Like arms and legs, external genitals are a result of adaptation to a terrestrial habitat. A study on snakes, lizards and mice financed by the Swiss National Science Foundation now shows why the embryonic development of genitals and hind legs is so similar.
When vertebrates left the seas and conquered the land, they not only adapted their limbs to the new environment, but also their reproductive organs. Whereas fish and amphibians reproduce under water, reptiles, birds and mammals do so on land. In order to prevent their eggs from drying up, they let their germ cells fuse together inside the body. For this purpose, they had to develop new features.
"Like branches from a tree trunk"
"External genitals make internal fertilisation possible," says Patrick Tschopp. In the journal "Nature", the Swiss biologist has traced the origins of the male sexual organ in snakes, lizards, chickens and mice together with his colleagues from Switzerland, France and the United States (*).
In very simplified terms, an embryo at first resembles a tube. As it continues to develop, the upper and lower limb buds begin to sprout. "Like branches from a tree trunk," says Tschopp. In mice, the hind-leg buds are always separate from the embryonic structures out of which the reproductive organ develops. In snakes and lizards, however, the genitals develop in a way very similar to the hind legs.
Sex-specific genes are only activated at a later stage, as the researchers have been able to show through elaborate experiments. Hemipenises, the lateral pair of reproductive organs in snakes and lizards, thus probably developed from hind legs (although snakes lost theirs in the course of evolution).
Tschopp specialises in basic research, no treatment methods can be derived from his findings yet. But Tschopp thinks that the results might at least partially explain why, in the case of certain congenital diseases, deformed arms and legs are often coupled with damage to the external genitals. The reason lies in the similar development processes and molecular affinity between sexual organs and hind legs.
(*) Patrick Tschopp, Emma Sherratt, Thomas J. Sanger, Anna C. Groner, Ariel C. Aspiras, Jimmy K. Hu, Olivier Pourquié, Jérôme Gros, and Clifford J. Tabin (2014). A relative shift in cloacal location repositions external genitalia in amniote evolution. Nature online. doi: 10.1038/nature13819 (available to journalists as a PDF from email@example.com)
Dr Patrick Tschopp
Department of Genetics
Harvard Medical School
Tel.: +1 (617) 432 65 32
Media - Abteilung Kommunikation | idw - Informationsdienst Wissenschaft
Unique brain 'fingerprint' can predict drug effectiveness
11.07.2018 | McGill University
Direct conversion of non-neuronal cells into nerve cells
03.07.2018 | Universitätsmedizin der Johannes Gutenberg-Universität Mainz
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
13.07.2018 | Event News
13.07.2018 | Materials Sciences
13.07.2018 | Life Sciences