The spatial interrelationship of the body wall mesoderm and ectoderm of the chick embryo at the level of the developing limbs
Seichert, V.
Folia Morphologica 27(4): 310-317
1979
ISSN/ISBN: 0015-5640 PMID: 511041 Document Number: 154162
The spatial interrelationship of the body wall mesoderm and ectoderm was studied by the linear marking method in 204 chick embryos. A cranicaudal shift of the ectoderm covering the lateral surface of the paraaxial mesoderm of the embryo's body was observed. This shift increased in a craniocaudal direction and was greater in young embryos. Laterally, this ectodermal shift is bounded by a line corresponding to the fold between the paraaxial mesoderm and the lateral body wall (the dorsal crease line). In the stages when morphological differentiation of the limb buds took place, shifts of the ectoderm lying laterally to the dorsal crease line and leading laterally towards the distal (apical) margin of the developing limb bud were observed. The ectoderm localized medially to the dorsal crease line stopped shifting in these stages and grew parallel with the underlying mesoderm. It was impossible to tell whether ectodermal shifts over the lateral plate mesoderm took place in the phase prior to morphological differentiation of the lumb buds. A constant proximodistal shift of the dorsal and ventral ectoderm over the limb bud mesoderm was observed. The rate of this ectodermal shift rapidly increased in a proximodistal direction and progressively slowed down as the embryos grew older.