19.1 Face and upper foregut

• Introduction
  
• Development of the facial region
• Oral cavity
• Tongue
• Development of the teeth
• Development of the salivary glands
• Definitive pharynx: Derivatives of the first and second pharyngeal arches
  • Thyroid
  • Middle ear
    
  • Tonsils
• Derivatives of the third and fourth pharyngeal arches
  • Thymus
  • Parathyroid glands and ultimopharyngeal bodies
    
• Lungs

Lungs

In the lower part of the pharynx arises ventrally from the midline towards the ventral direction a groove, the laryngotracheal sulcus (stage 10, ca. 28 days, 10). The caudal end develops to become the lung buds that, parallel to the esophagus, grow into the mesoderm. This part becomes the trachea. Through a series of interactions with the surrounding tissue these lung buds begin to divide and engender the right and left main bronchi (stage 13-14, ca. 32-33 days, 13). Through further subdivisions the whole left and right bronchial trees of the lungs arise step by step.
(see respiration tract module)

Fig. 17
In this median sagittal section median buddings of the intestinal tube can be recognized: the thyroid below the first aortic arch, the lungs at the level of the heart and the liver below the heart at the transition to the umbilical vesicle.