Assisted fertilization and embryonic axis formation in higher primates.

Area of Science:

• Developmental Biology
• Reproductive Medicine
• Cell Biology

Background:

• Sperm entry point (SEP) is a cue for embryonic patterning in naturally fertilized organisms.
• The role of SEP in intracytoplasmic sperm injection (ICSI) assisted reproduction is not well understood.
• Rhesus macaques serve as a valuable model for human reproductive studies.

Purpose of the Study:

• To investigate the influence of sperm placement during ICSI on embryonic patterning in rhesus macaques.
• To compare ICSI-derived patterning with naturally fertilized mammalian embryos.
• To explore potential insights into mammalian egg patterning mechanisms.

Main Methods:

• Fertilization of rhesus macaque oocytes using ICSI with controlled sperm placement.
• Analysis of the sperm entry point (SEP) localization relative to cleavage planes.
• Comparison of embryonic axis specification in ICSI and naturally fertilized embryos.

Main Results:

• The SEP in ICSI-fertilized embryos was frequently located near the first cleavage plane.
• SEP distribution correlated with the boundary between embryonic and abembryonic regions in blastocysts.
• Cleavage axes and embryonic axis specification in ICSI embryos mirrored those in naturally fertilized mouse embryos.

Conclusions:

• Sperm placement during ICSI can influence early embryonic patterning in rhesus macaques.
• ICSI-derived patterning in macaques shows similarities to natural fertilization in mice.
• This study offers valuable insights into sperm's role in mammalian egg patterning and has implications for assisted reproduction.