Heart myofibrillogenesis occurs in isolated chick posterior blastoderm: a culture model.
Early cardiogenesis including myofibrillogenesis is a critical event during development. -Recently we showed that prospective cardiomyocytes reside in the posterior lateral blastoderm in the chick embryo. Here we cultured the posterior region of the chick blastoderm in serum-free medium and observed the process of myofibrillogenesis by immunohistochemistry. After 48 hours, explants expressed sarcomeric proteins (sarcomeric alpha-actinin, 61%; smooth muscle alpha-actin, 95%; Z-line titin, 56%; sarcomeric myosin, 48%); however, they did not yet show a mature striation. After 72 hours, more than 92% of explants expressed I-Z-I proteins, which were incorporated into the striation in 75% of explants or more (sarcomeric alpha-actinin, 75%; smooth muscle alpha-actin, 81%; Z-line titin, 83%). Sarcomeric myosin was -expressed in 63% of explants and incorporated into A-bands in 37%. The percentage incidence of expression or striation of I-Z-I proteins was significantly higher than that of sarcomeric myosin. Results suggested that the nascent I-Z-I components appeared to be generated independently of A-bands in the cultured posterior blastoderm, and that the process of myofibrillogenesis observed in our culture model faithfully reflected that in vivo. Our blastoderm culture model appeared to be useful to investigate the mechanisms regulating the early cardiogenesis.
Matsui
Hiroko
H
Department of Anatomy and Cell Biology, Graduate School of Medicine, Osaka City University, 1-4-3 Asahimachi, Abenoku, Osaka 545-8585, Japan.
Sakabe
Masahide
M
Sakata
Hirokazu
H
Nakatani
Kazuki
K
Ikeda
Kazuo
K
Fukui
Mitsuru
M
Ando
Katsumi
K
Yamagishi
Toshiyuki
T
Nakajima
Yuji
Y