Grading cattle embryos for transfer or cryopreservation

Evaluating embryo quality prior to embryo transfer or cryopreservation relies on an embryologist’s experience. Within commercial laboratories, embryo quality is assessed visually using a dissecting microscope.

Grading usually takes into account several factors including cell numbers, size of the inner cell mass, developmental stage compared to embryo age, the presence of extruded or degenerated cells, and the number and presence of vacuoles. Media additives such as serum can greatly change an embryo’s appearance. To assist in evaluating embryo quality, the embryos can be rolled to change the perspective, and the angulation of the mirror can be adjusted for contrast.

In vivo and in vitro derived embryos visually differ, as do their growth rates and conception rates.

Try using this great resource, written by Jennifer Barfield from Colorado State University, Jennifer describes the evaluation of in vitro derived embryos.

Visit to access more details.

Note: The image featured in this article is derived from the link above.

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