Dear Patricia,
I have had also some troubles when transplanting into perivitelline space, and in most experiments I use other anatomical sites. For me it works best, if I inject into perivitelline space from posterior side and proximal to the body. So, approach the perivitelline space from tail side of the embryo, quite close to body and try not to extend the needle too deep in as it goes easily inside yolk. Having the needle coming in at a lower angle can also help. I wish that you find these tips useful.
best,
Ilkka
2019-03-05 22:49:38