Cytogenetic Analysis of Experimental Interspecies Goat-Sheep Chimera

Abstract

Chromosomal analysis was carried out on blood lymphocytes, skin fibroblasts, and germinal cells of an interspecies goat-sheep chimera. This chimera was produced by aggregation of blastomeres of goat and sheep embryos. A cell chimerism 54,XX/60,XY was found in blood lymphocytes and skin fibroblasts. At birth the percentage of lymphocytes with karyotype 54,XX (sheep) amounted to 80% and with karyotype 60,XY (goat) to 20%. With age the percentage of lymphocytes with chromosome complement 54,XX increased, so that at 18 months it was 94% sheep and 6% goat. At the same age, in skin fibroblasts the percentage of cells with goat karyotype reached 25%. Analysis of germinal cells showed in spermatogonia the presence of only karyotype 60,XY and in primary spermatocytes of 29 autosomal bivalents and the sex bivalent XY.

Cytogenetic study of some tissues and age-related changes in cell proportions in a goat-sheep chimera

“…In contrast, 2 wk after birth, lymphocytes of both sheep (54,XX) and goat (60,XY) origin were present in the chimera's blood, the sheep-type lymphocytes constituting 80 % of the total. The proportion of ovine cells progressively increased with time, culminating in the total elimination of cells of caprine origin from the blood of this chimera (Jaszczak et al, 1991). These results, as well as those reported by other authors, indicate that in the blood of a goat-sheep chimera there is a tendency for the ovine component to dominate, and the relative contribution of the two cell populations in the blood changes with the age of the chimera.…”

“…The chimera was produced by aggregating goat (White Polish breed) and sheep (Polish Merino breed) blastomeres of isolated embryos at the 8-to 12-cell stage. Details of the procedure were presented previously (Jaszczak et al, 1991). The chimera, born by a recipient ewe, was phenotypically a male goat with large patches of wool located on its shoulders and hindquarters, which remained to the end of its life at age 10.…”

“…In the case of lymphocytes, 300 metaphase spreads were karyotyped. Results of the cytogenetic analysis of the 6-and 10-yr-old goat-sheep chimera were compared with an earlier study on this animal (Jaszczak et al, 1991) to determine changes in the proportions between the two cell populations.…”

“…Different proportions of two cell populations were found in the tissues of different goat-sheep chimeras (Polzin et al, 1987;Roth et al, 1989;Ruffing et al, 1993). The proportions of the cell populations changed with the age of the chimeras (Fehilly et al, 1985;Jaszczak et al, 1991). The present study was aimed at a cytogenetic analysis of some tissues in a goatsheep chimera and investigation of changes in the proportions of the two cell populations with age.…”

Experimental embryology of mammals at the Jastrzebiec Institute of Genetics and Animal Breeding

“…The obtained chimaera (Czlonkowska et al, 1988;Jaszczak et al, 1991), a male named Hobgoblin (Fig. 3), survived ten years and served as the source of information about changing contributions from both embryo-derived components to the tissues of the chimaera throughout his lifespan (Jaszczak et al, 1999).…”