THE USE OF P-33 LABELED OLIGONUCLEOTIDES FOR IN-SITU HYBRIDIZATION OFVERTEBRATE EMBRYO FROZEN-SECTIONS

In situ hybridization was performed on frozen sections of whole E16 ra t embryos or whole E7 chick embryos using oligonucleotide probes tagge d with a P-33-poly A taiL We used two antisense oligonucleotide probes : a 57-mer rat agrin oligo and a 60-mer chicken B-cadherin oligo. Afte r exposure to Hyperfilm betamax for three days, mRNA was detected in d istinct organs and tissues of the embryo. After dipping the slides in liquid emulsion and exposing them for two weeks, the grains could be l ocalized to a specific cellular layer for example, the ganglion layer of the retina or the luminal epithelium of the gizzard. It is conclude d that P-33 autoradiography is excellent for defining gross areas or c ellular layers of mRNA in a vertebrate embryo with a resolution of abo ut 20 microns.