CELLULAR DIFFERENTIATION OF HEART AND VESSEL

1.心前中胚层与生长因子研究了成人心脏中具有向搏动心肌分化潜力的心前中胚层在生长因子的作用下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分化有刺激作用。用细胞化学和x射线微量分析方法对鸡心脏发育过程中的含钙空泡线粒体进行了检测。结果表明，空泡线粒体调节细胞内钙浓度。研究了鸡早期胚胎心脏肌浆网（SR）的发育及其钙释放功能。管状SR和结状SR分别出现在第11期和第12期。fura-2的细胞内钙浓度表明SR可能在10.4期引发其功能。在维甲酸诱导的小鼠先天性心脏畸形模型中，研究了大动脉转位（TGA）的发育机制。采用扫描电镜观察不同发育阶段的心内铸型模型。TGA的主要形态异常为圆锥枕脊发育不全。采用原位杂交技术对发育中的鸡胚中转化生长因子（TGF - BETA3） mrna转录物进行了检测。TGFBETA3 mRNA主要分布在发育中的动脉和心脏以及体腔上皮。这表明TGFBETA3可能在包括心血管系统在内的中胚层发育中起重要作用。

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.