Adler I D, Shelby M D, Bootman J, Favor J, Generoso W, Pacchierotti F, Shibuya T, Tanaka N
GSF-Institut für Säugetiergenetik, Oberschleissheim, Germany.
Mutat Res. 1994 Jun;312(3):313-8. doi: 10.1016/0165-1161(94)00017-4.
The two tests considered by the Working Group were the mammalian germ cell cytogenetic assay and the rodent dominant lethal test. It was agreed that both tests were mainly used for identification of germ cell hazards, however, that the commonly applied protocol of the dominant lethal assay often supplied information for hazard characterization such as sensitivity of particular developmental stages of male germ cells. No particular species or strains were indicated. Concurrent solvent controls were regarded as indispensable for both tests. In the discussion of the mammalian germ cell cytogenetic assay, harmonization was obtained to a large extent with the cytogenetic bone marrow assay regarding the number of animals (5), the number of cells analyzed per animal (200), the highest exposure dose (MTD) and sampling times (twice within 24 and 48 h after dosing). However, it was pointed out that only the single acute exposure was adequate for the mammalian germ cell cytogenetic assay. Furthermore, it was stated that only structural chromosome aberrations could be analyzed and that it was not informative to score polyploidies or aneuploidies. In the discussion of the rodent dominant lethal test, it was stated that the assay was generally performed with treated males, however, increasing concern about female specific effects required that a protocol for female dominant lethal testing should be developed and validated. Acute and subacute treatment schedules were considered equally acceptable. It was regarded as highly important that the entire male germ cell development from meiosis to mature sperm was covered in the test protocol either by the appropriate mating schedules after single dosing or by subchronic dosing during the respective period. Postimplantation loss, preimplantation loss and fertility rate were the main parameters to be assessed in the rodent dominant lethal tests. It was agreed that the size of the experiment depended on the spontaneous frequency of dead implants, the mating scheme and the statistical design of the experiment.
工作组审议的两项试验为哺乳动物生殖细胞细胞遗传学试验和啮齿动物显性致死试验。大家一致认为，这两项试验主要用于识别生殖细胞危害，不过，显性致死试验常用的方案通常会提供有关危害特征的信息，例如雄性生殖细胞特定发育阶段的敏感性。未指明具体的物种或品系。两项试验均认为同时设置溶剂对照必不可少。在讨论哺乳动物生殖细胞细胞遗传学试验时，在动物数量（5只）、每只动物分析的细胞数量（200个）、最高暴露剂量（最大耐受剂量）和采样时间（给药后24小时和48小时内各两次）方面，与细胞遗传学骨髓试验在很大程度上达成了一致。然而，有人指出，哺乳动物生殖细胞细胞遗传学试验仅单次急性暴露就足够了。此外，有人指出，只能分析结构性染色体畸变，对多倍体或非整倍体进行评分并无参考价值。在讨论啮齿动物显性致死试验时，有人指出该试验一般用经处理的雄性动物进行，不过，对雌性特定效应的日益关注要求制定并验证雌性显性致死试验方案。急性和亚急性处理方案被认为同样可以接受。试验方案通过单次给药后的适当交配方案或在相应时期进行亚慢性给药，涵盖从减数分裂到成熟精子的整个雄性生殖细胞发育过程，这一点被视为极为重要。植入后丢失、植入前丢失和生育率是啮齿动物显性致死试验中要评估的主要参数。大家一致认为，实验规模取决于植入物死亡的自发频率、交配方案和实验的统计设计。
