Microsurgical technique for the bisection of early embryos in the mouse, rabbit and cow.

Abstract

The technics developed for suitable bisection of mouse and rabbit early embryos were described: 1) bisection by lateral incision of embryos, applying a sharp glass microblade at the side face, and wedging it in a horizontal direction, 2) bisection by vertical incision, moving down a metallic microneedle (made from Pt-Ir alloy wire, tip point of which is ground electrolytically) vertically to press the mid-part of embryos. These 2 methods were applied to bisection of bovine morulae. Methods of removal and transfer of the demi-embryos from and shell of Z.P. by using a glass microtube which had a slightly bevelled tip point was also dis-cussed.In total, 25 out of 29 bovine morulae, using both methods, were successfully bisected. In conclusion, both methods are equally useful for the bisection of bovine morulae.By cultivation of bisected embryos using the medium of HER solution added to 18% calf serum at 37 C, under saturated humidity and 5% CO2 atmosphere, 22 out of 26 bisectomized demi-embryos in total (time required, about 2.5 h from collection to the onset of operation) showed the following in vitro development; i.e., 2 out of 2 halved naked embryos cut by a glass microblade, 16 out of 18 naked demi-embryos cut by a Pt-Ir metallic microneedle and 4 out of 6 zona enclosed demi-embryos cut by the metallic needle and transferred successfully into alien Z.P., developed up to late morula stage at 12 h culture and to early expanding blastocyst stage at 24h culture.