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When fathers are pregnant


Reproduction is still one of the greatest mysteries in nature. Pregnancies are usually carried out by the female sex. Only in pipefishes and seahorses males are the pregnant sex. An international team of scientists led by the GEOMAR Helmholtz Centre for Ocean Research Kiel has deciphered the complex modifications of their immune system that enabled male pregnancy. The results have now been published in Proceedings of the National Academy of Sciences (PNAS).

How the embryo develops in the womb is a complicated process, that is still puzzling today. In particular, it is unresolved how the paternal genetic information that is also present in the embryo, and the emerging body cells based on their mixed “blueprint” are tolerated by the maternal immune system and not rejected upon recognition as foreign. While this process is now well understood in humans, pregnancies in the animal kingdom still provoke many unanswered questions. An international team under the leadership of the GEOMAR Helmholtz Centre for Ocean Research Kiel has intensively studied the unique male pregnancy in 12 species of pipefishes and seahorses. In some species, the males carry the eggs only on their trunk, in others they protect them by skin flaps or even placenta-like systems which supply the offspring with nutrients and oxygen. MORE

Header image: S. Kaehlert, GEOMAR.

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