Rhesus offspring produced by intracytoplasmic injection of testicular sperm and elongated spermatids

OBJECTIVE: To establish pregnancies in rhesus monkeys using testicular sperm and elongated spermatids injected into oocytes. DESIGN: Comparative animal study. SETTING: Regional Primate Research Center. ANIMAL(S): Prime, fertile rhesus monkeys. INTERVENTION(S): Oocytes collected by laparoscopy from gonadotropin-stimulated female rhesus monkeys were injected with testicular sperm or elongated spermatids obtained from the testis of males. Cleavage stage embryos were transferred to surrogate females. MAIN OUTCOME MEASURE(S): Fertilization, embryo cleavage, and the establishment of pregnancies. Fertilization failures were fixed and processed for the detection of microtubules and chromatin configurations. RESULT(S): Fertilization, assessed by the presence of two pronuclei within 15 hours after injection, was 60% for intracytoplasmic sperm injection with testicular sperm and 47% for elongated spermatid injection. Fertilized zygotes co-cultured in Connaughts Medical Research Labs (CMRL) medium on a Buffalo Rat Liver cell monolayer resulted in hatched blastocysts after testicular sperm extraction-intracytoplasmic sperm injection and elongated spermatids. Embryos transferred at the 4- to 8-cell stage gave rise to three pregnancies: 2/3 from testicular sperm and 1/1 from an elongated spermatid. Three healthy infants were delivered by cesarean. Oocytes that failed to fertilize typically remained arrested in metaphase of meiosis. CONCLUSION(S): Testicular sperm and elongated spermatids can be used for fertilization in the rhesus monkey resulting in live births.