The efforts to map molecular pathways and the mechanical processes underlying morphogenesis are crucial to understanding: (1) the source of birth defects, (2) the formation of tumors and progression of cancer, and (3) basic principles of tissue engineering.
Underlying submandibular salivary gland branching morphogenesis is the regulated proliferation and differentiation of perhaps several progenitor cell populations, which have not been characterized throughout development, and yet are critical for understanding organ development, regeneration, and disease.
These processes, generically referred to as morphogenesis, are the underlying mechanisms for numerous developmental events including gastrulation, neurulation, organogenesis and metamorphosis.
Hox genes are classically ascribed to function in patterning the anterior-posterior axis of bilaterian animals; however, their role in directing molecular mechanisms underlying morphogenesis at the cellular level remains largely unstudied.
A balance model for the adaxial/abaxial determinants underlying integument morphogenesis was also proposed: in the inner integument, ATS and a proposed additional abaxial factor acted in balanced opposition to CNA/PHB/PHV and REV to promote inner integument growth; in the outer integument, the abaxial activities of INO, KAN1 and KAN2 acted in balance with REV to control morphogenesis [ 14].
To date, the molecular and cellular mechanisms underlying morphogenesis and regeneration of the SG are barely understood.
In the past years molecular mechanisms underlying cardiac morphogenesis were studied in vivo by the generation of gene-targeted animal models [ 34].
In his Nobel Lecture, Eric Wieschaus concluded that classic Drosophila screens failed to identify many morphogenesis genes and proposed as a result that the control of cell form that underlies morphogenesis may be unusually susceptible to genetic redundancy (W ieschaus 1997).
Redundancy among mechanisms that underlie morphogenesis has been called a "well-recognized aspect of development" (N ewman and C omper 1990).
One main advantage of the zebrafish model is its optical translucency, which facilitates live imaging of the cellular processes underlying morphogenesis.
