title: Spontaneous Cardiac Hypertrophy in a Crl:CD(SD) Rat.
abstract: Cardiac hypertrophy was observed in a 9-week-old Crl:CD(SD) rat that died unexpectedly. The animal was allocated to the control group of a toxicity study, and no abnormalities in its general conditions, body weight or food intake were observed. Necropsy revealed an increase in heart weight. Gross examination indicated cardiac enlargement with thickening of the right and left ventricular walls. Histopathological examination revealed hypertrophy of the cardiomyocytes in the right and left ventricular walls and the interventricular septum. Electron microscopic examination indicated bizarre nuclei and accumulation of an increased number of various sizes of mitochondria in the perinuclear region of the hypertrophied myocytes. Hypertrophied myocytes connected by intensely folded intercalated disks were also observed. Based on these findings, the animal was diagnosed with cardiac hypertrophy. This is the first case report of cardiac hypertrophy in this strain.
authors.affiliation: Safety Research Center, Yakult Central Institute for Microbiological Research, Yakult Honsha Co., Ltd., 1796 Yaho, Kunitachi-shi, Tokyo 186-8650, Japan.
authors.forename: Tomo
authors.initials: T
authors.lastname: Suzuki
authors.forename: Shoichi
authors.initials: S
authors.lastname: Kado
authors.forename: Minoru
authors.initials: M
authors.lastname: Ando
authors.forename: Yuriko
authors.initials: Y
authors.lastname: Nagata
authors.forename: Shin
authors.initials: S
authors.lastname: Iwata
authors.forename: Toshihide
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Kazumi
authors.initials: K
authors.lastname: Uchida