In Memoriam: Anna S. Teetsov (1935-2025)

There are few laboratory scientists who gain public acknowledgement despite their amazing contributions and the impact their work has on the world. This is certainly true of Anna S. Teetsov, a microscopist at McCrone Associates, who spent her 59-year career developing and using techniques for preparing and analyzing microscopic particles. Spending much of her time working in a cleanroom laboratory, Anna pioneered techniques for sample preparation, hand-sectioning, manipulating particles, and using light microscopes for microanalysis.

Anna’s path to the laboratory is quite remarkable considering she was born in Poland just before the start of World War II. After enduring immense hardships, Anna and her family were able to relocate to England during the war. This move, and another to the northwest side of Chicago after the war ended, forced her to learn the English language and provided her with formal education that exposed her to chemistry, which she enjoyed. Anna’s unwavering determination (a trait she was known for throughout her life) to continue her education in chemistry led her to the University of Illinois and the Illinois Institute of Technology where in 1958 she earned an undergraduate degree in Physical Chemistry.

After a short stint working for Abbott Laboratories, Anna returned to IIT to take graduate chemistry courses. The professor of her first class was Dr. Walter C. McCrone. Impressed by Anna’s intelligence, skills and work ethic, Dr. McCrone quickly convinced her to join McCrone Associates on July 1, 1961. During her first months at McCrone Associates, Anna began to develop the techniques for the isolation, handling, and analysis of individual, small particles.

Some of her most prominent public contributions include co-authoring the study “Microscopical Study of the Turin ‘Shroud’; III” with Dr. McCrone and others, in which she helped characterize pigment particles (including vermilion and iron oxides) on fibers from the Shroud of Turin. Also, she played a key role in the analysis of the Vinland Map, where she observed that the ink lines were “double-inked” (a yellow underlayer and black overlay), took microscopic ink samples, and helped identify synthetic anatase (a form of titanium dioxide) in the yellow stain — an indicator that the ink was modern, not medieval.

Anna also had a passion for mentoring and teaching new scientists the techniques she developed. Her instruction was always accompanied by intricate hand-drawings of each step required in the procedure. One of her favorite ways to have trainees practice their skills involved arranging butterfly scales into intricate, microscopic artwork. Of course, this was an art form she had mastered for decades.

Anna’s accomplishments and contributions during her career are difficult to quantify. She was a trailblazer when it came to developing methods for moving micrometer and eventually sub micrometer particles. In the lab, this will forever be her legacy!

We mourn the loss of another legendary microscopist but remember with fondness a friend and colleague to whom we owe a debt of gratitude.