Influence of sperm movement parameters on human sperm-oolemma fusion

Abstract

Flagellar dyskinesia is characterized by abnormal sperm movement parameters and a negative sperm mucus penetration test. It is associated with structural pathologies of the axonemal complex (lack of outer dynein arms), of the periaxonemal complex (sliding spermatozoa and periaxonemal dyskinesia), or of both structures (short flagella). Even during in vitro fertilization, dyskinesia prevents the spermatozoon from getting through the egg vestment. However, in some cases, fertilization has been achieved using subzonal insemination. Flagellar dyskinesia is therefore an interesting model for investigating the role of sperm movement in the fusion process between the spermatozoon and the oolemma. Thirty-one patients requiring assisted fertilization were included in the study. Fifteen had spermatozoa in which the flagellum lacked outer dynein arms, 11 had anomalies of the periaxonemal complex (five with sliding spermatozoa and six with periaxonemal dyskinesia) and five had spermatozoa with short flagella. Seven men who produced spermatozoa with normal movement were selected as controls. Movement was evaluated using a computer-assisted analyser, and penetration was assessed using zona-free hamster eggs. At 37 degrees C, in semen, the dyskinetic spermatozoa had reduced straight line and curvilinear velocity and lateral head displacement compared with controls (P < 0.01). In the Percoll-selected sperm suspension, the only difference was that spermatozoa with periaxonemal anomalies maintained a narrow lateral head displacement compared with the controls (P < 0.001). After 3 h of incubation at 37 degrees C, the lateral head displacement of dyskinetic spermatozoa had not changed, while that of the controls showed a significant increase (4.5 to 5.6 microns; P < 0.05). The results from the sperm penetration assay for the spermatozoa lacking outer dynein arms were lower than those of the controls (47% versus 77%; P < 0.05) and the results for sliding spermatozoa and spermatozoa with periaxonemal dyskinesia were even lower (25% and 34%, respectively; P < 0.01). The fertilization rates after subzonal insemination were 46.5% for spermatozoa lacking outer dynein arms, 36.1% for spermatozoa with short flagella, 24.8% for sliding spermatozoa and 17.3% for spermatozoa with periaxonemal dyskinesia. There was a significant correlation between the curvilinear velocity of the Percoll-selected sperm suspensions and their fertilization rates after subzonal insemination (r = 0.5; P < 0.05) and their sperm penetration assays (r = 0.7; P < 0.001). The data provide evidence that sperm velocity is correlated with the ability to fuse with the oolemma.

Fusexins, HAP2/GCS1 and Evolution of Gamete Fusion

“…Mechanical stress on the membranes can also be generated by the pushing and pulling movements of the sperm after attachment. Even though it was previously thought that motility was dispensable for mammalian gamete fusion ( Yanagimachi, 1988 ), recent studies have suggested that a specific beating mode of the flagellum is required for this process ( Ravaux et al, 2016 ) supporting older studies using human gametes ( Wolf et al, 1995 ). It is also possible that these kinetic perturbations are only required for the accumulation of CD9 to the fusion site ( Chalbi et al, 2014 ).…”

Sperm–egg adhesion and fusion in mammals

“…There is some evidence of human infertility caused by a failure of sperm -oolemma interactions in patients with autoimmune infertility or sperm flagellar defects ( Refs 65,66). Such infertility is potentially treatable using ICSI.…”

“…At the same time, oocyte microfilaments, instead of pulling the sperm head in, could simply reorganise the cortex around the sperm head to shore up walls around its perimeter that would eventually become a fertilisation cone. Some studies attributed the inability of human spermatozoa from infertile men to fertilise ova during subzonal sperm injection (SUZI) to the reduced motility of such subfertile spermatozoa (Refs 65, 66).…”

Spatial Distribution of Actin and Tubulin in Human Sperm Nuclear Matrix‐intermediate Filament Whole Mounts—A New Paradigm

“…The contractile actinomyosin complex is reported to play a critical role during sperm capacitation and acrosome reaction (Breitbart et al, 2005;Brener et al, 2003) and chromatin decondensation (Ocampo et al, 2005). Reports indicate that sperm velocity, governed by axonemal tubulin-dynein, is related to its ability to fuse with the oolemma (Wolf et al, 1995). Therefore, understanding the spatial distribution of cytoskeletal elements would aid in defining the morphology and functional ability of sperm.…”