Normal development of hamster and rabbit eggs fertilized by spermatozoa labelled with the fluorescent thiol alkylating agent, monobromobimane

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Abstract
Cauda epididymal spermatozoa of the golden hamster were labelled with the thiol‐alkylating reagent, monobromobimane (MB). Female hamsters underwent uterine insemination with labelled spermatozoa at laparotomy under metofane anesthesia. All 12 females examined between 5 and 54 h postinsemination yielded a total of 83/100 (83%) eggs in the process of fertilization or embryos. Under ultraviolet (UV) exposure all exhibited a fluorescent tail which, in the 4‐ and 8‐cell embryos, could be seen to be fraying or disintegrating. As cleavage progressed, labelled tail components came to be restricted among the blastomeres such that at the 4‐ and 8‐cell stage the tail could be seen in only one to three blastomeres. To study complete development and pregnancy another 12 females received uterine insemination. After recovery from anesthesia (≃ 4 h) these females were mated with a vasectomized male bearing a dominant genetic marker (black eyes) to allow unequivocal determination of paternity in the fetuses and young produced. Seven became pregnant with one female losing her pregnancy about Day 7 of gestation. Two females sacrificed on Day 13 produced 17 normal fetuses and one resorption. Four females delivered 16 young, all normal at birth and in subsequent growth and fertility. In addition, insemination of female rabbits with MB‐labelled spermatozoa yielded normal embryos (50/52 96%) from 3 does on Day 2 and (38/64 60%) from 4 does on Days 4 or 5. Two normal litters (9 bunnies) have delivered from 3 does allowed to carry to term. These results suggest MB‐labelling of the fertilizing spermatozoon does not compromise normal development and may provide a valuable tool to determine the role and fate of some sperm components (non‐nuclear) to the process of development, particularly in the preimplantation embryo.