10 research outputs found
Spontaneous Extraskeletal Osteosarcoma in the Stomach of an Aged F344 Rat
Extraskeletal osteosarcoma is a very rare tumor in humans and animals including
rats. This paper describes a case of extraskeletal osteosarcoma observed in the
glandular stomach of an aged female Fischer 344 rat. Grossly, a whitish solid
mass was observed at the greater curvature of the glandular stomach.
Histologically, the tumor consisted of both atypical polygonal and pleomorphic
spindle-shaped cells, with pleomorphic nuclei, and it contained variable amounts
of osteoids and small clumps of mature bone tissue. In addition, mitotic figures
were frequently observed. Neither invasion of the muscle layer or vessels in the
stomach nor metastasis to distant organs was detected. There were no skeletal
tumors in the body. Immunohistochemically, the tumor cells were positive for
osteocalcin, osteonectin, vimentin and S-100 protein. Judging from these
results, the present tumor was diagnosed as extraskeletal osteosarcoma. This is
the first report of spontaneous extraskeletal osteosarcoma arising from the
stomach in a rat
Ocular lesions induced in infant rats by busulfan
Although busulfan, a bifunctional alkylating
agent, is known to induce cataracts in infant rats, the full
nature of busulfan-induced ocular lesions has not yet
been shown. In order to clarify this point, 6-day-old rats
were treated with a single dose of 20 mg/kg busulfan and
the ocular tissue was histopathologically and
immunohistochemically examined at 1, 2, 4, 7 and 12
days after treatment (DAT). As a result, in the nuclear
layer (NL) of the peripheral retina, apoptotic cells
significantly increased at 1 DAT and peaked at 2 DAT
when cell proliferating activity was depressed. At 4
DAT, the NL showed wavy deformation with formation
of rosette-like structures, and these changes progressed
prominently at 12 DAT. In addition, a significant
reduction in the retinal thickness due to decreased
thickness of NL or inner NL was detected at 2 and 4
DAT. On the other hand, in the germinative zone of the
lens equator, apoptotic lens epithelial cells significantly
increased from 2 to 7 DAT, resulting in partial loss of
lens epithelial cells at 7 and 12 DAT. At 12 DAT,
prominent swelling and vacuolation of lens fibers were
observed in the area from the equatorial zone to the
posterior pole, indicating the development of cataract.
The present results strongly suggest that prominent
apoptosis in component cells was the initial and essential
event underlying the developpment of busulfan-induced
ocular lesions in infant rats