Chromosomal anomalies and disturbance of transcriptional activity at the pachytene stage of meiosis: relationship to male sterility.

Morphological analysis of pachytene spermatocytes obtained from male mice carrying three chromosomal rearrangements--a Robertsonian translocation, Rb(X-2)2Ad; an autosomal reciprocal translocation, T(16;17)43H; and a tertiary trisomic, Ts(113)70H--demonstrated frequent association between the XY bivalent and the T43H and T70H translocation chromosomes. Quantitative autoradiographic data revealed that the normal transcriptional inactivity of the XY bivalent was not significantly disturbed, in contrast to that of the 16;17 quadrivalent and the extra 1(13) marker chromosome. These results are interpreted as an extension of the XY inactivation process to the associated autosomes and discussed in relation to male sterility.