Lewis & Gregory (1929) were the first to culture the fertilized ovum of laboratory animals in vitro, using rabbit ova. Hammond (1949) cultivated 8-cell mouse ova to the blastocyst stage. This method was repeated and further developed by Whitten (1956), McLaren & Biggers (1958), Tarkowski (1961) and Brinster (1963), among others. However, there have been no reported attempts to culture rat ova in vitro.
Ovum culture in the Sprague-Dawley rat was developed in our laboratory to test the viability of ova recovered from rats previously treated with anti-fertility compounds. The method was also required for the in vitro testing of such compounds upon rat ova with or without subsequent transfer to recipient rats.
Attempts were made to culture 2-, 4- and 8-cell rat ova using various media, energy and nitrogen sources, and several tissue culture systems. The successful culture of rat ova, from the 8-cell to blastocyst stage, was achieved using the method of Brinster (1963), with sodium pyruvate and lactate as the energy source and with bovine serum albumin as the source of nitrogen (Thomson, 1966).