Hair Matrix
The hair matrix is wrapped almost totally around the papilla. It is a collection of cells, primarily comprising of epithelial cells and some pigment-producing cells called melanocytes. The continuous division of cells in the hair matrix forms the hair shaft (the strands of hair that we actually see) and the inner and outer root sheaths of the hair.
Infection is the invasion of an organism's body tissues by disease-causing agents, their multiplication, and the reaction of host tissues to these organisms and the toxins they produce. Infectious disease, also known as transmissible disease or communicable disease, is illness resulting from an infection.
Choice D. Schleiden and Schwann were the first to recognize the cell as the universal unit of life.
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There are no answer choices posted, so it is impossible to answer this. I apologise.