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English: Histology of Paneth cells, located at the base of the crypts of the small intestinal mucosa, and displaying merocrine secretion of bright red cytoplasmic granules. H&E stain. - Source for merocrine: Matsubara F (1977). "Morphological study of the Paneth cell. Paneth cells in intestinal metaplasia of the stomach and duodenum of man.".
Paneth cells are found throughout the small intestine and the appendix at the base of the intestinal glands. [2] There is an increase in Paneth cell numbers towards the end of the small intestine. [3] Like the other epithelial cell lineages in the small intestine, Paneth cells originate at the stem cell region near the bottom of the gland. [4]
During each mitosis, one of the two daughter cells remains in the crypt as a stem cell, while the other differentiates and migrates up the side of the crypt and eventually into the villus. These stem cells can differentiate into either an absorptive (enterocytes) or secretory (Goblet cells, Paneth cells, enteroendocrine cells) lineages. [3]
Subsets of sensory intestinal epithelial cells synapse with nerves, [9] and are known as neuropod cells. [10] Paneth cells produce antimicrobial peptides such as human alpha-defensin. [11] [12] Microfold cells (commonly referred to as M cells) sample antigens from the lumen and deliver them to the lymphoid tissue associated with the mucosa (MALT).
This controls peristalsis. Activity is initiated by the pacemaker cells (interstitial cells of Cajal). The gut has intrinsic peristaltic activity (basal electrical rhythm) due to its self-contained enteric nervous system. The rate can, of course, be modulated by the rest of the autonomic nervous system.
Hyperplasia of Brunner glands with a lesion greater than 1 cm was initially described as a Brunner gland adenoma. Several features of these lesions favor their designation as hamartomas, including the lack of encapsulation; the mixture of acini, smooth muscles, adipose tissue, Paneth cells, and mucosal glands; and the lack of any cell atypia ...
Intestinal villi (sg.: villus) are small, finger-like projections that extend into the lumen of the small intestine.Each villus is approximately 0.5–1.6 mm in length (in humans), and has many microvilli projecting from the enterocytes of its epithelium which collectively form the striated or brush border.
On 2021, Stephen Quake guessed that the upper limit of the number of human cell types would be around 6000, based on a reasoning that "if biologists had discovered only 5% of cell types in the human body, then the upper limit of cell types to discover is somewhere around 6000 (i.e., 300/0.05)." [10] Other different efforts have used different ...