Objective    To establish hematopoietic microenviroment damage model in BALB/c-nu/nu nude mice for transplant experiment.     Methods    Experimental nude mice were irradiated with 3.0

4.0

5.0

6.0 and 7.0 Gy

60

Co γ ray respectively. Then the hemogram changes were detected at 1

3

5

7

14

21 d after irradiation

the quantity of CFU-F and megakaryocyte was counted at 1

7

14

21 d after irradiation

and the biopsy of myeloid tissue was performed.     Results    Irradiated with 7.0 Gy

all nude mice died. Bone marrow of nude mice irradiated with 6.0 Gy was depressed obvi

ously

and did not recover within 21 d

and some of them died after irradiation. Slight bone marrow depression was observed in the nude mice irradiated with 3.0 Gy and 4.0 Gy. Nude mice irradiated with 5.0 Gy showed obvious bone marrow depression

but it recoverd within 21 d. CFU-F count had slight decrease in the nude mice irradiated with 3.0 or 4.0 Gy

and remarkable decrease in the nude mice irradiated with 6.0 Gy till the  21st day after irradiation. CFU-F count also had remarkable decrease after irradiation with 5.0 Gy and recovered in 21 d after irradiation.     Conclusion    The suitable radiation dose is 5.0 Gy for creating hematopoietic microenviroment damage model in BALB/c-nu/nu nude mice.