Quantitative analysis of temperature-dependent ciliary beat frequency in the human fallopian tube using optical coherence tomography

Fallopian tube cilia movement, quantified as cilia beat frequency (CBF), depends on temperature and the biochemical composition of surrounding fluid. In this study, we evaluated the effects of media type and temperature on the CBF measured from optical coherence tomography (OCT) images of an explanted human fallopian tube. Temperaturedependent effects were compared between measurements acquired in two immersion media: phosphate buffered saline (PBS) and GMOPS+ (an optimized in vitro fertilization medium). Five image sequences were obtained while the sample was immersed in room temperature PBS (~23°C) and heated to physiologic temperature (~37°C). The media was replaced with GMOPS+, and seven image sequences were acquired as the temperature was gradually decreased. A sliding window Fourier analysis of intensity fluctuations corresponding to cilia movement was performed to spatially map and quantify CBF for each image sequence. Normalized frequency distributions were averaged across all windows, and this averaged frequency distribution was qualitatively evaluated as temperature and media were changed. Image sequence CBF was calculated as the mean of the frequency distribution, and presented as mean ± standard deviation (Hz). Linear regression analysis was performed to investigate the effects of temperature on CBF in PBS and GMOPS+ media. Frequency distributions for CBF measured in GMOPS+ showed more prominent high-frequency content compared to that of PBS, and a visible overall shift toward high-frequency content was evident at higher temperatures for both media types. A strong positive relationship to temperature was demonstrated for CBF measured in both PBS (r² = 0.94, p = 0.0057) and GMOPS (r² = 0.97, p = 0.0001) media.