Cell Cycle Modification in Trophoblast Cell Populations in the Course of Placenta Formation

Three steps to the immortality of cancer cells: senescence, polyploidy and self-renewal

“…Somatic polyploidy (endopolyploidy) can be reversible and irreversible, differing in several key aspects. Irreversible polyploidy [ 24 - 26 ] occurs through re-replication in the absence of mitosis and can reach very high levels of genome duplication (up to several thousand or more), for example in the salivary glands of Diptera [ 27 ] and in the giant cells of the rodent trophoblast [ 28 ]. In contrast, endopolyploidy of mammalian hepatocytes and cardiomyocytes occurs through aborted mitoses, is less extensive; and typically does not revert [ 25 , 26 ], although it retains this potential [ 29 , 30 ], while transient polyploid mammalian tumour cells, which typically also do not exceed 32n, can revert to mitosis and initial para-diploidy [ 31 - 33 ].…”

“…Irreversible polyploidy [ 24 - 26 ] occurs through re-replication in the absence of mitosis and can reach very high levels of genome duplication (up to several thousand or more), for example in the salivary glands of Diptera [ 27 ] and in the giant cells of the rodent trophoblast [ 28 ]. In contrast, endopolyploidy of mammalian hepatocytes and cardiomyocytes occurs through aborted mitoses, is less extensive; and typically does not revert [ 25 , 26 ], although it retains this potential [ 29 , 30 ], while transient polyploid mammalian tumour cells, which typically also do not exceed 32n, can revert to mitosis and initial para-diploidy [ 31 - 33 ]. In tumours, this process is induced by DNA or spindle damage and occurs by aborted mitosis - ‘mitotic slippage’ (reset of tetraploid interphase from aborted metaphase) or by a-cytotomic DNA-bridged bi-polar mitosis starting endopolyploidy from bi-nuclearity and often followed by multi-nucleation [ 22 , 23 , 25 , 32 , 34 ].…”

Invasion and genome reproduction of the trophoblast cells of placenta junctional zone in the field vole, Microtus rossiaemeridionalis

“…Polyploidy of trophoblast cells at the border with maternal tissues, as pointed out before (Zybina and Zybina, , ), probably plays a protective role in embryo development. Indeed, close contact of semi‐allogenic trophoblast and decidual cells may result in mutual damaging, for example to chromosomes.…”

Functional consequences of somatic polyploidy in development

“…2A ), mammalian keratinocytes ( Gandarillas and Freije, 2014 ), C. elegans hypodermis and intestines ( Hedgecock and White, 1985 ), insect larval abdominal epithelium ( Bischoff and Cseresnyés, 2009 ; Nardi et al, 2018 ), insect Malpighian tubules ( Buntrock et al, 2012 ; Rangel et al, 2015 ; Wang and Spradling, 2020 ), mammalian and insect salivary glands ( Follette et al, 1998 ; Matsumoto et al, 2020 ), insect intestines ( Fox et al, 2010 ; Schoenfelder et al, 2014 ; Scholes et al, 2014 ), mollusk albumen glands ( Anisimov, 2005 ), mammalian pancreas ( Webb et al, 1982 ) and mammary glands ( Rios et al, 2016 ). In addition, many polyploid extra-embryonic tissues that play a role in providing nutrients to embryos are also important for creating a barrier or supporting the embryo micro-environment; for example, fish syncytial yolk nuclei ( Kageyama, 1996 ; Kondakova and Efremov, 2014 ), mammalian trophoblast giant cells ( Barlow and Sherman, 1974 ; Chen et al, 2012 ; Sher et al, 2013 ; Velicky et al, 2018 ; Zybina and Zybina, 2005 , 2011 , 2020 ) or syncytiotrophoblasts ( Azar et al, 2018 ) and Drosophila follicle cells ( Maines et al, 2004 ). Interestingly, many polyploid cell types undergo polyploidization during either postnatal development or reproduction, two periods in the life cycle when tissues need to grow and function simultaneously.…”