Validation of RNA localization by in situ hybridization. Labeled RNA probes were used to determine the expression of transcripts identified in microarray analysis as being enriched to the poles of the oocyte. Transcripts from the microarray analysis that were identified as being anteriorly enriched were found to be confined to the anterior half of the embryo these include Am-tsu, GB19578, GB13806, GB12151, Am-WntA, GB17957, GB14657, GB18516 and GB18412 (localized to the oocyte nucleus (asterisk)). Array posteriorly enriched RNAs (GB20112, GB12109, GB12215, GB11497, GB17175, GB14584, GB11911, GB14758) proved to be posteriorly localized in vivo. Transcripts found to be enriched to both poles were identified by central verses posterior comparison (GB17282, GB10488). Stage 7–8 oocytes are shown with anterior at the left and dorsal side up.