Periventricular leucomalacia (PVL)-like lesions in two neonatal cynomolgus monkeys (Macaca fascicularis).

Periventricular leucomalacia (PVL) is a lesion of immature cerebral white matter that occurs in the perinatal period. In man, PVL is the predominant form of brain injury and a cause of cerebral palsy and cognitive deficits in premature infants. PVL affects fetuses and newborns, particularly those who have undergone oxygen deprivation as may occur in premature birth. Many clinical and pathological studies of PVL have been performed in man, but there is no clear definition of PVL in animals. A few spontaneous PVL-like cases in puppies or experimental cases in other animal species have been reported. The present study reports the histopathological and immunohistochemical features of PVL-like lesions in two neonatal cynomolgus monkeys. In both cases, there was cerebral white matter necrosis with marked infiltration of lipid-laden phagocytes and a reduction of neurons in the cerebral cortex. In case 1 there was extensive cavitation of the cerebral white matter. In case 2 there was reactive astrocytosis associated with a decrease in oligodendroglial cells and a decrease in cerebral white matter myelin. To our knowledge, this is the first report of PVL-like leucoencephalomalacia in non-human primates.

Specific gravity of whole blood in cynomolgus monkeys (Macaca fascicularis), squirrel monkeys (Saimiri sciureus), and tamarins (Saguinus labiatus) and total blood volume in cynomolgus monkeys.

Blood collection is a common laboratory procedure in animal experiments. The purpose of this study is to establish baseline data for two essential hematologic parameters, total blood volume (TBV) and specific gravity of blood (SGB), of nonhuman primates. The SGB was determined by dropping samples of whole blood into cupric sulfate solution. The values for the mean SGB +/- 1 standard deviation are: cynomolgus monkeys, 1.0526 +/- 0.0019 [males (n = 39), 1.0531 +/- 0.0017; females (n = 48), 1.0522 +/- 0.001]; squirrel monkeys, 1.0555 +/- 0.0037 [males (n = 56), 1.0581 +/- 0.0027; females (n = 76), 1.0536 +/- 0.0032]; and tamarins, 1.0582 +/- 0.0020 [males (n = 13), 1.0582 +/- 0.0023; females (n = 17), 1.0581 +/- 0.0018]. To determine the TBV, blood was collected in tubes containing 1.5 mg EDTA after intravenous injection of Evans Blue solution. The TBV was obtained after correcting for the hematocrit and the dilution factor of the Evans Blue solution. The formulae were established to estimate TBV by referring to body weight (BW). There was no significance between TBV and BW in male monkeys weighing more than 6 kg.

[Management of cynomolgus monkey infants after separation from their mothers].

To establish an efficient rearing system for weaned cynomolgus infants, 51 groups composed of 4 weanlings each were formed. Of them each of thirty-eight groups had an adult female "nurse" monkey, who had no kinship with any of the 4 weanlings. The nurse was present during the first 4 weeks after weaning. The daily incidence of watery diarrhea was analyzed to assess the usefulness of the nurse monkey for stabilizing physiological conditions of the weanlings. Diarrheal incidence was significantly lower in the 38 groups with a nurse than in the 13 control groups without a nurse throughout the 4-week period of observation. This trend continued for more than 5 weeks after removal of the nurse. Thus, the time and manpower necessary for treating infant diarrhea were greatly reduced in this rearing system.

Normal hematologic values in the cynomolgus monkeys aged from 1 to 18 years.

Normal hematological values including erythrocyte count (RBC), hematocrit value (Ht), hemoglobin concentration (Hb), total leucocyte count (WBC), and differential leucocyte count were determined with 206 healthy cynomolgus monkeys (Macaca fascicularis) aged in 1 to 18 years. These animals were born and reared at Tsukuba Primate Center for Medical Science, NIH, Japan. Additionally, 32 cynomolgus monkeys of wild origin estimated to be 5 or more years old were examined for their hematology. The presence or absence of sex- and age-related differences in the values was statistically analysed. As regards infant and juvenile monkeys, there were no significant differences in RBC, Ht and Hb between males and females. However, these values became significantly larger in males than in females after sexual maturation. Lymphocyte count was larger than neutrophil count until 3 to 4 years of age after birth, but this relation was inverted in adult monkeys aged more than 5 years. Segmentation of the nucleus was a prominent finding in neutrophils. Neither sex- nor age-related difference in the number of nuclear segmentation was noted.

[Congenital cataract in a cynomolgus monkey].

The anterior part of the eye was examined with 1,531 newborn cynomolgus monkeys (Macaca fascicularis). A male (about 0.07%) of those newborns was noticed to have white opacities in his both eyes (Fig. 1). This finding was diagnosed to be bilateral congenital cataract by observing with a slit-lamp biomicroscope. Partial resorption of the white opaque part occurred one week after birth in the right eye (Fig. 2) and three weeks after birth in the left eye (Fig. 3). As a result of the resorption, observation of the ocular fundus by an ophthalmoscope became possible at two and seven weeks of age in the right and left eyes, respectively (Figs. 6 and 7), even though the ophthalmoscopic figures were not complete. White opacities occupied again nearly the whole area of the lens at 10 months of age in the left eye (Fig. 4) and at 14 months of age in the right eye (Fig. 5). Breeding studies are needed to determine if this case has any genetic background.

Relationship between fetal position and stillbirth in the cynomolgus monkeys (Macaca fascicularis): retrospective analysis.

Retrospective analyses were made on the relationship between fetal position and stillbirth, using 703 pregnant cynomolgus monkeys. Incidence of the breech position was 59.1% to 12 weeks of gestation. The rate decreased stepwise to 10.4% on the day before delivery. Twenty-one (65.6%) of 32 monkeys who were in the breech position on the day before delivery had stillbirths, whereas only one stillbirth occurred among 275 monkeys whose fetuses were in the cephalic position.