The deepest layer of cells in the epidermis, which is nourished by dermal blood vessels, is called the .

The deepest layer of cells in the epidermis, which is nourished by dermal blood vessels, is called the stratum basale or basal layer.

Here are the steps to answer this question:

1. Understand the question: The question is asking for the name of the deepest layer of cells in the epidermis (the outermost layer of the skin) that is nourished by dermal blood vessels.

2. Recall knowledge about skin anatomy: The skin is composed of three main layers: the epidermis, the dermis, and the hypodermis. The epidermis itself is composed of several layers.

3. Identify the correct layer: The deepest layer of the epidermis, which is in contact with the dermis and is nourished by dermal blood vessels, is the stratum basale or basal layer.

4. Answer the question: The deepest layer of cells in the epidermis, which is nourished by dermal blood vessels, is called the stratum basale or basal layer.