Capacitated, acrosome reacted but immotile sperm, when microinjected under the mouse zona pellucida, will not fertilize the oocyte

Abstract

We have devised a procedure for mechanically inserting intact, acrosome reacted spermatozoa under the mouse zona pellucida, and have examined the ability of sperm so inserted to fertilize the mouse oocyte. Sperm immobilized by a variety of different methods are unable to fertilize the egg, despite the fact that electron microscopy confirms that they are acrosome reacted. Control experiments show that the oocytes are capable of being fertilized by motile sperm after the microinjection procedure, and that the immobilized sperm are able to form male pronuclei after injection directly into the ctyoplasm. These results indicate that in addition to its importance for penetration of egg investments, sperm motility is required for fusion of the gametes. Alternatively, the findings suggest that the enzymatic machinery required for sperm motility is very similar to that utilized for gamete fusion, and that destruction of one is likely to lead to inactivation of the other.

Comparison of zona cutting and zona drilling as techniques for assisted fertilization in the mouse

“…Direct microinjection of spermatozoa or sperm nuclei into the cytoplasm of mouse oocytes (Uehara & Yanagimachi, 1976;Thadani, 1982;Markert, 1983) was associated with an unacceptably high rate of damage to the oocytes. Subzonal injection of spermatozoa has also been reported (Metka et al, 1985;Barg et al, 1986;Lassalle et ai, 1987). The disadvantages associated with this technique include the artificial selection of an individual spermatozoon, the time-consuming skills required for the technique, the low fertilization rate and questions relating to the karyotypic normality of the resulting embryos.…”

Activation of hamster zona-free oocytes by homologous and heterologous spermatozoa

“…They were incubated at 37.5°C under 5% C02 in air for 2 h to allow capacitation and acrosome reaction. The incidence of acrosome reaction in similar conditions was reported to be 20-30% (Barg et al, 1986). Insemination was carried on at 37.5°C by adding 5-10 µ of preincubated sperm suspension to 100 µ M16 containing zona-free hamster oocytes (final concentration of spermatozoa was approximately 1-2 x 10 spermatozoa ml~) .…”

Enhancement of acrosome reaction and subzonal insemination of a single spermatozoon in mouse eggs

“…Different biochemical compounds were used to induce the acrosome reaction: 1) After 1 hour of incubation in T6, spermatozoa were further incubated for 60 min in T6 containing 20 pM of A23187 (Sigma Chemical Co. St. Louis, MO) (Barg et al, 1986). 2) Spermatozoa incubated in T6 for 60, 90, or 120 rnin were further incubated in a medium containing 12 mM dbcGMP and 10 mM imidazole (Sigma Chemical Co., St. Louis, MO) for 30 min at 37°C (Talansky et al, 1987).…”

“…In the mouse, moreover, a n acrosome-free but immotile spermatozoon cannot achieve fertilization after injection into the perivitelline space of a n oocyte (Barg et al, 1986). Mann (1988), however, has demonstrated that after the subzonal injection of a single motile mouse spermatozoon, fertilization and development to term can be achieved.…”