Table 1.

Summary of thyroid and ultimobranchial body defects in Eya1^−/− animals

No. of animals analyzed	No. of ub defects	Types of ub defects	Thyroid isthmus defects
4 at E15.5*	4/4	2 persistent on both sides
		2 persistent on one side and absent on the other side
4 newborns†	4/4	2 persistent on both sides	3/4 absent
		2 persistent on one side and absent on the other side

^*Animals at E15.5 were analyzed by Pax8 expression. Ultimobranchial bodies (ub) showing weak Pax8 expression and located as separate structures anterodorsal to the thyroid lobes were scored as persistent. Absent ubs were scored as absence of both a persistent ub and weak Pax8 expression within the thyroid lobe on a single side.

^†Animals at newborn stage were analyzed by calcitonin staining. ubs were scored as absent if there was no persistent ub and no calcitonin-positive cells within the thyroid lobe on a single side. Three animals lacked an isthmus.