| Professor Zhongping Chen and Dr. Hongwu Ren at the Beckman Laser Institute (BLI) on the campus of UC Irvine graciously offered to collaborate with us in imaging gastrulation using their optical coherence tomography (OCT) instrument. We wondered if moving from our 843 nm superluminescent diode to their 1310 nm light source would permit better depth penetration. Indeed, the light source does make a slight difference, yielding better contrast in the blastocoel/yolk interface. Measurements of the attenuation coefficients in these embryos yield values of 19.0+-3.0 /mm at 843 nm and 14.0+-2.0 /mm at 1310 nm for mesoderm and ectoderm tissue. This amounts to a 36% deeper penetration at 1310 nm due to the longer wavelength. The slightly higher power of the BLI OCT source probably helps to image more deeply as well. |