Chromosome Number in Rabbit Blastocysts

Abstract

DURING recent years a series of papers have appeared discussing the constancy or inconstancy in the chromosome number in mammalian tissues. It is now generally agreed that some tissues show a certain degree of inconstancy in the chromosome number either by having aneuploid cells¹ or by developing more constant euploid (or polyploid) cells². I have shown³ that by careful attention to technique, including pre-treatment in hypotonic saline solution and using a gentle squash, about 95 per cent of the cells in rabbit blastocysts (five days old) will appear normal with 2n = 44, whereas 2–3 per cent have hypo- or hyper-ploid numbers. The reason for low numbers seems in many cases to have been mechanical disturbances introduced by the squash technique.