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Alexandra Eicher, PhD




Research Fellow




Postdoctoral Research Fellow




Alexandra K. Eicher1 and Olivier Pourquié1,2

Cellular Control of Vertebrate Embryo Axis Elongation

My interests and skills lie in the intersection of biology and engineering. My Ph.D. is in developmental biology, and my B.S. is in biochemical engineering. An undergraduate in a male-dominated field, I joined the Society of Women Engineers to interact with other female engineers. I also joined a multicultural sorority with a tenet of advancing women through higher education. Attending this symposium, I will meet fellow women similarly interested in advancing healthcare, medicine, and science. My broad interests are translational medicine, stem cell technologies, and replacement tissues. My specific focus is understanding how developmental forces control tissue organization and morphogenesis.


The presomitic mesoderm (PSM) is an embryonic tissue that elongates, giving rise to dermis, cartilage, and muscle. Defects can cause caudal regression syndromes that have no cure. We know a tissue-level gradient of random cellular motility directs PSM elongation, but it is unknown how individual PSM cells form this gradient.


We segmented PSM from 44-hour chicken embryos into anterior to posterior sections, dissociated each section into single cells, and sparsely plated the cells onto glass-bottomed chamber slides for overnight culture and time-lapse imaging. We analyzed the resulting videos for appropriate motility properties, such as total motile cells and mean speed of motile cells.


Motile cells had multiple protrusions and non-motile cells were round. By this morphology, posterior sections contained more motile cells and anterior sections contained more non-motile cells. Motile cells, regardless of region, all moved with a comparable speed; posterior motile cells did not move faster than anterior motile cells.


This suggests that the tissue-level motility gradient along the PSM is formed by the graded distribution of motile (versus non-motile) cells with more motile cells existing in the posterior, rather than by the graded distribution of motile ability (i.e. speed).