Table 3.

Summary of in vitro sperm selection methods based on physiological selection in the oviduct

Technique	Rationale	Mechanism	References
Microfluidic based systems	Functional sperm present chemotactic, thermotactic, and rheotactic behaviors.	Sperm are exposed in a microfluidic device to a chemical gradient, thermal gradient, or different fluid flows. Sperm that accumulate on specific parts of the device are selected.	[195–200]
Hyaluronic acid-based selection	Functional sperm present specific receptors that allow them to bind to hyaluronic acid.	PICSI: Sperm are cultured on a Petri dish coated with hyaluronic acid. Sperm bound to the bottom of the dish are selected.	[160–163,167,201]
		Hyaluronan-rich medium: A droplet of medium with sperm is put in contact with a droplet of medium with hyaluronic acid. Sperm in the interface of the droplets are selected.	[165, 201, 202]
Cumulus oophorous column	Functional sperm go through the cumulus oophorous matrix.	Sperm that traverse a capillary filled with cumulus cells are selected.	[156–158]
ZPBA	Functional sperm bind the oocyte ZP during fertilization.	Sperm are cultured with oocytes and those attached to ZP are aspirated and used for ICSI.	[184–186]