ALL PHOTOS ARE IDENTIFIED IN THE LOWER RIGHT CORNER WITH THE MAGNIFICATION POWER THAT THE PHOTO WAS TAKEN WITH. SCAN - THIS IS A VERY LOW POWER IMAGE THAT WE USE WHEN A SAMPLE IS SO BIG THAT YOU CAN’T GET THE WHOLE SAMPLE INTO THE FIELD OF VIEW AT LOW POWER. YOU WON’T SEE THIS IN YOUR MICROSCOPE. LOW – THIS IS THE 40X MICROSCOPE LENS MED – THIS IS THE 100X MICROSCOPE LENS HIGH – THIS IS THE 400X MICROSCOPE LENS SUPERHIGH – THIS IS USING THE 400X LENS, AND THEN USING THE ZOOM ON THE CAMARA. YOU WON’T SEE THIS SUPERHIGH POWER IN THE MICROSCOPE.

EVERYTHING THAT YOU ARE RESPONSIBLE FOR ON THE HISTOLOGY IS LABELED AT LEAST ONCE IN THIS PPT. THERE ARE ALSO EXPLANATIONS OF WHAT MAKES SOMETHING DISTINCTIVE, SUCH THAT YOU CAN IDENTIFY IT.

SIMPLE SQUAMOUS EPI

LOW ARTERY VEIN EPITHELIAL TISSUES ARE EITHER GLANDULAR OR LINING. HERE WE’RE LOOKING AT THE LINING AND WE’LL USE THE ARTERY

MED LINING!

HIGH SEE HOW THE TEXTURE OF THE LINING IS DIFFERENT THAN THE UNDERLYING STUFF (MUSCLE). THAT IS THE SINGLE LAYER OF FLAT (SQUAMOUS) CELLS.

SIMPLE CUBOIDAL EPI

SCAN This is a whole kidney, which is divided into layers. The middle layer is called the medulla, and is where we’ll find our simple cuboidal epithelium medulla

LOW SEE THAT THERE ARE DIFFERENT TEXTURES IN THIS SLIDE? THE NATURE OF THE KIDNEY IS THAT THESE TUBULES ALL SWEEP DOWN TOWARDS THE SAME PLACE TO EXIT THE KIDNEY. SO A SECTION THRU THE KIDNEY IS GOING TO CATCH SOME OF THE TUBULES IN CROSS SECTION AND SOME IN LONGITUDINAL SECTION. WE’LL SEE HIGH POWER OF BOTH AREAS

MED THIS IS MEDIUM POWER OF THE LEFT PORTION OF THE PREVIOUS PHOTO – THE LONGITUDINAL SECTIONS…

HIGH Simple cuboidal epi lining - a cross section of a tubule

HIGH Simple cuboidal epi lining a longitudinal section of a tubule

HIGH Simple cuboidal epi lining a longitudinal section of a tubule WHY DO THESE CELLS APPARENTLY HAVE NO NUCLEI?

SIMPLE COLUMNAR EPI

LOW THE STOMACH HAS BOTH LINING EPITHELIUM AND GLANDY EPITHELIUM. THE VERY EDGE IS THE LINING AND ALL THE PURPLE STUFF UNDER IT ARE THE GASTRIC GLANDS

MED WE’RE LOOKING HERE

HIGH SEE HOW THE LINING CELLS ARE TALL AND HAVE NUCLEI AT THE BASE, AND HOW THE NUCLEI ARE LINED UP IN A NICE ROW?

STRATIFIED SQUAMOUS EPI – NON-KERATINIZED

LOW Note the dark staining at the bottom of the tissue, reflecting the packed nuclei.

MED As the cells are pushed away from the basal layer, they get flatter, and the nuclei get spread out too.

HIGH flattening

HIGH In this slide the flattening isn’t as obvious, but we can still see the the density of the nuclei decrease as the cells are pushed to the surface

STRATIFIED SQUAMOUS EPI – KERATINIZED

LOW Look here for the epi THIS IS ALL ADIPOSE TISSUE

MED The basal layer of the st. sq epi curves around as the epidermis invaginates into the dermis. There are clearly layers here – we’ll get to them later. For now just note the concentrated, darkly staining nuclei at the base, thinning out a bit as they get pushed off the basal layer. Also note the thick superficial layer of pure keratin.

HIGH KERATIN BORDER BETWEEN THE EPI AND THE UNDERLYING TISSUE THINNING AND FLATTENING

SIMPLE COLUMNAR EPI. W/ MICROVILLI

LOW JEJUNUM BLOOD VESSELS A SNIPPET OF THE PANCREAS LINING THE LUMEN…

MED

HIGH THIS IS A SINGLE LAYER, SO LOOK AT HOW THE NUCLEI ARE LINED UP, AND LOOK AT THE EDGE OF THE CELLS, THAT DARKEaNED LINE ARE THE PACKED MICROVILLI (TOO SMALL TO BE SEEN ONE BY ONE, BUT SO DENSE THEY COLLECTIVELUY STAIN DARKER

PSUEDOSTRATIFIED, CILIATED COLUMNAR EPI.

LOW NEXT TO THE LUMEN

MED

HIGH THIS IS A BLOB OF LYMPHATIC TISSUE - WBCS THESE ARE COLUMNAR CELLS, BUT THE NUCLEI AREN’T IN A NICE ROW – THEY’RE IN A JUMBLED MESS WE CAN SEE THE CILIA THIS IS MUSCUS GUNK ON THE SURFACE OF THE CILIA

TRANSITIONAL EPI.

MED Bladder slides are tough to make, the layer under the epithelial layer separates as the section is made, resulting in all those spaces, which are ‘artifacts’

HIGH Transitional epi is designed to be able to stretch and collapse as the bladder slowly fills and then quickly collapses. The nuclei are jumbled, but are clearly NOT columnar.

LOOSE CT

LOW WHEREAS EPI CONSISTS OF TIGHTLY PACKED CELLS WITH ALMOST NO MATERIAL BETWEEN THEM, CT IS MOSTLY ‘INSTITIAL’ STUFF (FIBERS AND SUCH), AND THE CELLS ARE WIDELY SCATTERED. EVERYWHERE YOU SEE A NUCLEUS IS A CELL

MED

HIGH Look at how scattered the nuclei (and therefore the cells) are. Most of the mass of CT is extracellular material, made by the fibroblasts. All the pinkish and thin black strands are the fibers that give the tissue (along with the nature of the ground substance) its character This is loose ct, disorganized with the fibers not nearly as compacted as Dense CT

DENSE IRREGULAR CT

LOW Back to the skin to see DICT. It’s here, below the epithelial layer, but above the fatty layer

MED There are a bunch of accessory structures here. Ignore them for now. Look at the disorganized stuff that is the ‘stuff ‘ of this layer

HIGH Ignore all the extra stuff in the layer – there are blood vessles and glands here – and look at the thick pinkish collagen fibers. They’re not regularly arranged and there are way more of them than in LCT

REGULAR DENSE CT

LOW EVEN AT LOW POWER WE CAN SEE HOW THERE IS AN ORGANIZATION, REFLECTING THE FIBERS BEING PARALLEL TO EACH OTHER AND GIVING THE TISSUE POINT-TO-POINT STRENGTH AS OPPOSED TO DISTRIBUTED STRENGTH

MED

HIGH

HYALINE CARTILAGE

LOW Back to the trachea for hyaline cartilage

MED

HIGH Note the chondrocytes in their lacunae, and the perichondrium

ELASTIC CARTILAGE

LOW This is an animal ear. We can see the epidermis, then a layer of muscle, then the cartilage layer

MED Elastic cartilage has much less interstitial area than any other CT, but what it has stains dark with elastic fibers

HIGH Chondrocyte in its lacunae Perichondrium

FIBROUS CARTILAGE

LOW Part of an intervertebral disk, so the cartilage is mostly collagen with very little elastin; it’s also layered for additional strength

MED The chondrocytes are stacked between the layers.

HIGH

COMPACT BONE

LOW WE USE A DIFFERENT STAIN FOR BONE, THAT MAKE MINERALS LOOK GOLDISH. AND WHEN THE SLIDE IS MADE, THE STAIN (WHICH STARTS BLACKISH) DOESN’T WASH AWAY FROM SPACES, LEAVING THEM BLACK. SO ALL THE BLACK AREAS ARE ACTUALLY EMPTY.

MED THIS IS A HAVERSIAN SYSTEM, WITH A CANAL IN THE MIDDLE,, SURROUNDED BY 3 OR 4 HAVERSIAN LAMELLAE VOLKMAN’S CANAL THESE LAMELLAE, WHICH DON’T BELONG TO ANY SYSTEM, ARE INTERSTITIAL LAMELLAE

HIGH INTERSTITIAL LAMELLAE HAVERSAINA LAMELLAE ALL THE LITTLE LINES SPOKING OUT ARE CANALICULI ALL THE SMALL BLACK SPOTS ARE LACUNAE WITH OSTEOCYTES HAVERSIAN CANAL

SKIN

LOW HYPODERMIS WITH ADIPOSE TISSUE DERMIS WITH DICT EPIDERMIS WITH STRATIFIED SQUAMOUS EPI THIS IS A FINGERTIP WHICH HAS A THICK KERATIN LAYER PACINIAN CORPUSULE TRUE SWEAT GLAND WITH PIECES OF ITS DUCT HEADINIGI TOWARDS THE SURFACE

LOW THIS IS THE SCALP, WITH A THINNER KERATIN LAYER AND LOTS OF HAIR FOLLICLES SHAFT ROOT SURROUNDED BY FOLLICLE SEBACEOUS GLANDS TRUE SWEAT GLANDS

MED ST CORNEUM ST GRANULOSUM ST SPINOSUM RETICULAR LAYER OF DERMIS PAPILLARY LAYER OF DERMIS DERMAL PAPILLA ST BASALE – THE ONE LAYER AT THE BASE OF THE EPIDERMIS

HIGH PACINIAN CORPUSULE

HIGH DERMIS WITH DICT THE STRATUM CORNEUM IS MUCH THINNER AND LESS STURDY ON THE SCALP, SO IT SEPARATES INTO ARTIFACTS WHEN THE SLIDE IS MADE ALL WE CAN REALLY POINT TO HERE IS THE ST BASALE, ST SPINOSUM AND ST CORNEUM

HIGH SEBACEOUS GLAND

SUPERHIGH ARRECTOR PILI

SUPERHIGH ST BASALE ST SPINOSUM MEISSNER’S CORPUSULE WITHIN DERMAL PAPILLA