Stratified squamous keratinized epithelium

et_06. Stratified squamous keratinized epithelium
(Skin, hematoxylin-eosin)

1. Find the epithelial layer lining the surface of the skin:

epithelial border with adjacent connective tissue is uneven: the germinal layer (joining the basal and spinous layers together) makes imprints - dermal ridges;
over the germinal layer there is the granular layer, prominent due to well-defined basophily;
above you can see homogenous oxyphilic-colored lucid layer (Stratum Lucidum) and a thick superficial keratinized layer (stratum corneum);
make a primary sketch of a picture, see to the adequate thickness correlation of the keratinized layer to the others.

2. Study the morphology of stratified squamous keratinized epithelium:

on the convoluted basal membrane cuboidal or prismatic cells with axially-oriented oval nuclei are placed - the basal layer;
over them there are several layers of large uneven epithelial cells having multangular shape and numerous processes (spines) - the spinous layer;
the granular layer is formed by several rows of squamous fusiform cells having a flattened dark nucleus and basophilic granules of keratohyalin in the cytoplasm;
the lucid layer (Stratum Lucidum) consists of dead squamous cells which remain invisible due to their optical characteritics; looks like a continuous oxyphilous band;
the thick keratinized layer is made up of postcellular structures - nucleus free squamous horny scales;
loose connective tissue underlies the basal membrane;
count the total number of epithelial cells in the layer and separately – within the spinous layer and squamous layer consequently.

3. Draw a segment of the epithelium. See to the number of cells in each layer. Point out:

4. Define and write significant features of the epithelium and its embryonic origin.