MICROTUBULE AND CHROMATIN CONFIGURATIONS DURING RHESUS INTRACYTOPLASMIC SPERM INJECTION - SUCCESSES AND FAILURES

Intracytoplasmic sperm injection (ICSI) was performed on rhesus monkey oocytes, and the resultant microtubule and DNA configurations were im aged by laser-scanning confocal microscopy, In addition, polyspermic o ocytes fertilized by ICSI were examined by transmission electron micro scopy (TEM). Successful rhesus fertilization by ICSI revealed microtub ule and DNA configurations similar to those observed during in vitro f ertilization of human and rhesus monkey oocytes, including sperm aster formation, pronuclei decondensation, spindle formation, and cell divi sion, Several abnormalities, however, were also observed: 1) inability to complete meiosis; 2) inability to undergo male or female pronucleu s formation; 3) separation of the sperm tail from the sperm nucleus; 4 ) premature chromosome condensation with the formation of a paternal m eiotic spindle; and 5) formation of multiple female pronuclei (karyome res) during chromosome decondensation. TEM analysis revealed that sper m can undergo decondensation in the presence of an intact acrosome at least 18 h after sperm injection. These results demonstrate the utilit y of rhesus ICSI in pre-clinical applications as well as with endanger ed species. However, the different types of fertilization failures obs erved here indicate that although ICSI may be a readily accepted means of fertilization of human oocytes in many clinics, we should further characterize the cellular and genetic abnormalities associated with IC SI in both human and nonhuman primates.