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→Stratified Epithelium
This “pavement epithelium” has flattened scale-like or plate-like cells.
==== Slide 118: Kidney (PASH) ====
On Slide 118, Kidney (PASH) locate the parietal layer of Bowman’s capsule surrounding the glomeruli (blood capillaries). Identify the layer of simple squamous epithelium which forms the parietal layer of Bowman’s capsule. These cells rest on a pink-staining basement membrane. Note that you can see only the nuclei clearly; the attenuated cytoplasm is indistinct.
<peir-vm>UAB-Histology-00118</peir-vm>
==== Slide 18: Spleen (H&E) ====
On slide 18, Spleen (H&E), locate the connective tissue capsule that covers the spleen and note the simple squamous epithelium covering the capsule. This lining is called the mesothelium. A mesothelium is defined as a single layer of flattened cells forming an epithelium that lines serous (body) cavities. Note the shapes of the cells. In some regions, they may appear to be slightly cuboidal.
In this kind of epthelium, the height of each component cell is approximately equivalent to its width.
==== Slide 114: Kidney (H&E) ====
On slide 114, Kidney (H&E), locate segments of kidney tubules lined with simple cuboidal epithelium. In this type of epithelium the nucleus is round and located in the center of the cell. Other segments of a kidney tubule may be lined by epithelial cells ranging from simple squamous to low columnar or pyramidal (modified columnar) in shape. On slide 118, Kidney (PASH) note how well the PAS stain demonstrates the basement membranes underlying the various epithelial. Cells of different heights are also readily observed on this slide.
In this kind of epithelium, the height exceeds the width of the cell.
==== Slide 140: Duodenum (PASH) ====
On slide 140, duodenum, (PASH), observe the layer of columnar cells that cover the villi. The ovoid nuclei are located in the lower one-half of the cells. Study the shapes of the cells, the location of the nuclei and the specialization of the free surface. These columnar cells are absorptive cells that have microvilli forming a striated border and covered by a PAS-positive glycocalyx. Goblet cells, which are columnar cells modified to secrete mucus, can be seen interspersed among the absorptive columnar epithelial cells. The goblets in these cells exhibit heavy PAS staining.
In this type of simple epithelium the nuclei of the cells appear in irregular layers and may give the false impression that the cells themselves are stratified. In a pseudostratified epithelium all the cells reach the basement membrane even though the nuclei lie at different levels in the tissue. Only the tall cells, however, reach the free surface.
==== Slide 2: Trachea (H&E) ====
On slide 2, Trachea (H&E), identify the pseudostratified columnar ciliated epithelium which lines the lumen of the trachea. Find an area where the epithelium is intact; it is torn off in places. The epithelium rests on a thick basement membrane. Scattered throughout the epithelium are numerous goblet cells that produce a mucous secretion that traps inspired particles. Study the position of the nuclei. Note once again the cilia of the tall cells of the pseudostratified columnar epithelium.
<peir-vm>UAB-Histology-00002</peir-vm>
==== Slide 6: Epididymis (H&E) ====
On slide 6, Epididymis (H&E), is a section through the epididymis, a highly coiled genital duct of the male. The cross and oblique sections of this duct are the most numerous of the tubular structures on this slide. Study the pseudostratified columnar epithelium lining the lumen of the epididymis. Goblet cells and cilia are lacking and the basement membrane is not as prominent as it is for the epithelium of the trachea. Tall columnar cells with stereocilia are present. Smaller basal cells can be identified by observing their nuclei that are located close to the basement membrane.
This type of epithelium has more than one layer of cells present. The epithelium is named according to the shape of the surface cells even though the underlying cells may be a different shape. For example, if the surface cells are squamous, but the underlying cells are cuboidal or columnar, the epithelium is a stratified squamous epithelium.
=== Stratified Squamous Epithelium, Noncornified /Nonkeratinized (Moist) ===On slide 131, Esophagus (H&E) identify the noncornified/nonkeratinized, stratified squamous epithelium. Note the flattened, nucleated surface cells, the “middle zone” of the polyhedral shaped cells, and the basal layer of the polyhedral shaped cells, and the basal layer of columnar cells which rests on the basement membrane. Characteristically, the lower surface of the epithelium is undulated.
==== Slide 131: Esophagus (H&E) ====
<peir-vm>UAB-Histology-00131</peir-vm>
=== Stratified Squamous Epithelium, Cornified /Keratinized (Dry) ===On slide 4, Thin skin (H&E) and Slide 46, Thick skin (H&E), study the representative types of cornified/keratinized, stratified squamous epithelium. Note the characteristics of the cells at the various levels. The surface layer of cells, represented by the stratum corneum of the epidermis, lacks nuclei and keratin proteins have replaced the cytoplasm. The surface cells of the skin are constantly desquamated. They are replenished by mitotic divisions occurring in the basal layer of epithelial cells. Note how much thicker the stratum corneum is for thick skin than for thin skin.
==== Slide 4: Thin Skin (H&E) ====
<peir-vm>UAB-Histology-00004</peir-vm>
==== Slide 46: Thick Skin (H&E) ====
<peir-vm>UAB-Histology-00046</peir-vm>
On slide 111, Epiglottis (H&E), look in the connective tissue underlying the surface epithelium for ducts of glands lined with stratified cuboidal or stratified columnar epithelium. The surface epithelium of the epiglottis is an intermediate type where a change is being made from stratified squamous to pseudostratified columnar epithelium (some of the surface cells are torn off).
==== Slide 111: Epiglottis (H&E) ====
<peir-vm>UAB-Histology-00111</peir-vm>
On slide 121, Urinary bladder (H&E), identify the transitional epithelium and study its characteristics. Are any of the surface cells binucleated?
==== Slide 121: Urinary Bladder (H&E) ====
<peir-vm>UAB-Histology-00121</peir-vm>