English: Ultrathin-section TEM imaging of Noumeavirus-infected Acanthamoeba cells. (a) 10 min pi, virions have been engulfed and are in vacuoles. (b) 20 min pi, virions in vacuoles exhibit holes (black arrows) in their external translucent shell and appear more spherical. (c) 30 min pi, virions have entirely lost their external shell and appear as spherical electron-dense nucleoids, which can be seen in vacuoles as well as in the cell cytoplasm (and Fig. 9, black arrows). Scale bar, 100 nm. (d) 1 h pi, electron-dense tubular structures (black arrowheads) appear in the cytoplasm. (e) 4 h pi viral factories (VF) settle in the cell cytoplasm next to the nucleus and the cell organelles are pushed at their periphery (scale bar, 2 μm). The new virions are assembled and the electron-dense mature (white arrows) and immature (white arrowheads) virions are scattered in the same VF. Inset: immature and mature virions inside the VF along with tubular structures (black arrowheads). Scale bar, 200 nm. (f) 7 h pi, the newly synthesized virions are gathered into vacuoles inside the cytoplasm before being released in the extracellular environment (scale bar, 500 nm).