Electron microscopy of the tracheal ciliated mucosa in rat

J Rhodin, T Dalhamn - Zeitschrift für Zellforschung und mikroskopische …, 1956 - Springer
J Rhodin, T Dalhamn
Zeitschrift für Zellforschung und mikroskopische Anatomie, 1956Springer
The structure of the tracheal epithelial cells from rat has been studied by electron
microscopy on approximately 200 Å thick sections with a resolution of better than 30 Å. The
epithelium is found to be of a simple columnar type composed of ciliated cells, mucus
producing (goblet) cells, basal cells and a fourth kind of cell, here called brush cell. A great
number of non-ciliated cells has also been encountered. It has been proved that these
represent goblet cells in different stages of intracellular synthesis of mucous granules. The …
Summary
The structure of the tracheal epithelial cells from rat has been studied by electron microscopy on approximately 200 Å thick sections with a resolution of better than 30 Å.
The epithelium is found to be of a simple columnar type composed of ciliated cells, mucus producing (goblet) cells, basal cells and a fourth kind of cell, here called brush cell. A great number of non-ciliated cells has also been encountered. It has been proved that these represent goblet cells in different stages of intracellular synthesis of mucous granules.
The ciliated cells have approximately 8–9 cilia per square micron and there are about 270 cilia on each cell, the calculated surface area being 33 square microns. They are covered by a 70 Å thick membrane. The ciliary filaments are arranged in a pattern of 2 separate ones in the center and a ring of 9 peripheral ones, each divided into 2 subfilaments by a wall with same thickness as the filamentous wall itself, this being 60 Å. The peripheral filaments are continuous with the basal corpuscles. The structure of the corpuscles as compared with earlier findings is discussed. A number of 0.05 micron thick and 1 micron long filiform projections emerge from the cell surface. No cuticle is present.
The cell membrane facing adjacent cells is 90 Å and separated from their cell membrane by a 105 Å wide space, this space, being expanded towards a level corresponding to the proximal parts of the cell. A structure that represents terminal bar has been encountered. The cytoplasm is loose and composed of 160 Å thick granules. Spaces enclosed by 50 Å thick membranes with attached 160 Å thick granules (α-cytomembranes) are rare. The Golgi zone is analyzed and its regular composition of γ-cytomembranes, granules and vacuoles is confirmed. The mitochondria with a mean width of 0.23 micron differ to their inner structure from the common type in that the triple layered membranes are highly interconnected. Large opaque granules are encountered in the cytoplasm. Ring-shaped, 850 Å wide, structures are present in the nuclear membrane.
The goblet cells are not as abundant as the ciliated cells, the ratio being 1∶4. Small filiform projections covered by a 95 Å thick membrane protrude from the cell surface. This membrane is continuous with the cell membrane, the latter with the same dimensions as in the ciliated cells. Terminal bars are present. The cytoplasm is very opaque due to a dense packing of the 165 Å opaque granules, many in clusters of 4–6. The α-cytomembranes have the same dimensions as mentioned above for those present in the ciliated cells. The Golgi zone is of regular composition. There is a suggestion that the Golgi vacuoles and the γ-cytomembranes are involved in the formation of mucus. In the stage of cellular activity with but few mucous granules, there is a great number of large opaque granules, the size varying from 0.4–1 micron. The mitochondria with a mean width of 0.23 micron have an outer triple layered membrane with a total thickness of 180 Å. The central less opaque layer is 70 Å and the opaque layer on either side is 55 Å. The inner membranes are arranged parallel to each other and have a triple layered composition where the central less opaque layer is 65 Å and the opaque layers each 60 Å.
The brush cells belong to the non-ciliated cells. They are encountered singly, surrounded by goblet cells. The surface structures are shaped like brushes or clumsy protrusions which emerge from the distal end of the cell, and are covered by a 95 Å thick membrane. There have been no suggestions of the brushes being cilia in a stage of growth, nor is it probable that they …
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