Limits...
Transmission electron microscopy of the preclinical phase of experimental phytophotodermatitis.

Almeida HL, Sotto MN, Castro LA, Rocha NM - Clinics (Sao Paulo) (2008)

Bottom Line: Free desmosomes and membrane ruptures were also seen.At two hours after induction, similar changes were found, and granular degeneration of keratin was also observed.The interaction of sunlight and psoralens generates a photoproduct that damages keratinocyte proteins, leading to keratinocyte necrosis and blister formation.

View Article: PubMed Central - PubMed

Affiliation: Department of Dermatology, Federal and Catholic University of Pelotas, Pelotas, RS, Brazil. hiramalmeidajr@hotmail.com

ABSTRACT

Objective: To examine the epidermis in induced phytophotodermatitis using transmission electron microscopy in order to detect histologic changes even before lesions are visible by light microscopy.

Introduction: In the first six hours after the experimental induction of phytophotodermatitis, no changes are detectable by light microscopy. Only after 24 hours can keratinocyte necrosis and epidermal vacuolization be detected histologically, and blisters form by 48 hours.

Methods: The dorsum of four adult rats (Rattus norvegicus) was manually epilated. After painting the right half of the rat with the peel juice of Tahiti lemon, they were exposed to sunlight for eight minutes under general anesthesia. The left side was used as the control and exposed to sunlight only. Biopsies were performed immediately after photoinduction and one and two hours later, and the tissue was analyzed by transmission electron microscopy.

Results: No histological changes were seen on the control side. Immediately after induction, vacuolization in keratinocytes was observed. After one hour, desmosomal changes were also observed in addition to vacuolization. Keratin filaments were not attached to the desmosomal plaque. Free desmosomes and membrane ruptures were also seen. At two hours after induction, similar changes were found, and granular degeneration of keratin was also observed.

Discussion: The interaction of sunlight and psoralens generates a photoproduct that damages keratinocyte proteins, leading to keratinocyte necrosis and blister formation.

Conclusions: Transmission electron microscopy can detect vacuolization, lesions of the membrane, and desmosomes in the first two hours after experimental induction of phytophotodermatitis.

Show MeSH

Related in: MedlinePlus

One hour after the experimental induction a. Cytoplasmic and intercellular vacuolization (x 62.000). b. Vacuolization at the dermal-epidermal junction (x 62.000)
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2664235&req=5

f2-cln63_3p0371: One hour after the experimental induction a. Cytoplasmic and intercellular vacuolization (x 62.000). b. Vacuolization at the dermal-epidermal junction (x 62.000)

Mentions: One hour after the experimental procedure, the ultrastructural findings revealed more dramatic changes. Vacuolization was seen in the intercellular spaces, in the cytoplasm, and at the dermal-epidermal junction (Figs. 2a and b). In addition, desmosomal changes were also evident; in many areas keratin filaments were no longer attached to the desmosomal plaques and desmosomes were found freely in the sections (Figs. 3a and b). At higher magnifications, the desmosomal plaques were seen to be rounded, with the cell membrane folded over the plaque, and they were not binding desmosomes to one another (Figs. 4a and b). Membrane degeneration was also visible (Fig. 4b). Keratinocyte nuclei appeared normal.


Transmission electron microscopy of the preclinical phase of experimental phytophotodermatitis.

Almeida HL, Sotto MN, Castro LA, Rocha NM - Clinics (Sao Paulo) (2008)

One hour after the experimental induction a. Cytoplasmic and intercellular vacuolization (x 62.000). b. Vacuolization at the dermal-epidermal junction (x 62.000)
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2664235&req=5

f2-cln63_3p0371: One hour after the experimental induction a. Cytoplasmic and intercellular vacuolization (x 62.000). b. Vacuolization at the dermal-epidermal junction (x 62.000)
Mentions: One hour after the experimental procedure, the ultrastructural findings revealed more dramatic changes. Vacuolization was seen in the intercellular spaces, in the cytoplasm, and at the dermal-epidermal junction (Figs. 2a and b). In addition, desmosomal changes were also evident; in many areas keratin filaments were no longer attached to the desmosomal plaques and desmosomes were found freely in the sections (Figs. 3a and b). At higher magnifications, the desmosomal plaques were seen to be rounded, with the cell membrane folded over the plaque, and they were not binding desmosomes to one another (Figs. 4a and b). Membrane degeneration was also visible (Fig. 4b). Keratinocyte nuclei appeared normal.

Bottom Line: Free desmosomes and membrane ruptures were also seen.At two hours after induction, similar changes were found, and granular degeneration of keratin was also observed.The interaction of sunlight and psoralens generates a photoproduct that damages keratinocyte proteins, leading to keratinocyte necrosis and blister formation.

View Article: PubMed Central - PubMed

Affiliation: Department of Dermatology, Federal and Catholic University of Pelotas, Pelotas, RS, Brazil. hiramalmeidajr@hotmail.com

ABSTRACT

Objective: To examine the epidermis in induced phytophotodermatitis using transmission electron microscopy in order to detect histologic changes even before lesions are visible by light microscopy.

Introduction: In the first six hours after the experimental induction of phytophotodermatitis, no changes are detectable by light microscopy. Only after 24 hours can keratinocyte necrosis and epidermal vacuolization be detected histologically, and blisters form by 48 hours.

Methods: The dorsum of four adult rats (Rattus norvegicus) was manually epilated. After painting the right half of the rat with the peel juice of Tahiti lemon, they were exposed to sunlight for eight minutes under general anesthesia. The left side was used as the control and exposed to sunlight only. Biopsies were performed immediately after photoinduction and one and two hours later, and the tissue was analyzed by transmission electron microscopy.

Results: No histological changes were seen on the control side. Immediately after induction, vacuolization in keratinocytes was observed. After one hour, desmosomal changes were also observed in addition to vacuolization. Keratin filaments were not attached to the desmosomal plaque. Free desmosomes and membrane ruptures were also seen. At two hours after induction, similar changes were found, and granular degeneration of keratin was also observed.

Discussion: The interaction of sunlight and psoralens generates a photoproduct that damages keratinocyte proteins, leading to keratinocyte necrosis and blister formation.

Conclusions: Transmission electron microscopy can detect vacuolization, lesions of the membrane, and desmosomes in the first two hours after experimental induction of phytophotodermatitis.

Show MeSH
Related in: MedlinePlus