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Nervous tissue

What are lipofuscin granules?

They are residual bodies formed by indigestible substances in lysosomes accumulated in long-age cells as nerve cells. It has golden brown color and appears even with H&E.

The prominent nucleolus in the neuron nucleus reflects the intense synthetic activity of these cells...What does it synthetize? rER and polysomes??

Neurones are very active protein forming cells. The nucleus is open face and the cytoplasm is very rich in Nissl's granules "rER+polyribosomes". Also, they have many mitochondria. Polyribosomes synthesize intracellular proteins including tubulins responsible for formation of the micro tubules. RER synthesizes the neurotransmitters.

I can't Imagine a myelinated nerve fibre with out neurolemma (shwann's cells) !!! they're supposed to form myelin !!!!

Oligodendroglia are the cells responsible for formation of myelin sheath in central nervous system (white matter),so the nerve fibers in white matter are without Schwann cells.after the nerve fiber leaves the white matter it receives myelin formed by Schwann so it is covered then with neurolemma.

axon hillock?

It apart of the perikaryon the axon arise from it. It is conical in shape and appear lighter in staining. (Suggest why)

The axon does not contain Nissl's granules.

,In Nervous tissue, the collateral branch of axon arise from mylienated or unmyleinated nerve fibres or from both and what is the function of it?

A collateral axon or an axon collateral is a branch off of the main axon that usually feeds back onto the soma. The function is to provide modulation of cell firing. It may arise from myelinated or unmuelinated nerve fiber.

Drs plz, what is meant by "neurokeratin"?

Transverse section through myelinated fibers within a nerve fascicle (Triple stain). This is a higher power view of the preceding section. Blue endoneurium surrounds myelin sheaths. Myelin neurokeratin appears as well defined red circles. Axons (asterisks) within myelin rings generally are not distinct with this stain. Lemmocyte cytoplasm or nuclei are occasionally visible (e.g., below the lower, right asterisk).
Neurokeratin is a protein network seen in histological specimens of the myelin sheath after the myelin has been removed. It is not true keratin, i.e. keratin-like substance.It has no known function and may be probably an artifact appearing during preparation of the specimen. Not important at all, but it appears in the histological sections. So, it is mentioned as a finding in histological sections. 

In Nervous tissue, the collateral branch of axon arise from mylienated or unmyleinated nerve fibres or from both and what is the function of it?

A collateral axon or an axon collateral is a branch off of the main axon that usually feeds back onto the soma. The function is to provide modulation of cell firing. It may arise from myelinated or unmyelinated nerve fiber.

Drs plz, in nervous tissue, it's said that axons has no spines, my question is in axo-axonic synapse how can the nerve ending synapse with the axon?

Through 2 areas of contact without a spine.

What is "transneuronal degeneration"?

Injured nerve cell stops to send impulses to the neurons which make synapse with the so these neurons become in turn inactive and start to degenerate.


Drs, I can't understand nerve regeneration clearly, I want a diagram for more clarification..Thank you