Page 31 - Headlines Histology2024_Neat

• At the cytoplasmic aspect of each plasma membrane, there is an electron-
dense layer into which fibriller elements of the cytoskeleton appear to
converge.

Gap junctions
• At these areas the opposing plasma membranes are very close to one

another, but there is no fusion occurs. They are still separated by a narrow
gap.
• The Gap junctions function primarily as a passageway for ions and small
molecules between adjacent cells. Thus, it is responsible for metabolic
coupling and functional synchronization between adjacent cells (smooth
and cardiac muscle).
Alteration of cell constituents in correlation to function
Protein secreting cells
• The protein secreting cells are characterized by the presence of rough
endoplasmic reticulum with abundant fixed ribosomes and polyribosomes,
many mitochondria, well-developed Golgi stacks and less electron dense
nucleus with extended chromatin.
• Zymogen granules are being discharged at the secretory surface of the cell.
The unit membrane of secretory vesicles being added to cell membrane.
Glycoprotein-secreting cells
• The glycoprotein secreting cells have abundant basal rER, well-developed
Golgi and numerous secretory granules that are extruded at the free surface
of the cell by exocytosis.
Ion transporting cells
• The ion transporting cells have multiple and deep invaginations of the basal
lamina being associated with abundant vertically oriented mitochondria.
Steroid secreting cells
• The steroid secreting cells have abundant sER, numerous mitochondria with
tubular cristae and many lipid droplets.

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