A new method for the investigation of capillary structure

Area of Science:

• Neuroscience
• Vascular Biology
• Histology

Background:

• Central nervous system (CNS) vascular structure is influenced by various physiological and behavioral conditions.
• Traditional methods for studying CNS vasculature involve perfusing viscous substances like India ink, which can lead to incomplete perfusion.

Purpose of the Study:

• To evaluate a novel method for investigating brain vascular structure using fixative perfusion, celloidin embedding, and Methylene Blue-Azure II staining.
• To compare this new method against the standard India ink perfusion technique.

Main Methods:

• Tissue from six rats was perfused with fixative, embedded in celloidin, and stained with Methylene Blue-Azure II.
• This was compared to tissue from six rats perfused with India ink in gelatin and stained with cresyl violet.
• Quantitative and qualitative analyses of vascular structure were performed.

Main Results:

• The celloidin embedding method provided clear visualization of vessels and stained pericytes.
• No significant differences were found in branch point to cell ratio, capillary length, vessel length per volume, or capillary tortuosity between the two methods.
• Capillary diameter measurements were greater and potentially more accurate with the celloidin method compared to India ink.

Conclusions:

• Perfusion with standard fixative followed by celloidin embedding is a viable alternative for quantitative analysis of brain vascular structure.
• This method offers advantages including improved pericyte visualization, enhanced perfusion completeness, and clearer views of surrounding cells.
• It also allows for potential ultrastructural analysis in the contralateral hemisphere.