1.General feature: (1) contain more cells and less extracellular ground substance (2) Polarisaton: ---free outer surface: face air or other things ---basal surface: face underlying CT, havebasement membrane (3) Avascularity,but innervation: ---no blood vessels ---rich in nerve terminals

一、肝、胆、胰的发生 (一)肝与胆的发生 肝憩室:前肠末端腹侧壁内胚层细胞增生 头支:肝细胞索→肝板、肝内胆管上皮 尾支:柄→胆囊管

人体内最大的器官。由表皮和真皮构成。参与保护,感觉和体温调节等功能。 1.表皮(Epidemis):角化的复层扁平上皮,由2类细胞构成 A.角化细胞(Keratinocyte):分5层排列,参与皮肤的角化。角化须2~4周完成

(1) extra-embryonic blood vessels ---blood island: at the middle of 3 rd week, wall of the yolk sac mesenchyma proliferate and form isolated cell clusters, the peripheral cell become flattened and differentiate into endothelial cell to from endothelial tube; central located cells are detached and develop into primitive blood cells(blood stem cell)

digestive and respiratory system derived from primitive gut /foregut /midgut /hindgut ---epi. of digestive and respiratory system derived from endoderm ---CT and MT of digestive and respiratory system derived from splanchnic or visceral mesoderm

1. General features: （1) small number of cells and large amount of extracellular ground substance （2) extracellular is composed of fibers and amorphous ground substance-matrix （3) all of them originate from mesenchyme￾embryonal CT （4) have functions of connection, supporting, protecting, nutrition, defence and repairing

1.眼(Eye):高度特化的视觉感受器。 A.眼球壁:3层。 1.纤维膜(Fibrous membrane):最外层。a.角膜(Cornea):占据前1/6,无色透明,无血管。富含神经末梢。分5层

1、肾脏与输尿管的发生 前肾 中肾 后肾:起源于输尿管芽和生后肾原基 输尿管芽向后上方引伸→输尿管 末端膨大肾盂、肾大盏、肾小盏、集合小管 生后肾原基:细胞团→中空泡状→S形小管→肾小管

一、心血管系统的发生 (一)原始心血管系统的建立 1、血岛和胚内、外毛细血管的发生 卵黄囊壁胚外中胚层→血岛(blood island) 周边细胞变扁→内皮→原始血管 中央游离细胞→造血干细胞

一.基本构成: A.细胞外间质:血浆(Plasma)占血液总体积55~56%左右。 1.基质:血清(Serum),血凝块中渗出的淡黄色液体。 2.纤维:可溶性的纤维蛋白原,在凝血时转变为不溶的纤维蛋白