Magic embryology: human development is slower (Introduction)

by David Turell @, Saturday, September 19, 2020, 18:21 (1363 days ago) @ David Turell

Control mechanisms are found:

"All mammals follow the same steps to grow from embryo to adult. This involves the same series of events, in the same sequence, using similar genes and molecular signals. However, the speed of progress through these steps differs considerably from one species to another. For instance, motor neurons -- the nerve cells that control muscle movement -- take about three days to develop in mice, but over a week to develop in humans.


"...the researchers discovered that differences in the speed at which proteins are broken down and replaced explains the difference in speed between the two species. Proteins are constantly turned over -- made and dismantled -- in cells, and this happens twice as fast in mouse cells compared to human cells. This faster rate of protein turnover in mouse cells accounts for the faster pace of motor neuron formation.

"Teresa Rayon explained, "Human and mouse motor neurons use the same genes and molecules for their embryonic development, it just takes longer for the process to play out in humans. Proteins are simply more stable in humans than mouse embryos and this slows the rate of human development."

"'It's as if mouse and human embryos are reading the same musical score and playing the same tune but the metronome ticks more slowly in humans than in mice. Now that we've found the metronome, we want to understand how to change its speed.'"

Comment: The differences are not surprising, but humans are not the slowest. Gestation in elephants is 22 months.

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