MICRO IMAGE REVIEW #2: LABS 4-6

boggusrl@email.uc.edu

LAB #4 - EPITHELIUM• Epithelia:1. lines tubes or 2. covers surfaces

Cells held together by:1. Cell junctions2. Interdigitation of cell membranes3. Glycocalyx

Intro to Epi• Number of cells layers:

– 1 = simple– More than 1 = stratified

Shape of cells:- Squamous = flat- Cuboidal = square w/round nucleus- Columnar = taller than they are wide,

oval nucleus

Simple Epithelium• Has 3 surfaces:1. apical/upper/free surface that faces

outside or into a lumen2. Lateral surface that connects it to

other cells3. Basal surface that lies against the

basement membrane

Simple Squamous

More Simple Squamous

Simple Cuboidal

Look how the tops are flat…. • Transitional would be rounded on

top. Don’t confuse!

Simple Columnar• Oval nuclei

Tip:• They will almost always have to

show you simple columnar in the intestine b/c it isnt found a lot of other places.

• Keep an eye out for the goblet cells and microvilli that are also associated with it.

• Also, they may ask you about “interdigitating cell membranes.”

Here are goblet cells and microvilli w/ simple columnar

Microvilli

Goblet cell

Interdigitating cell membranes• Will most likely have to show you

with EM

Pseudostratified columnar epithelium – ciliated and with goblet cells• Nuclei not at the same level• All touch the basement membrane

but not all reach the lumen

Pseudo blah blah blah

If they show you pseudostrat it may have stereocilia if it is in the epididymis. Be aware.

Simple summary

Stratified epi of many fun varieties• Name them according to the cells

facing the lumen – outermost cells. • Does not matter what the ones

touching the basement membrane look like

Stratified squamous epi• If top layer has nuclei – NON

keratinized– On wet surfaces - mucosa

• If top layer has no nuclei and looks flaky and like its pulling off – keratinized– On dry surfaces, usually skin of some

sort

NON keratinized

keratinized

Non-keratinized vs. keratinized

Again…..

Stratified cuboidal• Usually in glands

Stratified columnar• In glands too, don’t confuse with

stratified cuboidal. Make sure to see if nucleus is round and in center of cell. If so, cuboidal. If nuclei a little more oval and not exactly in center, go for columnar

Strat. columnar• So even though the bottom layer

here is cuboidal that doesn’t matter

More strat. columnar

Transitional• Pretty much only in the bladder• Often binucleate• Tops of cells bulge into lumen

Transitional

LAB 5 – Cellular Specializations

Cell contacts• Terminal bar (my favorite) vs.

junctional complex– Terminal bar in LM– Junc. Complex in EM

*They will try to trick you. Do not be fooled.*

What is this?

JUNCTIONAL COMPLEX!!!!!!!!

The JC has 3 parts• Zonula occludens

– Tight junction– Cells pressed close together, looks black in between

the 2 cells in EM• Zonula adherens

– Lighter between the 2 cells than the zon occludens– If you cant see anything and there is an arrow in

between a zon. occludens on top and a desmosome beneath (both of which are easier to see) then it is a zonula adherens

• Macula adherens– Desmosome– Looks spiny b/c of the filaments branching out

*they will ask you these. Be able to tell them apart*

Desmosomes- aka macula adherens- Have intercellular bridges- Can be more than one down the

length of a cell

Gap Junction• This is what I found on google for

gap junction. I don’t think this will be on the test

Will the real gap junction please stand up• Not spiny on the sides like the

desmosome

They can show it to you like this too:

Often in cardiac muscle

Interdigitation of lateral membranes• Its in the lab book, its fair game

Basement membrane• Between epithelial cells and

underlying tissue• Made by both epithelial cells and

connective tissue cells– Epi cells secrete basal lamina =

collagen and other stuff– CT cells secrete reticular fibers and

other stuff

Basement membrane

Don’t be alarmed• They may stain it funny

BASAL LAMINA• Like the terminal bar, different names

in different tissues

hemidesmosomes• Pretty much just desmosomes on the

basal side of the cells

Also note the lamina lucida and lamida densa – they can only label these on EM

Bottom of cells and looks like desmosome?? HEMIDESMOSOME

STUFF ON TOPS OF CELLSMicrovilliStereociliaCiliaFlagella

microvilli• Smooth border on top – not rough

like cilia• Cant really distinguish individual

microvilli like you can with cilia• Filled with actin filaments• Often in intestine

– For absorption– Look for the columnar cells that you find

there

Pics of microvilli• P.S. microvilli does NOT =

glycocalyx. Glycocalyx is a carb covering. Lets demonstrate:

Microvilli contd• When in cross section do not

confuse with cilia – cilia have TUBES inside them in the special arrangement, while microvilli have roughly 50 actin filaments in a bundle

microvillicilia

Even more……..

In LM:• Look at how smooth it is vs. cilia

Cilia above

Microvilli below

stereocilia• More like microvilli than cilia

– REALLY long and stringy – cant mistake them!

– Core of actin– Function in absorption– In epididymis

stereocilia

More stereo

cilia• Core of microtubules• Note the basal bodies underneath

them – these can be labeled as well• Remember they have a rough top• We have seen them 2034873489

million times, but just for good measure….

Cilia w/basal bodies

Cilia – note longer than microvilli and ragged top edge

flagella• Structure similar to cilia (microtubules

inside) but only one per cell• Sperm have them…. Hot!

Glands

Unicellular glands• aka goblet cells• Look for possible PAS staining• Lots in GI and respiratory system• Product goes into a lumen, like the

stomach or trachea, as opposed to a duct

NO PAS PAS

Multicellular Glands• Invaginations of epithelium• 2 kinds:

– Exocrine – still connected to surface epithelium through ducts; 2 kinds of exocrine

• Mucus• serous

– Endocrine – no connection

Exocine serous secreting vs. mucus secreting• Serous stain more darkly b/c product

is protein – thus cell making lots of protein…. Cytoplasmic basophilia!

duct

Serous also have rounder nuclei• Compare serous vs. mucous here

mucus• Stain lightly – product is mucus so

this makes sense• Sometimes cells are so packed with

mucus that the nuclei are pressed flat against the bottom of the cell

Mucus glands with demilunes

Serous demilunes• Half moon shaped• Pressed against mucous glands

Blue arrow = demilune

Loose irregular connective tissue aka areolar• Looks really irregular• All sorts of fun fibers

– Elastic – usually need special stain, can be coiled – purple in this pic

– Reticular – really thin, need special stain– Collagen – fat

• Pink here

– Also look forfibroblast nuclei

Dense irregular connective tissue• Compared to loose, it looks packed• Lots of times found under

skin/epidermis – a good clue

Dense irregular• Look and see the dense irreg CT

under the epidermis– FYI this is called the dermis, one place

you often see dense irreg CT

Dens irreg CT:not as many fibroblasts or elastic fibers – more collagen…. tougher

-makes sense that its under epidermis that takes a lot of wear and tear

Mast cells• Purple granules and blue nuclei

found in CT – BLATANT granules

Mast cells in EM• Tricky, but look for scroll-like things

in the granules• Know its not lipid b/c granules in

mast cells are perfectly round like lipid would be

Scroll stuff in granules

Metachomasia – what is it and why do we care• Use one stain and get a blue nucleus

and red/purple granules• This shift in staining color =

metachromasia

• Was it all you dreamed of and more??

EM collagen• Not to be confused with glycogen

please

Not the red arrows…. the black dots

Dense regular connective tissue• Fibroblast nuclei are smashed• May be wavy and/or shiny• Usually a tendon, keep your eyes

open for any skeletal muscle

Tight parallel arrangement of collagen

Elastic fibers• wavy• Usually funky stain like resorcin

– Stains them purple