The Notch signalling pathway is involved in the very early decision embryonic cells make to become placenta or body
Life starts from one single cell, which ultimately multiplies into millions, taking countless different forms. But before anything else can take shape, the first few cells must become either part of the placenta – a temporary organ that nourishes and protects the embryo – or the body. This fate is typically decided by a sequence of molecular interactions called a signal pathway. Researchers investigating a particular pathway that guides cells towards placenta or body, called ‘Notch’, examined mouse embryos (one pictured, with levels of Notch activity reflected in the colours of cells). They found Notch signalling active after just the second cell division, when the soon-to-be animal is nothing more than four little cells. Details like this are crucial to researchers, who are are keen to learn precisely how and when signals prompt cells to follow particular paths so they can repeat the trick when producing restorative new material from starter cells in promising new stem-cell therapies.
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