“…To sum up, the efficiency of intra-species and inter-species somatic cell cloning of domesticated mammals is affected, to a great extent, by three factors: the provenance of frozen/thawed and ex vivo-expanded nuclear donor cell lines (NDCLs) that provide genetic resources from different livestock species or breeds (Samiec and Skrzyszowska, 2010;Li et al, 2013;Olivera et al, 2016;Lee et al, 2019), the morphological, cytogenetic, cytophysiological and molecular quality parameters of the NDCLs (Samiec et al, 2013(Samiec et al, , 2019Zhang et al, 2019;Wiater et al, 2021); and the subsequent incidence of programmed (apoptotic or autophagic) cell death in the development of cloned embryos (Chi et al, 2017;Samiec et al 2015;Jeong et al, 2020). This efficiency is also dependent on such molecular mechanisms as the epigenetic ability of the nuclear donor cell-inherited genome to be reprogrammed in SCNT-derived oocytes and result in cloned embryos (Samiec and Skrzyszowska, 2018;Deng et al, 2020;Sampaio et al, 2020;Wang et al, 2020b) and the intergenomic crosstalk between nuclear and mitochondrial DNA fractions in the host cytoplasm of nuclear recipient oocytes and the blastomeres of the developing cloned embryos (Srirattana et al, 2011;Samiec and Skrzyszowska, 2021;Takeda, 2019;Xu et al, 2019;Magalhães et al, 2020) (Figure 1).…”