1. The first few pairs of somites that form do not persist; they disappear and are incorporated into the head.

2. The somite forms the myotome, sclerotome and perhaps dermatome.

3. A somite is an early body segment in the developing embryo that gives rise to most of the adult body muscle and skeleton.

4. It is therefore suggested that the presumptic somite attained its stable determination at mid-neurula stage.

5. The simplest two-instrument cell injection technique for both primitive streak stage and for early somite stage embryos will be described.