Medical Terminology Daily (MTD) is a blog sponsored by Clinical Anatomy Associates, Inc. as a service to the medical community. We post anatomical, medical or surgical terms, their meaning and usage, as well as biographical notes on anatomists, surgeons, and researchers through the ages. Be warned that some of the images used depict human anatomical specimens.

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A Moment in History

Larsen

William J. Larsen, PhD
(1942-2000)

An American scientist, Dr. Larsen was a gifted scientist, consistently producing research at the forefront of cell, developmental, and reproductive biology. Early in his career he published a landmark paper that conclusively established mitochondrial fission as the mechanism of mitochondrial biogenesis. He went on to become the first to demonstrate the endocytosis of gap junctions. Moreover, his work on the hormonal regulation of gap junction formation and growth culminated in an authoritative review article in Tissue and Cell, “Structural Diversity of Gap Junctions (1988)”, which became a citation classic.

Throughout his 25 year teaching career, his sixty-seven peer reviewed publications—not to mention numerous invited reviews, abstracts, and book chapters—covered a wide range of research areas including adrenal cortical tumor cells, human ovarian carcinomas, preterm labor, cumulus expansion, oocyte maturation, ovulation, folliculogenesis, and in-vitro fertilization.

In addition to his many contributions to basic research, Dr. Larsen loved to teach and was much appreciated by his students. His exceptional ability was reflected in the four teaching awards he received as a professor at the University of Cincinnati.

Notably, he was the author of Human Embryology, a textbook for medical students that was the first to incorporate modern experimental research into a subject that had traditionally been taught in a strictly descriptive style. On its initial publication in 1998 it was hailed as, “a magnificent book…” by the European Medical Journal. With the release of the fourth edition in 2008, the book was renamed “Larsen’s Human Embryology” in recognition of Dr. Larsen's place as the originator of this revolutionary text. This book is today in it's 6th Edition.

His stellar scientific career would be enough for most people, but Dr. Larsen pursued his numerous and varied interests with such extraordinary passion, energy, and skill that he seemed to have more hours in a day than the ordinary person. He was fascinated with the American Southwest and studied and collected traditional arts and crafts of the Hopi, Zuni, and Navajo peoples. He was a woodworker who built three harpsichords and a fortepiano for his wife, and, with his two children, over 100 pieces of gallery-quality furniture. In addition, he loved to regale his friends, colleagues, and students with jokes and stories, and to share his love for gourmet cooking.

The William J. Larsen Distinguished Lecture Series

An annual lecture series was created for the Department of Cancer & Cell Biology at the University of Cincinnati to honor Dr. Larsen's research which was at the forefront of cell developmental and reproductive biology. This series recognizes forward-thinking research scientists in the field of developmental biology and asks that they share their research and findings with students and faculty of the University of Cincinnati, College of Medicine.

Personal note: I had the opportunity to meet and attend Dr. Larsen’s embryology lectures as he and I worked in the Anatomy, Embryology, and Histology program at the University of Cincinnati Medical College. Unfortunately, I never had the opportunity to have Dr. Larsen sign my personal copy of his book. He is sorely missed, Dr. Miranda

Sources:

1. "The William J. Larsen Distinguished Lecture Series" University of Cincinnati, College of Medicine.
2. https://www.larsenbooks.com
3. 2022 Larsen Lecture Series brochure (download here)
4. Dr. Larsen's family personal communications


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Embolus

The medical term embolus arises from the Greek [έμβολο] (pronounced émvolo) meaning "a plug", or "a plunger". This Greek term was later adopted in Latin [embolus] and is used in this unchanged form today. The plural for embolus is [emboli].

In medicine, the term embolus usually refers to a free blood clot that travels down the bloodstream. When in the veins, emboli will travel easily to and through the heart. This is because veins increase in diameter towards the heart. The opposite happens in arteries. Free blood clots (emboli) that passed through the heart with no problem now enter the pulmonary arteries whose branches get smaller and smaller until the emboli plug the arterioles, and now the patient has a pulmonary embolism.

When thrombi are generated in the heart, they are usually generated in the left atrial appendage in cases of arrhythmia or atrial fibrillation.  If these thrombi embolize, that is, they become free, these now emboli will continue downstream in the arteries and progressively smaller arterioles until they are bigger that the vessel and plug it, cutting off blood supply. This condition can cause an infarction, also known as a stroke. 

The term embolus can also refer to liquids. fat, or gases that enter the blood stream and are not diluted. 

The first use of this term in modern medicine was by Virchow in 1846 in his paper "On the Occlusion of the Pulmonary Arteries"

The root term for this word is [-embol-]. Examples of its use are:

Embolism:  The suffix [-ism] means "behavior" or "pathology".
• Thromboembolism: A combination of root terms; the root term  [-thromb-] means "fixed clot" and [-embol] means "a free clot". A condition or presence of both trombi and emboli.

Sources:
1. "The Origin of Medical Terms" Skinner, HA 1970 Hafner Publishing Co.
2. "Medical Meanings - A Glossary of Word Origins" Haubrich, WD. ACP Philadelphia