Epidermal Vesicles

After 21 hours the increase in spongiosis gives the appearance of intra-epidermal vesicles (W. Jadassohn, Bujard and Brun, 1955). These histological lesions correspond to those observed in man. 

After 14 hours there are well formed spongiosis, occasionally intra-epidermal vesicles and an infiltrate which is rather moderate and composed of immature cells of connective tissue, small lymphocytes and eosinophils at times. 

Fourteen hours after the test, we observe spongiosis and intra-epidermic vesicles, as seen in the eczema caused by DNCB. However, the dermal infiltration is much more extensive with citraconic anhydride and contains lymphocytes and above all numerous eosinophils which invade the epidermis (Fig. 19). In eczema due to DNCB the infiltration is mainly by lymphocytes. 

If pure PA is applied to the flank and nipple of unsensitized guinea pigs, a light redness is observed after 14 hours. Under histological examination the lesions of the flank and nipple are numerous intra-epidermal vesicles, epidermal detachment, epidermal necrosis, dermal infiltrate with numerous eosinophils which also invade the epidermis. 

After 14 hours, the epidermal lesions are significant in certain places the epidermal cells are extremely swollen (pseudo-acanthosis ), elsewhere we see an atrophy of the epidermis and next to it, either a pseudo-acanthosis, or an acanthosis. Intra-epidermal vesicles are frequently seen (Fig. 20). 

Figure 6. A Photomicrograph (x 51,000) of caffeine treated leaf epidermal cell showing electron-dense deposits on cell wall and membrane vesicles fusing with the plasmalemma (arrows). B Immunofluorescence labeling of flavonoids in cell walls of leaf epidermal strips (arrows) and autofluorescent stomata (x 62.5). C Immunogold labeling of the walls of a mesophyll cell (left, x 41,000). Ch, chloroplast EC, epidermal cell G, Golgi IS, intercellular space MC, mesophyll cell (right, control x 19,500).

Cohen, S., Ushiro, H., Stoscheck, C., and Chinkers, M. (1982). A native 170,000 epidermal growth factor receptor-kinase complex from shed plasma membrane vesicles./. Biol. Chem. 257, 1523-1531. 

Several plants produce milk juice sequestered in laticifers in several plant genera alkaloids are mainly stored in latex vesicles, such as isoquinoline alkaloids in Papaver and Chdidonium, or piperidine alkaloids in Lobelia. If herbivores wound such a plant, the latex will spill out and the herbivore will immediately be confronted with alkaloids. Since most of them are strong poisons, a deterrent effect is usually achieved. Another strategic way to store alkaloids is their sequestration in epidermal vacuoles or in trichomes. These tissues have to ward off not only herbivores (especially small ones) but also microorganisms in the first place. Several classes of alkaloids have been found in epidermal tissues, such as quinohzidine and tropane alkaloids [2,3]. 

Histopathological examination typically shows epidermal changes, including spongiosis with or without intraepider-mal vesicles. In the dermis there is a perivascular mononuclear cell infiltrate, which may also be interstitial, often containing eosinophils. 

In many types of drug reactions, bullae and vesicles may be found in addition to other manifestations. Bullae are usually noted in erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis, fixed eruptions when very intense, urticaria, vasculitis, porphyria cutanea tarda, and phototoxic reactions (from furosemide and nalidixic acid). Tense, thick-walled bullae can be seen in bromoderma and iododerma as well as in barbiturate overdosage. 

During recent years, the topical delivery of liposomes has been applied to different applications and in different disease models (188). Current efforts in this area concentrate around optimization procedures and new compositions. Recently, highly flexible liposomes called transferosomes that follow the trans-epidermal water activity gradient in the skin have been proposed. Diclofenac in transferosomes was effective when tested in mice, rats and pigs (189). The concept of increased deformability of transdermal liposomes is supported by the results of transdermal delivery of pergolide in liposomes, in which elastic vesicles have been shown to be more efficient (190).The combination of liposomes and iontophoresis for transdermal delivery yielded promising results (191, 192). 

Once the skin is exposed, blisters develop after a period of itching and erythema, with the basal epidermal cell as the key cellular target of sulfur mustard in skin. By light microscopy, nuclear swelling begins within 3 to 9 hr after exposure, followed by nuclear pyknosis and vacuolation of cytoplasm. Edema at the epidermal-dermal junction is seen within 12 hr of exposure, and by 16 hr there is separation, with formation of coalescing vesicles. Blisters break and denude during the first week after exposure, and new blisters may form near others that are well developed. 

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