Histo Lab: Nervous System Flashcards
Looking at cerebrum, what do you see
Two distinct areas, the grey matter and the white matter (grey matter is on the periphery and white matter is in the inside).
They grey matter is further divided into subcortical layers.
What kind of cells do we see here in the grey matter.
How are these cells arranged?
We see pyramidal cells that are triangular shaped and larger (also they have some hollow space around them). These cells are arranged in a specific manner such that the apex of the cells (the open mouth) faces the inside of the grey matter whereas the pointed end is towards the outside. The branches we see are the dendrites.
Together with these cells we also see supportive neuroglia cells that are smaller and have a darker staining nucleus. These are more in number.
This was in the H&E dye.
Thionin stain
The grey matter and the white matter are clearly visible. They grey matter is more dense or the cells have larger nuclei.
Also the position of the pyramidal cells is more obvious.
What is the identifying cell of the cerebrum
Pyramidal cell
What are the 3 layers of the grey matter, how are they situated
Molecules, purkinje and granular, from out to in
Where is the grey and white matter in the cerebellum
They grey matter is peripheral, white is inside, know where they are
What does the molecular layer consist of
Basket and stellate cells
How do you identify the purkinje layer
It is one cell thick, has pukinje cells which are multipolar, dark staining and larger than other cells and appear to be like the palmof the hand with the fingers representing the dendrites.
How do you identify the granular layer
Made of small neurons called the granule cells
Thionin stain for cerebellum
Purkinje are more obvious, it sys you can see their nucleolus inside their deep staining nucleus.
What is the differentiating feature of cerebellum
Purkinje cells
Spinal cord layers
White matter is in the outside, grey matter is in
How do you see the white matter of the spine
These are myelinated fibers, cut in cross section so you can only see them as a dot. These are surrounded by empty space which was occupied by the myelin sheath.
Grey matter of the spinal cord
It is divided into dorsal and ventral horns, know where these are. Dorsal horns were the smaller ones and ventral were larger ones facing down.
What kind of cells does grey matter has
Multipolar nerve cell bodies of motoneurons, also called ventral horn cells. They are stellate shaped, has a sperical nuclei, scanty chromatin and they have a single nucleus.
Glia cells are also visible, although more obvious in the thionin stain, these cells are smaller
Other cells that we can see are the ependymal cells. They line the central canal where CSF resides.
Spinal cord in thionin stain
The dendrites have darkly staining features due to the presence of ER called the Nissle substance, the staining is diffused.
This staining pattern allows us to distinguish the axons from dendrites.
What is the main identifier of the spinal cord
The diffusing pattern of the Nissle substance.
What are the 3 layers of CNS
These are connective tissues:
- Dura mater
- Archnoid
- Pia Mater, from outside in.
Know that because of disection and preperation these layers are not always visible
How is vascularization in these layers
Pia mater is most extensively vacularized. Know where the sub hematoma is within these layers, it is present on the empty spaces.
What is a ganglion
Group of nerve cells located outside of the CNS, assciated with the sensory or autonomic nervous system
How do these ganglions look like
Their cross sectional cut has a wagon wheel like appearence whereas longitudinal is more of a classic cell type
What are glia cells (or astrocytes)
How can you identify them
They are supporting cells, present in different forms based on their location, appearence and fucntion. They are usually small and can only be seen by their nuclei. They are the ones that induce the endothelium to form blood-brain barriers.
They can be seen by their characteristic star like appearance.
Functions of astrocytes, oligodendrocytes, Schwann cells and microglia
Astrocytes: Detoxifies the brain, blood-brain barrier
Oligodendrocytes: Myelinates in CNS
Microglia: macrophages of the CNS
Schwann cells: Analogous to oligodendrocytes in PNS
How do you differentiate between the molecular layer and the white matter in cerebellum
Molecular layer is surrounded by pia mater
What stains in the purkinje cells
NUCLEOLUS!
Not the nucleus
Where is the wagon wheel like appearence
Dorsal root ganglion, when they are cut in cross sections
What glia cells are star shaped
Only astrocytes
