Q.8 Nude mice refers to
(A) mice without skin (B) mice without thymus
(C) knockout mice (D) transgenic mice

Nude mice are immunodeficient strains characterized by the absence of a functional thymus due to Foxn1 gene mutation, making (B) the correct answer. Their hairless phenotype and T-cell deficiency make them ideal for xenograft studies in cancer research.​

Correct Answer

The correct option is (B) mice without thymus. Nude mice (nu/nu) carry a spontaneous Foxn1 mutation causing thymic aplasia, preventing T-lymphocyte maturation and adaptive immunity while retaining limited B/NK cell function. This enables tumor engraftment without rejection.​

Option Explanations

Nude mice arise from natural mutation, not genetic engineering, distinguished by specific immunodeficiency.

• (A) mice without skin: Incorrect; “nude” refers to hairlessness from defective follicles, not skin absence—skin remains intact.​

• (B) mice without thymus: Correct; congenitally athymic with vestigial, nonfunctional thymus lacking thymic epithelium for T-cell education.​

• (C) knockout mice: Incorrect; targeted gene disruption (e.g., Foxn1 KO mimics phenotype) differs from spontaneous nude mutation.​

• (D) transgenic mice: Incorrect; involves foreign gene insertion (e.g., oncogenes), unlike nude’s loss-of-function mutation.​

Mechanism Overview

Bone marrow T-progenitors reach nonfunctional thymus, yielding <1% mature T cells (θ-antigen low). B cells hyperactive without T regulation, causing autoantibodies. Used for human tumor xenografts, infectious disease, and immunology.​