Nude Mouse is able to accept Xeno-Graft because they lack:
**Core Concept**
Nude mice are a type of immunocompromised animal model used in research, particularly in the field of oncology and transplantation. Their unique characteristic is the absence of a fully functional immune system, which makes them an ideal host for xenografts, or grafts from different species.
**Why the Correct Answer is Right**
Nude mice lack a thymus, which is essential for the development and maturation of T cells, a crucial component of the adaptive immune system. Without a thymus, nude mice are unable to produce functional T cells, making them more susceptible to infections and allowing them to accept xenografts from other species. This characteristic is due to a mutation in the hairless (hr) gene, which affects the development of the thymus and other lymphoid tissues.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the question, as the absence of a specific gene or protein is not the primary reason for nude mice's immunocompromised state.
**Option B:** Nude mice do have a functional B cell system, which is responsible for producing antibodies. Therefore, this option is incorrect.
**Option C:** While nude mice do have some limitations in their immune response, their lack of a thymus is the primary reason for their immunocompromised state.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that nude mice are just one example of immunocompromised animal models used in research. Other models, such as SCID mice and beige mice, also have unique characteristics that make them useful for specific studies.
**Correct Answer: C. A thymus.**