Abstract
Human fertilization and embryo development involve a wide range of critical processes that determine the successful development of a new organism. Although Assisted Reproduction Technologies (ART) may help solve infertility problems associated to severe male factor, the live birth rate is still low. A high proportion of ART failures occurs before implantation. Understanding the causes for these failures has been difficult due to technical and ethical limitations. Diagnostic procedures on human spermatozoa in particular have been limited to morphology and swimming behaviours while other functional requirements during early development have not been addressed due to the lack of suitable assays. Here, we have established a quantitative system based on the use of Xenopus egg extracts and human spermatozoa. This system provides novel possibilities for the functional characterization of human spermatozoa. Using clinical data we show that indeed this approach offers a set of complementary data for the functional evaluation of spermatozoa from patients.
Highlights
After ovulation, the human oocyte is arrested at the metaphase of meiosis II (MII)
We developed an ex vivo heterologous system based on the incubation of human spermatozoa in Xenopus egg extract system (XEE) in order to obtain functional information on the activity of the human sperm once placed in an oocyte cytoplasm environment
The present study describes a quantitative ex vivo heterologous system based on the use of XEE and human spermatozoa to evaluate the sperm capacity for driving microtubule nucleation and spindle assembly, providing a functional overview of the sperm behaviour during fertilization and early development
Summary
The human oocyte is arrested at the metaphase of meiosis II (MII). When the sperm fuses with the oocyte, the oocyte is activated, meiosis resumes, and half of the sister chromatids are extruded into a second polar body[7]. Xenopus eggs are naturally arrested in MII by a CSF-dependent mechanism and do not contain centrosomes, resembling human oocytes. The cytoplasm of these eggs can be collected and centrifuged at low speed to obtain a large volume of cytoplasm arrested in MII-phase (CSF-XEE). The CSF-XEE can be manipulated in the test tube by addition of components (i.e. sperm) and the cell cycle state controlled to follow interphase and mitotic events associated with chromatin and microtubules. These events are physiologically relevant as they occur in vivo upon fertilization and culminate with the assembly of the first mitotic spindle[13]. We show that this system provides functional data that may improve clinical diagnosis as well as our basic knowledge of the mechanisms that the spermatozoon triggers upon fertilization
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
