{Reference Type}: Journal Article {Title}: Lower developmental potential of rat zygotes produced by ooplasmic injection of testicular spermatozoa versus cauda epididymal spermatozoa. {Author}: Ide M;Saito I;Sanbo M;Kanatsu-Shinohara M;Shinohara T;Hirabayashi M;Hochi S; {Journal}: J Reprod Dev {Volume}: 70 {Issue}: 4 {Year}: 2024 Aug 7 {Factor}: 2.215 {DOI}: 10.1262/jrd.2024-030 {Abstract}: Intracytoplasmic sperm injection (ICSI) is clinically used to treat obstructive/nonobstructive azoospermia. This study compared the efficacy of ICSI with cauda epididymal and testicular sperm in Wistar (WI) and Brown-Norway (BN) rats. The transfer of ICSI oocytes with cryopreserved epididymal and testicular WI sperm resulted in offspring production of 26.2% and 3.7%-4.7%, respectively (P < 0.05). Treatments for artificial oocyte activation (AOA) and acrosome removal improved pronuclear formation in BN-ICSI oocytes; however, only AOA treatment was effective in producing offspring (3.7%-6.5%). In the case of ICSI with testicular sperm (TESE-ICSI), one offspring (0.6%) was derived from the BN-TESE-ICSI oocytes. The application of AOA or a hypo-osmotic sperm suspension did not improve the production of TESE-ICSI offspring. Thus, outbred WI rat offspring can be produced by using ICSI and less efficiently by using TESE-ICSI. Challenges in producing offspring by using ICSI/TESE-ICSI in inbred BN strain require further investigation.