Rapid dissection of day 8 embryos. Two pair of fine forceps (Dumont No. 5 or No. 5 Biologie forceps, Fine Science Tools, Foster City, CA), disposable petri dishes, a dissecting microscope and cold PBS are required.
The decidua are not removed from the uterus, allowing for rapid dissection. Place the dissected uterus in small petri dish and cover with cold PBS. Arrange the uterus such that the membrane that attached the uterus to the body wall (the mesometrium) is facing away from you (A). Instead of exposing the entire antimesometrial pole of the deciduum, rip a hole in the uterus to expose a small portion of the side of the deciduum (A and B). With a pair of forceps make a shallow gash in the deciduum large enough for the embryo to pass through (C). Press gently on the deciduum through the covering wall of the uterus (D). A gentle push will cause the embryo to slide out (E). (If the embryo does not slide out, the cut in the decidual wall was not deep enough. However, if the cut is too deep, the embryo will be damaged. It will take some practice to determine the correct depth of the cut.) If the embryo does not come completely free (E), grasp the yolk sac of the embryo (F) to pull it free (F and G). Embryos that have finished turning (as shown in this figure) are ready to be fixed. Embryos that have not completed the inversion need to be dissected further.
Further dissection of early embryonic day 8 embryos. Flatten the embryo by grasping the amnion between head and tail with both pairs of forceps and pulling towards the head and tail (A). Dorso-ventrally flattened embryos are easier to photograph (B).
A Conlon Lab Protocol
pdf file for this protocol