Identification of Marker Gene of Pars Tuberalis Morphogenesis in Chicken Embryo. The expression of Cytokine-like 1 and Gap junction protein alpha 5 in the pars tuberalis

Adenohypophysis delivered from oral ectoderm consists of pars distalis (PD), pars intermedia and pars tuberalis (PT). The mechanisms of development of PD has been well studied, and the cell differentiation of PD has been well understood. However, the morphogenesis and the differentiation of PT are still unclear, and the gene expression during the PT development remains largely unknown. In this study, we explored the specifically expressing genes in PT during development and analyzed its spatiotemporal expressions pattern. Microarray analysis on laser-captured PT and PD tissues obtained from chicken embryos on embryonic day 10 (E10.0) showed high expressing genes, Cytokine-like 1 (CYTL1) and Gap junction protein alpha 5 (GJA5) in PT. A detail analysis of spatiotemporal expressions pattern during chick embryo development by in situ hybridization revealed that CYTL1 mRNA was first detected in lateral head ectoderm and ventral head ectoderm in E1.5. The CYTL1 expressions moved into Rathke’s pouch at E2.5, then it was localized in PT primordium and continuously expressed in PT primordium until E12.0. On the other hand, GJA5 mRNA was transiently detected in PT primordium from E6 to E14.0, while the expression was not detected in PD during development. These results suggested that these genes may be involved in the regulation mechanism of PT development and could be a useful marker in the PT development