An In vitro Study on Chick Somite Ability to Express Cerberus, Chordin, FGF8,Follistatin, and Noggin Transcripts

Somites are transient developmental structures and the derivatives of paraxial mesoderm which have an important role in organization of segmented pattern of vertebrate embryos 1. In vitro simulation of developmental mechanisms of vertebrates، especially mammals، could help us to find out the intrinsic molecular events involved in the development of organs and differentiation of various kinds of cells like CNS neurons. It is almost impossible to isolate developmental structures such as somite and notochord in human to study their functions in vitro. Even in laboratory mammals like mice، somites are too small to isolate and meticulous work should be done for separating them. Thus، the sole way is to separate such structures in chicken 2. In such situation، chick embryos are the best choice for somite isolation and in vitro simulation of developmental process of neurons. This simulation helps us to find out whether human embryonic cells respond to the molecular signals sent by somite، thereby exploring a new way for regeneration of damaged neural tissues. Previous studies 3 have shown that co-culture of somites derived from chick embryos of stages 9-12 of Hamburger and Hamilton 4 caused an increase in TUJ1/HOXB4 double positive group among human neural progenitors. Also it has been shown by Sagha et al 5 that somites maintain their neural induction ability in mouse embryonic stem cells. They have shown that somites thicken the adjacent part of neural tube، thereby affect the proliferation of neural tube precursors 6. So far، there is no confirmation on expression of secretory factors by somite، whether they are able to co-express several neurogenic factors like noggin، chordin، follistatin، cerberus and FGF8 in vitro. The neurogenic activity of noggin 7، chordin 8، follistatin 9، cerberus 10 and FGF8 11 has already been established. Thus، this study investigated the co-expression of the mentioned factors by somites at mRNA level.