Not as simple as AI. First, there are different methods of freezing (e.g. glycerol, direct thaw) embryos that require different methods of thawing. Direct thaw is the easiest to work with....basically the same as thawing semen. Another important aspect is matching the stage of the embryo to the stage of estrus of the recipient. Frozen embryos can typically be anywhere from Stage 5 to Stage 8. That "roughly" corresponds to the number of days post-fertilization. So, you want to put a Stage 7 embryo into a recipient that showed the onset of standing heat 7 days ago. Next, as you alluded, you must be able to detect a good CL on the ovary. Ovaries can have many different structures throughout the estrus cycle (follicle, CL, cyst, etc.). Not surprisingly, there is a lot of variability in size and shape of ovaries and CLs. It just takes practice to get used finding good CLs....and sometimes an ultrasound to determine the difference between a CL and a cyst. Passing the ET gun through the cervix and to the proper location within the appropriate uterine horn is not so different than AI. You just go further into the horn ipsalateral to the CL carefully as to cause as little trauma to the uterus as possible. This part takes a little longer than AI because you are going deeper and being very careful about where the ebryo is deposited. That means that the cow is pushing on your arm much longer. So, blocking the cow with an epidural is highly recommended, especially if you are doing multiple transfers.
