Changes

===Proximal - Distal Patterning===

===Proximal - Distal Patterning===

*Governed by the PZ.

Proximal to distal patterning is governed by the PZ. The first cells to leave the PZ have a proximal identity as these cells have been in the PZ for a shorter amount of time than those that leave the PZ last, which have a distal identity. The "identity" of the cell is achieved by the HOX - A gene expression in that cells that leave the PZ early have fewer HOX - A genes expressed than those which leave later. Less HOX - A  gene expression results in a more proximal cell appearance.

*The first cells to leave the PZ have a proximal identity.

*These cells have been in the PZ for a shorter amount of time than those that leave the PZ last, which have a distal identity.

*"Identity" is achieved by the HOX - A gene expression.

**Cells that leave the PZ early have fewer HOX - A genes expressed than those which leave later.

**Less HOX - A  gene expression results in a more proximal cell appearance.

===Anterior - Posterior Patterning===

===Anterior - Posterior Patterning===