Ls. Palazon et Ar. Burgos, LOCALIZATION OF ALPHA-FETOPROTEIN DURING THE FORMATION OF THE NEURAL-TUBE AND SOMITES IN CHICK-EMBRYO, Tissue & cell, 26(4), 1994, pp. 579-586
Very little is known about the biological role of alpha-fetoprotein (A
FP) in normal development. This study was undertaken to look for AFP-p
ositive tissues involved in active morphogenetic and histogenetic even
ts. Using a polyclonal antibody specific for AFP and the immunoperoxid
ase technique, we have studied the AFP localization during the formati
on of the neural tube and somites in chick embryo. Immunostaining of e
arly whole embryos, cephalic fold stage, shows a strong immunoreaction
for AFP in the cephalic and neural folds. In a more advanced stage of
the development (6-somite stage), the AFP expression has followed the
caudal direction of the neural fold forming process. Immunostaining o
f 6- and 9-somite embryo sections shows an increase of AFP expression
from the most undifferentiated (the neural fold), to the most differen
tiated (the neural tube). AFP does not label the nonsegmented paraxial
mesoderm, from which the somite is derived. Instead, when the paraxia
l mesoderm is segmented and has formed a somite, AFP positive cells ar
e detected in the somite. The morphological differentiation of somite
is joined to one biochemical differentiation, since the myotome and sc
lerotome cells are AFP positive while the dermatome cells are AFP nega
tive. The sclerotome cells become AFP negative when they surround the
notochord to form the vertebral body. The results presented here stron
gly suggest a close association of AFP with cell proliferation and dif
ferentiation.