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The medulla is the innermost layer of the hair shaft. This nearly invisible layer is the most soft and fragile, and serves as the pith or marrow of the hair. Some mammals don't have a medulla in their hair. The presence or absence of this layer and the characteristics of the medulla can aid taxonomists in identifying what taxa a hair comes from.
A few plants, such as walnuts, have distinctive chambered pith with numerous short cavities (see image at middle right). The cells in the peripheral parts of the pith may, in some plants, develop to be different from cells in the rest of the pith. This layer of cells is then called the perimedullary region of the pithamus.
Bast fiber from oak trees forms the oldest preserved woven fabrics in the world. It was unearthed at the archeological site at Çatalhöyük in Turkey and dates to 8000-9000 years ago. [5] Dress of unspecified bast fibre, Yuracaré, Rio Chimoré, Bolivia 1908–1909. Cycling suit of linen bast fiber, New York, New York, United States, 1908
Medulla of the thymus, a part of the lobes of the thymus; Medulla of lymph node; Medulla (hair), the innermost layer of the hair shaft; Medulla, a part of the optic lobe of arthropods; Medulla (lichenology), a layer of the internal structure of a lichen; Pith, or medulla, a tissue in the stems of vascular plants
Medulla oblongata. Medullary pyramids; Arcuate nucleus; Olivary body. Inferior olivary nucleus; Rostral ventrolateral medulla; Caudal ventrolateral medulla; Solitary nucleus (Nucleus of the solitary tract) Respiratory center-Respiratory groups. Dorsal respiratory group; Ventral respiratory group or Apneustic centre. Pre-Bötzinger complex ...
Diagram of the hair shaft, indicating medulla (innermost), cortex, and cuticle (exterior.) Anatomy of hair. The cortex of the hair shaft is located between the hair cuticle and medulla and is the thickest hair layer. It contains most of the hair's pigment, giving the hair its color. The major pigment in the cortex is melanin, which is also ...
Fibers of the posterior column, which transmit sensory and proprioceptive information, are located behind the pyramids on the medulla oblongata. The medullary pyramids contain motor fibers that are known as the corticobulbar and corticospinal tracts. The corticospinal tracts are on the anterior surface of the pyramids.
In mammalian outer hair cells, the varying receptor potential is converted to active vibrations of the cell body. This mechanical response to electrical signals is termed somatic electromotility; [13] it drives variations in the cell's length, synchronized to the incoming sound signal, and provides mechanical amplification by feedback to the traveling wave.