Cleavage-stage embryo rotation tracking and automated micropipette control: Towards automated single cell manipulation

摘要

Micromanipulation of individual biological cells, such as embryos during preimplantation genetic diagnosis (PGD), is a delicate and time-consuming task. Two major procedures in PGD include the rotation of the embryo to gain a more favorable position for zona breaching, and the extraction of a blastomere after an opening has been made in the zona pellucida. Rotation tracking of cleavage-stage embryos has not been reported given their lack of distinctive features. In this manuscript, a geometric model for partially determining the three dimensional (3-D) angular position of 2-cell embryos using two dimensional (2-D) microscopic brightfield images was derived and verified using a computer generated model. This model was then applied using computer vision algorithms on a rotating cleavage-stage mouse embryo, demonstrating partial 3-D rotation tracking. Furthermore, embryo micromanipulation tasks are typically performed manually using micropipettes. Technological advances have made automation of these tasks possible. This manuscript also presents computer vision algorithms for the segmentation and calibration of micropipettes. The calibration procedure allowed automated position control of the micropipettes without the need for real-time vision feedback using micropipette recognition algorithms, and effective position control was verified using semi-automated blastomere extraction experiments. This manuscript presents preliminary work towards the automation of cell manipulation procedures.