MEIOTIC CHROMOSOME-STUDIES IN A RAM CARRYING A RECIPROCAL TRANSLOCATION

The behaviour of meiotic chromosomes of a ram carrying the reciprocal translocation (1;20)(p23,q24) was studied by synaptonemal complex anal ysis in an electron microscope and conventionally stained meiotic chro mosome spreads in a light microscope. In all of the studied primary sp ermatocytes a cross-shaped quadrivalent configuration at pachytene sta ge was identified. No association or pairing between the sex bivalent and the quadrivalent was recognized. On conventionally stained prepara tions a high incidence of polyploid reads was found. Among 21 analysab le metaphase II spreads 24 % were diploid and 9 % were id. A single sp read was hyperhaploid (n = 28). At diakinesis and metaphase I stages a ring-quadrivalent was observed. At these stages the polyploid cells o ccurred with a frequency of 25 and 18 %, respectively.