0504 - Histology of Brain Tissue Flashcards
How can Neurons be categorised?
By structure, or function, or both.
What are the different types of Neuron?
Multipolar - More than 2 dendrites
Bipolar - Single axon with single dendrite equal length
Pseudounipolar - Single dendrite longer than single axon.
What are the layers of the cerebellum? Where do the axons go?
Molecular layer - Paucicellular
Neuronal layer with Purkinje cells - Few here and there
Granular layer - Dense collection of small neurons.
Axons all go to Medulla
What is the morphology of a motor neuron?
Describe the histology and function of astrocytes
Lots of processes going out - provide structural and metabolic support to neurons and form blood-brain barrier.
Stain better in non-H&E. Round/oval nuclei with evenly dispersed pale chromatin. Processes are often in contact with a blood vessel (perivascular), and provide physical and metabolic support to CNS.
Describe the histology and function of Oligodendrocytes
Wrap Axons in myelin sheaths.
Dark blue cells very close to axons (running along the axon line).
Small round nucleus with dense, homogenous chromatin. Few, short cytoplasmic processes which wrap around neuron. Main neuroglia of white matter.
Describe the histology and function of Microglia
Macrophages of the brain - don’t see them unless something bad is happening.
Elongated, rod-shaped nucleus with clumped chromatin.
Describe the histology and function of Ependymal cells
Found lining ventricles of brain and spinal canal.
Ciliated, columnar or cuboidal epithelium. Lack of tight junctions between cells allows free exchange between CSF and nervous tissue.
What are the three parts of the meninges?
Dura mater - tough, fibrous tissue, not many cells.
Arachnoid - Cobweb-like, cellular material with fibrous tissue.
Pia mater - Covering of the brain - Cells without much fibrous tissue.
All are covered with flattened cells.
Briefly outline the choroid plexus. What is it, what does it do, and how is it constructed?
Vascular structure arising from wall of ventricles. Responsible for producing CSF.
Constructed of modified ependymal cells over invaginated fronds of leptomeninges (arachnoid and pia mater). Larger and more cobblestoned than ependymal cells.
Only place in the body with physiological papillomas.
Describe the histology and function of Dura Mater
Dense, fibroelastic tissue with internal surface of flat cells
Continuous with periosteum of the skull, but at upper cervical vertebrae, begins to cover spinal cord.
Describe the histology and function of Arachnoid Mater
Layer of fibrocollagenous tissue covered by inconspicuous flat epithelial cells. CSF transfers with blood via projections of arachnoid villi.
Describe function of Dorsal Horns and Ventral horns of the spinal cord
Dorsal - Sensory neurons enter
Ventral - Motor Neuron cell bodies and can exit.
What is the function of each layer of neurons in the neocortex?
I-3 - Supragranular layers - primary origin and termination of intracortical connections
4 - Receives thalamocortical connections
5-6 - Connect cerebral cortex with subcortical regions.
