Epidermal Cell Membrane Research Articles

A light and electron microscope study of the structure of Protopterus annectens epidermis. I. Mucus production

The structure of the epidermis of Protopterus annectens is described from light microscope and electron microscope observation with emphasis on mucus production. The epidermis contains a great number of goblet cells which are PAS-positive to varying degrees. Based on the difference in staining reaction the goblet cells are divided into three types (I, II, and III). Also PAS-positive is a narrow zone of cytoplasm below the plasma membrane of the surface epidermal cells. In the material prepared for the electron microscope the goblet cells are found to be of three types (A, B, and C) classified according to the size and electron opacity of the mucus droplets. Epidermal cells of the upper middle layer begin to show a division into two distinct cytoplasmic zones with the appearance of new organelles, particularly in the perinuclear zone. The cytoplasmic zonation is more pronounced in the surface cell layer and vesicles filled with amorphous material (first noticed in the upper middle layer) are concentrated below the surface plasma membrane. Light microscope and electron microscope results are correlated and it is concluded that all epidermally derived cells at some time become involved in mucus production.

Fine structure of the developing down feather

Developing down feathers of the chick embryo were examined with special reference to the dermoepidermal boundary and the formative area of barb ridges. Numerous granules, 10–20 mμ in diameter, were seen in the cytoplasm of all cells. Similar granules were found in the matrix of the mitochondria. The latter were most abundant in the basal cytoplasm of the epidermal cells. Cells of the barb ridge contained many intracytoplasmic clusters of granules of similar size. Such clusters occurred in the light zone of the dermoepidermal boundary, and in the basal cytoplasm both apart from the surrounding the mitochondria. The dermal cells appeared to have more Golgi substance than those in the epidermis. The basement membrane was identified as a granular layer 15 mμ in width, separated from the epidermal cell membrane by a light zone 35 mμ wide. It showed no breaks or poses.

Electron Microscope Studies of Dermal-Epidermal Separation in Human Skin

Electron microscope studies by several workers (1, 2, 3) have demonstrated an homogeneous, relatively dense membrane at the upper limit of the dermis, 200-400 A in width, separated from the epidermal cell membranes by a less dense zone approximately 300 A in width. Selby (2) has called this submicroscopic structure the dermal membrane to distinguish it from the controversial “basement membrane” described in light microscope studies (4, 5, 6), but her term has not yet come into general use.

The fine structure of nerves in the epidermis of regenerating salamander limbs

Intraepidermal nerves in the apical epithelial cap of the regenerating larval salamander limb were found to be entirely extracellular in their course. Bulbous enlargements of the nerves are intimately related to the epidermal cells. These nerve bulbs, which contain numerous mitochondria, small granules and vesicles, are similar in their general morphology to nerve terminals elsewhere in The body. The plasma membranes of nerve bulb and epidermal cell are separated by a space of about 200 Å and in these regions of close apposition, the plasma membranes of both nerve and epidermal cell appear very dense and an osmiophilic material is concentrated beneath the epidermal cell membrane. The morphology of the nerve bulb and nerve fibers is discussed in relation to other studies on the fine structure of nerves and the concept of a trophic action by nerves in regenerating epidermis is emphasized.

Electron microscope studies of the human epidermis; the cell boundaries and topography of the stratum malpighii.

The thin skin of the left upper quadrant of the human abdomen has been studied by electron microscopy. Tissue removed with a high speed rotary punch was fixed in osmium tetroxide or potassium permanganate. The latter fixative in our preparations is superior to osmium for the demonstration of epidermal cell membranes and certain other membranous structures of the epidermis. The cytoplasmic membranes of basal cells and cells of the stratum granulosum have been found to be relatively straight, while those of most spinous cells are sharply scalloped. The deep cells of the stratum spinosum in the rete ridge area show cell membranes and cytoplasmic structure intermediate between true basal cells and most cells of the stratum spinosum. The extracellular material of the desmosome has been found to consist of alternate dark and light laminae similar to those described by Odland (13) and Horstmann and Knoop (7).

The Fine Structure of the Interrelationship of Cells in the Human Epidermis

In the present investigation an analysis has been made of the fine structure of the interrelationships of cells in human forearm epidermis by means of the electron microscope. The "intercellular bridges," here called attachment zones, are more complex than has previously been recognized. It is shown that dense oval thickenings, called attachment plaques, appear in apposed areas of adjacent epidermal cell membranes. The tonofibrils terminate at the internal face of the attachment plaque and do not traverse the 300 A distance between apposed plaques. Seven intervening layers of unidentified substance occupy the space between attachment plaques. The attachment zones appear in all of the classical histological layers of the epidermis. The portions of epidermal cell membrane not involved in intercellular attachments have extensive surface area resulting from plication of the membrane, and its further modification to form microvilli. The possible functional significance of these observations is discussed. Prior observations concerning the basement membrane of epidermis are confirmed. Identification of epidermal melanocytes is achieved, the finer morphology of their dendritic processes is described, and their relationship to epidermal cells is discussed.

Biochemical studies on Cochliobolus miyabeanus. III.

The resistance of the leaf-sheath cells of rice plants against Cochliobolus miyabeanus was markedly decreased by adding reducing agents, such as ascorbate or glutathione, to the inoculum.Phytoalexin-like antifungal substance was produced as a result of interaction between the cells of rice plants and the germinating spores of C. miyabeanus. However, since ascorbate and glutathione did not either decrease the activity of phytoalexin, or did not inhibit the formation of such a substance, the active principle in resistance which was inactivated by adding reducing agents would not be referred to the activity of phytoalexin.The invaded cells of leaf-sheath and their neighbouring cells were oxidatively stained with various rH indicators at the begining of hyphal penetration. It is noticeable that the parts of mycelia which were in contact with the membranes of inner epidermal cells of the leaf-sheath were also oxidatively stained in deep colour. The invaded cells of the resistant variety, Kameji, were stained with methylene blue in green colour at the begining of invasion, while in the susceptible variety, Asahi, the colour reaction was nearly blue.Judging from these results, it was concluded that the resistance of rice plant against hyphal penetration of C. miyabeanus is, to some extent, attributable to the fungal oxidation products, perhaps quinones, which are derived from the host cells or membranes.