Detailed human embryo development revealed in three-dimensional 'atlas'
A new three-dimensional "atlas" of human embryonic development shows the early stages of growth in stunning detail.
A team of researchers from the Academic Medical Centre in the Netherlands created interactive modelling software to study the early stages of human development from conception to two months.
The digital model and the resulting atlas offers embryologists and researchers a searchable glimpse into the first eight weeks of development in the human womb.
In doing so, the researchers say their work highlighted many medical textbooks were out of date and often use imagery and diagrams from decades ago.
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In some cases, diagrams used in textbooks dated to the early 20th century.
The research, published in Science and on a standalone website, said there were few specimens of early-development embryos and inaccuracies in the descriptions of embryonic growth had crept into textbooks from the study of animal embryos.
By mapping human development, embryologists can better understand normal growth, organ placement, and congenital defects.
They used the Carnegie collection of human embryos at the National Museum of Health and Medicine in Washington DC - named for the American institution which started collecting specimens in the early 20th century.
"These interactive models will serve as educational and scientific resources for normal and abnormal human development.
"The basic human body plan, the arrangement of organs in the body, is laid down during embryonic development.
"Insight into the formation of this plan informs researchers and clinicians about normal development versus the development of congenital malformations, the latter of which have an incidence of 3 per cent in the human population and cause up to one-quarter of all neonatal deaths," the researchers said.
The study said the intricacies of embryo development were difficult to understand and textbooks were often based on the work of early embryologists.
Around the world there are only a small number of collections of authentic human embryos.
"Textbooks on human development are often based on the works of early embryologists, some published more than 100 years ago.
"Because of the limited availability of human embryonic specimens, it is difficult or impossible to independently verify the information carried in these textbooks, or even to assess whether this information is derived from studies on human or animal models."
The 3D software - from thousands of digital scans of the Carnegie embryo collection - gives researchers a choice of developmental stages to view, from conception to two months. The image can be manipulated, to reveal individual organs, skeletal development, the nervous system and so on.
Researchers concluded that some descriptions of organs, such as the kidneys and a structure called the notochord - a rod of cells that forms one of the bases for the human skeleton - were based on animal models in many textbooks rather than factual observations of human specimens.
University of Otago department of anatomy lecturer and stem cell researcher Dr Tim Hore said the medical establishment was only just beginning to understand human development, for the simple reason human embryos were rarely available for scientific study and available collections were difficult to access.
Hore studies the first two weeks of human development, about which little is known. Science was constantly interrogating previous findings and many textbooks struggled to keep pace with developments, he said.
From a teaching perspective, computer modelling was welcome as many of the foundations of embryology were based on a small number of old collections.
"This is really helpful. People like us who teach development, we're constantly having to update all of our stuff to keep pace with these new developments and refinements and how we understand human development. There are a lot of areas of science where text books are not keeping pace.
"It's a very exciting time for embryologists.
"My research interests are even earlier in development than those discussed in this paper and although we know quite a lot from IVF clinics about what happens immediately after fertilisation, there is a big black hole of understanding regarding the events beyond this.
"Moreover, we are only just beginning to benefit from the power of computational modelling when it comes to these early events in human development, and this study is a powerful example of the gains that can be made."