Common Features of Eye and Limb Development

A comparison of the embryonic development of the very much different organs, the eyes and the limb, points to various interesting common features of organogenesis.

1) Both the eye and the limb originate in a morphogenetic field, which may be described as a sum total of properties and commitment of a specific area of embryo in time to form an organ. The concept of a morphogenetic field describes many experimental observations.

2) In both organs the participating cells comprise diverse origins: surface ectoderm, neural ectoderm, mesenchyme derived from neural crest cells and head mesoderm in the case of eyes; and surface ectoderm, somitic and lateral plate mesoderm in the limbs. In addition cell types such as those in the circulating blood and of nervous tissue invade both the organs.

3) Tissue interaction plays a main, in fact decisive role in the proper development of both the organs. The interactions of two types: one way inductions and two way reciprocal interactions.

The instance of one way induction includes corneal induction by the lens in the eye and the instances of two way tissue interaction include mesoderm-AER interaction in the limbs and optic vesicle-lens ectoderm interaction in the limbs. These make sure the harmonious development of all parts in both the organs.

4) In the organogenesis of both of the inductive messages from one tissue to another are often operative across the non-specific and species.

5) In the development of both the eyes and limbs massive cell death takes place which is genetically programmed and plays a role in pattern creation.