Preparation of Mammalian Oocytes for Transmission Electron Microscopy

The visualization of subcellular organelles and structures is a valuable tool for understanding cellular changes that occur in oocytes and early embryos as a result of genetic alterations, incubation conditions, drug treatments, and many other manipulations. Preparing oocytes for transmission electron microscopic analysis can be challenging as these cells cannot be visualized without a microscope and they are more susceptible to mechanical disruption during manipulation. Here we describe methods for immobilizing oocytes on either a solid surface or within a matrix and then document our embedding techniques which work well for preserving the ultrastructure of the mouse oocyte.