Is there a future for spermatid injections?

Area of Science:

• Reproductive biology
• Assisted reproductive technology (ART)

Background:

• Microinjection of spermatids into oocytes is a successful ART in animals.
• Human intracytoplasmic sperm injection (ICSI) with round spermatids shows low fertilization and cleavage rates.
• Implantation rates are significantly lower with round spermatid injection compared to conventional ICSI-testicular sperm extraction (TESE).

Purpose of the Study:

• To investigate the challenges and potential of using round spermatids for human assisted reproduction.
• To identify factors contributing to the low success rates of round spermatid injection.

Main Methods:

• Review of existing literature on spermatid injection techniques in humans and animals.
• Comparison of outcomes between round spermatid injection and conventional ICSI-TESE.
• Discussion of cell selection, viability, and genetic factors.

Main Results:

• Round spermatid injection in humans results in dramatically low implantation rates.
• Morphological identification of round spermatids does not guarantee viability or genetic normality.
• Spermatogenic blocks at the round spermatid level may indicate genetic factors.

Conclusions:

• Spermatid injection may be a viable option for men with some sperm production capacity.
• Significant improvements in cell selection, handling, and understanding of genomic imprinting are required for clinical application.
• Mandatory patient screening and follow-up are essential when using immature cells for conception.