Tuesday, 26 April 2016

A placenta pioneer from Philadelphia

Newborn and afterbirth of six-banded armadillo
(Euphractus sexcinctus) from Chapman 1901
Some of the earliest studies of placenta in the United States were those of Henry C. Chapman published in Proceedings of the Academy of Natural Sciences of Philadelphia (available on JStor). His observations on the placenta of a six-banded armadillo (Euphractus sexcinctus) were published in 1901 and went unsurpassed for over a century. Importantly, Chapman noted that polyembryony, known from the more widely studied nine-banded armadillo (Dasypus novemcinctus), did not occur in Euphractus.

Fetal membranes of a kangaroo (Macropus giganteus).
Note the small allantois. From Chapman 1881
Chapman is notable for an early study of the fetal membranes of the Eastern grey kangaroo (Macropus giganteus). He noted that there was a large yolk sac but a relatively small allantois that did not form a placenta.

Zonary placenta of an African elephant (Loxodonta africana)
From Chapman c. 1880
Chapman got his armadillo and kangaroo specimens from the Philadelphia Zoo, but his African bush elephant (Loxodonta africana) placenta was from Cooper and Bailey’s London Circus. His was one of several early descriptions of elephant placentation, including a paper by Assheton (here), but there was then a hiatus until the classical work by Amoroso and Perry in 1964 (here). Based on the records of the elephant keeper, Chapman was able to estimate gestation to 650-655 days.

Henry Cadwalader Chapman (1845-1910)
Chapman came from a prominent Philadelphia family. His grandmother was a Biddle and her sister had married a Cadwalader, which may explain his middle name. He studied medicine then spent three years in Europe under Richard Owen in London and Alphonse Milne-Edwards in Paris.

Chapman’s work has been cited by Mossman, Amoroso, Wislocki and Enders (here), but is in danger of being forgotten. When the next paper on Euphractus appeared in 2012 (here), Chapman’s earlier contribution was not acknowledged.

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