Scientists from the University of North Carolina School of Medicine (USA) made a series of images of the microcosm to show the coronavirus "in the face", as well as to clearly demonstrate how it attacks the human body. For this purpose, they used a grown culture of bronchial epithelial cells, which are the first to get in the way of viruses. A live sample of SARS-CoV-2 was added to the tube and left for 96 hours.
The outer part of the bronchial epithelium is covered with special cilia that act as a mechanical barrier between pathogens in the air and the respiratory system. They help the lungs maintain moisture and self-cleanse, but they also become the first breeding ground for coronavirus. In a contrasting, specially colored image, the cilia are greenish-blue, yellowish sputum filaments are visible between them, and the coronavirus particles themselves are shown in bright red.
96 hours after infection, scientists counted 3 × 10 ^ 6 new virions in the sample. This allows you to roughly estimate the rate of spread of the pathogen in the body. The pictures were taken using an electron microscope, the size of one virion is about 50 nm, but we see that they do not work alone, preferring to accumulate and stick around the cilia.
Some of these red virions will penetrate the cilia and attack the cells of the bronchi and lungs. But much more will remain outside, where they will be picked up by air currents and carried out with particles of saliva when breathing and coughing. This is how the virus is transmitted between carriers - and this is the main reason why you need to wear a mask and, if possible, not breathe towards uninfected people.