Table 1. Megakaryocyte number and myeloid: erythroid ratio in intact control (I−R) and irradiated (I+R) mice estimated by a board certified veterinary clinical pathologist (LS) according to standard protocols.

Treatment	Day	Megakaryocytes					Myeloid∶Erythroid ratio
Control	3	N	N	N	N	N	N	N	N	N	N
	8	N	N	N	N	N	N	N	N	N	N
	30	N	N	N	N	N	N	N	N	N	N
Irradiated	3*	−3	−3	−3	−3	−3	NA	NA	NA	NA	NA
	8* †	−3	−3	−3	−2	−2	+2	+2	+2	+2	+2
	30* †	−1	−1	−1	−1	N	+2	+2	+1	+1	+1

Cells contain the data for individual mice (n = 5/group); N = normal, NA = too few cells to reliably estimate. Numerical scale: −4 severely decreased, −3 markedly decreased, −2 moderately decreased, −1 mildly decreased, +1 mildly increased, +2 moderately increased, +3 markedly increased, +4 severely increased, normal assigned a value of 0 for statistical calculations. Megakaryocyte numbers were significantly depressed by radiation exposure on Days 3 and 8, with a trend towards ongoing suppression on Day 30. Too few hematopoietic precursors were available for interpretation in the markedly hypocellular Day 3 post-irradiation marrow, but the recovery phase was accompanied by significantly increased myeloid to erythroid ratios characterized by persistent erythroid hypoplasia. Wilcoxon rank-sum test:

^*Megakaryocytes, Irradiated significantly decreased compared with Control of the same day, Day 3, p = 0.0182; Day 8, p = 0.0236; Day 30, p = 0.0450.

^†Myeloid:Erythroid ratio, Irradiation significantly increased when compared with Control, Day8, p = 0.0182; Day 30, p = 0.0236.