Cano_zoo303hw_4b9.docx

CANO, Jason Kidd B. 4Bio9 A History of Embryology Dr. Joseph Needham, in 1931, published a book called “A History of Embryology.” Maude E. Abbott reviewed this book in 1936, citing the book itself and some of Dr. Needham’s talks in the University of London. According to him, the book was subdivided into four chapters in which Needham narrates the history of embryology. According to Abbott, the curiosity in the phenomena of the development of an embryo dates back to 3000 BC, where Egyptians and Chinese would artificially incubate hens’ eggs. However, the first scientific was written by Hippocrates (circa 400 BC). He wrote on the observation of the natural method of hatching, connecting to the growth of an embryo to an ‘internal fire’, which Abbott says he was relating to oxidation. His conclusion was that, as he observed the eggs in their embryonic stages, that a bird resembles a human. In the 4th century, Aristotle wrote a book called “On The Generation of Animals” where he details a comparative embryology chart. He was able to put this up by studying chick embryos under the stages of incubation from the third day onwards, and by dissecting and studying every embryo of every animal available to him. Later on Aristotle would be described as the Father of Embryology. Soon after, Herophilus, Soranus, & Galen would contribute in their discoveries in embryology; with Soranus being the first to draw the uterus and is anatomically knowledgeable, and Galen closing then the studies on embryology because their collective studies were established as facts. Long after that, in the 16th century, Aldrovandus (1522) would follow Aristotle in studying the successive stages of hens’ embryonic development. He asked his students to keep 23 eggs and opened one every day to see the veins’ origins and which organs would first develop in the animal. Fabricius (1604) would be known to contribute accurate drawings of the early chick embryo. Empirical studies grew in the 17th century, with many names contributing to the modern studies on embryology: 1. Sir Kenelm Digby (1664) who provided a deterministic account of development; 2. Nathaniel Highmore (1651), who first treated embryology as an anatomical study; 3. Sir Thomas Browne who first did experiments in chemical embryology; 4. William Harvey, who authored “De Generatione Animalium” and “De Motu Cordis”, where he declared against spontaneous generation and supported epigenesis (an embryo develops progressively from an undifferentiated egg cell); 5. Walter Needham, who’s named as the founder of the dynamic aspect of embryology; 6. de Graff & Swammerdam (1672), who discovered the follicles in the mammalian ovary;

7. Marcello Malphigi, who represented the early chick embryo as seen in the simple microscope and provided drawings of the chick embryo at 85 hours’ incubation; 8. John Mayow, who contributed to the physiological aspect of embryology; 9. And Anton van Leeuwenhoek, who discovered the spermatozoa in 1677. All of these would pave way for the further development of embryology as a science, continuing further in the succeeding centuries. Just in the 18th century, another long list of contributors who led these studies in embryogenesis expanded embryology even more: 1. Herman Boerhaave detailed the biochemistry of the incubated egg; 2. Albrecht von Haller, Boerhaave’s pupil, published his collections of papers in embryology and provided concrete study on the development of the heart of the chick, and estimation of the rate of growth of fetal bones; 3. Caspar Friedrich Wolff focused on the development of the intestine and further disproved the theory of pre-formation and supported epigenesis; The now known as the father of modern embryology, Karl Ernst von Baer, from Germany, would establish his laws of embryology based on all of these past studies. Von Baer published the book “On the Developmental History of Animals” in 1828, positing that embryos develop starting from forms that are similar in some animals (general form), but would later branch out into different developing patterns which would differentiate an embryo from another (specific form).

Reference: Abbott, M. E. (1936). A History of Embryology. Can Med Assoc J,34(1), 82-85. Retrieved August 14, 2018, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1561353/. Von Baer's laws (embryology). (2018, August 10). Retrieved August 14, 2018, from https://en.wikipedia.org/wiki/Von_Baer's_laws_(embryology)