A new embedding medium for cryo-sectioning eggs of high yolk and lipid content.

Eggs can be cryo-sectioned without rupture of the yolk- and lipid-containing areas after embedding in a mixture of polymerized acrylamide, crosslinked gelatine, 'Jung' medium and buffer. For initial fixation of the section on the slide a fixative containing glue is employed, followed by postfixation treatment. The new technique improves sectioning of large eggs including embryonic stages for histological and histochemical studies. It is especially useful for eggs containing large amounts of yolk (insects, snails, fishes and newts) and for secretory organs containing high levels of proteinaceous material.