CELLULAR DIFFERENTIATION OF HEART AND VESSEL

1.心前中胚层与生长因子心前中胚层在成人心脏中具有向搏动心肌分化的潜能，本实验研究了在生长因子存在下，心前中胚层是否发育为搏动组织。胰岛素样生长因子、激活素A和碱性成纤维细胞生长因子对心肌细胞分化有促进作用。2.心脏发育和含钙线粒体用细胞化学和X线微区分析方法观察了鸡发育心脏含钙空泡线粒体。3.肌浆网与心脏发育本实验观察了鸡胚早期心脏肌浆网（sarcoplasmic reticulum，SR）的发育及其钙释放功能。管状SR和连接SR分别出现在第11和12阶段。Fura-2测定细胞内钙离子浓度提示SR可能在10.4期开始发挥功能。大动脉转位（TGA）在维甲酸诱导的小鼠模型上研究了大动脉转位（TGA）的发生机制。用扫描电镜观察不同发育阶段的心内铸型模型。TGA的主要形态学异常为圆锥垫嵴发育不全。5.转化生长因子β_3（TGF β_3）与鸡胚发生用原位杂交技术检测了鸡胚发育过程中TGF β_3的mRNA转录本。TGF β 3 mRNA主要分布于发育中的动脉和心脏以及体腔上皮。提示TGF β 3可能在中胚层发育包括心血管系统发育中起重要作用。

1.Precardiac mesoderm and growth factorsPrecardiac mesoderm, which has potential ability of differentiation to beating myocardium in the adult heart, was examined whether it developed to beating tissue in the presence of growth factors. Insulin-like growth factor, activin A,and basic fibroblast growth factor showed a stimulating effect on myocardial differentiation.2.Heart development and calcium-containing mitochondriaA calcium-containing vacuolated mitochondria in chick developing heart was examined by cytochemistry and X-ray microanarysis. Results suggested that vacuolated mitochondria regulated intracellular calcium concentration.3.Sarcoplasmic reticulum and heart developmentDevelopment of sarcoplasmic reticulum (SR) and its calcium releasing function were examined in early chick embryonic heart. Tubular SR and junctional SR appeared at stage 11 and 12, respectively. Intracellular calcium concentration by fura-2 suggested that SR might elicit its function at stage 10.4.Transposition of the great arteries (TGA)Developmental mechanism of TGA,one of the congenital heart malformations, was examined in retinoic-acid induced mouse model. Intraracardiac cast models at various developmental stages were examined by scanning electron microscopy. Primary morphological abnormality of TGA was hypoplasia of cushion ridges in conus cordis.5.Transforming growth factor (TGF) BETA3 and chick embryogenesismRNA transcripts of TGFBETA3 was examined in developing chick embryos by in situ hybridization. TGFBETA3 mRNA was distributed mainly at developing artery and heart as well as epithelium of body cavity. This suggested that TGFBETA3 may play important roles in mesodermal development including cardiovascular system.