Keratohyaline granules are found in:
**Core Concept**
Keratohyaline granules are a type of cytoplasmic inclusion found in the suprabasal layers of the epidermis. They are composed of a mixture of keratin filaments, lipid, and other cellular components, and play a crucial role in the formation of the skin's natural barrier function.
**Why the Correct Answer is Right**
Keratohyaline granules are produced by the activity of the enzyme loricrin, which is expressed by keratinocytes in the suprabasal layers of the epidermis. The accumulation of these granules contributes to the formation of a strong, impermeable barrier that prevents water loss and protects the skin from external damage. The presence of keratohyaline granules is a key feature of the stratum granulosum, a layer of the epidermis where keratinocytes undergo terminal differentiation.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the formation of keratohyaline granules.
**Option B:** While keratin filaments are a component of keratohyaline granules, this option is too broad and does not specifically address the granules themselves.
**Option C:** This option is incorrect because keratohyaline granules are not a feature of the stratum corneum, which is the outermost layer of the epidermis.
**Clinical Pearl / High-Yield Fact**
Keratohyaline granules are an important diagnostic feature of conditions such as ichthyosis, where the formation of these granules is impaired, leading to a defect in the skin's natural barrier function.
**Correct Answer:** C. Stratum granulosum.