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Meckel's cartilage is a piece of cartilage from which the mandibles (lower jaws) of vertebrates evolved. Originally it was the lower of two cartilages which supported the first branchial arch in early fish. Then it grew longer and stronger, and acquired muscles capable of closing the developing jaw. [1]
The theory of recapitulation, also called the biogenetic law or embryological parallelism—often expressed using Ernst Haeckel's phrase "ontogeny recapitulates phylogeny"—is a historical hypothesis that the development of the embryo of an animal, from fertilization to gestation or hatching (), goes through stages resembling or representing successive adult stages in the evolution of the ...
In contrast to the Meckel's cartilage of the first pharyngeal arch it does not constitute a continuous element, and instead is composed of two distinct cartilaginous segments joined by a faint layer of mesenchyme. [15]
The mesenchymal cells within the mandibular prominence condense to form Meckel's cartilage. [2] ... hednk-032—Embryo Images at University of North Carolina
The face and neck development of the human embryo refers to the development of the structures from the third to eighth week that give rise to the future head and neck.They consist of three layers, the ectoderm, mesoderm and endoderm, which form the mesenchyme (derived form the lateral plate mesoderm and paraxial mesoderm), neural crest and neural placodes (from the ectoderm). [1]
Meckel's cartilage has an additional projection right before the joint with the palatoquadrate. This extra process, unique to Helicoprion , likely served to limit jaw closure to prevent the whorl from puncturing the chondrocranium.
Pattern of the pharyngeal arches.I-IV pharyngeal arches, 1-4 pharyngeal pouches (inside) and/or pharyngeal grooves (outside) a Lateral lingual swellings b Median tongue bud c Foramen cecum
The postdentary trough is a skeletal feature seen in Mesozoic mammals.It is found on the inside of the lower jaw (), at the back behind the molar teeth.It is the hollow in which the postdentary bones and Meckel's cartilage sit.