title: The megakaryocyte DNA content and platelet formation after the sublethal whole body irradiation of rats.
abstract: The DNA content of rat bone marrow megakaryocytes (MK) was studied by Feulgen photometry, following whole body irradiation with 2 Gy. The DNA measurements were preceded by acetylcholinesterase staining to avoid missing the smaller 2N-8N MK. The number of 2N-8N MK declined immediately following irradiation, whereas the number of 16N-64N MK remained normal for 4 days before decreasing. The number of 2N-8N and 16N-64N MK reached minimum around days 7 and 10, respectively, and thereafter increased to supranormal values at days 14 and 20, respectively. Platelet production, measured by 35S incorporation into platelets, increased during the first 4 days, then decreased to minimum about day 10. A rise to supranormal values was present at day 20. All values were about normal 30 days after exposure. The observed pattern may be explained as follows: Most of the 16N-64N MK survive the applied dose and maintain their ability to produce platelets. Some of the 2N-4N and 8N MK survive irradiation and transform into platelet-producing MK. No influx of cells from the MK stem cell compartment into the MK compartment can be observed before day 7 after irradiation. One explanation for this time lag may be that thrombocytopenia, which does not occur before then, is an essential stimulus for MK stem cell activation.
mesh_terms: D000818:Animals; D001792:Blood Platelets / Q000166:cytology / Q000528:radiation effects*; D004247:DNA / Q000096:biosynthesis*; D006410:Hematopoiesis / Q000528:radiation effects*; D008297:Male; D008533:Megakaryocytes / Q000166:cytology / Q000528:radiation effects*; D010976:Platelet Count; D011003:Ploidies; D051381:Rats; D011917:Rats, Inbred Lew; D014916:Whole-Body Irradiation
chemical_list: D004247:DNA