Gendron-Maguire M, Mallo M, Zhang M, Gridley T:
Hoxa-2 mutant mice exhibit homeotic transformation of skeletal
elements derived from cranial neural crest.
Cell 1993 Dec 31;75(7):1317-31
ABSTRACT
Mice homozygous for a targeted mutation of the Hoxa-2 (Hox 1.11)
gene are born with cleft palates and die within 24 hr of birth.
Analysis of stained skeletons revealed that homozygous mutant
animals contained multiple cranial skeletal defects, including a
duplication of the ossification centers of the bones of the middle
ear. Histological analysis suggested that this duplication resulted
from the transformation of skeletal elements derived from the second
branchial arch into more anterior structures, resulting in a
duplication of Meckel's cartilage adjacent to the otic capsule.
Skeletal elements normally derived from the second arch were absent
in the mutants. These data provide direct experimental evidence for
the existence of a branchial Hox code.
