![This is blank.](https://digitalhistology.org/wp-content/themes/histology-unified/imgs/trans.png)
Trachea
The trachea and primary bronchi, extrapulmonary components of the conducting portion of the respiratory system, cannot be distinguished from each other histologically. The trachea, continuing inferiorly from the larynx, lies anterior to the esophagus. The patency of these respiratory organs is maintained by C-shaped cartilage rings, whose openings face the esophagus. The two main lobes of the thyroid gland are located at the lateral boundaries of the trachea. 10x
![Esophagus <p>The trachea and primary bronchi, extrapulmonary components of the conducting portion of the respiratory system, cannot be distinguished from each other histologically. The trachea, continuing inferiorly from the larynx, lies anterior to the esophagus. The patency of these respiratory organs is maintained by C-shaped cartilage rings, whose openings face the esophagus. The two main lobes of the thyroid gland are located at the lateral boundaries of the trachea. 10x </p>](https://digitalhistology.org/wp-content/uploads/2019/01/O.R.E.T.P01.png)
Esophagus
The trachea and primary bronchi, extrapulmonary components of the conducting portion of the respiratory system, cannot be distinguished from each other histologically. The trachea, continuing inferiorly from the larynx, lies anterior to the esophagus. The patency of these respiratory organs is maintained by C-shaped cartilage rings, whose openings face the esophagus. The two main lobes of the thyroid gland are located at the lateral boundaries of the trachea. 10x
![Trachea <p>The trachea and primary bronchi, extrapulmonary components of the conducting portion of the respiratory system, cannot be distinguished from each other histologically. The trachea, continuing inferiorly from the larynx, lies anterior to the esophagus. The patency of these respiratory organs is maintained by C-shaped cartilage rings, whose openings face the esophagus. The two main lobes of the thyroid gland are located at the lateral boundaries of the trachea. 10x </p>](https://digitalhistology.org/wp-content/uploads/2019/01/O.R.E.T.P02.png)
Trachea
The trachea and primary bronchi, extrapulmonary components of the conducting portion of the respiratory system, cannot be distinguished from each other histologically. The trachea, continuing inferiorly from the larynx, lies anterior to the esophagus. The patency of these respiratory organs is maintained by C-shaped cartilage rings, whose openings face the esophagus. The two main lobes of the thyroid gland are located at the lateral boundaries of the trachea. 10x
![Primary bronchi <p>The trachea and primary bronchi, extrapulmonary components of the conducting portion of the respiratory system, cannot be distinguished from each other histologically. The trachea, continuing inferiorly from the larynx, lies anterior to the esophagus. The patency of these respiratory organs is maintained by C-shaped cartilage rings, whose openings face the esophagus. The two main lobes of the thyroid gland are located at the lateral boundaries of the trachea. 10x </p>](https://digitalhistology.org/wp-content/uploads/2019/01/O.R.E.T.P03.png)
Primary bronchi
The trachea and primary bronchi, extrapulmonary components of the conducting portion of the respiratory system, cannot be distinguished from each other histologically. The trachea, continuing inferiorly from the larynx, lies anterior to the esophagus. The patency of these respiratory organs is maintained by C-shaped cartilage rings, whose openings face the esophagus. The two main lobes of the thyroid gland are located at the lateral boundaries of the trachea. 10x
![Cartilage ring <p>The trachea and primary bronchi, extrapulmonary components of the conducting portion of the respiratory system, cannot be distinguished from each other histologically. The trachea, continuing inferiorly from the larynx, lies anterior to the esophagus. The patency of these respiratory organs is maintained by C-shaped cartilage rings, whose openings face the esophagus. The two main lobes of the thyroid gland are located at the lateral boundaries of the trachea. 10x </p>](https://digitalhistology.org/wp-content/uploads/2019/02/O.R.E.T.P04A.png)
Cartilage ring
The trachea and primary bronchi, extrapulmonary components of the conducting portion of the respiratory system, cannot be distinguished from each other histologically. The trachea, continuing inferiorly from the larynx, lies anterior to the esophagus. The patency of these respiratory organs is maintained by C-shaped cartilage rings, whose openings face the esophagus. The two main lobes of the thyroid gland are located at the lateral boundaries of the trachea. 10x
![Cartilage ring opening <p>The trachea and primary bronchi, extrapulmonary components of the conducting portion of the respiratory system, cannot be distinguished from each other histologically. The trachea, continuing inferiorly from the larynx, lies anterior to the esophagus. The patency of these respiratory organs is maintained by C-shaped cartilage rings, whose openings face the esophagus. The two main lobes of the thyroid gland are located at the lateral boundaries of the trachea. 10x </p>](https://digitalhistology.org/wp-content/uploads/2019/01/O.R.E.T.P05.png)
Cartilage ring opening
The trachea and primary bronchi, extrapulmonary components of the conducting portion of the respiratory system, cannot be distinguished from each other histologically. The trachea, continuing inferiorly from the larynx, lies anterior to the esophagus. The patency of these respiratory organs is maintained by C-shaped cartilage rings, whose openings face the esophagus. The two main lobes of the thyroid gland are located at the lateral boundaries of the trachea. 10x
![Thyroid gland <p>The trachea and primary bronchi, extrapulmonary components of the conducting portion of the respiratory system, cannot be distinguished from each other histologically. The trachea, continuing inferiorly from the larynx, lies anterior to the esophagus. The patency of these respiratory organs is maintained by C-shaped cartilage rings, whose openings face the esophagus. The two main lobes of the thyroid gland are located at the lateral boundaries of the trachea. 10x </p>](https://digitalhistology.org/wp-content/uploads/2019/01/O.R.E.T.P06.png)
Thyroid gland
The trachea and primary bronchi, extrapulmonary components of the conducting portion of the respiratory system, cannot be distinguished from each other histologically. The trachea, continuing inferiorly from the larynx, lies anterior to the esophagus. The patency of these respiratory organs is maintained by C-shaped cartilage rings, whose openings face the esophagus. The two main lobes of the thyroid gland are located at the lateral boundaries of the trachea. 10x
![Next image <p>The next image is similar to that outlined by the rectangle.</p>](https://digitalhistology.org/wp-content/uploads/2019/02/O.R.E.T.P07Apng.png)
Next image
The next image is similar to that outlined by the rectangle.
![Image credit <p>This image is from the University of Iowa slide collection.</p>](https://digitalhistology.org/wp-content/uploads/2019/02/Iowa-source-ping-left.png)
Image credit
This image is from the University of Iowa slide collection.