Parametrisation of gradients.

The table shows the expressions for the concentrations [EphA] and [ephrinA of EphA and ephrin-A at a distance along the nasotemporal axis of the retina and the concentrations [ephrinA] and [EphA of ephrin-A and EphA at a distance along rostrocaudal axis of the SC. The temporal pole of the retina lies at and the nasal pole at . In the SC is the rostral pole and is the caudal pole. The heights of gradients in the retina and SC are denoted by and respectively, with a subscript ''E'' or ''e'' to denote whether it is an Eph or ephrin. These subscripts are also applied to the decay or rise constants of retinal and SC gradients, denoted and respectively.