Vivo Mammalian Cytogenetic Tests

A variety of tissues can be utilized for cytologic analysis of mutagen treated animals with bone marrow being one of the more commonly used cell sources. 

The micronucleus test, which analyzes the effects of mutagen exposure on developing bone marrow red blood cells, is probably the most rapid of the cytogenetic assays and compares well in sensitivity with cytogenetic analyses of more complex cell types.  

In essence the test screens mammalian red blood cells, which in their mature form lack a nucleus, for remnants of chromosomal fragments generated by mutagen exposure. These fragments are left behind when the nuclei are extruded from the maturing cells and they form the micronuclei for which the test is named. Experimentally, the test is normally conducted by administering the test substance by a route which enables it to enter the blood stream. In a t3T)ical assay four different dosages with five mice or rats per dose may be used. The bone marrow cells are isolated about 30 hours later and stained slides prepared. Approximately 1,000 red blood cells per animal are scored and the total test takes about 1 week to complete. 

---

It must be emphasized that the dominant lethal assay should be applied together with other in vivo- mammalian mutagenicity tests, notably in vivo cytogenetics, karyotype analysis of bone marrow, and the host-mediated assay, in addition to ancillary submammalian tests. Such mammalian systems can be simply and practically incorporated in the course of routine toxicity testing. 

OECD (1983). OECD Guidelines for the Testing of Chemicals. No. 475. Genetic toxicology in vivo mammalian bone marrow cytogenetic test chromosomal analysis. Adopted 4 April 1984. 

Sofuni, T., Hayashi, M., Matsuoka, A., Sawada, M., Hatanaka, M. Ishidate, M., Jr (1984b) Cytogenetic effects of gaseous and volatile chemicals on mammalian cells in vitro and in vivo. II. Mieronueleus tests in mice. Eisei Shikenjo Hokoku, 10, 84-90 (in Japanese)... 

Like other cytogenetic tests, SCE tests can be performed on cells treated in culture or in vivo. For the in vivo method, cells from treated animals can be excised and cultured in vitro in the presence of BrdUrd or the animal itself can be given an injection or infusion of BrdUrd so that SCE can be observed in bone marrow or spermatogonial cells directly. The latter method is one of the simplest and least expensive ways to observe the effects of chemicals in gonads. The test is not limited to mammalian cells, but has been successfully carried out in plants, insects, and fish. 

Fertility and early embryonic development rats Developmental rats, rabbits Prenatal and postnatal development rats Genetic toxicology Ames test, in vitro mammalian chromosome aberration assay, in vivo cytogenetic test, FIGPRT test with V79 cells... 

In vivo Mammalian Bone Marrow Cytogenetic Test -... 

Pati, P.C. and S.P. Bhunya. 1989. Cytogenetic effects of fenvalerate in mammalian in vivo test system. Mutat. Res. 222 149-154. 

Under Guideline S2B, the following standard test battery is recommended (1) a test for gene mutation in bacteria, (2) an in vitro test with cytogenetic evaluation of chromosomal damage with mammalian cells or an in vitro mouse lymphoma thymidine kinase (TK) assay, and (3) an in vivo test for chromosomal damage using rodent hematopoietic cells. 

Natarajan AT, Boei JJ (2004) Formation of chromosome aberrations insights from FISH. Mutation Res 544 299-304 OECD Guideline 475 (1997) Mammalian Bone Marrow Chromosome Aberration Test. Adopted July 21 Preston RJ, Dean BJ, Galloway S, Holden H, McFee AF, Shelby M (1987) Mammalian in vivo cytogenetic assays Analysis of chromosome aberrations in bone marrow cells. Mutation Res 189(2) 157-165... 

---