STRAIN DIFFERENCE IN GROWTH OF AHA AND HAN-WISTAR RAT EMBRYOS IN-VIVOAND AFTER EXTENDED CULTURE IN-VITRO

Recently, a rationalization of strains used in our laboratories has le d to the adoption of the Han Wistar rat as the standard strain for rep eat dose and reproductive toxicity studies. Earlier work on developing an extended whole embryo culture model in which AHA (Alien and Hanbur y Albino)rats were grown from day 10 to day 14 of pregnancy was theref ore repeated in the Han Wistar strain. Differences were seen in rate o f embryonic growth in vivo for the two strains of rat, particularly in terms of crown-rump length and protein content. No such differences w ere seen in rate of morphological development. Extending the period of whole embryo culture up to day 14 of pregnancy using a novel protocol further illustrated these differences in growth characteristics. Resu lts showed marked differences in growth, but not in general morphologi cal development, when a standard culture technique was used. These fin dings indicate that accepted standard culture regimens are unsuitable for some strains of rat, and that the development of strain-specific m ethodology must be considered when such models are to be used for mech anistic studies. Copyright (C) 1996 Elsevier Science Ltd.