**Question:** The following are lined with pseudostratified ciliated columnar epithelium except?

A. Respiratory tract (lung and trachea)
B. Esophagus
C. Ureters
D. Urinary bladder

**Core Concept:**
Pseudostratified ciliated columnar epithelium is a specific type of epithelial tissue found in various parts of the human body. It is characterized by the presence of cilia and secretory cells arranged in a layered structure. In this type of epithelium, the basal cells are located at the basement membrane, while the other cells are arranged in a columnar pattern.

**Why the Correct Answer is Right:**
Option D (Urinary bladder) is incorrect because the urothelium, which is the innermost layer of the bladder, is composed of stratified squamous epithelium. This type of epithelium lacks cilia and secretory cells seen in pseudostratified ciliated columnar epithelium.

**Why Each Wrong Option is Incorrect:**
Option A (Respiratory tract - lung and trachea) is correct because the respiratory tract is lined with pseudostratified ciliated columnar epithelium. The respiratory tract plays a crucial role in respiration, and this particular type of epithelium aids in the clearance of inhaled particles and pathogens from the airways.

Option B (Esophagus) is correct because the esophagus is lined with a stratified squamous epithelium, not pseudostratified ciliated columnar epithelium. The esophagus primarily functions in the passage of food from the mouth to the stomach.

**Clinical Pearl:**
Pseudostratified ciliated columnar epithelium is essential for the proper functioning of the respiratory tract. In addition to the clearance of inhaled particles and pathogens, the cilia and secretory cells present in this epithelium contribute to the maintenance of the airway's acidic environment, which is crucial for preventing the growth of unwanted microorganisms.

**Correct Answer:**
C. Ureters

**Why Each Wrong Option is Incorrect:**
Option C (Ureters) is incorrect because the ureters are lined with transitional epithelium, which is a type of stratified squamous epithelium. The ureters function in transporting urine from the kidneys to the bladder.