Method for controlled reduction in temperature and preservation of embryos in a cryogenic state

Abstract

An apparatus for reducing the temperature of articles to the cryogenic state in reducing the temperature of embryos at a controlled and predetermined rate is disclosed comprised of a housing defining an insulated cooling chamber employed in association with support means for removably suspending the embryos within a chamber. A gaseous medium, such as, air circulates along a closed path through the chamber so that the embryos are disposed in its path and a heat exchanger including a heat transfer medium is positioned in the flow path of the gaseous medium together with a temperature sensor so that the rate of cooling may be programmed and regulated automatically by correlation of the temperature sensor with the heat exchange medium. The method comprises the steps of removably supporting embryos in an insulated chamber; positioning a heat transfer medium therein; circulating air or another gaseous medium through the chamber across the heat transfer medium and the embryos; and programming the rate of cooling of the air by imposing close control over the temperature of the heat transfer medium while avoiding uneven temperature zones in the chamber.

Dependencies are inferred from the claim text.