Which of the following statements is incorrect?

Options

A. Pseudostratified epithelium has multiple layers of cells with nuclei at different levels
B. Endocrine glands lack ducts, so they secrete their products directly in the blood
C. Buccal cavity is lined by stratified non-keratinised squamous epithelium
D. In humans mammary gland is compound tubuloalveolar

Answer

To determine which statement is incorrect, we will analyze each option provided in the question step by step.

### Step 1: Analyze Option A
**Statement:** Pseudostratified epithelium has multiple layers of cells with their nuclei at different levels.

- **Analysis:** Pseudostratified epithelium appears to be stratified because the nuclei are at different levels, but it is actually a single layer of cells. The term "pseudo" means false, indicating that it is not truly stratified. Therefore, this statement is incorrect.

### Step 2: Analyze Option B
**Statement:** Endocrine glands lack ducts and secrete products directly into the blood.

- **Analysis:** This statement is correct. Endocrine glands are ductless and release hormones directly into the bloodstream, which then transport these hormones to target organs.

### Step 3: Analyze Option C
**Statement:** Buccal cavity is lined by stratified non-keratinized squamous epithelium.

- **Analysis:** This statement is also correct. The buccal cavity (mouth) is lined with stratified non-keratinized squamous epithelium, which provides protection against abrasion while maintaining a moist surface.

### Step 4: Analyze Option D
**Statement:** In humans, mammary gland is compound tubulo-alveolar.

- **Analysis:** This statement is correct. The mammary glands consist of clusters of alveoli (sac-like structures) and tubular ducts, making it a compound tubulo-alveolar gland.

### Conclusion
After analyzing all the statements, we find that the only incorrect statement is **Option A**, which mischaracterizes pseudostratified epithelium as having multiple layers.

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