Novel polychrome staining distinguishing osteochondral tissue and bone cells in decalcified paraffin sections.

The bone is a dynamic and metabolically active organ in which growth and resorption of the osteochondral matrix is orchestrated by osteoblasts and osteoclasts. For decalcified paraffin-embedded specimens, decalcifying agents alter the staining intensity, and excess decalcification interferes with bone staining. Robust bone staining methods independent of the decalcification conditions and animal species are lacking. In this study, we have developed a novel polychrome staining method, named JFRL staining, which stains the components of osteochondral tissue in different colors. With this staining we could visualize the hyaline cartilage as blue by alcian blue, osteoid as red by picrosirius red, and mineralized bone as green by picro-light green SF or picro-naphthol green B and easily distinguished osteoblasts, osteocytes, and osteoclasts. In mineralized bone, this staining revealed the obvious lamellar structures and woven bone. Notably, this staining was independent of the decalcification conditions and experimental animal species examined. To verify the usefulness of JFRL staining, we observed cotton rat tail which has shorter length and shows a false autotomy. The caudal vertebrae were normally developed via endochondral ossification without a fracture plane. At 6 months of age, the number of chondrocytes declined and the hypertrophic zone was absent at the epiphyseal plate, which might reflect the shorter tail. In conclusion, JFRL staining is the first method to simultaneously distinguish osteochondral matrix and bone cells in one section regardless of decalcifying conditions. This robust staining will provide new information for a wide number of biomedical fields, including bone development, physiology, and pathology.

Slc:Wistar/ST rats develop unilateral thyroid dysgenesis: A novel animal model of thyroid hemiagenesis.

Developmental anomalies of the thyroid gland lead to congenital malformations such as thyroglossal duct cysts and thyroid dysgenesis. However, the pathogenesis of thyroid dysgenesis remains unclear due to the lack of suitable animal models. This study demonstrated that Slc:Wistar/ST rats frequently developed unilateral thyroid dysgenesis, including hemiagenesis, characterized by the absence of one lobe. In Wistar/ST rats, each thyroid lobe was frequently different in size, and approximately 27% and 20% of the rats presented with hemihypoplasia and hemiagenesis of the thyroid gland, respectively. Dysgenesis was predominant on the left side in both sexes, without sex differences. At a young age, thyroid hemiagenesis did not alter body weight. In rats of both sexes with thyroid hemiagenesis, plasma total triiodothyronine and total triiodothyronine levels remained unchanged while plasma thyroid-stimulating hormone levels were significantly elevated in young rats. The remaining thyroid lobes increased in weight, but the follicular epithelial cells appeared normal in terms of their height and proliferating activities. On the side of thyroid dysgenesis, the parathyroid glands were normally localized and were situated at the same location as the contralateral glands. The ultimobranchial body remnants were localized at the level of the thyroid gland along with the cranial thyroid artery and vein, forming cell clusters or cystic structures and containing calcitonin-positive C-cells. In conclusion, Wistar/ST rats developed unilateral thyroid dysgenesis and may be novel and useful animal models for thyroid hemiagenesis in humans and for morphogenesis of pharyngeal pouch-derived organs.

Slc:Hartley guinea pigs frequently possess duplication of the caudal vena cava.

The formation of the caudal vena cava is a complex process involving development, regression, and anastomosis. In mammals, the normal caudal vena cava runs to the right side of the abdominal aorta, while duplication of the caudal vena cava has been identified as a congenital abnormality in both companion animals and humans. The present study demonstrates that Slc:Hartley guinea pigs frequently possess asymptomatic duplicated caudal vena cava. The prevalence was 30% and 24% for males and females, respectively, with no sex-related differences. In accordance with Saad et al. (2012)'s criteria, duplicated caudal vena cava were classified into two distinct variations. The dominant variation was a complete duplication without iliac anastomosis where the left caudal vena cava continued from the left common iliac vein and joined the left renal vein; the left renal vein ran to the right to join the right caudal vena cava. The alternative variation was an incomplete duplication where the left caudal vena cava joined the right infrarenal caudal vena cava at a more cranial point than in normal cases; the renal segment was unchanged. Iliac anastomosis was not found in any cases. Duplicated caudal vena cava neither affected the body weight nor the kidney weight. In conclusion, Slc:Hartley guinea pigs frequently possess asymptomatic duplicated caudal vena cava in the absence of iliac anastomosis and appear to be a novel and useful animal model for duplicated caudal vena cava in animals and humans.

Effects of a mixture of medetomidine, midazolam and butorphanol on anesthesia and blood biochemistry and the antagonizing action of atipamezole in hamsters.

Syrian golden hamsters (Mesocricetus auratus) are useful laboratory rodents for studying human infectious diseases, metabolic diseases and cancer. In other rodents, such as mice and rats, a mixture of medetomidine, midazolam and butorphanol functions as a useful anesthetic, although it alters some blood biochemical parameters. In this study, we examined the effects of this mixture on anesthesia and blood biochemical parameters, and the action of atipamezole, a medetomidine antagonist, in hamsters. Intramuscular injection of a mixture of medetomidine, midazolam and butorphanol at doses of 0.15, 2.0 and 2.5 mg/kg, respectively, had a short induction time (within 5 min) and produced an anesthetic duration of approximately 100 min in hamsters. We also demonstrated that 0.15 mg/kg of atipamezole, corresponding to the same dose as medetomidine, made hamsters recover quickly from anesthesia. The anesthetic agent markedly altered metabolic parameters, such as plasma glucose and insulin; however, 0.15 mg/kg of atipamezole returned these levels to normal range within approximately 10 min after the injection. The anesthetic also slightly altered mineral levels, such as plasma inorganic phosphorus, calcium and sodium; the latter two were also improved by atipamezole. Our results indicated that the mixture of medetomidine, midazolam, and butorphanol at doses of 0.15, 2.0 and 2.5 mg/kg, respectively, functioned as an effective anesthetic, and atipamezole was useful for antagonizing both anesthesia and biochemical alteration in hamsters.

Usefulness of an anesthetic mixture of medetomidine, midazolam, and butorphanol in cotton rats (Sigmodn hispidus).

Tne cotton rat (Sigmodon hispidus) is a laboratory rodent used for studying human infectious diseases. However, a lack of suitable anesthetic agents inconveniences the use of cotton rats in surgical manipulation. This study demonstrated that subcutaneous injection of the mixture of medetomidine, midazolam, and butorphanol (0.15, 2.0, and 2.5 mg/kg, respectively), which is a suitable anesthetic agents for mice and rats, produced an anesthetic duration of more than 50 min in cotton rats. We also demonstrated that 0.15 mg/kg of atipamezole, an antagonist of medetomidine, produced a quick recovery from anesthesia in cotton rats. This indicated that the anesthetic mixture of medetomidine, midazolam, and butorphanol, functioned as a useful and effective anesthetic for short-term surgery in cotton rats.