Why does a mouse become hairless? - briefly
Hair loss in mice is caused by genetic mutations, hormonal disruptions, or experimental manipulations that interfere with hair‑follicle development. These disturbances trigger follicular apoptosis or halt the growth cycle, producing a smooth, hairless appearance.
Why does a mouse become hairless? - in detail
A mouse may lose its coat due to genetic mutations that disrupt the production of keratin or the signaling pathways governing hair follicle development. The most common hereditary condition is the “nude” phenotype, caused by a loss‑of‑function mutation in the Foxn1 gene, which eliminates thymic epithelial cells and impairs the formation of functional hair follicles. As a result, the animal is born without visible fur and remains hairless throughout life.
Environmental factors can also induce alopecia. Severe burns, extensive skin infections, or chronic dermatitis damage the epidermis and destroy follicular structures, preventing regrowth. Parasitic infestations—such as mange caused by Sarcoptes mites—lead to intense scratching, inflammation, and secondary bacterial infection, which frequently culminates in patchy or complete hair loss.
Nutritional deficiencies affect hair integrity. Insufficient protein, essential fatty acids, or micronutrients (zinc, biotin, vitamin A) impair keratin synthesis, causing brittle fur that sheds prematurely. In laboratory settings, dietary imbalances are often controlled, but in wild populations, scarcity can trigger noticeable thinning.
Endocrine disorders influence the hair cycle. Hyperthyroidism accelerates the catagen phase, shortening the growth period of each hair shaft, while hypothyroidism prolongs telogen, resulting in prolonged shedding. Hormonal imbalances related to stress (elevated corticosterone) suppress follicular stem cell activity, leading to reduced fur density.
Pharmacological agents may produce temporary or permanent hair loss. Chemotherapeutic drugs, glucocorticoids, and certain antihistamines interfere with cell proliferation in the skin, causing reversible alopecia. Topical irritants, such as strong disinfectants, can damage the cutaneous barrier, resulting in localized depilation.
In summary, the loss of mouse fur can be attributed to:
- Genetic mutations (e.g., Foxn1 deficiency)
- Physical injury or infection
- Parasitic disease (mange)
- Nutritional insufficiency
- Hormonal dysregulation
- Drug‑induced toxicity
Each factor disrupts the normal hair follicle cycle at a specific stage, preventing the maintenance of a full, healthy coat.