Suzanne,

Maybe it would be possible to look at using the tip of an Atomic Force
Microscope to rupture the shell?  I have not heard of one being used in this
way, but if it makes sense, you may be able to see if a University lab will
allow you to try.

Neal

Suzanne Walmsley  wrote:
Hello everyone:

I am only vaguely familiar with MEMS technology, but I have a question
about a possible application. I am a veterinary embryologist and I am
trying to do "surgery" on embryos that are 100 to 150 microns in
diameter (they are about 3 days post fertilization and have
approximately 8 cells). These embryos consist of a clump of very
fragile cells surrounded by a very small fluid-filled space
approximately 1 to 5 microns wide, and then enclosed in a soft but tough
shell approximately 10 microns thick. I need to remove the clump of
cells in the middle from their "shell" (the zona pellucida) without
ripping them apart or bursting them. This can be accomplished using an
enzyme to dissolve the shell, but the enzyme does some damage to the
inner cells. I have also tried using a laser fitted onto the objective
lens of a microscope to cut the shell, but the cells are so close to the
shell (touching in places) that I can't avoid overexposure to heat from
the laser. I can rip a hole in the shell by holding the embryo with
suction on one side applied to a fine glass pipette, while piercing the
other side with a glass needle; however, when I try to remove the embryo
by suctioning it out with a glass pipette, the cells get pulled apart or
ruptured. I have come to the conclusion that I must cut the embryo's
shell with a blade (but can't find one small enough) or make a large
hole, almost the diameter of the entire embryo, with a sharp "biopsy"
device while holding the embryo with my suction device (I have tried
unsuccessfully to produce a biopsy tool using a glass pipette and a
grinding wheel). I have a set of micromanipulators that allow me to
move two tools visualized through an inverted microscope. The problem
is that I don't have the tools I need. I am limited to working with
glass rods or tubing and can pull it, cut it, and do some fairly crude
filing with a grinding wheel. The embryo must remain in a liquid medium
during this procedure and is generally placed in a drop of this medium
in a dish filled with silicone oil. Is there any way that MEMS
technology could be used to solve my problem?
Thank you very much for your time.
Suzanne Walmsley

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