What looks like a pair of scary alien eyes is actually the final stage in the duplication of a cell. Cell duplication is preceded by a process called mitosis, which is that moment in the evolution of a cell when the replicated chromosomes are separated into two new nuclei. Mitosis is the prerequisite for a cell to divide into two identical ones.
During mitosis, the chromosomes – visible in cyan in this image – which have already replicated, condense and attach to spindle fibres that pull one copy of each chromosome to opposite sides of the cell. This picture of the week shows two cells, almost completely separated, and connected to each other only in one small area. Pictured in red are elements of the cytoskeleton – a protein structure that gives cells their shape and assists in cell division.
Mitosis is the origin of all multicellular life. Every human and every animal starts its existence as a single cell. Only as a result of mitosis can this one cell became a multicellular organism.
Image: Markus Mund & Philipp Hoess / EMBL