BIO380H5 Lecture Notes - Lecture 18: Apical Ectodermal Ridge, Lateral Plate Mesoderm, Limb Bud
Document Summary
Bio 380 lecture 18 limbs development. The limb buds are derived from the somatic lateral plate mesoderm. The anterior limbs buds form earlier because the development of the embryo starts maturation from cephalic to caudal. Limb formation begins at the end of the fourth week. Limb bud consists of mesenchymal cells that are covered by the ectoderm: the mesenchymal cells are derived from the somatic lateral plate mesoderm. Cells that express the transcription factor tbx 5 will develop the upper limbs. Cells that express tbx 4 will develop the lower limbs. The anterior part of the limb bud will express gli 3, while the posterior will express hand 2. Look over slide 4: the mesenchymal cells can form a complete limb bud even if the pieces are disintegrated, split in two, composed of two of the same halves, etc. If the limb is split in two and are blocked from fusing again, then each half forms its own limb bud.
