Observation of X-Y chromosomal configuration in spermatocytes of infertile PD strain male rats

ABSTRACT PD strain male rats that carry an autosomal recessive gene, preaxial duplication (gene symbol: pd), are sterile in the homozygous condition (pd/pd) due to a spermatogenic breakdown in the process of spermatogenesis at the spermatocyte and/or spermatid stage(s), although heterozygotes (pd/+) are normal. In this study, pd/pd males were examined for the presence of abnormal association of the sex chromosomes that might lead to spermatogenic breakdown. Light and electron microscopic observations of the chromosomes at meiotic prophase and metaphase in primary spermatocytes revealed several types of abnormal X‐Y association and configurations in pd/pd males. However, the incidences of the abnormal configuration were comparable to those in pd/+ males. These results suggest that abnormal X‐Y chromosome association in the germ cells is not a significant cause of spermatogenic breakdown in pd/pd males.