Three-dimensional mapping of almost 15,000 human tissue samples has been used to update the world’s understanding of early embryonic development. Remarkably, until now, our knowledge of the first two months of pregnancy was based in part on articles written more than a century ago.
“It is exceedingly difficult to verify this knowledge, given the restricted availability of human embryos,” write Bernadette de Bakker at the Academic Medical Center in Amsterdam, the Netherlands, and colleagues in a paper published in Science.
Because of these restrictions, much of the existing information on early development is based on old anatomical texts, or data drawn from chickens or other animals.
To increase accuracy, the researchers analysed samples from the massive collection of sectioned human embryos held by the Carnegie Institution for Science in Washington DC – a trove dating back to 1914.
“We identified and labelled up to 150 organs and structures per specimen and made three-dimensional models to quantify growth, establish changes in the position of organs, and clarify current ambiguities,” the researchers explain.
The first two months of embryonic development are crucial in the development of the body’s internal structures, and this period is often when genetic malformations occur.
Bakker’s team spotted discrepancies between certain organs in actual embryo specimens and the information in textbooks.
“Our interactive atlas allows the user to directly link the annotated organs in the 3D reconstructions with the underlying histological sections of the Carnegie Collection, thereby enabling independent verification and further analyses,” they explain.
The new digital atlas shows organs at various stages of growth and illustrates how they connect with circulatory and nervous systems. The researchers say the database will provide an invaluable resource for studies on early human development, growth and genetic disorders.