Fig. 1: Microgravity alters human sperm navigational ability and improves hyaluronan-binding capacity.

A Human spermatozoa challenged to swim through a micro-channel slide under microgravity in either gamete or female fluid mimic media prior to sperm functional assessments (compared to normal gravity control); B swim through recovery efficiency; C total motility; D progressive motility; E curve linear velocity F lateral head displacement; G swim through recovery efficiency following exposure to progesterone at 10 and 100 µM; H binding to hyaluronan (normal gravity vs microgravity only); I swim through recovery efficiency following ‘swim up’ sperm selection; and J binding to hyaluronan following ‘swim up’ sperm selection. Data are presented as mean ± SEM, with unique symbols representing individual men. Normal gravity controls denoted in white (gamete medium), and light purple with diagonal stripes (female fluid mimic medium), whilst simulated microgravity treatment indicated by pink (gamete medium) or dark purple with diagonal stripes (female fluid mimic medium). Experiments where sperm were selected by ‘swim up’ are indicated by red. Statistical significance characterized as * P < 0.05, and ** P < 0.01. Parts of this image were created in BioRender. Mcpherson, N. (2026) https://BioRender.com/k8p7vd5.