Questions: What are the characteristics of the histology of the esophagus? Select all that apply. - The mucosa is composed of thick, ciliated pseudostratified columnar cells. - The mucosa is composed of thick, non-keratinized stratified squamous epithelium. - The serosa is made of cartilage. - It is composed entirely of smooth muscle. - The two layers of muscle in the superior one third of the muscularis are skeletal.

The characteristics of the histology of the esophagus include:

• The mucosa is composed of thick, non-keratinized stratified squamous epithelium.
• The two layers of muscle in the superior one third of the muscularis are skeletal.

Explanation for each option:

1. The mucosa is composed of thick, ciliated pseudostratified columnar cells.
   This is incorrect. The esophagus is lined with non-keratinized stratified squamous epithelium, which is suited to protect against abrasion from food particles.

2. The mucosa is composed of thick, non-keratinized stratified squamous epithelium.
   This is correct. The esophagus has a lining of non-keratinized stratified squamous epithelium to protect against mechanical stress.

3. The serosa is made of cartilage.
   This is incorrect. The esophagus does not have a serosa made of cartilage. Instead, it has an adventitia, which is a connective tissue layer.

4. It is composed entirely of smooth muscle.
   This is incorrect. The esophagus has a combination of skeletal and smooth muscle. The upper third contains skeletal muscle, the middle third contains a mix of skeletal and smooth muscle, and the lower third is composed of smooth muscle.

5. The two layers of muscle in the superior one third of the muscularis are skeletal.
   This is correct. The upper third of the esophagus contains skeletal muscle, which is under voluntary control, aiding in the initiation of swallowing.

In summary, the correct characteristics of the esophagus histology are the presence of non-keratinized stratified squamous epithelium in the mucosa and skeletal muscle in the superior one third of the muscularis.