1. Observe the structural features of neurons and the morphology and distribution of nidus.
2. Observe the morphology and distribution of neurogenic fibers.
3. Observe the morphology of synapses
4. Observe the morphology and structure of myelinated fibers, nerves, motor endplates, and ring-layer vesicles.
5. Observe the morphology of tactile vesicles, glial cells, cortical pyramidal cells, and cerebellar cortical pyriform neurons.
Operation method
Nervous tissue observation experiment
Materials and Instruments
Intercostal muscles Spinal cord gray matter smear Spinal cord transverse section Nerve longitudinal and transverse section Nerve longitudinal section Circumferential lamellar vesicles on mesentery Skin section Cerebral cortical section Cerebellar cortical section Neurocellular bodies Synapses Myelinated fibers Motor endplates Move I. Materials and utensils For more product details, please visit Aladdin Scientific website.
Slides Coverslips Ophthalmic forceps Microscope
Intercostal muscles impregnated with gold chloride method.
Smear of gray matter of spinal cord (Niss1 stain), transverse section of spinal cord (Cajal silver stain), longitudinal and transverse section of nerves (H I E stain), longitudinal section of nerves (silver stain), section of annulus laminaris vesiculosus on mesenteric membrane (H-E stain), section of skin (silver stain), section of cerebral cortex (Golgi or Cox's method), section of cerebellar cortex ( Golgi or Cox method). Electron microscopic pictures of neuropil cell bodies, synapses, myelinated fibers and motor endplates.
Slides, coverslips, ophthalmic forceps, microscope.
II. manipulation
Multipolar neurons
(i) Observation of gray matter smear (Nissl staining) of bovine spinal cord
Because it is a smear, it shows the structure of the neuron more completely. This stain stains the nuclei and Nissl 's body (Nissl's body) blue.
1. Low magnification observation A multipolar neuron stained dark blue with multiple protrusions can be seen. Select a large, clear neuron for high magnification.
2. High magnification observation Polygonal cell body can be seen. Inside the cytoplasm, there is a spherical lightly stained nucleus with a dark blue nucleolus in the center. The cytoplasm contains many irregular stained dark blue small pieces, that is, the Nippert's body around the cytoplasm issued many protrusions, most of these protrusions for the dendrites, because there is only one axon, so it is sometimes difficult to see on the smear. The nidus is striated within the dendrites. The cytosol has no nidus in a conical area, which is the axial mound. If you see a protrusion attached to the axon, you can conclude that it is an axon. The axon and axon hillock are free of Nitrosomes.
(ii) Demonstration of the electron microscopic structure of a neuronal cytosol.
Observe the neuronal cytosol with a transmission electron microscope picture. In the cytoplasm, a large number of rough endoplasmic reticulum in regular parallel arrangement, Golgi complex, mitochondria, microfilaments and microtubules are also well developed. The chromatin granules of the nucleus were fine and evenly distributed, with obvious nucleoli and high electron density.
Neural fibers and synapses
(A) Observations on transverse sections of cat spinal cord (Caial silver staining)
The morphology of neurogenic fibers and terminal boutons can be observed in this section.
The center of the spinal cord in transverse section is in the shape of "H", the part stained brownish-yellow is the gray matter, and the wider end of the gray matter is the anterior horn of the gray matter of the spinal cord.
In the anterior horn of the gray matter, large, polygonal cells with protrusions can be seen, which are multipolar nerve cells. Find a nerve cell with more protrusions and cut to the nucleus and observe it with high magnification.
3. High-magnification observation, you can see the cell body and protrusions are brown-colored filamentous structure, this is the neural fibers. They are arranged in the cytosol in the form of a network, while in the protrusion is arranged in parallel.
If the slice of silver staining is appropriate, can also be seen in the cell body or dendrites on a number of small black circle or buckle ring structure (similar to tadpoles) both for the end, is the formation of synapses under the light microscope to see the site.
(ii) Demonstration of transmission electron microscopy pictures of synapses
Observe the presynaptic membrane, the synaptic gap and the postsynaptic membrane. Within the axoplasm near the presynaptic membrane, many small vesicles called synaptic vesicles can be seen, in addition to varying numbers of mitochondria, microfilaments and microtubules.
Cerebral cortical pyramidal cells and cerebellar cortical pyriform neurons
Sections of the cerebral cortex and cerebellar cortex of the cat are observed (Golgi or Cox method). This section makes the neurons and glia all black, and the nuclei and cytoplasm are indistinguishable.
(i) Cerebral cortical pyramidal cells
The superficial layer of the specimen is the cortex, in the cortex with low magnification observation, the cone cell cytosol is shaped like a cone, from the tip of the dendrites issued a thickest dendrites for the parietal dendrites, from the parietal dendrites repeatedly branching, and gradually become thinner. In addition, there are some thinner dendrites emanating from other parts of the cell body. If the section is cut squarely into the axon, an axon can be seen emanating from the bottom of the cone cell. When the dendritic branches are viewed under high magnification, there are many small drumstick-like projections on the surface of the dendrites, which are dendritic spines.
(II) Pyriform neurons of the cerebellar cortex
The superficial layer of the specimen is the cortex, and when observed with low magnification in the cortex, the cytosol of the pyriform neuron is large and pear-shaped or flask-shaped. From one end of the cell body issued 1~3 thick dendrites, from which the dendrites and then repeatedly branching, forming a flat cypress dendrite, from the other end of the cell body can be seen an axon, due to the relationship between the section of the axon seen to have a long or short.
Myelinated fibers and nerves
(A) Observation of longitudinal and transverse sections (H-E staining) of the sciatic nerve of rabbits.
1. Longitudinal section: Observe this section to understand the structure of the nerve fibers.
(1) Observation with low magnification: The nerve fibers are closely arranged one by one in parallel. Select a cut and straight nerve fiber for high magnification observation.
(2) High magnification observation In the center of each nerve fiber, a purple-red line is seen as the axon. The axon is surrounded by a myelin sheath. The myelin sheath is dissolved by lipoid during the preparation process, leaving only a red protein reticular scaffolding. The thin membrane outside the myelin sheath is the nerve membrane. The narrowing of each nerve fiber at a certain distance from each other due to the interruption of the myelin sheath is known as the Ranviernode. The neuromembrane between the two knots contains a nucleus stained blue-violet oval, but it is not always visible on the section.
2. Transverse section Observe this section to learn about the structure of a nerve.
(1) Low magnification observation The entire nerve is covered with a layer of connective tissue, the outer membrane of the nerve. It contains blood vessels and fat cells. Blood vessels extend into the nerve along with the connective tissue of the nerve periphery, dividing the nerve into many nerve fiber bundles of different sizes, and the connective tissue outside each nerve fiber bundle is the nerve bundle membrane. Inside each nerve fiber bundle, many small circles are seen, which is the cross section of each nerve fiber. Each nerve fiber is also wrapped in a thin layer of connective tissue for the nerve lining.
(2) High-power microscopic observation Each nerve fiber in the cross-section was thick, thin and unequal round. The purple-red dot in the center of the fiber is the axon, surrounded by light red reticulation or colorless myelin sheath and nerve membrane, if the section is cut to the nucleus of the nerve membrane cells, the nucleus can be seen stained blue-purple.
(ii) Demonstrate the observation of myelin cuttings.
Take a longitudinal section of the sciatic nerve of a rabbit (silver-stained) and observe it with high magnification, a funnel-shaped fissure can be seen on the myelin sheath, i.e. the incisure of myelin.
(C) Demonstrate the electron microscopic structure of myelin.
With the myelinated fiber transmission electron microscope picture observation, can be seen in each myelin sheath cross-section under the electron microscope in many concentric circles arranged spiral membrane plate layer-like structure.
Motor endplates
(A) Preparation and observation of a specimen of a motor endplate.
A small piece of rabbit intercostal muscle treated with gold chloride and soaked in glycerol was forcefully taken and placed on a slide. Add a small drop of glycerol, cover the coverslip and press the coverslip gently with your finger to crush the muscle tissue, then it can be used for observation.
1. low magnification observation, skeletal muscle fibers are light blue-purple, some are purple-red. The transverse striations of myogenic fibers are clearly visible. Nerves and nerve fibers are black. The end of the nerve fibers into claw-like branches, attached to the surface of the muscle fibers, and muscle fibers attached to the formation of the oval plate-like elevation, that is, the motor end plate.
2. High-magnification observation: The claw-like branches of the motor end plate are often button-shaped and enlarged at the end.
(ii) Transmission electron microscope picture demonstrating the observation of the motor endplate.
It can be seen that there is a gap between the axon terminals and the muscle membrane, and there are neuromembrane cells covering the surface of the axon terminals. The myotome in contact with the axon terminals is concave and forms many small folds in the direction of the myoplasm, and the axon terminals are rich in synaptic vesicles, mitochondria, microtubules and microfilaments, etc. The myotome is also rich in sub-synaptic vesicles. The submembrane is also rich in myoplasm, mitochondria and more nuclei of myofibrils.
Cyclic vesicles
Taking sections of cat mesentery (H-E stained) and observing them with low magnification, ring-layer vesicles can be found in longitudinal and transverse sections. In the longitudinal section, the small bodies are ovoid in shape. If the section is cut to the center of the vesicle, the center of the vesicle can be seen as a stick-like structure (inner column), which is surrounded by multiple layers of connective tissue fibers arranged in concentric circles, with flattened connective tissue cells sandwiched between the layers. At one end of the vesicle, a myelinated fiber is seen, which loses its myelin sheath as it passes through the connective tissue fibers. Therefore, only red-colored axons are seen in the inner column.
Tactile vesicles
Observe a section of human skin (silver-stained) at low magnification for the morphology and distribution of tactile vesicles. First, we find the complex flat epithelium of the skin, below the epithelium is connective tissue, connective tissue protrudes into the epithelium to form a number of papillae, in the papillae can be found in the oval tactile vesicles. Tactile vesicles are surrounded by a very thin connective tissue peritoneum, which contains transverse rows of flat cells, nerve fibers are black, coiled in the tactile vesicles
Glial cells
Demonstration of a cat cerebral cortex section ((Golgi or Cox method) using low magnification 7. There are various kinds of neuroglia, only astrocytes are observed here in a small demonstration. Astrocytes have a large cytosol with many long protrusions and a cellular morphology resembling radiating asterisms.