Figure 4

Transmission electron photomicrographs showing pathological ultrastructural changes in bMECs infected withS. agalactiae. A, B Non-infected bMECs are rich in microvilli and have abundant organelles in cytoplasm, especially mitochondria; C after 6 h infection, bMECs show deformation, loss of microvilli, nuclear swelling and rupture (black arrows); D Organelle disruption and swollen endoplasmic reticulum (white arrows), chromatin spread to the nuclear membrane edge (black arrow). E Mitochondria with decreased electron density, cristae degeneration and accumulation of dense granules. F Some cells show disruption and loss of organelles. n nucleus, m mitochondrion, mv microvillus, er endoplasmic reticulum.