The ubiquitous hyaluronan: Functionally implicated in the oviduct?

Area of Science:

• Reproductive Biology
• Glycosaminoglycans
• Immunology

Background:

• Hyaluronan (hyaluronic acid) is a ubiquitous glycosaminoglycan involved in various physiological and pathological processes.
• In reproduction, hyaluronan plays critical roles from sperm survival to embryonic development.
• Its synthesis, binding (via CD44 receptor), and degradation occur in reproductive organs, including the oviduct.

Purpose of the Study:

• To review the current knowledge on the roles of hyaluronan in the survival of immunologically foreign spermatozoa within the pig oviduct.
• To highlight the significance of hyaluronan in maintaining fertility by supporting sperm storage and immune evasion.

Main Methods:

• Literature review focusing on hyaluronan's function in the female reproductive tract.
• Analysis of hyaluronan and CD44 receptor distribution in the oviductal sperm reservoir.
• Examination of hyaluronan's role in regulating sperm capacitation and immune response.

Main Results:

• Hyaluronan is synthesized by oviduct epithelium and concentrated in mucosal furrows where spermatozoa are stored.
• Spermatozoa are embedded in hyaluronan-rich environments, ensuring their survival, preventing capacitation, and evading immune detection.
• Hyaluronan in seminal plasma and oviduct contributes to the production of anti-inflammatory cytokines like interleukin-10, promoting maternal immune tolerance.

Conclusions:

• Hyaluronan is essential for maintaining the viability and immune privilege of spermatozoa in the pig oviduct.
• The interaction between hyaluronan and its CD44 receptor is critical for establishing a functional sperm reservoir and ensuring successful fertilization.
• Hyaluronan facilitates maternal immune tolerance towards spermatozoa, a key factor for reproductive success.