Poly(A) RNA was isolated from microdissected guinea pig crista ampullaris epithelium and converted into cDNA with RNase H- murine leukemia virus reverse transcriptase. After size fractionation, the cDNA was directionally ligated into the vector pSPORT 1 and the plasmids electroporated into E. coli. The library was found to have 1.6 x 10(7) independent colonies with 5% of the colonies lacking an insert. Thirty randomly selected colonies were checked for inserts and the average insert size was 833 base pairs with a range of 400 to 2300 base pairs. The library was screened with a beta-actin guinea pig cDNA probe and 0.16% of the colonies contained an insert hybridizing to the probe.