Monday, 4 September 2017

Hermann von Ihering and polyembryony in armadillos

Uterus of the mulita (Dasypus hybridus) with 9 identical
embryos. From Fernandez Morph Jahrb 1909; 39:302-333
In 1886 Hermann von Ihering opened the uteri of two pregnant armadillos. Both contained 9 fetuses of the same sex. Each fetus had its own amnion but all were enclosed in a common chorion (placenta). He was the first to propose that the embryos were derived from a single fertilized egg with splitting into separate embryos occurring early in development.
Arrangement of fetal membranes in the mulita (Dasypus hybridus).
From Fernandez Morph Jahrb 1909; 39:302-333
Ihering had studied the mulita or Southern Long-Nosed Armadillo (Dasypus hybridus). Later Fern├índez demonstrated that splitting occurred at the embryonic shield stage in the mulita. Newman & Patterson, working with the nine-banded armadillo (D. novemcinctus), came to a similar conclusion. Fern├índez, however, was the first to obtain early stages before splitting occurred. More recently, the nine-banded armadillo was the object of elegant studies by Allen Enders (summarized here). Specific polyembryony is known only from Dasypodinae and is thought not to occur in the two other subfamilies of armadillo.
Hermann von Ihering (1850-1930)
CC BY-SA 3.0 Wikimedia Commons
Hermann von Ihering was a German zoologist who relocated to Brazil in reaction to his family's disapproval of his marriage to a widow with a child. This was in 1880. His first years were spent as a collector in the southern state of Rio Grande do Sul, based on an Island known as Ilha do Doutor (Doctor's Island). In 1893 he became the first director of Museu Paulista (State Museum of Sao Paulo) and held this post for 23 years.

Hermann von Ihering´s principal area of expertise was mollusks. He also became an expert on the birds of the State of Sao Paulo, of which he observed 695 species and subspecies. For my Brazilian readers there is an excellent recent biography by Hitoshi Nomura (open access here). It lists 338 of his publications.

His son Rodolpho von Ihering (1883-1939) was also a zoologist. He was appointed vice director of Museu Paulista, which led to the accusation of nepotism that was to force Hermann's resignation. Rodolpho was an expert on fish and is credited with founding Brazilian pisciculture with stations at Porto Alegre in Rio Grande do Sul and Pirassununga, S.P.

References: Biol Zentralblatt 1886; 6:532-9 and Arch Physiol 1886; pp. 443-50

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