1. Figure 5 Sperm chemotaxis
Figure 5 | Sperm chemotaxis. a | The signalling pathway in sea urchin sperm. Resact stimulation results in intercellular alkalization and polarization, which open the sperm-specific Ca2+ channels (CatSper). An increase in intercellular Ca2+ concentration influences the flagellar beat asymmetry, aligning the sperm with the gradient. b | Deterministic chemotaxis. Sea urchin sperm detect chemical gradients by measuring concentration of chemicals in space over time to modulate their swimming path toward the egg. c | Schematic of a microfluidic device with hydrostatic flow control to study sperm chemotaxis. Three inlet channels containing ovary extract, sperm, and buffer merge into a 600-µm wide channel to perform the chemotaxis assay (right inset). d | A hydrogel-based microfluidic platform to study sperm chemotaxis. Part a is reproduced from Jikeli et al. Sperm navigation along helical paths in 3D chemoattractant landscapes. Nat. Commun. (2015)148 Part b is reprinted from Trends Cell Biol. 24, Alvarez et al., The computational sperm cell. 198–207, Copyright (2014), with permission from Elsevier145. Part c is reprinted (adapted) with permission from Koyama et al. Chemotaxis assays of mouse sperm on microfluidic devices. Anal Chem. 78, 3354–3359 (2006). Copyright 2006 American Chemical Society151. Part d is from Chang et al. Different Migration Patterns of Sea Urchin and Mouse Sperm Revealed by a Microfluidic Chemotaxis Device. PLoS ONE (2013)153. CNGK, cyclic nucleotide-gated K+-selective channel; HCN, hyperpolarization-activated and cyclic nucleotide-gated channels; GC, guanylyl cyclase; sNHE, Na+/H+ exchanger.
Part a is reproduced from Jikeli et al. Sperm navigation along helical paths in 3D
chemoattractant landscapes. Nat. Commun. (2015)148 Part b is reprinted from
Trends Cell Biol. 24, Alvarez et al., The computational sperm cell. 198–207, Copyright (2014), with permission from Elsevier145. Part c is
reprinted (adapted) with permission from Koyama et al. Chemotaxis assays of mouse sperm on microfluidic devices. Anal Chem. 78,
3354–3359 (2006). Copyright 2006 American Chemical Society151. Part d is from Chang et al. Different Migration Patterns of Sea Urchin
and Mouse Sperm Revealed by a Microfluidic Chemotaxis Device. PLoS ONE (2013)153.
Nosrati, R. et al. (2017) Microfluidics for sperm analysis and selection
Nat. Rev. Urol. doi: /nrurol