Histopathological Assessments of Animal Models of Cerebral Ischemia - Animal Models of Acute Neurological Injuries: Injury and Mechanistic Assessments - page 2

Chapter 1
Histopathological Assessments of Animal Models
of Cerebral Ischemia
Ami P. Raval and Bingren Hu
Abstract
Histology is an essential technique to evaluate ischemic damage in the animal models. Histopathology
often refers to the microscopic examination of pathological changes in the tissue. This chapter describes
the procedure to prepare brain for histopathological evaluation. The basic steps for histological procedure
includes perfusion of brain following desirable experimental condition, fi xation of brain, paraffi n embedding,
cutting of brain sections, staining, and observation. In this chapter, we clearly defi ne what precautions are
to be taken while performing these steps. Regarding staining of brain sections to evaluate ischemic damage
we describe hematoxylin and eosin Y method routinely used by various laboratories. Finally, we also present
a monograph of histological outcome after global cerebral ischemia (10 min of 2-vessel occlusion and
hypotension (2VO)) in a rat model. There are two chief histopathological changes in this 2VO ischemia
model: (1) selective neuronal vulnerability; typically, CA1 pyramidal neurons of the hippocampus are most
vulnerable, followed by dorsoventral striatal small-and medium-sized neurons, and pyramidal neurons in
the layers 3-4 of the dorsolateral neocortex and (2) delayed neuronal damage, i.e., neuronal death does
not occur immediately after transient ischemic episode, but takes place after 2-3 days of reperfusion. Using
histology, we can identify characteristic neuronal loss in ischemic rat brain.
Key words: 2-Vessel occlusion and hypotension model, Selective vulnerability, Perfusion fi xation of
brain, Hematoxylin and eosin Y method
1. Introduction
Histopathology is an essential technique for evaluation of pathological
changes in animal models. In acute neurological injury models,
histopathology is often employed to examine neurological injuries
in tissue sections from animal brain or spinal cord. Conventional
histopathology procedures include chemical fi xation, embedding,
sectioning, histological staining, and microscopic examination.