TISSUE-SPECIFIC LOSS OF PROLIFERATIVE CAPACITY OF PARTHENOGENETIC CELLS IN FETAL MOUSE CHIMERAS

Parthenogenetic cells are lost from fetal chimeras. This may be due to decreased proliferative potential. To address this question, we have made use of combined cell lineage and cell proliferation analysis. Thu s, the incorporation of bromodeoxyuridine in S-phase was determined fo r both parthenogenetic and normal cells in several tissues of fetal da y 13 and 17 chimeras. A pronounced reduction of bromodesoxyuridine inc orporation by parthenogenetic cells at both developmental stages was o nly observed in cartilage. In brain, skeletal muscle, heart and intest inal epithelium, this reduction was either less pronounced or observed only at one of the developmental stages analysed. No difference betwe en parthenogenetic and normal cells was observed in epidermis and gang lia. Our results show that a loss of proliferative potential of parthe nogenetic cells during fetal development contributes to their rapid el imination in some tissues, The analysis of the fate of parthenogenetic cells in skeletal muscle and cartilage development demonstrated diffe rent selection mechanisms in these tissues. In skeletal muscle, parthe nogenetic cells were largely excluded from the myogenic lineage proper by early post-midgestation. In primary hyaline cartilage, parthenogen etic cells persisted into adulthood but were lost from cartilages that undergo ossification during late fetal development.