A pathological study of experimental long-standing Schistosoma bovis infection in sheep.

The pathological response of sheep to two dose levels (400 or 10,000 cercariae) of Schistosoma bovis was evaluated 24 weeks after infection. The results confirmed that a single low or high dose causes lesions in the liver and intestine, and that the lungs, lymph nodes, pancreas and abomasum are affected in sheep given a single high dose. In addition, the study showed that pathological changes (mainly a granulomatous inflammatory reaction) were induced not only by eggs but also by adult worms, and that their severity was in general related to the dose of S. bovis. Hoeppli reaction product, observed on the surface of adult schistosomes in some parasitic granulomas, showed no immunoreaction for IgG, IgA or IgM.

Biological characterization of ovarian granulosa cell tumours of slaughtered cattle: assessment of cell proliferation and oestrogen receptors.

Of 1489 slaughtered cattle, 11 had ovarian granulosa cell tumours (GCTs). These GCTs were examined immunohistochemically for proliferating cell nuclear antigen (PCNA) and oestrogen receptor (ER) in relation to histopathological features (growth pattern, nuclear atypia and mitotic count). On the basis of nuclear atypia and mitotic count, the prognosis for GCTs with a diffuse growth pattern appeared less favourable than that for GCTs with a follicular or trabecular pattern. Increased PCNA expression was significantly associated with nuclear atypia but not with histological growth pattern or mitotic count. A novel finding was the presence of ERbeta but not ERalpha in bovine ovarian GCTs. However, ERbeta expression did not appear to be related to the histopathological features examined. The results indicate that PCNA expression may be of value in establishing the biological behaviour of bovine GCTs. However, a larger series of bovine GCTs should be examinated to assess the prognostic significance of ERbeta.

Effects of in-utero exposure to zeranol or diethylstilboestrol on morphological development of the fetal testis in mice.

The morphological development of the fetal mouse testis exposed to alpha-zearalanol (zeranol) or diethylstilboestrol (DES) was evaluated as part of an examination of the effects of transplacental exposure to non-steroid oestrogens on susceptible tissues. On days 9 and 10 of gestation, pregnant NMRI mice were given subcutaneous injections of ethyl oleate alone (0.1 ml) or zeranol or DES (150 micrograms/kg body weight) in ethyl oleate. The mice were killed from days 12 to 18 of gestation and the male fetuses were examined. Microscopical examination of the gonads indicated that the onset of testicular differentiation was earlier in the oestrogen-treated fetuses than in controls. Abnormal differentiation of gonocytes and foci of hyperplasia of fetal Leydig cells were observed in the oestrogen-treated mice. Male fetuses from female mice treated with DES showed a delay in testicular descent and progressive decrease in reactivity for cytokeratin (CK) 8 in fetal Sertoli cells. These morphological findings suggest that prenatal exposure to zeranol or DES induces abnormal testicular differentiation in the mouse.

Optimization of the immunohistochemical demonstration of keratins in paraffin wax-embedded mouse skin.

The purpose of this study was to develop an immunoperoxidase technique for the detection of cytokeratins in samples of paraffin wax-embedded adult and fetal skin from NMRI mice, with various antibodies (Troma-1, LL001, 8.60, MCK5, MCK6, AF129) that have been tested mainly on fresh-frozen sections. Each antibody was tested with three different fixatives (10% neutral buffered formalin, Bouin's fluid, and 70% ethanol) and two distinct pretreatments (enzymatic digestion with trypsin, or heat treatment). The best results, in terms of non-specific background labelling, morphological preservation and intensity of specific labelling, were obtained (1) for adult skin, by the use of Bouin's fluid, heat pretreatment and antibodies LL001, MCK5, MCK6 or AF129, and (2) for fetal skin, by the use of 70% ethanol, heat pretreatment and antibody Troma-1. Monoclonal antibody 8.60 gave the best results when the use of 70% ethanol was combined with either enzymatic digestion or heat pretreatment.

Common epithelial tumours of the ovary in cows.

A morphological study of the epithelial tumours diagnosed during examination of 1489 cows slaughtered in León, Spain was carried out. Epithelial neoplasms were observed in four animals which represents an incidence of 0.27 per cent. So far as the authors are aware it is the first time that two serous papillary cystadenomas and one serous superficial papilloma have been described in cows. The fourth neoplasm was a mucinous cystadenoma.

Spontaneous mouse mammary tumours: incidence and cytokeratin expression.

The purpose of this study was to advance our knowledge of the histogenesis of spontaneous mammary tumours in laboratory mice. Normal mammary tissue and 19 spontaneous mammary tumours from adult female mice were examined using monoclonal and polyclonal antibodies differing in their recognition of various cytokeratin intermediate filament proteins (CKs). All neoplasms were intraductal and were invasive carcinomas with a tubular, papillary, cystic or solid growth pattern. CK8-positive reactions were detected in the normal alveolar and ductal epithelia and CK5- and CK14-positive reactions were seen in myoepithelial cells of nonlactating mammary glands. Positive staining for CK5 and CK8 was detected in all tumours and CK14 was expressed in those with a papillary pattern. Comparisons between non-lactating glands and tumours indicated that the neoplasms were well or moderately differentiated, there was no squamoid differentiation and that they arose from the alveoli and duct system, not the myoepithelial cells.

Effects of in utero exposure to nonsteroidal estrogens on mouse testis.

Male mice exposed in utero to alpha-zearalanol (zeranol) or diethylstilbestrol (DES) were analyzed postnatally to evaluate the possible changes on their testicular morphology as part of an examination of the effects of transplacental exposure to non-steroidal estrogens on sensitive tissues. Pregnant NMRI mice were injected subcutaneously with ethyl oleate (0.1 mL) alone (negative control) or with 150 micrograms/kg of body weight of zeranol or DES (positive control) on days 9 and 10 of gestation. Experimental and control male offspring were euthanized at days 45 (n = 47), 90 (n = 44), 180 (n = 40) and 365 (n = 26) after birth and their gonads were examined by light and electron microscopy. The results suggested that prenatal zeranol or DES exposure induced more severe and earlier (at 45 d) testicular abnormalities than in negative control (at 6 mo). These age-related alterations were characterized by regressive changes in the germinal epithelium and Sertoli's cells as well as foci of Leydig's cells around atrophied seminiferous tubules and dysplasia of the rete testis epithelium. On the contrary, the presence of Leydig's cells with immature morphology and their arrangement in sheet could be attributable exclusively to estrogen treatment. The presence of no neoplasm was confirmed.

Effect of diethylstilbestrol or zeranol on fetal development, gestation duration, and number of offspring in NMRI mice.

OBJECTIVE: To evaluate the effects of diethylstilbestrol (DES) or alpha-zearalanol (zeranol) on fetal development, gestation duration, and number of offspring. DESIGN: Study effects of prenatal administration of DES or zeranol on various pre- and perinatal variables in an experimental group of mice, compared with effects in a control group. ANIMALS: Pregnant NMRI mice. PROCEDURE: Diethylstilbestrol or zeranol (150 mg/kg of body weight) or vehicle (controls) was administered SC to pregnant mice on days 9 and 10 of gestation. Fetuses from pregnant mice of each group were counted and weighed, and their size and head length were recorded. Additional pregnant mice delivered their fetuses naturally, and pups from each group were counted and their sex was determined. At the end of gestation, abortions were evaluated. All data were statistically analyzed. RESULTS: Mean number of fetuses was significantly lower (P < 0.0001) in DES-treated (4.59 +/- 0.48) than in control mice (8.33 +/- 0.49). Both estrogenic substances significantly reduced fetal size and weight (P < 0.0001), compared with control mice. Diethylstilbestrol significantly increased abortion frequency (P < 0.0001) and gestation duration (P < 0.0001), compared with values for control mice. A reduced number of live pups (P < 0.0001) from pregnant mice administered DES (5.48 +/- 0.38) or zeranol (5.97 +/- 0.49) was observed, compared with control mice (8.52 +/- 0.50), because of reduced number of male offspring (P < 0.0001). CONCLUSIONS: Diethylstilbestrol or zeranol administered during mid-pregnancy leads to decreased fetal weight and size and lower numbers of male offspring at birth. Likewise, DES induced a significant increase in abortions and gestation duration.

Effects of retinoic acid exposure in utero on mouse vibrissal follicle development.

It is known that topical all-trans-retinoic acid (RA) modulates growth and differentiation of skin and its cutaneous appendages. To examine whether a pre-natal exposure to a potentially non-teratogenic dosage of all-trans-RA had any effect on vibrissal follicle development, the histologic and immunohistochemical responses to RA during its morphogenesis in NMRI mouse were investigated. After a single oral dose of 30 mg/kg body weight of all-trans-RA on day 11.5 of gestation, no fetal malformations were detected and the histological features and the distribution of keratin (K) proteins in comparable stages of vibrissal development were similar for the untreated, vehicle-treated and RA-treated mice. The absence of teratogenic response and of adverse effects on the vibrissae under the experimental conditions indicates that this protocol may be useful for investigation of the effects of pre-natal exposure to RA on the post-natal development of experimental tumours in the mouse skin.

[Ultrastructure of the luteal cells of female cattle]. / Ultraestructura de las Células Luteínicas en la Hembra Bovina.

An ultrastructural study to the corpus luteum (CL) from 263 non pregnant female cattle slaughtered in slaughter-houses of León (Spain) was done. The luteal cells are classified in five types, noted with roman numbers. We made a comparison between these cells and the cells described in the literature. We believe that luteal cells have a development from type I to V, the first type is the principal inside the developing CL. The types II and III are in the mature CL, and the two last types are in the degenerating CL. It will be the same cell in different stages of development. We did not find characteristic structures to differentiate luteal cells originating from the granulosa or the theca.

Incidence and pathomorphology of uterine tumours in the cow.

A statistical and pathological study on uterine tumours during the examination of 1489 female bovines at slaughter was carried out. A 0.4% (n = 6) incidence of uterine neoplasms, being 50% adenocarcinomas and the other 50% leiomyomas, was diagnosed. With regard to age groups, tumours were more frequent in the 11-15-year-old group. Two animals affected by adenocarcinoma were not fertile and they had ovarian metastasis that, to the author's knowledge, has been cited as extremely rare in cows. An ultrastructural study of these carcinomas and their metastasis was also made. Two leiomyomas were intramural and another one was pedunculated and subserous located. All leiomyomas showed the features of old tumours.