Which of the following are mesodermal and endodermal in origin respectively ?

Options

A. Urinary bladder - Kidney
B. Kidney - Inner lining of urinary bladder
C. Urinary ducts - Genital ducts
D. Genital ducts - Urinary ducts

Answer

To determine which structures are mesodermal and endodermal in origin, we need to understand the roles of these germ layers in human development.

### Step-by-Step Solution:

1. **Understand Germ Layers**:
- The human embryo develops three primary germ layers: ectoderm, mesoderm, and endoderm.
- The mesoderm is the middle layer, while the endoderm is the innermost layer.

2. **Identify Mesodermal Structures**:
- The mesoderm gives rise to various structures, including muscles, bones, and the urogenital system (which includes the kidneys and urinary bladder).

3. **Identify Endodermal Structures**:
- The endoderm primarily forms the lining of the gastrointestinal tract and associated organs, including the urinary bladder.

4. **Analyze the Options**:
- If the options provided include "urinary bladder" and "kidney", we can analyze their origins:
- **Kidney**: The kidney originates from the mesoderm.
- **Urinary Bladder**: The urinary bladder originates from the endoderm.

5. **Conclusion**:
- Therefore, the correct answer is that the kidney is mesodermal in origin and the urinary bladder is endodermal in origin.

### Final Answer:
- The structures that are mesodermal and endodermal in origin respectively are: **Kidney (mesodermal) and Urinary Bladder (endodermal)**.