You've got some nerve . . . . .

Sorry for the pun.... :)  You guys are all expert histologists now. Feels pretty good doesn't it?? If I were you, I would keep reviewing the midterm material over the next few weeks up until the final, because the new is definitely lighter than past lectures. One of the key things for this week is to recognize what nerve cells look like. Check out the pictures below. Notice that they all are fairly similar looking (as are most nerve cells)--central nucleus, large cytoplasm, etc.

The nerve cells are those running diagonally down the middle of the pic.

Other Key Things to Remember:
-The anatomical names of the nerve connective coverings are the same as muscle (epi-, peri-, and endoneurium), but the histological classifications are slightly different. Remember that the epineurium is the thickest covering that surrounds the entire nerve. Anything that is cutting through the middle of the nerve will be perineurium, and anything surrounding a single fiber/axon will be endoneurium.

-What stains nerve tissue??? (hint: Gold, _____, Bronze)

-Know what satellite cells are, where to find them (p. 46), and what they do.

-For the central nervous system, don't go off of the color of the tissue on the slides to determine what is white/grey matter because white matter can be the darker of the two... you think they would have figured that one out right??? :) Remember from your anatomy days that the brain is like an oreo (grey matter on the outside, white on the inside) and your spinal cord is like a hotdog (white on the outside and grey on the inside).

-Make sure you can ID the dorsal and ventral sides of the spinal cord. The easiest way for me to do that is to remember the pneumonic "Heading to the back dor (like door, stands for dorsal)." Let me explain... the dorsal horn is in the back, and it touches the edge of the spinal cord while the ventral horn does not. It looks like the DORsal horn is heading to the back door. Also, the dorsal horn is usually narrower. Whatever works for you!

See the dorsal horn heading to the back door???

-Make sure you memorize the layers of the cerebrum!!! And that you can name them in order... Don't worry too much about being able to distinguish between all the layers on the slide, they can be pretty ambiguous. Remember the PP sandwhich :) And that it's inner inner, outer outer with pyramids on the bottom and crumbling granules on top of them ( i.e. inner pyramidal, inner granular, outer pyramidal, outer granular).

-For the cerebellum, know the layers and how to ID them on a slide or on a U-Find. They're pretty logical though - white matter on the inside (remember... OREO!!), then comes the granular layer which looks.... very granular :) (always does...), and the outermost layer is the molecular layer (think: molecules are smaller than granules... can't really see molecules). In between the molecular and granular layers is the purkinje cell layer (looks like a row of nerve cells separating the two layers). Here are some pics for your viewing pleasure...

This picture should look familiar to all of those who are in physiology. Aren't those purkinje cells cool?!?! Which layer is more granular looking?

If you're having a hard time orienting yourself, look for the sulci (grooves of the brain).

- For the meninges, in between the lobes of the brain is a good place to point to for pia mater on U-Finds. Dura mater is often not present...

-Ependymal cells - where are they present??? (choroid plexus and central canal). Remember that they change histologically over time. I like the remember it this way: as you get old, you get short and bald (ciliated simple columnar --> sparsely ciliated simple cuboidal -->simple squamous).

-Auerbach's and Meissner's plexi both help regulating peristalsis. Auerbach's is found between the inner circular and outer longitudinal layers (think Auerbach sounds Austrian, kinda like Arnold Schwarzenegger, who has lots of muscles . . . so Auerbach's is gunna be between all those muscles). Zoom in and look for cells that fit the look of the ones at the beginning of this blog post. I prefer to look in the jejunum for these plexi, just because there aren't really any other structures there to confuse them with (no Brunner's or Peyer's patches). The Meissner's plexus is found at the very basal edge of the submucosa right before you get to the inner circular muscle layer (think Meissner Mucosa). Once again, zoom in and scan around until you find something that fits the profile of a nerve cell. 

Here's a little game of "Where's Waldo" for you. These pictures were both taken of that slide.

Meissner's (Base of sub-mucosa)

Auerbach's (lighter clustered structures toward the left-middle) - notice the smooth muscle on either sides??

Other Random Pics:

Meissner's

Auerbach's (notice the muscle layers on either side)

-For the retina: Be able to identify (slide and U-Find) all of the layers and name them in order. The inner/outer nuclear layers are highly nucleated. The ganglionic cell layer can also look nucleated, but will sometimes, but not always, be thinner than the nuclear layers; generally the ganglionic cell layer will have much larger nuclei. The plexiform layers look clear (like plexiglass). Remember that outer isn't referring to the outer part of the body, but the outer part of the slera (think the backside of your eyeball).

Notice how the ganglionic cell layer is thick here? (see E) However, the nuclei aren't as tightly packed, are larger, and have colored cytoplasm - fairly common characteristics for this layer

-Make sure you know what neurons are unipolar, bipolar, etc. Some people like to remember it using the following: one tongue --> unipolar neuron, two ears --> modified bipolar neuron, two nostrils-->bipolar neuron, two retinas --> bipolar neuron.

Good luck on the quiz!! As always, feel free to let us know if you have any questions.

Nervous Review Sheet

Key: Know the anatomical and histological names (including modifications) for the following bolded structures; assume that you will be required to find the structures indicated by * on your own slides.

***This list is not guaranteed to be exhaustive, and only includes terms from this unit. While we will not focus on quiz information from previous weeks, knowledge of previous material may be useful***

Focus on nervous histology, but keep in mind all of the following terms.

Cross Section of Nerve

·       Epineurium*

·       Perineurium*

·       Endoneurium*

Myelinated Longitudinal Section of Nerve

·       Nerve axon

·       Node of ranvier

Neuron Cross Section

·       Nerve cell body

·       Satellite cells

·       Epineurium*

·       Endoneurium*

Spinal Cord

·       White matter*

·       Grey matter*

·       Dorsal horn*

·       Ventral horn*

·       Posterior median sulcus*

·       Anterior median fissure*

Cerebrum

Focus on the organization of the layers

·       White matter

·       Polymorphous/Multiform layer

·       Inner (pyramidal) ganglionic layer

·       Inner granular

·       Outer pyramidal cell layer

·       Outer granular

·       Plexiform (molecular) layer

Cerebellum

·       White matter*

·       Granular layer*

·       Purkinje cell layer*

·       Molecular layer*

Meninges

·       Pia mater*

·       Arachnoid mater

·       Dura mater

Choroid Plexus

Know how ependymal cells change with age

·       Ependymal cells*

Associated Nervous Tissue

·       Auerbach’s plexus*

·       Meissner’s plexus*

·       Intrafusal fiber

·       Purkinje fiber*

Multipolar Neuron

·       Dendrite

·       Nerve cell body

Special Senses

Retina

·       Inner limiting membrane*

·       Optic nerve fiber layer*

·       Ganglionic cell layer*

·       Inner plexiform*

·       Inner nuclear*

·       Outer plexiform*

·       Outer nuclear*

·       Outer limiting membrane*

·       Rods and cones*

Taste Bud

·       Tongue epithelium

·       Sustentacular cells*

·       Taste bud*

·       Taste pore

Organ of Corti

·       Hair cells*

·       Tectorial membrane*

·       Vestibular membrane*

·       Basilar membrane*

Olfactory Epithelium

·       Bowman’s gland

·       Olfactory receptor cells*

·       Olfactory epithelium