13 research outputs found
Bilateral Cataract in a Cynomolgus Monkey
Severe bilateral cataract was found in a 7 year-old naïve female cynomolgus monkey
(Macaca fascicularis) 3 months before necropsy. During macroscopic
examination, severe opacity and thinning of the lens were observed in both eyes.
Histopathology revealed that the lens nuclei and majority of cortex lens fibers had
disappeared and become excavated, while the lens fibers in the subcapsular area were
swollen and distorted. Other observations included atrophy and vacuolation in the lens
epithelial cells and proliferation of spindle cells and collagen fiber beneath the
anterior capsule of the right eye. Immunohistochemical staining of these spindle cells
revealed the presence of vimentin, cytokeratin and α-smooth muscle actin (α-SMA), which
were considered to be derived from lens epithelial cells. This is a rare case of
spontaneous, bilateral, hypermature cataract in a cynomolgus monkey
Porencephaly in a Cynomolgus Monkey (Macaca Fascicularis)
Porencephaly was observed in a female cynomolgus monkey (Macaca fascicularis) aged 5 years and 7 months. The cerebral hemisphere exhibited diffuse brownish excavation with partial defects of the full thickness of the hemispheric wall, and it constituted open channels between the lateral ventricular system and arachnoid space. In addition, the bilateral occipital lobe was slightly atrophied. Histopathologically, fibrous gliosis was spread out around the excavation area and its periphery. In the roof tissue over the cavity, small round cells were arranged in the laminae. They seemed to be neural or glial precursor cells because they were positive for Musashi 1 and negative for NeuN and GFAP. In the area of fibrous gliosis, hemosiderin or lipofuscin were deposited in the macrophages, and activated astroglias were observed extensively around the excavation area
Fetal and Neonatal Goiter in Cynomolgus Monkeys Following Administration of the Antithyroid Drug Thiamazole at High Doses to Dams During Pregnancy
To evaluate morphologic alterations in the thyroid gland in the second generation in cynomolgus monkeys, pregnant dams were exposed to high doses of thiamazole. In Experiment A, dams received thiamazole intragastrically via a nasogastric catheter from gestation day (GD) 50 to GD 150 or on the day before delivery. Initially, the dose level was 20 mg/kg/day (10 mg/kg twice daily); however, the dose level was subsequently decreased to 5 mg/kg/day (2.5 mg/kg twice daily), since deteriorated general conditions were observed in two dams. Six out of seven neonates died on the day of birth. The cause of neonatal death was tracheal compression and suffocation from goiter. The transplacental exposure to thiamazole affected the fetal thyroid glands and induced goiter in all neonates. The surviving neonate was necropsied 767 days after discontinuation of thiamazole exposure and showed reversibility of the induced changes. In Experiment B, dams were intragastrically administered thiamazole at 5 mg/kg/day (2.5 mg/kg twice daily) for treatment periods from GDs 51 to 70, 71 to 90, 91 to 110, 111 to 130 and 131 to 150. All fetuses showed enlarged thyroid glands but were viable. Histopathologically, hypertrophy and/or hyperplastic appearance of the follicular epithelium of the thyroid gland was observed at the end of each treatment period. The most active appearance of the follicular epithelium, consisting of crowded pedunculated structure, was demonstrated at end of the treatment period from GD 131 to 150. This is the first report on the morphology of fetal and neonatal goiter in the cynomolgus monkey