Chromosomal anomalies of preimplantation rabbit blastocysts and human artificial abortuses in relation to maternal age.

It is well established that in man there is a higher frequency of chromosomally and phenotypically abnormal offspring and a decline in fertility as maternal age increases. This paper describes preliminary work on some chromosomal aspects of 5- and 6-day old preimplantation rabbit embryos, with attention to maternal age dependence of chromosome anomalies. Chromosome preparations were made by a modification of the method of Shaver and Carr (1967). Two trisomic blastocysts were observed among 50 embryos examined from 10 does of 40 to 52 months of age, that is, 45XY with an extra submetacentric chromosome and 45XX with an extra acrocentric chromosome. In man, three trisomies (47XX, G+, 47XX, D+, and 47XY, G+), one monosomy (45X or 45XX, C-) and one double trisomy (48XY, C+, E+ or 48XXY, E+) were karyotyped out of 32 early induced abortuses from women older than 40. Among the 22, induced abortuses analyzed from women between 35 and 39, one trisomic embryo of 47XY, G+ was observed.