We are unable to detect ephrinA5 transcription before stage 7. During stages 7-12 (Fig. 1D-F), ephrinA5 expression is prominent in the neural folds, with highest levels present throughout the presumptive brain. Weak ephrinA5 expression is also detected in the head mesenchyme during stages 9-12.
According to the authors, "The cDNA clones used to generate in situ probes for EphA3, EphA4, ephrin-A5, ephrin-A2, EphB2, EphB3, ephrin-B1, ephrin-B2 or RCS, which recognizes a viral core protein, were described elsewhere (Schulte et al., 1999) or were gifts from J. Flanagan, C. Cepko (Harvard Medical School, Boston), or E. Pasquale (The Burnham Institute, La Jolla, California; Holash and Pasquale, 1995 and Cheng et al., 1995). As information provided was insufficient to verify exact sequence used to synthesize probe, the sequence below was obtained from NCBI (acc #NM_205184)