The veins in the lobes of the lung merge, forming the lobe veins. When going to the periphery, the veins in the lungs form the interlobar veins, which run in the connective tissue layer between the lobes of the lung. The pulmonary veins receive pleural branches and a network of blood vessels that develop from the top of the bronchial tree.
The veins in the lungs are made up of the mesenchymal tissue layer. The major pulmonary veins are developed from the atrial germ. As the lungs develop, pairs of arteries and bronchi are centrally located each, subdividing into branches. These pairs of arteries and bronchi enter the lobes of the lung, branch off into the segments, and develop into the lung parenchyma. Each pulmonary artery is closely related to the main bronchus, which develop into branches accompanying the corresponding bronchus. By the 6th week of pregnancy, the left 6th aortic arch will form the left and right pulmonary arteries. As the lungs develop, they will protrude from the sides into the thoracic cavity to later form the pleural cavity. An airway consisting of terminal bronchi has been formed. From the 6th week of pregnancy, the development of the components of the bronchi complete. The right lung is divided into 3 lobes, the left lung is divided into 2 lobes. Initially, the 2 lung buds develop symmetrically and symmetrically, but from 6 to 7 weeks, the lungs begin to divide into lobes.
From the tail of the germ tube, on the 2 side walls grow 2 buds of the right and left lungs. The first part of the germ tube develops into the larynx and trachea.
The germ tube is covered by endodermal tissue (this organization later develops into the epithelial layer of the respiratory organs). Before learning about lung anatomy, everyone should understand the formation of the lungs from the embryonic stage: The germ of the respiratory organs is a long groove, appearing in the 4th week of the embryo.
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