Материал: Kaplan USMLE-1 (2013) - Anatomy
Chapter 1 • Cell Biology and Epithelia
Figure 1-1 -1 1 . Freeze-fracture of tight junction
Connexon
Figure 1-1 -1 2. Gap junction
Gapjunctions-direct passage forsmallparticles andions between cells via con nexon channel proteins
Microvilli
Microvilli contain a core of actin microfilaments and function to increase the absorptive surface area ofan epithelial cell. They are found in columnar epithelial cells ofthe small and large intestine, cells ofthe proximal tubule ofthe kidneyand on columnar epithelialrespiratory cells.
Stereocilia are long, branched microvilli that are found exclusively in the male reproductive tract (e.g., epididymis).
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Section I • Histology and Cell Biology
Clinical Correlate
Kartagener syndrome is characterized by immotile spermatozoa and infertility. It is due to an absence of dynein
that is required for flagellar motility. It is usually associated with chronic respiratory infections because of similar defects in cilia of respiratory epithelium.
Glycocalyx-.
Microvilli
Zonula occludens (tightjunction)
Zonula adherens
Desmosome
Figure 1-1 -1 3. Apical cell surface/cell junctions
Cilia
Cilia contain 9 peripheral pairs ofmicrotubules and 2 central microtubules. The microtubules convey motility to cilia through the ATPase dynein. Cilia bend and beat on the cell surface ofpseudostratified ciliated columnar respiratory epithe lial cells to propel overlying mucus. They also form the core of the flagella, the motile tail ofsperm cells.
B =Basal body
IJ = Intermediate junction
M =Microvillus
OJ =Occluding junction
Copyright Lippincott Williams & Wilkins. Used withpermission.
Fiaure 1-1 -1 4. Cilia
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Section I • Histology and Cell Biology
Hematoxylin is a blue dye which stains basophilic substrates that are the acidic cellular components such as DNA and RNA. Hematoxylin stains nuclei blue, and may tint the cytoplasm ofcells with extensive mRNA in their cytoplasm.
Eosin is a pink-to-orange dye which stains acidophilic substrates such as basic components ofmost proteins. Eosin stains the cytoplasm ofmost cells and many extracellular proteins, such as collagen, pink.
EpithelialTypes
Simple columnar epithelium is foundin the small and large intestine.
Copyright McGraw-Hill Companies. Used with permission.
Figure 1·1-17. Small Intestine Simple Columnar Epithelium
Enterocytes (arrow), Goblet cells (arrowhead)
Simple squamous epithelium forms an endothelium that lines blood vessels, a mesothelium that forms part ofa serous membrane or forms the epithelium lin ing ofthe inside ofthe renal glomerular capsule.
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Chapter 1 • Cell Biology and Epithelia
Copyright McGraw-Hi/I Companies. Usedwithpermission.
Figure 1-1-18. Kidney simple squamous epithelium (arrows), simple cuboidal epithelium (arrowheads)
Pseudostratified columnar epithelium is found in the nasal cavity, trachea, bronchi, and epididymis.
Copyright McGraw-Hill Companies. Used withpermission.
Figure 1-1-19. Trachea pseudostratified columnar epithelium with true cilia (arrow) and goblet cells (arrowhead), basement membrane (curved arrow)
Transitional epithelium is found in the ureter and bladder.
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