DIFFERENCE IN SENSITIVITY OF INNER CELL MASS AND TROPHECTODERM TO X-IRRADIATION IN MOUSE BLASTOCYSTS

Citation
T. Kumazawa et al., DIFFERENCE IN SENSITIVITY OF INNER CELL MASS AND TROPHECTODERM TO X-IRRADIATION IN MOUSE BLASTOCYSTS, Teratology, 57(3), 1998, pp. 146-151
Citations number
30
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Toxicology,"Developmental Biology
Journal title
ISSN journal
0040-3709
Volume
57
Issue
3
Year of publication
1998
Pages
146 - 151
Database
ISI
SICI code
0040-3709(1998)57:3<146:DISOIC>2.0.ZU;2-6
Abstract
Pregnant B6C3F1 mice were exposed to a single whole body X-irradiation on day 4 (73-74 hr postconception) of gestation. In experiment 1, the y were sacrificed at 2, 4, 6, or 9 hr after a dose of 2 Gy, and their embryos were removed and examined with light and electron microscopy. In experiment 2, dose-response effects of irradiation on the embryos w ere examined 4 hr after doses of 0-4 Gy. In experiment 3, DNA fragment ation (a marker of apoptosis) was observed by 3'-OH nick-end labeling technique. In inner cell mass (ICM) and trophectoderm (TE) of blastocy sts exposed to 2 Gy, cells with cytoplasmic degeneration, or dead cell s phagocytosed by their neighboring cells, were found. Although morpho logical features of these dying cells did not reveal typical character istics of apoptosis such as nuclear condensation and membrane blebbing , DNA fragmentation was detected by nick-end labeling technique. The d egenerated cytoplasm consisted of aggregating ribosomes. Degenerated c ells began to increase from 2 hr after irradiation and reached maximal at 4 hr in both ICM and TE. The incidences of degenerated cells in IC M were higher than those in TE at any time point. These findings provi de evidence that cell death observed in blastocysts after X-irradiatio n is apoptotic and sensitivity of the two groups of cells (ICM and TE) to X-rays is different. (C) 1998 Wiley-Liss, Inc.