Sperm, Female Tract Interaction

cellular, physiological, anatomical mechanisms of female tract in selecting sperm

Female control types

• Sperm selection

• Fertilisation selection

• Embryo implantation/survival (pregnancy progression)

Sperm progression

• Immediate transport

  • Retrograde loss

  • Phagocytosis

  • Entrance into cervix (rings)

• Cervix → mucus removes DNA damaged sperm with poor motility

• Uterus → neutrophils remove membrane damaged sperm

  • Capacitation initiated

• Utero-tubal junction → restricts entry into oviduct to minimise polyspermy

• Oviductal storage/selection

  • Sperm bind to oviductal epithelial cells → held in place as selective mechanism

  • Controls access to oocyte

Sperm surface markers

• Sex specific gene expression → oviductal responses for sex selection

UTJ Molecular recognition system in place → ADAM3 surface protein required to progress

• A Disintegrin And Metalloprotease 3

• despite normal motility + morphology

• Surface proteins could be used for sex selection

CD52 (membrane glycoprotein)

• Correlates with sperm DNA integrity

• High CD52 = reduced oviduct binding, enhanced zona pellucida binding.

X vs Y chromosome sperm

Morphology

• X bigger head, larger midpiece, longer tail

Protein expression

• Cytoskeletal structures influence motility

• Regulation of metabolism → glycolytic enzymes and calmodulin

• Presence/absence of gene product

Individual sperm microRNAs

• Unique 3D shapes for sperm recognition in oviduct

• Modulate gene expression

Upregulated immune responses with y sperm

• Detect IRF7 (interferon regulatory factor) via TLRs

Summary for female selection

Environment

Sperm selection

Genetic profiling

X and Y differences

• morphology, protein expression - surface or cytoskeletal, microRNAs, immune responses

• X and Y sperm induce sex specific gene expression in the female tract → TLRs?