Ochotona rufescens is an animal species native to Afghanistan, and is among many new animal species currently being rasied for use in experimental research in Japan. In the present paper, we report morphological findings on ocular and auditory character of Ochotona rufescens examined first under normal conditions and then under the influence of various agents, and the results were compared with those on other experimental animals used in this study. On histological examination, the cochlear portion of the labyrinth was found to consist of a coiled canal making two and one half turns from its basal end to the upper turn, and was identical to those of cats and rabbits. Moreover, triple rows of outer sensory hair cells and a single row of inner sensory hair cells were observed. Kanamycin and furosemide (Lasix^®), a diuretic, were administered 10 min. apart to determine the effects of these drugs on pinna reflex, however, as a result of these administrations, none of the Ochotona rufescens tested showed any appreciable depression of this reflex. By f unduscopic observation with photographic records, principal retinal arteries were hardly demonstrable except for extremely vague chorioidal vessels, in the layer of the pigmented epithelium which had a puce-like color. By contrast, retinal veins were seen in the f undus oculi, as well as whitish optic nerves. The amplitude of the“a” wave in the electroretinogram (ERG) of Ochotona rufescens was only 1/6 that of albino rats or albino rabbits, but the“b” wave was similar in amplitude for all these three species. Atropine and pilocarpine are known to cause pupil dilation or contraction, respectively, in other test animals, i. e. beagle dogs, albino rabbits and guinea pigs. Both agents were thus given as 1 % solutions in the form of eye drops. Atropine caused no dilation of the pupils in the Ochotona rufescens, while pilocarpine had a miotic effect upon this animal.

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Electrocardiogram (ECG) was taken fromMacaca fuscatain the supine position under secobarbital anesthesia. The ECGs were recorded in the leads of standard (I, II, III), augmented unipolar limb (aVR, aVL, aVF) and unipolar chest (V_4R, V₁, V₂, V₃, V₄, V₅, V₆, ) . The ECG was similar to that of humans as well as the monkeys of other species in their general patterns and the voltage of each wave (P, Q, R, S, T), though the heart rate was considerably different. The direction of T wave was consistent with that of human ECG. The PR, QRS and QT intervals and the duration of P wave were in good agreement with those of monkeys of other species, and amounted to about 50% of those of human ECG. His bundle electrogram (HBE) was recorded with a tripolar electrode catheter inserted into the right ventricle via the femoral vein, and PA, AH, HV and PV intervals were measured. All of the values were also approximately 50% of those reported in human HBE. Such short time intervals observed inMacaca fuscatamay be due to a smaller heart size of the monkey as compared to the human's. The measurements of ECG and HBE reported in the present study may be used as a normal reference in ECG and HBE ofMacaca fuscataunder anesthesia. The study suggests that theMacaca fuscatais useful as an animal model to investigate the repolarization process of human ECG.

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The parotid glands of Djungarian hamster were examined by the light and electron microscopy. The acinar cells contained acidophile granules and reacted with the periodic acid-Schiff (PAS) and stained slightly with alcian blue (AB) ; they were thought to be seromucous in nature. The acinar epithelia were composed of light cells, dark cells and specific light cells containig spheroid granules. Cytoplasmic crystalloids of moderate to high densities were observed in nearly all light cells. The intercalated duct cells were composed of light cells alone, and contained the granules of moderate density in the apical and supranuclear regions. The striated duct cells consisted of light and dark cells. The most of these cells contained small granules of low to high densities in the apical and supranuclear regions. Myoepithelial cells were detected around the acini, and nerve terminals were observed among the adjacent acinar cells. The parotid gland of Djungarian hamster revealed no histological differences between the sexes.

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Attempts at inducing experimental hypertension by loading with NaCI have been undertaken in six Göttingen mini-pigs (G-mini-pigs) . In this connection, a paraperitoneal nephrectomy method was established and the renin-angiotensinaldosterone system after bilateral nephrectomy was investigated. Paraperitoneal nephrectomy was considered to be a safe and convenient method because the operation was accompanied with little hemorrhage and completed in a short time. Using three animals, the renin-angiotensin-aldosterone system was examined after surgical removal of bilateral kidneys. After removal of both kidneys, plasma renin activity decreased rapidly while plasma renin substrate gradually increased. Plasma angiotensin II and aldosterone levels underwent a striking increase. This increase of plasma renin substrate was considered to be due to the presence of an endogenous renin-like substance, while angiotensin II and aldosterone levels appeared to undergo secondary stimulation. Plasma cortisol showed a transient increase after removal of the two kidneys and then remained at a low level, which implies that the adrenocortical function was normal. In the other three animals, hypertension was induced by NaCl loading and unilateral nephrectomy and the blood pressure remained increased persistently. Concomitantly with this phenomenon, plasma renin activity was gradually suppressed and the aldosterone level showed a similar tendency. It is suggested that sustained hypertension can be induced in G-mini-pigs by NaCl loading combined with unilateral nephrectomy.

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InMicrotus arvalis Pallas, new born voles were fostered to ICR mice and supplied with pellets for mice after weaning. A high concentration of glycosuria was shown in about 50 % of the voles and continued for over ten weeks. Concentrations of blood glucose and plasma FFA in glycosuric voles were three or four times as high as those in normal controls. The fermentation ability and pH lowered in the esophageal sac, and comparatively large amount of starch existed in the pyloric stomach of the glycosuric voles. This demonstrated that the dietary starch were tolerably transported to the pyloric stomach without being fermented in the esophageal sac. Glycosuria was also induced in about 50% of the voles supplied with an acidified water (0.02 N HC1, pH 1.7), and the glycosuric voles showed a low pH (1.4- 4.2) and lowering of the fermentative ability in esophageal sac. Such an abnormal fermented condition in the esophageal sac is considered to induce glycosuria in the voles. Glucose tolerance in the diabetic voles which were supplied with pellets for mice lowered considerably with the progress of the disease. On the other hand, plasma insulin levels in the slight diabetic cases rose to eight times as high as normal level, but they lowered considerably with the progress. In the serious cases, the voles fell into complete insulin deficiency. From the above results, the herbivorousMicrotusspecies was considered to be useful as an“animal model”of the dietetic diabetes.

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The present study is an attempt to utilize hybrids among several inbred strains of rats as useful animals for the studies of effectiveness and toxicology on drugs. Four-way crosses were made among the LEW, WM, F344 and DRY strains of rats, and their characteristics were examined. From the breeding data of diallel crosses among these four strains and reciprocal crosses among their F₁hybrids, the mating type indicating the highest reproductivity was (LEW×WM) F₁× (F344×DRY) F₁. These four-way crosses were designated as LWFD. The reproductivity of this mating type was exceedingly higher than those of four strains. In order to examine the susceptibility to thiamine hydrochloride, the acute toxicity test was practiced in inbred strains, F₁hybrids and four-way crosses. As a result, in spite of highly heterogeneous population, the LWFD did not show a peculiar response in comparison with four strains and their F1 hybrids. Furthermore, hematological and clinico-biochemical values of the LWFD did not show a large variability as presumed. From these results, it is suggested that hybrids such as four-way crosses among inbred strains can be used as useful animals for the studies of effectiveness and toxicology on drugs.

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A manual palpation method has been devised for early detection of pregnancy of the rat. One hand gently restrains the animal by holding it from behind in the usual manner. The thumb of the other hand is placed on the posterior abdomen and the first three fingers on the ventral midline. The three fingers were pressed gently upward and laterally. The embryos can then be palpated through the abdominal wall between the thumb and the three fingers. The number of fetuses was not affected by this palpation method. Using this technique, pregnancy was detected on the 5 th day of gestation with an accuracy rate of 80% and between the 6 th and 9 th days with a 100% accuracy.

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The relationship between the microbial organism infection and the vaginal smear cycle was investigated using 12 germf ree Wistar Imamichi rats at 50 days of age. Germfree rats exhibited continuous vaginal cornification which occasionally interrupted by the appearance of nucleated epithelial cells. However, leukocytes which are characteristic of the metestrus and diestrus stage in conventional rats were not observed in the vaginal smear of these animals. At 70 days of age, 8 animals were taken out from the germfree isolator and conventionalized. In other 4 animals, the vaginal lumen was contaminated withEnterobacter cloacaein the isolator. Within 3 days after the treatments, leukocytes appeared in the vaginal smear of all animals in both groups. Thereafter, these animals continued the regular 4 days vaginal cycle to 90 days of age, at which the observation was terminated. The above results suggest that the appearance of leukocytes in the vaginal smear in the rat is closely related to the bacterial colonization in the lumen, together with the action of the progesterone secreted from the ovary.

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