The paramyxovirus family comprises major human and animal pathogens such as 
measles virus (MeV), mumps virus (MuV), the parainfluenzaviruses, Newcastle 
disease virus (NDV), and the highly pathogenic zoonotic hendra (HeV) and nipah 
(NiV) viruses. Paramyxovirus particles are pleomorphic, with a lipid envelope, 
nonsegmented RNA genomes of negative polarity, and densely packed glycoproteins 
on the virion surface. A number of crystal structures of different paramyxovirus 
proteins and protein fragments were solved, but the available information 
concerning overall virion organization remains limited. However, recent studies 
have reported cryo-electron tomography-based reconstructions of Sendai virus 
(SeV), MeV, NDV, and human parainfluenza virus type 3 (HPIV3) particles and a 
surface assessment of NiV-derived virus-like particles (VLPs), which have 
yielded innovative hypotheses concerning paramyxovirus particle assembly, 
budding, and organization. Following a summary of the current insight into 
paramyxovirus virion morphology, this review will focus on discussing the 
implications of these particle reconstructions on the present models of 
paramyxovirus assembly and infection.