The visible embryo: a visual history

The Moment of Conception and Ensoulment
Illumination from Jean Mansel, Vie de Nostre Seigneur Jesus Christ,
fifteenth century, fol. 174. 11.1 x 15.8 cm.
Bibliotheque Nationale, Paris
From "Making Visible Embryos"

Via the invaluable Morbid Anatomy, I discovered a remarkable new website, "Making Visible Embryos." Assembled by Tatjana Buklijas and Nick Hopwood of the University of Cambridge, with the support of the Wellcome Trust, it traces the evolution of our understanding of the human embryo, beginning with an unexplored mystery within the inaccessible womb, through epigenesis and preformationism, until developmental embryology became a standard medical field.

As illustrations, Buklijas and Hopwood have pulled together a wealth of historical resources, including several old favorites of mine - including wax models from La Specola and Jan van Rymsdyk's obstetric engravings for Hunter's medical atlases. When I started blogging a few years ago, it was hard to find any of these materials online. This is a very pleasant change!

paper-mache gynecological model
after Dr. Louis Auzoux, c. 1880

One of the fascinating aspects of this subject is that physicians wishing to study the developing fetus had to negotiate some powerful cultural taboos. Anatomical models of pregnant women, not to mention actual specimens of aborted fetuses, were often considered unacceptable for public display or discussion, much less dissection. The lines between obscenity, sexuality, sensationalism and medicine easily blurred: Joseph Kahn, for example, was the author of the atlas below - but also the proprietor of a London anatomical museum with a reputation as a quack venereal clinic. In 1873, the authorities invoked the Obscene Publications Act, closed his museum, and destroyed the exhibits with hammers.

Color lithograph by J. C. Frank
from Joseph Kahn, Atlas of the formation of the human body
London, 1852
Cambridge University Library
From "Making Visible Embryos"

Eventually, as the details of human development were teased out with dissections and microscopes, the field became more respectable. But teaching the subject actually grew more difficult. How could an instructor portray cell layers that move and enfold one another, processes poorly captured in text, and incompletely represented in either 2D slides or static 3D models? As the website puts it,

Keen students and lay listeners were extremely excited to see embryos for the first time, but as the courses became routine many medics found the complicated bendings and foldings of cell layers, and the abstruse terminology, difficult and dull.

I've taught developmental biology, and it really is brutal: students either love it or hate it. Many students are turned off by the counterintuitive cellular processes, the tininess of the embryo, its concealment behind layers of uninteresting-looking tissue, and the esoteric lexicon required to discuss its geography. Ingenious models like the following, which swivels open to show cross-sections of various organs, are invaluable to helping students (and instructors!) understand what's going on.

human embryo model
wax on iron frame
Friedrich Ziegler, 1902
Institut fur Anatomie I, Universitat Jena.
From "Making Visible Embryos"

Irrespective of scientific precision, any portrayal of an embryo is laden with subtext. Do we consider the embryo an integral part of the female anatomy, or a separate entity? Is it a human being or a mass of cells? Ensouled or inert? Though we've unraveled many of the biological mechanisms of development, we've been unable as a culture to agree on the very definition and identity of an "embryo". "Making Visible Embryos" illustrates how the images used to study and teach embryology, and to practice medicine, have also influenced the popular understanding of pregnancy and reproduction - for better or worse.

Related: Wombs, Waxes, and Wonder Cabinets