文档介绍：组织胚胎学课件 七年制英文医学班专用
中国医科大学
基础医学院
组胚—英文教学组
Chapter 24 Development of digestive and respiratory system
* 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 digestive system
1) derivatives of pharyngeal pouch
---pharyngeal pouch:
/outpocketings of endodermal lining of the primary pharynx (extends from the opharyngeal membrane to the tracheobronchial diverticulum)
/5 pairs
---derivatives of pharyngeal pouch:
① First pharyngeal pouch:
---distal portion: widen into a sac-like structure-middle ear cavity, the branchial membrane form tympanic membrane or eardrum
---proximal part: remain narrow to form the pharyngotympanic or Eustachian tube
② Second pharyngeal pouch:
---distal portion: obliterated
---remaining part proliferate and form primordium of the palatine tonsil
③ Third pharyngeal pouch:
---dorsal portion: differentiates into inferior parathyroid gland
---ventral part: cells differentiates and form two cell cords, fuse with each other behind the thorax to give rise to the promordium of the thymus
④ Fourth pharyngeal pouch:
---dorsal portion: forms superior parathyroid gland
---ventral portion: degenerates
⑤ Fifth pharyngeal pouch:
---gives rise to the ultimobranchial body, immigrate into thyroid and differentiate into parafollicular cells
*development of thyroid gland
---thyroid primordium: by the 4th week, endodermal proliferation of the floor of primitive pharynx, then descends in front of the primitive pharynx as a bilobed diverticulum
---thyroglossal duct: a narrow canal connecting primitive pharynx with thyroid primordium, by the 6th week, es solid and disappears.