We transfused concentrated primordial germ cells (PGCs) of the black strain (D: homozygous for the autosomal incomplete dominant gene, D) of quail into the embryos of the wild-type plumage strain (WP: d⁺/d⁺) of quail. The recipient quail were raised until sexual maturity and a progeny test of the putative germline chimeras was performed to examine the donor gamete-derived offspring (D/d⁺). Thirty-one percent (36/115) of the transfused quail hatched and 21 (13 females and 8 males) of them reached maturity. Five females and 2 males were germline chimeras producing donor gamete-derived offspring. Transmission rates of the donor derived gametes in the chimeric females and males were 1.8-8.3% and 2.6-63.0%, respectively. Germline chimeric and the other putative chimeric males were also test-mated with females from the sex-linked imperfect albino strain (AL: d⁺/d ⁺, al/W, where al indicates the sex-linked imperfect albino gene on the Z chromosome, and W indicates the W chromosome) for autosexing of W-bearing spermatozoa: No albino offspring were born.

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In the present study we macroscopically examined a change in the distribution of coronary atherosclerosis in cholesterol-fed rabbits. Rabbits were fed a cholesterol-enriched diet for 15 weeks, then replaced by a normal diet, and were sacrificed at 15, 24, 32 and 42 weeks after the start of the experiment. The coronary atherosclerosis in the cholesterol-fed rabbits was distributed more densely in the proximal portion than in the middle and distal portions, and the lesions were severe at 24 and 32 weeks after the start of the experiment. Comparison of lesions in the three portions at these time points showed that the percentages of lesion areas in the proximal portion, the middle portion and the distal portion were approximately 51%, 21 to 25% and 0.2 to 3.7%, respectively. Macroscopic observation of the coronary atherosclerotic lesions showed that the lesions formed over the vessel lumen in the proximal portion within the range of approximately 5 mm from the orifice of the left coronary artery. In the middle portion, the lesions formed predominantly around the orifices of branches as small patchy lesions from 1 to 3 mm in diameter. These findings support previous histopathological reports that suggested that the incidence of stenosis in the proximal portion was high, and the incidence of lesion occurrence in the middle and the distal portions varied. The method, macroscopical investigation of the coronary artery, is useful for analyzing coronary atherosclerosis in the rabbit.

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Morphological and immunohistochemical features of the abdominal mesotheliomas that were developed by inoculation of 3 cell lines (MeET-4, -5 and -6) established from spontaneous abdominal mesotheliomas in male F344 rats. Although the original tumors of three cell lines showed signs of epithelioid growth with a predominantly simple papillary pattern, transplanted tumors revealed a variety of morphologic features including epithelioid with glandular structures, sarcomatous, and a mixture of these components. All tumor cells of transplanted tumors were positive for α-smooth muscle actin (ASMA) but almost negative for desmin as were epithelioid cells of the original tumors, and the cell lines were positive for desmin but not for ASMA. These results suggested that mesothelioma in the F344 rat had the potential for wide spectrum differentiation under in vitro conditions. The microenvironmental factors obtained in vivo can modify their potential ability and their morphological aspects. These factors may be related to tumor cell re-expression of ASMA of tumor cells that were masked under in vitro culture conditions.

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To investigate the pathogenesis of hyperlipidemia-induced atherosclerosis, we examined age-dependent changes in platelet activity, blood coagulation and fibrinolysis in susceptibility to a high cholesterol diet (HCD) feeding in male ICR mice. Pretreatment of platelet-rich-plasma from HCD feeding mice for 3 days with epinephrine (300 μM) resulted in a marked enhancement of adenosine 5'-diphosphate (ADP: 0.1 μM) or collagen (0.7 μg/ml)-stimulated aggregation compared with the same in control mice. Yohimbine as α₂-adrenergic blocker antagonized these aggregations in a dose-dependent manner. A significant increase in plasma total cholesterol and VLDL (very low-density lipoprotein)-LDL (low-density lipoprotein)-cholesterol and the liver/body weight ratio was observed in mice fed on HCD for 3 months (3-month HCD mice). In the early phase of this experiment, a significant increase in fibrinogen was observed. In the middle phase, increases in the activity of antithrombin III (ATIII) and α₂-plasmin inhibitor (α₂-PI) followed. Plasminogen content gradually decreased in both normal diet and HCD mice throughout the experiment. The activity of plasminogen activator inhibitor (PAI) decreased in 3-month HCD mice. Morphological observation of the aortic arch from 3-month HCD mice revealed apparent atheromatous plaques not seen in control mice. These results suggest that 3-month HCD mice can be a convenient hyperlipidemia-induced atherosclerotic model and the changes in platelet activity, coagulation and fibrinolysis in the early phase may be a cause of pathologic changes in this model.

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The present study was designed to determine age-related changes in intestinal and hepatic antioxidant enzymes including superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), and glutathione -S- transferase (GST), and lipid peroxidation in male Wistar rats (n=8) aged 2 wk, 2.5 mon, 5 mon, 10 mon, and 23 mon. In the small intestine, cytosolic SOD, GSH-PX activities and lipid peroxidation were not affected by age, but intestinal GST activity was noticeably enhanced as age increased. In particular, intestinal GST activity in 23 mon old rats was 3 times as strong as that in 2 wk old rats. In the liver, the activity of hepatic cytosolic SOD was not affected by age, whereas GSH-PX and GST activities in rats aged 10 mon and 23 mon were much stronger than those in rats aged 2 wk, 2.5 mon, and 5 mon. The increased lipid peroxidation in 2.5 mon and 5 mon old rats was observed when compared with that of other groups. It is therefore concluded from the results presented here that age greatly increases GST activity in the small intestinal mucosae and increasing GSH-PX, GST activities and lipid peroxidation in the liver from male Wistar rats.

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The hairless rat (WBN/Kob-Ht), a dominant mutant rat derived from the Wistar strain, rarely develops spontaneous erythema of a progressive nature on its skin. Erythema was first observed at 8 weeks of age and the incidence at 20 weeks of age was about 4% in both males and females. Histopathologically, erythema was characterised by dermatitis induced by an immunological reaction. Areas of erythema in the skin were decreased by treatment with dexamethasone (1 mg/kg) or ciclosporin (25 or 50 mg/kg). These results suggested that erythema on the hairless rat could be used as an animal model of spontaneous dermatitis.

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Preventive effects of dehydroepiandrosteone acetate (DHEA-A) and clofibrate (positive control substance) on the fatty liver induced by orotic acid (OA) were examined on the male Sprague-Dawley rats fed a high sucrose based diet containing 1% OA and this diet further mixed with 0.5% DHEA-A or 0.5% clofibrate for 2 weeks. Numerous lipid droplets were observed in the hepatocytes of the rats treated with OA alone, but not in those treated with DHEA-A or clofibrate. In comparison to the group with OA alone, the DHEA-A or clofibrate treated rats showed a larger relative liver weight (to body weight) which was accompanied by increased peroxisomes in the hepatocytes. These results indicate that DHEA-A, as well as clofibrate, may prevent OA-induced fatty liver.

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The usefulness of RT-PCR for the detection of MHV in tissues and feces of experimentally infected animals has been reported, but it was unclear whether the method was also applicable for the detection of MHV during a natural outbreak. Enterotropic infection is considered to be the most common form of natural infection among various forms of MHV infection. In this paper, RT-nested PCR was performed to detect MHV excreted in the feces during an outbreak in an immunocompromised A/WySnJ mouse colony. The expected bands were amplified after nested PCR from 20 fecal samples out of 37. These results showed that RT-nested PCR could be applicable for the diagnosis for MHV natural infection.

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Piebald (Ednrb^s) is a coat color mutation of laboratory mice caused by a decreased expression of endothelin-B receptor gene (Ednrb). The IITES and JF1 mouse strains, whose origins are believed to be different from those of the common laboratory inbred strains, also show a phenotype similar to Ednrb^s. In the present study, we found that the nucleotide sequence of the Ednrb gene of the IITES and JF1 mice is identical to that of the Ednrb^s allele, Ednrb ^s allele has an RFLP of the Ednrb gene identical with that of M. m. molossinus but different from other subspecies, and at least particular regions of chromosome 14 proximal to the Ednrb locus of the IITES and JF1 strains are derived from M. m. molossinus. These findings clearly indicate that the Ednrb^s allele of the laboratory mice has its origin in M. m. molossinus.

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Female guinea pigs with synchronized ovulation by means of implantation of progesterone-filled tubing (P-tube) followed by a progesterone injection, were inseminated by intraperitoneal injection with sperm suspension. First, to obtain the optimum conditions for insemination, the females were inseminated singly over the range of 1-10 × 10 ⁷ spermatozoa before and after the synchronized ovulation. The incidence of conception and implantation was 100% in the females given more than 5 × 10⁷/animal at 9:00 h on the 5th day after removal of the P-tube. Second, the reproductive ability of the inseminated females under this optimal condition was observed throughout the pregnancy to delivery. Inseminated females had a mean ± S.D. gestation period of 68.7 ± 0.5 days, a litter size of 2.8 ± 0.6 pups and body weight of 110 ± 14 g. These data were comparable to those of naturally-mated females. Our findings suggest that the artificial insemination by intraperitoneal injection in combination with the synchronized estrus technique is very useful for production control in a small colony of guinea pigs.

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The midpalatal suture was observed histologically in both toothless osteopetrotic (op/op) and normal (control) mice. The normal mice had a mature sutural structure, which consists of a well-developed cartilage cell zone and palatal bone. In contrast, the thickness of the cartilage cell zone was substantially greater in the op/op mice than that in the controls. Moreover, the cartilage cells in the op/op mice were frequently found in the palatal bone as well as in the sutural space, exhibiting an imperfect fusion. It seems that immature fusion at the sutural interface in the op/op mice is related to a decrease in biting or masticatory force accompanied by the failure of tooth eruption in addition to an essential defect in osteoclast differentiation, which is a congenital symptom in op/op mice.

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