part_of part of part of develops from develops from ends during starts during ectoderm fin UBERON:0008897 xenopus_anatomy XAO:0000002 Surface structure that has an important role in tadpole locomotion. It starts to develop along the trunk and tail of the embryo at the tail bud stage and continues to grow until the start of metamorphosis when it begins to regress. It consists of flattened epidermal cells elevated into a keel-like structure by a supporting core of mesenchyme and extracellular matrix. surface structure NF stage 25 NF stage 66