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In some melanocytes, the melanosomes remain static within the cell. In others the cell can extend its surface lengthwise as temporary projections known as pseudopodia , which carry melanosomes away from the center of the cell, thereby increasing the cell's effectiveness in absorbing light.
These stem cells develop into both keratinocyte precursors and melanoblasts - and these melanoblasts supply both hair and skin (moving into the basal layer of the epidermis). There is additionally evidence that melanocyte stem cells are present in cutaneous nerves, with nerve signals causing these cells to differentiate into melanocytes for the ...
A pseudopod or pseudopodium (pl.: pseudopods or pseudopodia) is a temporary arm-like projection of a eukaryotic cell membrane that is emerged in the direction of movement. Filled with cytoplasm , pseudopodia primarily consist of actin filaments and may also contain microtubules and intermediate filaments .
In the first the cell extends small pseudopods which then move down the sides of the cell, acting like paddles. [9] [10] [12] In the second the cell generates an internal flow cycle, with the cytoplasm flowing backward along the membrane edge and forward through the middle, generating a force on the membrane which moves the cell forward. [10] [12]
The main type of cells that make up the epidermis are Merkel cells, keratinocytes, with melanocytes and Langerhans cells also present. The epidermis can be further subdivided into the following strata (beginning with the outermost layer): corneum, lucidum (only in palms of hands and bottoms of feet), granulosum, spinosum, and basale.
Melanocytes insert granules of melanin into specialized cellular vesicles called melanosomes. These are then transferred into the keratinocyte cells of the human epidermis . The melanosomes in each recipient cell accumulate atop the cell nucleus , where they protect the nuclear DNA from mutations caused by the ionizing radiation of the sun's ...
A clear cell's plasma membrane is highly folded, more so on the apical and lateral surfaces. The cytoplasm of clear cells contains large amounts of glycogen and many mitochondria. Melanocytes appear as clear cells when in the stratum basale of the skin, and Langerhans' cells appear as clear cells in the stratum spinosum. [2]
P protein, also known as melanocyte-specific transporter protein or pink-eyed dilution protein homolog, is a protein that in humans is encoded by the oculocutaneous albinism II (OCA2) gene. [5] The P protein is believed to be an integral membrane protein involved in small molecule transport, specifically of tyrosine —a precursor of melanin .