The history of Embriology

Although the word "anatomy" is derived from the Latin word "anatomia," its roots can be traced back to two Greek words: "tomia," meaning to cut, and "ana," meaning up. This suggests that the word literally describes the process of dissecting a living being to study its internal organs, or "viscera."

In the early days, the founders of anatomy had a multidisciplinary approach to studying the human body. However, their understanding was limited due to ancient methods and rules. They often relied on drawing parallels from animal dissection since human dissections and the study of anatomy were banned in ancient and medieval times. Eventually, anatomy became a separate field from physiology and pathology, focusing on studying body parts such as organs and systems on a larger scale, known as gross anatomy.

Some experts consider histology, the microscopic study of cells and tissues, as part of anatomy. However, others draw a clear distinction between the two fields, as they require different tools and vocabulary for description.

Michiel van Mierevelt's depiction of an Anatomy Lesson of Dr. Willem van der Meer, 1617 © Wikimedia Commons

Even in ancient times, philosophers pondered not only the functioning of the human body but also its formation and development. This led to the formation of embryology, the study of the development of the human body from fertilization to prenatal and postnatal stages.

The word "embryology" itself derives from the Greek words "embryo" (a young one) and "logia" (to speak or tell). The roots of this science can be traced back to ancient Egypt, where the first descriptions of the placenta and observations of embryo development in chicken eggs were made. However, the study of embryology was first mentioned in ancient Greece by philosophers such as Diogenes, Anaxagoras, Empedocles, and Hippocrates. These philosophers were not only interested in gross anatomy but also in the study of human reproduction and development.

Nicolaas Hartsoeker - Tiny man in sperm, 1695

During the Middle Ages, books on embryology primarily focused on the development of animals. The study of human fetal development was limited, and researchers had to rely on extrapolating from dissecting animal embryos. However, notable advancements were made during this time, including the work of Albertus Magnus of Cologne, who interpreted and conducted rigorous scientific investigations into previously proposed ideas. Leonardo da Vinci also contributed to the field by studying and creating drawings of human fetuses in the womb.

Leonardo da Vinci - Studies of the Fetus in the Womb

Hieronymus Fabricius is considered the father of modern embryology. He successfully dissected and observed human and various animal species, making correlations based on their different developmental processes, a remarkable achievement never before accomplished.

Thus, the story of anatomy and embryology reveals the curiosity and dedication of ancient philosophers, the challenges faced by early anatomists, and the progress made in understanding the human body's intricate structure and development.

In the eighteenth century, embryology saw a debate between preformationists and epigeneticists, who argued whether embryos pre-existed or developed gradually from unorganized material. During the nineteenth century, notable figures such as Albrecht von Haller, Caspar Friedrich Wolff, and Karl Ernst von Baer made significant contributions to embryology, establishing the foundation of modern embryology and the germ layer theory. Matthias Schleiden and Theodor Schwann proposed the cell theory, stating that all living things are composed of cells. They also studied the ovum and established its role in embryonic development.

In the twentieth century, the fields of chemical embryology and molecular embryology emerged, seeking to explain embryonic induction and the differentiation of cells into specific tissues and structures at the genomic level. Hans Spemann conducted pioneering research on embryonic induction, demonstrating the ability to transplant specific groups of cells that could induce secondary embryonic primordia. Gerald Edelman proposed the concept of topobiology, which explains how differential adhesive interactions among cell populations drive morphogenesis and the formation of complex multicellular organisms.

Fetal development © Wellcome Collection gallery, CC-BY-4.0

References

1. Lessons from History: Human Anatomy, from the Origin to the Renaissance; A. O. Malomo, O. E. Idowu et al.; International Journal of Morphology, 24, 1, 2006

2. Clinical Embryology: An Atlas of Congenital Malformations; Robert Carachi, Sameh Helmi Edward Doss; Springer Link, 2019

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