(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. Development of branchial apparatus * branchial apparatus: including branchial arch, branchial groove, branchial membrane and branchial pouch

1. Components: ---testis: produce the male germ cells- gametes(sperm) produce androgen-testosterone ---gernital ducts: store and conduct the sperm epididymis ductus deferens ejaculatory duct

1. Components ---nose ---pharynx ---larynx ---trachea ---bronchi ---lung

---Digestive system: Digestive tract Digestive gland

1. General description: ---Components: nerve cell: neuron Glial cell: neuroglial ---Function: Neurons : receive the stimulation, conduct the nerve impulse Glial cell: support, protect and insulate, nourish neurons

1. General description (1) components: ---cell: muscle fiber-myofiber elongated thread-liked Sarcolemma Sarcoplasm sarcoplasmic reticulum: SER

---Closed tubular system ---Blood circulatory or cardiovascular S ---Lymph vascular S

1. Cartilage: organ=Cartilage tissue+perichondrium