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The pseudopodial process (aka the tanning process) happens slowly in dermal melanocytes in response to ultraviolet light and to production of new melanosomes and increased donation of melanosomes to adjacent keratinocytes, which are typical skin surface cells. Donation occurs when some keratinocytes engulf the end of the melanocyte pseudopodia ...
Melanocytes are melanin-producing neural crest-derived [3] cells located in the bottom layer (the stratum basale) of the skin's epidermis, the middle layer of the eye (the uvea), [4] the inner ear, [5] vaginal epithelium, [6] meninges, [7] bones, [8] and heart found in many mammals and birds. [9] Melanin is a dark pigment primarily responsible ...
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 .
It is a crawling-like type of movement accomplished by protrusion of cytoplasm of the cell involving the formation of pseudopodia ("false-feet") and posterior uropods. One or more pseudopodia may be produced at a time depending on the organism, but all amoeboid movement is characterized by the movement of organisms with an amorphous form that ...
Most lobosans possess broad, bluntly rounded pseudopods, although one genus in the group, the recently discovered Sapocribrum, has slender and threadlike (filose) pseudopodia. [1] In current classification schemes, Lobosa is a subphylum , composed mainly of amoebae that have lobose pseudopods but lack cilia or flagella .
Melanocytes produce two types of melanin. The most common form of biological melanin is eumelanin, a brown-black polymer of dihydroxyindole carboxylic acids, and their reduced forms. Most are derived from the amino acid tyrosine. Eumelanin is found in hair, areola, and skin, and the hair colors gray, black, blond, and brown. In humans, it is ...
Nevus cells are a variant of melanocytes. [1]: 684 They are larger than typical melanocytes, do not have dendrites, and have more abundant cytoplasm with coarse granules. [2] They are usually located at the dermoepidermal junction or in the dermis of the skin. Dermal nevus cells can be further classified: type A (epithelioid) dermal nevus cells ...
The pars intermedia secretes α-melanocyte-stimulating hormone (α-MSH), and corticotropin-like intermediate peptide. [ citation needed ] It appears to be tonically inhibited by the hypothalamus . In the human fetus , this area produces melanocyte stimulating hormone (MSH) which causes the release of melanin produced in melanocytes that can ...