Sticky fallopian tube fluid key to causes of female infertility

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"... They found a thicker, sticky fluid environment promotes the growth of cells responsible for transporting eggs or embryos towards the uterus and even made them better at coordinating their movement.

This explains why flushing fallopian tubes with oil-based dye during X-ray imaging procedures significantly improves fertilisation outcomes when compared to the use of water-based dyes. ...

The fallopian tubes of the female reproductive system contain fluid that varies in viscosity both along the tube and throughout the menstrual cycle, ranging from as thin as water, to as thick as glycerine at ovulation.

The research looked at how the change in this viscosity influences the development and function of the cells that cover the inside of the fallopian tubes: secretory and ciliated epithelial cells (ECs). ..."

From the abstract:

"The rheological properties of the extracellular fluid in the female reproductive tract vary spatiotemporally, however, the effect on the behaviour of epithelial cells that line the tract is unexplored. Here, we reveal that epithelial cells respond to the elevated viscosity of culture media by modulating their development and functionality to enhance cilia formation and coordination. Specifically, ciliation increases by 4-fold and cilia beating frequency decreases by 30% when cells are cultured at 100 mPas. Further, cilia manifest a coordinated beating pattern that can facilitate the formation of metachronal waves. At the cellular level, viscous loading activates the TRPV4 channel in the epithelial cells to increase intracellular Ca2+, subsequently decreasing the mitochondrial membrane potential level for ATP production to maintain cell viability and function. Our findings provide additional insights into the role of elevated tubal fluid viscosity in promoting ciliation and coordinating their beating—a potential mechanism to facilitate the transport of egg and embryo, suggesting possible therapeutic opportunities for infertility treatment."

Sticky fallopian tube fluid key to causes of infertility

Like treading honey: fluid ‘stickiness’ in female reproductive tract influences fertility (original news release)

Fallopian tube rheology regulates epithelial cell differentiation and function to enhance cilia formation and coordination (open access)

Coloured scanning electron micrograph (SEM) of the surface of a female human fallopian tube.
The epithelium consists of columnar cells, many of which have cilia (red). Coloured blue are the secretory cells with their microvilli projections. These cells secrete a substance that maintains a moist environment in the tube and may provide nutrients for the egg.

Fig. 4: Characterisation of cilia beating and coordination under viscous loading.