Metaplastic ossification of a cervical sialocoele in a dog.

Metaplastic ossification of a long-standing cervical sialocoele was identified in a 2-year-old male Hellenic Hound dog. Diagnosis was based upon history, clinical findings, paracentesis and histopathology. Trauma or chronic inflammation of the mandibular gland/duct complex were the most probable causes of the ossification. Surgical excision of the ossified mass, as well as of mandibular and sublingual salivary glands/ducts of the affected side, resulted in clinical remission.

Immunohistochemical study of a granular cell tumor on the tongue of a dog.

A granular cell tumor (GCT; myoblastoma) was diagnosed on the tongue of a 12-year-old English Pointer with clinical signs of mild oral dysphagia. The diagnosis was confirmed by histopathologic examination and immunohistochemistry. The tumor was positive for S-100 protein, but also was positive for desmin, and was only weakly positive for PAS, which is unusual for GCTs. An epithelioid type of leiomyoma (leiomyoblastoma) was considered less likely on the basis of negative staining for smooth muscle actin. Treatment consisted of surgical resection of the tumor. The animal was in excellent clinical condition 1 year after surgery. Although GCT of the tongue has been reported previously in the dog, determining the cell of origin is still problematic. Immunohistochemistry is helpful for histogenetic classification and necessary for differentiation from leiomyoblastoma.

The age at onset of diabetes influences functional and structural changes in the pituitary-thyroid axis of streptozocin-diabetic male rats.

Severe structural changes leading to marked alterations in secretory activity are known to occur in the pituitary-thyroid axis 1 month after induction of postpuberal streptozocin (SZ)-diabetes. However, SZ-diabetic rats of different age groups have not been compared, nor has the maturity of the pituitary and thyroid glands at the onset of diabetes been correlated with the type and evolution of functional and structural changes. We thus induced diabetes in 1-month (prepuberal of 3-month (postpuberal) old male rats and compared diabetic with control groups 4 and 8 months after SZ or saline injection. We determined: 1) pituitary and thyroid weights, 2) the basal plasma TSH, T3, and T4 concentrations, and 3) several morphometrical measurements in the pituitary and thyroid glands. After 4 months, 1) the pituitary and thyroid weights were decreased, 2) plasma TSH and T3 were unchanged, plasma T4 was reduced. and 3) the number of thyrotropes, degenerative changes of follicle cells, and colloid area were increased, the follicle cell height as well as the number of fused cold follicles decreased, and the follicle area was unchanged in diabetic compared with control rats. The lesions were more conspicuous in pre- than in postpuberal diabetic animals. After 8 months, plasma TSH, T3, and T4 were decreased in diabetic compared with control rats. Except for the increased colloid area, all other lesions were similar, though more severe in prepuberal diabetic rats after 8 than 4 months. Few changes were found in postpuberal diabetic rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Reverse hemolytic plaque assay study of luteinizing and follicle-stimulating hormone and thyrotropin secretion in diabetic rat pituitary glands.

Numerous studies indicate that an impaired hypothalamopituitary axis plays an important role in reproductive and thyroid disorders in diabetic humans and animal models. Yet, several questions about the pathogenesis of these diabetic complications have not been answered. To evaluate the basal secretion of single gonadotrophs and thyrotrophs in vitro, uncultured pituitary cells from control rats and 1-mo streptozocin-induced diabetic (STZ-D) rats were studied with a reverse hemolytic plaque assay and morphometry. After light-microscopy immunocytochemistry for gonadotropin and thyrotropin (TSH), we recorded the ratio of plaque-forming to non-plaque-forming cells. The area of plaques produced by luteinizing hormone (LH), follicle-stimulating hormone (FSH), and TSH cells and the area of plaque-forming and non-plaque-forming cells were clearly smaller in diabetic than control rats. The plaque area, however, was more severely reduced than the cell area. The percentage of LH-, FSH-, and TSH-immunoreactive plaque-forming cells was greatly decreased in diabetic compared with control animals. In conclusion, our findings demonstrate that the LH-, FSH-, and TSH-secreting cells of diabetic rats released less hormone and were less numerous than the corresponding cells of control rats. Thus, several pathogenetic mechanisms might be involved in reduced gonadotropin and TSH release at the cellular level: 1) anatomical lesions of organelles involved in glycoprotein hormone synthesis and secretion, possibly due to insulin deficiency; 2) decreased gonadotropin-releasing hormone (GnRH) and thyrotropin-releasing hormone (TRH) receptors on pituitary cells; 3) inadequate GnRH and TRH stimulation; 4) high plasma corticosterone levels; or 5) a combination of points 1-4.

[Alternative methods: development and use of two "in vitro" models for endocrine studies]. / Méthodes alternatives: développement et utilisation de deux modèles'in vitro' pour des études endocriniennes.

Most endocrinological studies are normally performed on several animal groups: one group for the determination of hormonal levels in tissues and plasma under basal conditions, a second group for the same determinations after "in vivo" treatment of the animals (stimulation or inhibition of the endocrine activities) and two additional groups for morphological investigations. Surgical approaches belong not rarely to the "in vivo" treatment of the animals. Moreover, the results from the different animal groups have to be extrapolated. In order to overcome these drawbacks, we have developed two "in vitro" models by means of which we can study on the tissues from the same animal: 1. function and structure of the hypothalamus and 2. function and structure of isolated pituitary cells. By using these models we can considerably reduce the number of animals needed for the studies, replace the "in vivo" by the "in vitro" experiments and refine the methods avoiding, among others, the extrapolation of results.