Nuclear invaginations carrying nuclear pores may facilitate increased mRNA export and protein import to areas inside the nucleus remote from the nuclear border. In this study on @entity95 embryos, we investigated whether large early embryonic nuclei and the increased import/export demands around major embryonic genome activation (MGA) at the 8-cell stage affected the quantity of nuclear invaginations carrying nuclear pores. To achieve this objective, we used super-resolution 3-dimensional structured illumination microscopy on 10 pronuclei or nuclei per stage of 23 in vivo-fertilized and in vitro-cultured embryos stained with antibodies for the nucleoporin @entity68569 and lamin B and stained with @entity14939 ( @entity14939 ) for chromatin. Statistical comparisons between stages were performed using the Wilcoxon rank-sum test. At the zygote stage, the female pronucleus displayed on average 16.5 and the male pronucleus featured on average 15.25 wide and narrow nuclear envelope invaginations, carrying large or tiny amounts of cytoplasm. Subsequent stages showed predominantly wide invaginations targeting nucleoli. The contact areas between nucleoli and invaginations were free of nuclear pores. In contrast, @entity3473 , which are the almost exclusive @entity3473 during @entity291 and @entity19 pre-implantation development, were not in contact with nucleoli. At the 2-cell stage, the number of invaginations increased to an average of 27.3 invaginations per nucleus (P<0.05) and increased again to peak at the 4-cell stage with 51.2 invaginations per nucleus (P<0.01). At the 8-cell stage (MGA), the amount of nuclear invaginations was reduced to 25.4 invaginations per nucleus (P<0.01). The reduced number of nuclear invaginations at the 8-cell stage could be associated with a significant decrease in average nuclear volume from 2593  m(3) at the 4-cell stage to 960  m(3) at the 8-cell stage (P<0.001) and a subsequent reduced average distance from areas inside the nucleus to the nuclear border. Nuclear invagination numbers continued their decline at the 21-cell stage with 5.2 invaginations per nucleus (P<0.001), whereas nuclear volumes decreased to 618  m(3) (P<0.001). The morula stage, with 6.9 invaginations per nucleus (P=0.9), and the blastocyst stage, with 4.5 invaginations per nucleus (P=0.5), showed no more significant changes. Large @entity68569 cytoplasmic clusters present before MGA may represent a maternally provided @entity68569 deposit. MGA may mark the switch from the use of a @entity68569 deposit to on-demand production. Additionally, over- and under-representation analyses on mitotic blastomeres revealed that @entity68569 association with chromatin is initiated during metaphase before the initiation of the regeneration of the lamina (P<0.001; chi-squared goodness-of-fit test). In conclusion, @entity95 embryonic development is accompanied by stage-dependent changes of the amount of nuclear invaginations carrying nuclear pores. Although @entity291 and @entity19 embryos almost exclusively feature @entity3473 restricted to the nuclear periphery and not in contact with nucleoli, @entity95 embryos feature additional wide invaginations that can reach across the nucleus and target nucleoli.

92 nuclear invaginations adapt to XXXX early embryonic development.

@entity19 :: ('10090', 'Species') :: ['mouse'] @entity95 :: ('9986', 'Species') :: ['rabbit'] @entity68569 :: ('100341571(Tax:9986)', 'Gene') :: ['NUP153'] @entity3473 :: ('MESH:D007443', 'Disease') :: ['type of invaginations', 'narrow invaginations'] @entity291 :: ('9913', 'Species') :: ['cattle'] @entity14939 :: ('MESH:C007293', 'Chemical') :: ["4',6-diamidino-2-phenylindole", 'DAPI']
@entity95 :: (9986,Species) :: ['rabbit']
