(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

一、鳃器官 鳃弓胚体头部两侧柱状隆起6对 鳃沟相邻鳃弓之间的沟5对 咽囊咽壁内胚层向外凸出5对 鳃膜鳃沟底的外胚层和咽囊顶的内胚层相贴 二、颜面的发生

一、气管 (一)黏膜 1、假复层柱状纤毛上皮 纤毛细胞:数量最多,纤毛摆动,将表面黏液及其尘埃、细菌等推向咽部 排出

一、概述 (一)组成 卵巢:女性生殖腺,产生卵子,分泌性激素 输卵管:受精的场所,并将受精卵输送到子宫 子宫:孕育胎儿 乳腺:分泌乳汁,是哺乳的器官 外生殖器