Lizard males have paired genitals called hemipenes - now research shows their genetic origin comes from limbs
In order for vertebrates to evolve from the sea to the land, some drastic evolutionary changes were needed.
Their ancient sea-dwelling ancestors had no need for external sex organs whereas their land relatives did. Now a new study offers insights into the genetic changes that allowed land-dwelling animals to develop sex organs.
The Nature research
They found that when a given nudge, embryonic
limb cells of lizards and snakes could then be turned into genitals. In
mice, tail bud cells could be manipulated in a similar way.
'Genital fate'
The team did this by moving the position of "a signalling
source" called the cloaca - a transient embryonic structure which gives
off signalling molecules informing genes to switch on or off."It demonstrates that there is a flexibility with what kind of cells can get recruited during development to form genitalia," explained lead author of the research, Dr Patrick Tschopp from the Harvard Medical School in Cambridge, US.
suggests the key to the origin of genitalia lies in the limbs, at least in snakes and lizards.
For their genitals - called hemipenes - to develop, a signalling centre instructs the relevant genes to switch on.
Initially the researchers wanted to understand why snakes do not develop limbs but then soon discovered that the earliest stages of genital development closely resembled limb formation.