Mhm.

In this program we will examine discuss 

the microscopic and the light microscopic appearance of 

selected portions of the gi tract 

objectives for this program may be found in the accompanying 

study guide.

This cross sectional diagram 

Shows the four basic layers 

of the gi tract 

First the mucosa,

the sub mucosa,

muscular as external,

and the cirrhosis 

variations on this basic plan can help 

identify the specific area of the gi tract.

Understudy.

This drawing is divided Into two sections.

The left side 

represents the 

characteristic structure of the small intestine.

The right side represents a section of the 

colon beginning on 

the Luminal side.

We see the covering epithelium which 

may be either stratified squamous or 

simple kilometer epithelium depending upon 

the area 

immediately underline the 

epithelium.

We have a loose connective tissue layer 

termed the lamb inappropriate.

The next layer contains smooth 

muscle and it's called the 

muscular eras mucosa.

These three layers together 

I called the mucosa.

Next there's a layer of connective tissue,

the sub mucosa and within the sub 

mucosa there's a group of 

nerve cells and bundles of nerve fibers 

termed the mice ners 

plexus.

The next layer is usually made up of 

smooth muscle but may under 

certain conditions be made up of skeletal 

muscle.

This layer is termed the 

muscular rose X.

Turn up and generally 

consists of an inner circular 

and an outer longitudinal layer.

There is a group of nerve cells and 

fibers located within the muscular sex terna 

termed the our box 

plexus.

Both the meisters and our 

box plexus is formed the 

intrinsic nerve supply of the 

intestinal wall 

immediately outside of the 

must get rs external.

We see a layer of connective tissue 

with a covering mesophyll idea layer.

This is termed the cirrhosis.

On the left side.

We see mucosal glands 

and projections of the 

lamb inappropriate characteristic of the small 

intestine.

These projections are termed Valli.

In addition,

we see sub mucosal folds,

term clicky circular areas.

We also see large ducks 

penetrating the wall 

like those coming from the pancreas.

Then after their secretions into the gi 

tract,

we also see sub mucosal glands 

characteristic of the duodenum.

The right side represents a 

section of the colon with the 

lymphatic tissue,

and there are no.

They live.

Now let's look at a series of slides 

of the gi tract beginning with the lip.

This is the all side,

all the lip.

We see a thickened 

non carotene eyes,

stratified squamous epithelium.

As we move around 

the edge 

of the lip,

we see the transition at this point 

to the carotene.

Ized,

stratified squamous epithelium 

with numerous hair follicles,

and associated sebaceous glands.

In this area 

we see numerous mucous 

glands,

as well as the 

skeletal muscle fibers 

present within the 

obituaries Oris muscle.

As we can see in this 

area here.

Well,

next demonstrate three types of pili 

with three different slides of the tongue.

The first slide shows the fill,

a form capelli.

On the surface we see 

the carrot,

ionized,

stratified squamous epithelium 

with an underlying lamb inappropriate.

We see that the lamb inappropriate is thrown 

into basil folds to 

reflect it as surface 

projections.

These folds are 

called happily.

There are elevations are both connective tissue and the 

epithelium.

There may be smaller projections,

connective tissue in the epithelium,

resulting in secondary,

properly on 

the surface of the epithelium.

We could see threadlike 

projections of the stratified squamous epithelium,

which contains a small core of connective tissue.

These projections are termed the fill a 

form happily 

the years.

Capelli do not 

contain taste buds.

We can also now see 

skeletal muscle 

fibers arranged in a very 

characteristic criss cross 

pattern within the substance of the tongue.

On the next slide we see foliate 

papillae.

They are more common in certain rodents than man,

but do resemble the fungi form 

Papillion,

man.

The foliate capelli,

our dome shaped 

and are more dome shaped than the fill,

a form papillae,

note that the secondary 

projections of connective tissue 

are not reflected by the covering 

epithelium.

Therefore,

the vascular supply is brought in 

very close contact to the 

outside surface.

This creates a pinkish appearance in the living 

state.

In the substance of the tongue,

we see that there are 

large groups of syria's 

glands,

which are termed the glands of von 

Ebner.

On the lateral border 

of the people,

we see the lighter stained areas 

which are the taste buds.

Mhm.

Now in this field 

we see first the 

opening 

all of the taste buds,

which is called the taste poor.

We see that there are two general cell 

types within the taste buds.

First there would be the 

supporting 

sustain tacular cells which 

contain lightly stained nuclei 

and are arranged like staves of a barrel,

around the taste poor 

between the substance of the cells.

Our darker stained 

neural epithelial cells.

On the next slide we'll examine the validate 

happily.

On our low power objective,

we see that the valid happily 

tends to be recessed below the surface of the town,

therefore they frequently appear to be isolated.

It is important to remember that they do 

open to the surface of the tongue.

Note the general characteristics of the 

tongue with the covering 

epithelium,

the underlying connective tissue,

skeletal muscle 

and the serious glands 

notice on the lateral surface 

of the validate.

Hopefully the 

taste buds 

as we continue down the gi tract,

we will next Examine The Upper 1/3 of the 

Esophagus.

This is a macroscopic cross sectional 

view of the esophagus.

If we began on the Luminal 

side,

we can see first the 

epithelium,

the underlying lamb inappropriate,

The sub mucosa 

and the outer more darkly 

sustained muscular areas.

External.

We're on our low power objective.

On the microscope.

Beginning on the Luminal side,

we see the covering non 

carotene.

Ized stratified squamous 

epithelium.

Next we see the connective tissue layer,

the lamb inappropriate,

followed by a smooth muscle layer 

termed the muscular as 

mucosa.

Outside of the muscular S.

Mucosa,

we see the sub mucosa,

another connective tissue layer containing 

blood vessels.

Yeah,

and connective tissue fibers.

As we move to the 

muscularity external,

we see that the 

muscle and skeletal muscle 

with the characteristic 

peripheral 

nuclei the presence of 

skeletal muscle and the muscular sex turner is 

evidence that this is the upper 

1/3 of the Esophagus.

Next we will examine the lower 1/3 of the 

esophagus.

As we began on the Luminal side,

we see again a non 

carotene.

Ized stratified squamous epithelium 

with its underlying lamb 

inappropriate.

We see 

below that the muscular 

areas,

mucosa 

and a very thin 

underlying sub mucosal connective 

tissue layer.

As we move to the muscular is 

external,

we see that it consists of an inner 

circular layer 

and an outer longitudinal 

layer of smooth muscle.

On high power.

We can now see a junction all area 

between the inner circular 

seen in cross section 

and the outer longitudinal 

layers of smooth muscle fibers During 

contrast to the skeletal muscle fibers 

of the Upper 1/3 of the Esophagus.

To distinguish between the upper third,

one third and the lower third of the 

esophagus.

One must examine the type of muscle 

present within the muscular as external.

There is skeletal muscle present in the upper part,

A blending of the two types in the middle 

3rd and a predominance of smooth 

muscle in the 

lower part.

As we continue,

we will examine the junction all area between the 

esophagus and the stomach.

On our low power objective we can see 

the abrupt transition between 

the esophagus 

and the stomach.

We can see the stratified squamous epithelium,

non character knives to the esophagus 

and in this area 

the simple 

kilometer epithelial lining of the 

cardiac portion of the stomach.

Note the presence of glands 

within the lamb inappropriate of the 

stomach.

These may be either simple 

or compound tubular types of lands and 

generally function to secrete 

mucus.

They have little impact on the total 

function of the stomach.

The following slide is from the funders of the 

stomach.

This is a microscopic view We 

see first what appears to be a very 

thick 

epithelium.

In fact this area consists of glandular 

in folding from the surface.

We can also see large 

sub mucosal folds which in the stomach 

are termed Rudy.

To the outside we can 

see the muscular us 

external.

And before proceeding to the microscopic study of this 

slide we will examine a diagram 

are the characteristic gastric 

glands.

This diagram shows the gastric 

gland which is divided into four 

basic parts.

Beginning on the surface 

we see the covering 

service epithelial cells and 

the imaginations 

of the apathy ideal surface which is termed the 

pit.

Second we see an area 

it contains 

the isthmus.

It has pink staining parietal 

cells 

and the surface epithelial cells.

Below this we 

see the neck of the gland,

which again contains the ready 

stained parietal cells 

and the 

mucus.

Next cells 

in the deepest portion of the gland 

we see the base of the gland containing again 

parietal cells 

and the base of filic zima 

genic cells.

We are now on the low power objectives with the 

funding of the stomach.

Take special note of the very 

thick mucosa which 

contains numerous 

glands 

changing to her high power.

On the surface 

we see the surface epithelial 

cells 

and the pit.

Below this we see 

several piggy stain cells 

term the parietal cells 

that will in combination with the 

surface epithelial cells 

comprise the isthmus.

Below this we 

begin to pick up the parietal cells 

and more darkly stained 

cells which are termed the mucus Next 

cells 

This area would be the neck of the 

gland.

In the deeper areas 

we see basa filic cells 

two term the zimet and cells 

with occasional parietal cells 

immediately below 

the glands.

We see a very thin 

muscular mucosa 

and then the underlying 

seven mucosa 

note in this area,

the presence of fibers of my 

sinners plexus.

To the outside,

we can now begin to see beginning of 

the muscular sx turn up 

containing smooth muscle 

and in this case showing the characteristic inner 

circular 

and to the outside 

the outer longitudinal layers.

In some places within the 

stomach,

you may see an additional circular 

layer.

Okay,

note in this area the 

presence of fibers of the our 

box plexus.

We will continue our examination of the gi 

tract with the polaris of the stomach 

On our 10 x.

objective.

Take note of the very deep 

and elongate pits 

within the polaris.

The pets are lined by surface 

epithelial cells.

Note that these extend down at least 

halfway through the mucosal 

layer.

In the basal area,

the glands become coiled and contain 

mucus producing cells.

Below this we see 

the musket,

irish mucosa and the 

underlying sub mucosa.

The muscular s,

external is cut 

in an oblique section,

but in this area 

one can see nerve fibers and cells 

of the our box plexus,

again noting the nerve fibers 

and the bluish staining ganglion 

cells.

Mhm.

Now in review 

there are two general features which serve to 

distinguish the polaris from the funders 

portion of the stomach,

first very deep 

pit in the polaris 

compares with a very shallow pit in the 

fungus.

Secondly,

the homogeneous cell types 

present within the polaris 

contrast with the heterogeneous cells 

lining the funding glands.

The next slide will show the first 

portion of the small intestine called the 

duodenum.

We're looking at a macroscopic view 

and beginning on the Luminal side,

one can see first the presence of 

Valli or 

folds of the lamb inappropriate.

These light stained patches 

within the sub mucosa,

our glands and to the 

outside we see a thick,

muscular as external.

On our scan objective,

we can see the characteristic Valli 

or folds of lamb inappropriate.

With some of the valley cut in cross 

section.

Note the presence of the 

mucosal glands 

and a rather conspicuous mucosa 

In the 70 Koza,

no the presence of the light staining 

mucous producing glands,

which are termed Brunner's glands.

Again in the 

muscular wrist X.

Turn up,

we can see the inner circular 

and the outer longitude and the layers.

Note the presence of several lymphatic 

Nigel's which can be 

present either in the mucosa 

or the sub mucosa.

The amount of lymphatic tissue present within the connective 

tissue tends 

to increase as one moves down the gi 

tract.

Changing to our 10 X.

Objective 

note that as the Valli 

project above the surface there are 

small glandular 

imaginations 

which project into the lamb 

inappropriate.

And these mucosal glands 

are termed the crips of liberty.

Changing now to our high power objective.

As we began 

to examine the surface 

epithelium,

we see the presence of first goblet cells 

and these are not present in the stomach and are unique 

to the small and large intestine.

Note the presence of the brush border 

on the service of the epithelial cells,

the lamb inappropriate within the 

Valli contained in this case 

several plasma cells and other 

lymphoid cells 

within the core.

one can see very small emphatic 

channels 

which are termed lacked eels.

To review this section can be 

identified as small intestine because of the 

presence of Valli 

and goblet cells.

To distinguish the duodenum 

from the other portions of the small 

intestine.

You must identify the 

sub mucosal Brunner's 

glands which are not present 

in any other part of the gi tract.

Let's now examine the next section of the small intestine,

the Juno,

this is on low power with an asian 

e stain.

We again see both Valli 

and the presence of individual 

goblet cells 

to all characteristic of the small intestine,

changing to our high power 

as we move deeper 

into the glandular portion of the crips of labor 

coun 

we see at the extreme 

basil portion 

of the land,

the presence of reddish cells.

These cells are termed pan.

It sells 

the cells such as the Ar Gentlemen 

cells are also 

present but will not show with a 

standard Hema toxin and es and 

stain.

Now in review we 

see the Valli.

It's a characteristic of the small 

intestine.

We do not see sub mucosal 

Brunner's glands.

This fact will serve to distinguish the june um 

from the duodenum.

Although the number and the shape 

of the village,

I will change gradually from the jejune 

um to the ilium.

You will not be required to distinguish between the 

june um and the ilium.

We will now examine the structure of the colon 

or large intestine.

On the microscopic view,

we see the epithelial surface 

and the dark stained area 

which contains the sub mucosa 

and the muscular as external.

Notice that the colon does not contain 

ville I as the small intestine does 

but does contain 

sub mucosal folds.

On high power.

We see first the surface 

epithelial cells and begin to then pick up 

presence of goblet cells.

These are indicated here 

this combination of godless cells but 

novell I tells you it is the colon.

Below this we see the 

muscular as mucosa 

and a relatively thin 

sub mucosa.

Yes,

you may see frequently within the 

mucosa and the sub mucosa,

lymphatic modules.

Externally we see 

the muscular is external 

with a characteristic inner circular 

and outer longitudinal 

arrangement.

Note the presence of both 

cells and fibers of our box 

plexus.

Changing back to our scan objective 

note 

that the outer circular muscle 

is thickened into bands 

that are known as Tenia coli.

Will now examine a cross section of the appendix 

beginning on the Luminal side.

Yeah,

we see first goblet cells 

and no Valli.

This finding is compatible with the distinguishing 

characteristics in the colon.

Within the lamb inappropriate.

We see a very heavy invasion of lymphocytic 

cells and a 

conspicuous muscular as 

mucosa.

Okay,

and the sub mucosa 

we again see several modular masses 

of lymphatic tissue.

And on the outside 

we see a rather 

than muscular eras 

external.

Again,

we have an inner circular 

and an outer longitudinal 

arrangement of smooth muscle cells.

So in review the 

appendix has the structure 

of the colon,

but it's always heavily 

infiltrated with 

lymphoid cells.

Therefore,

the appendix can be considered as a 

council.

This mask 

within the lumen is partially 

digested material.

On the last slide we'll examine the 

rectal anal canal.

Yeah,

in the rectum we continue to have the 

glands,

our cribs,

nobody broken with no 

Valli and a 

large number from God,

but cells,

this finding is consistent with the 

morphology of the colon.

However,

there are no 10ia coli in 

the rectum 

due to the oblique section 

of this slide,

the outer longitudinal and 

the inner circular layers of the muscular s.

External do not show.

As we 

move 

toward the anal canal.

We see that in the anal canal there is 

a transition from a simple kilometer 

epithelium to a non 

carotene.

Ized,

stratified squamous epithelium.

There is not a sharply 

defined muscular as mucosa,

and therefore the separation 

between the mucosa and the 

sub mucosa is not clear 

due to the heavy concentration of the lymphatic 

tissue within the mucosal 

and sub mucosal areas.

These features will help to 

differentiate this part of the anal canal 

from the esophagus.

Now,

as we move down 

the anal canal,

there will be a transition 

from the non character in Ized 

stratified squamous epithelium to the carotene.

Ized empathy Veum 

as seen in these areas,

and this will become continuous then with the 

skin thin skin.

At this point 

this area contains 

para follicles 

and sebaceous glands,

all of which are consistent with the 

structure of thin skin.

This completes the tape on the GI tract.