detected in 50% (16/32) of the benign tumors and in 19.1% (9/47) of the malignant tumors. P53 expression was detected in 16% (4/25) of the benign tumors and in 30.6% (11/36) of the malignant tumors. Co-expression of c-Yes and ErbB-2, ErbB-2 and p53, and all 3 products was detected in 6, 1 and 7 tumors, respectively.     

A pleomorphic adenoma of the lacrimal gland in a dog

A 13-year-old female mongrel dog had a pleomorphic adenoma of the lacrimal gland in the right upper orbit. The tumor measured 3.8 x 3.0 x 3.3 cm, appeared white, round, and firm, and pressed the right globe and surrounding tissues. Histopathologically, the tumor had a thin connective tissue capsule and was composed of tubules with two cell types, some resembling luminal epithelial cells making up the tubular structures and the other of myoepithelial cells. Epithelial tubules were disposed in an adenomatous fashion and separated from each other by proliferating pleomorphic myoepithelial cells. Immunohistochemically, large numbers of the luminal epithelial cells revealed an immunopositive reaction against keratin/cytokeratin (AE1/AE3), and some epithelial cells reacted against cytokeratin 14. Spindle-shaped myoepithelial cells revealed an immunopositive reaction against cytokeratin 14, alpha-smooth muscle actin, and vimentin. A small number of myoepithelial cells reacted against desmin. S-100 protein immunopositivity was frequently found in luminal epithelial cells and rarely in the pleomorphic myoepithelial cells. Glial fibrillary acidic protein positivity was commonly found in myoepithelial cells, myxoid matrices, and intracystic materials, but not in luminal epithelial cells.     

Histologic, immunohistochemical, and clinical features of 27 mammary tumors in 18 male dogs

Twenty-seven mammary tumors from 18 male (3 intact, 15 neutered) dogs were collected. The average age at diagnosis was 9.2 years (range, 2-14 years). Seven of the dogs were Cocker Spaniels. Five dogs had multiple mammary tumors. All tumors were benign. Twenty-six were simple adenomas with mixed acinar and papillary patterns. The acinar pattern was predominant in 17 cases. One adenoma was complex with a prominent myoepithelial component. The myoepithelial component of 25 of the 25 tumors was immunohistochemically positive for calponin and p63. In the cases for which relevant clinical information was available, there was no reported history of obesity, testicular tumors, or sex hormone therapy. Surgery was the only reported treatment for these tumors. Only 1 dog was reported to have developed an additional mammary tumor. None of the dogs for which case outcome was known died or was euthanatized as a result of mammary tumor. Although uncommon, mammary tumors do occur in male dogs. Although mammary tumors may be quite cellular, the presence of an intact myoepithelium, which can be demonstrated with immunohistochemistry for calponin and p63, indicates benignancy, as the clinical behavior documents.     

Mammary mucinous carcinoma in the cat

Mucinous carcinoma of the mammary gland is a rare tumor characterized by excessive mucin production. In human and canine pathology, the diagnosis of mucinous carcinoma is based on the demonstration of an epithelial phenotype of mucus-producing cells and periodic acid-Schiff (PAS)-diastase positivity of the mucin. The histologic and immunohistologic characteristics of feline mucinous mammary carcinoma were examined. Of 656 cases of feline mammary neoplasms and dysplasias, 3.2% were found to be mucin-producing tumors. Cytokeratin 19 (16 cases positive, 4 heterogenous, and 1 negative) and vimentin (15 cases positive, 2 heterogenous, and 4 negative) expression were examined, and the mucin produced was alcian blue positive. PAS-diastase staining was variable (38.1%). Based on these findings, mucinous mammary carcinoma in the cat varies significantly from the human and canine varieties and alcian blue is the prominent stain in the diagnosis of feline mucinous carcinoma.     

Ultrastrukturelle und ultrahistochemische Untersuchungen an der Milchdrüse des Hundes: II. Ultrahistochemische Untersuchungen

Ultrastructural and ultrahistochemical examinations on the canine mammary gland II. Ultrahistochemical examinations Mammary glands of mostly oldder bitches were examined ultrahistochemically for the distribution of ATPase, alkaline phosphatase, and acid phosphatase. The reactions for ATPase were found regularly in the walls of the blood vessels and often on the plasma membranes of the myoepithelial and epithelial cells. However, plasma membranes adjacent to lumen and basement membrance did not show the reaction. Alkaline phosphatase was found regularly only on the plasma membranes of the myoepithelial cells. Acid phosphatase was found in the lysosomes of myoepithelial and epithelial cells, and increased in amount during the regression of the gland.