Fundele R H, Norris M L, Barton S C, Fehlau M, Howlett S K, Mills W E, Surani M A
Department of Molecular Embryology, AFRC Institute of Animal Physiology and Genetics Research, Babraham, Cambridge, UK.
Development. 1990 Jan;108(1):203-11. doi: 10.1242/dev.108.1.203.
The fate of parthenogenetic cells was investigated during development of fetal and early postnatal chimeras. On day 13 of embryonic development, considerable contribution of parthenogenetic cells was observed in all tissues of chimeric embryos, although selection against parthenogenetic cells seemed to start before day 13. Between days 13 and 15 of development, parthenogenetic cells came under severe selective pressure, which was most striking in tongue. The disappearance of parthenogenetic cells from tongue coincided with the beginning of myoblast fusion in this tissue. Severe selection against parthenogenetic cells was also observed in pancreas and liver, although in the latter, parthenogenetic cells were eliminated later than in skeletal muscle or pancreas. In other tissues, parthenogenetic cells may persist and participate to a considerable extent throughout the gestation period and beyond, although a significant decrease was observed in all tissues. Parthenogenetic in equilibrium fertilized chimeras were significantly smaller than their non-chimeric littermates at all developmental stages. These results suggest that the absence of paternal chromosomes is largely incompatible with the maintenance of specific differentiated cell types. Furthermore, paternally derived genes seem to be involved in the regulation of proliferation of all cell types, as indicated by the drastic growth decceleration of parthenogenetic in equilibrium fertilized chimeras and the overall decrease of parthenogenetic cells during fetal development. Chromosomal imprinting may have a role in maintaining a balance between cell growth and differentiation during embryonic development. The major exception to the selective elimination of parthenogenetic cells appear to be the germ cells; viable offspring derived from parthenogenetic oocytes were detected, sometimes at a high frequency in litters of female parthenogenetic in equilibrium fertilized chimeras.
在胎儿及出生后早期嵌合体的发育过程中，对孤雌生殖细胞的命运进行了研究。在胚胎发育第13天，嵌合胚胎的所有组织中均观察到孤雌生殖细胞有相当大的贡献，尽管对孤雌生殖细胞的选择似乎在第13天之前就已开始。在发育的第13天至15天之间，孤雌生殖细胞受到严重的选择压力，这在舌部最为明显。孤雌生殖细胞从舌部消失与该组织中肌母细胞融合的开始同时发生。在胰腺和肝脏中也观察到对孤雌生殖细胞的严重选择，尽管在肝脏中，孤雌生殖细胞的消除比在骨骼肌或胰腺中要晚。在其他组织中，孤雌生殖细胞可能会持续存在，并在整个妊娠期及之后在相当程度上参与其中，尽管在所有组织中都观察到了显著减少。孤雌生殖平衡受精嵌合体在所有发育阶段都明显小于其非嵌合的同窝仔。这些结果表明，父本染色体的缺失在很大程度上与特定分化细胞类型的维持不相容。此外，父本来源的基因似乎参与了所有细胞类型增殖的调控，这表现为孤雌生殖平衡受精嵌合体的生长急剧减速以及胎儿发育过程中孤雌生殖细胞的总体减少。染色体印记可能在胚胎发育过程中维持细胞生长与分化之间的平衡中发挥作用。孤雌生殖细胞选择性消除的主要例外似乎是生殖细胞；检测到了来自孤雌生殖卵母细胞的有活力后代，有时在雌性孤雌生殖平衡受精嵌合体的窝仔中频率很高。
