Melanoblast cells appear in basal layer of epidermis during –
**Core Concept**
Melanoblast cells are a type of neural crest-derived cell that migrates to the epidermis and differentiates into melanocytes, responsible for producing melanin, the pigment responsible for skin color. The appearance of melanoblast cells in the basal layer of the epidermis marks the beginning of melanogenesis.
**Why the Correct Answer is Right**
Melanoblast cells migrate to the epidermis during fetal development, specifically around the 10th to 12th weeks of gestation. They appear in the basal layer of the epidermis, where they differentiate into melanocytes and begin to produce melanin. This process is crucial for the development of skin pigmentation. The basal layer of the epidermis is the layer of epithelial cells that is closest to the dermis and plays a key role in the regeneration of the epidermis.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify the correct developmental stage or location of melanoblast cells.
**Option B:** This option is incorrect because it suggests a later developmental stage than when melanoblast cells first appear in the basal layer of the epidermis.
**Option C:** This option is incorrect because it does not accurately describe the developmental origin of melanoblast cells.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that melanoblast cells originate from the neural crest, a group of cells that also gives rise to other important cell types, such as Schwann cells and cartilage cells. This correlation highlights the complex and diverse developmental origins of various cell types in the human body.
**Correct Answer:** C. During fetal development, around the 10th to 12th weeks of gestation