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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 ...
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 .
Illustration of a melanocyte Micrograph of melanocytes in the epidermis. Through a process called melanogenesis, melanocytes produce melanin, which is a pigment found in the skin, eyes, hair, nasal cavity, and inner ear. This melanogenesis leads to a long-lasting pigmentation, which is in contrast to the pigmentation that originates from ...
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 ...
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 ...
In some cases the cell moves by "walking", with relatively permanent pseudopodia serving as limbs. The most important genera are Amoeba and Chaos, which are set apart from the others by longitudinal ridges. The best known of the species in this family is Amoeba proteus, commonly used in classrooms to demonstrate movement by pseudopodia.
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 .
Actinophryids are unicellular and roughly spherical in shape, with many axopodia that radiate outward from the cell body. Axopodia are a type of pseudopodia that are supported by hundreds of microtubules arranged in interlocking spirals and forming a needle-like internal structure or axoneme. Small granules, extrusomes, that lie under the ...