Factors related to successful sperm microinjection of hamster eggs: The effect of sperm species, technical experience, needle dimensions, and incubation medium on egg viability and sperm decondensation following microinjection.
A series of experiments was designed to identify factors in a sperm microinjection system that could influence egg viability and decondensation of sperm nuclei after microinjection. Egg viability and sperm decondensation rates were not different among eggs microinjected with rodent sperm. The microinjection of ram sperm required a larger diameter needle for injection, which resulted in low egg viability and sperm decondensation in the first 3 mo of the study but improved greatly after 9 mo of technical experience. The degree of technical experience (3 vs 9 mo) also improved (P<0.05) egg viability after microinjection with rodent sperm; however, the rate of sperm decondensation remained unaffected. Altering the dimensions of the injection needle from a tapered needle barrel to a more uniform needle barrel increased egg viability from 61 to 96% and sperm decondensation from 3 to 27%. The use of medium 199 for incubating microinjected eggs further increased (P<0.05) the percentage of eggs containing decondensed sperm nuclei (52%) compared to eggs incubated in Holmes defined medium (28%). By altering the dimensions of the injection needle, by selecting an appropriate incubation medium, and by gaining technical experience in microinjection, the efficiency of a sperm microinjection system was improved for both rodents and domestic animals.
Clarke
R N
RN
US Department of Agriculture. Agricultural Research Service Reproduction Laboratory Beltsville, MD 20705 USA.
Johnson
L A
LA