β catenin: Protein involved in the Wnt signalling pathway, degraded by slimb in the absence of Wnt.

BMP-4: is a member of the Bone Morphogenetic protein family, which is apart of the TGFβ superfamily.

Brachyury: a transcription factor that induces mesodermal fate in cells.

Cereberus: BMP antagonists expressed by the Spemann Organiser. Responsible for differentiation of the mesoderm.

Chordin: BMP antagonists expressed by the Spemann Organiser. Responsible for differentiation of the mesoderm.

Cortical rotation: Movement of the membrane brought about by sperm entering the oocyte. 

Destruction Complex: Responsible for the breakdown of β catenin in the absence of Wnt.

Dishevelled: Recruited to Frizzled in the presence of Wnt. 

Follistatin: BMP antagonists expressed by the Spemann Organiser. Responsible for differentiation of the mesoderm.

Frizzled: A cell surface receptor in the Wnt/Wingless signalling pathway.

Goosecoid: Gene activated by Siamois causing the expression of several diffusible molecules. Regulates its own expression, sustaining the Organiser.

Mesoderm: is a primary germ layer, later becoming neural tissue and a variety of organs.

Nieuwkoop center: group of cells which express siamois and induce the formation of the spemann organiser.

Nodal: a member of the TGFβ superfamily and is triggered by VegT and Vg1.

Noggin : BMP antagonists expressed by the Spemann Organiser. Responsible for differentiation of the mesoderm.

Siamois: Gene which encodes for the secreted protein 'siamois'. Activated by high levels of β catenin.

Spemann Organiser: a group of cells which express goosecoid and BMP antagonist, so involved in patterning the embryo.

VegT: Maternal protien involved in Nodal expression.

Vg1: is a member of the TGFβ superfamily and involved in Nodal expression.

Wnt: protein involved in siganlling via Frizzled receptor, known to be involved in development and cancer.