Pseudovagina

The pseudovagina is a connective tissue hollow cord of female marsupials (Marsupialia), which is formed from a vaginal sinus and represents the birth canal of the young animals.

anatomy

Marsupials have two wombs and two vaginas , which, due to the lack of fusion of the paired Mullerian ducts, do not fuse into one vagina during embryonic development, as in the placenta . Both vaginas open separately into the urogenital sinus and only in kangaroos grow together in the area of ​​the entry point to form a short tube. The uteri each also open into a vagina; medial to this junction, both often grow together into an unpaired vaginal sinus ; In the case of the actual nasal aspirators this is expanded to a receptaculum seminis .

At birth, a cord of connective tissue is formed starting from the vaginal sinus, which extends between the two vaginae to the urogenital sinus. Before the birth, a cavity through which the birth takes place, the so-called pseudovagina, forms within this cord. With the exception of the kangaroos and honeybuckling , in which the canal remains after the first birth, the pseudovagina forms anew before each birth.

Systematics

Since a pseudovagina is developed in all marsupials and only occurs in them, it is a derived, apomorphic characteristic that can be used to justify the marsupials as a kinship group.

literature

• Ulrich Zeller: Marsupialia (Metatheria, Didelphia), marsupials. In: W. Westheide, R. Rieger: Special Zoology. Part 2: vertebrates or skulls. Spektrum Akademischer Verlag, Munich 2004, ISBN 3-8274-0307-3 , pp. 491-492.