The megakaryocyte DNA content and platelet formation after the sublethal
whole body irradiation of rats
G Tanum
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.
Volume 63,
Issue 4,
pp. 917-920,
04/01/1984
Copyright © 1984 by The American Society of Hematology
