Elsevier

Urology

Volume 62, Issue 1, July 2003, Pages 158-161
Urology

Basic science
Confocal laser scanning microscopy of urinary bladder after intravesical instillation of a fluorescent dye

https://doi.org/10.1016/S0090-4295(03)00121-3Get rights and content

Abstract

Objectives

To assess the potential of confocal laser scanning microscopy for imaging of the urinary bladder after intravesical instillation of a fluorescent dye.

Methods

The study was performed on the bladder of male Copenhagen rats. For confocal fluorescence microscopy (CFM), a standard confocal laser scanning microscope (Zeiss LSM 410) was used. Before measuring, the fluorescent marker SYTO 17 was instilled intravesically. After 2 hours of incubation, the rat was killed, the bladder excised and opened, and CFM was performed starting from the surface going through the urothelium and superficial layers of the lamina propria. Except for the opening incision, the bladder was left intact and no biopsies were taken. After imaging, the bladder was sent for conventional histologic studies.

Results

CFM allows imaging of cellular details of the entire urothelium (superficial umbrella cells, intermediate, and basal urothelial cells) and superficial layers of the lamina propria. CFM images are close to those obtained by standard microscopy after conventional hematoxylin-eosin staining. Cell structure (eg, shape, size, chromatin texture, nucleoli, mitotic figures, nuclear/cytoplasmic ratio), as well as the structure of the connective tissue (eg, collagen fibers, blood vessels, erythrocytes), can be studied, allowing a standard histologic evaluation. Furthermore, in contrast to conventional histologic evaluation, CFM provides three-dimensional information and allows the study of intact tissue representing the true in vivo situation.

Conclusions

CFM enables the study of the microscopic anatomy of bladder mucosa in its in vivo state. In combination with optical fiber bundles, endoscopic microscopy of the bladder may be possible in the future.

Section snippets

Material and methods

The study was performed on the bladder of male Copenhagen rats. Experimental studies were done using a CLSM (Zeiss LSM 410 invert beam scanning) and a 40× water immersion objective (Zeiss, C-Apochromat, W Korr) with a numeric aperture of 1.2. For CFM, beam splitters FT 515 and FT 655 (Zeiss), as well as filters LP 515 and RG 665 for excitation at 488 nm (argon laser) and 633 nm (helium-neon laser), were used, respectively. The bladder was illuminated with a power of 38 μW at 488 nm and 45 μW at

Results

CFM allowed imaging of cellular details of the entire urothelium. This included the large, flat, umbrella cells on the surface, as well as the underlying intermediate and basal urothelial cells. In addition, below the urothelium, a tight network of capillaries and the underlying superficial layers of the lamina propria could be studied (Fig. 1). The CFM images were close to those obtained by standard microscopy after conventional hematoxylin-eosin staining (Fig. 1). Cell structure, such as

Comment

CFM enables the study of the microscopic anatomy of normal bladder mucosa and superficial layers of the lamina propria. The study was performed on intact tissue, representing the in vivo situation. To our knowledge, this is the first time that rat bladder tissue has been studied by CFM using a fluorescent marker like SYTO 17. Regarding the possible applications in humans, the use of SYTO 17 is purely experimental. The potential toxicity and mutagenicity, as well as the optimal incubation

Conclusions

To date, the current CFM system allows the study of horizontal tissue planes only. This is a disadvantage, especially if one looks at carcinoma in situ, for which it is important to assess the maturation of the urothelium. However, through automation of the diagnostic process and the use of computer-based technology during endoscopy, cancer screening may become three-dimensional, less time consuming, less invasive, and highly efficient at a lowered expense.7 In the future, with the development

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