الرحيم الرحمن الله بسم

Dr. Qasem started the lecture by saying that the exam is going to be online and the questions are going to be regarding the slides which you have seen in the lab and what you covered during lectures .Also he discussed the homework .. And he said that it is just related to the academic process so .. No there will be no bonus, no

extra marks for those who did it .

Osteoblasts – Bone Formation

An osteocyte, is the most commonly found cell in mature bone . some of which differentiate into active osteoblasts . In mature bone, osteocytes and their processes reside inside spaces called lacunae and canaliculi. When osteoblasts become trapped in the matrix they secrete, they become osteocytes. Osteocytes are networked to each other via long cytoplasmic extensions that occupy tiny canals called canaliculi, which are used for exchange of nutrients and waste through gap junctions. The space that an osteocyte occupies is called a lacuna (Latin for a pit).

Osteoclasts

Now this is a picture of Osteoclasts which can be identified as very large and multinucleated cells and it has an attachment process

creating the Ruffled border .

Osteoclasts – Ruffled Border

Here is a picture showing the Ruffled border .In active Osteoclasts, the surface against the bone matrix is folded

into irregular projections which form this border .

Trabecular Bone – Periosteum

Notice the Periosteum , Bone matrix and Osteocytes in lacunae.

- The periosteum. A thin layer of cell-rich connective tissue.- The Endosteum, lines the surface of the bone facing the marrow

cavity .

Compact Bone – Haversian System

Now this is a picture of a compact bone showing Central Canal of Haversian System.

Haversian System

Again we have the same picture over her and you have to notice the Osteocytes, the Canaliculi , the Central Harvesian Canal and the

Proximal canal .

Harvesian System – Proximal Canal

Here you can see the Proximal Canal , which connects the adjacent Osteons ( Harvesian Systems ) .

Zones Of Bone Ossificatin

(1 )Resting Zone

(2) Zone of proliferation(3) Zone of hypertrophy

(4) Zone of calcification

(5) Zone of ossification

-Identify the zones of bone conformation:

Cartilage

Here we can see the cartilage and of course other structures like Pseudostratifed Ciliated Epithelum .

On top we can see the cilia .

Hyaline Cartilage

This is a typical structure Hyaline Cartilage where we have chondrocytes in lacunae , in between the extra cellular matrix and

down there we have perichondrium.

Elastic Cartilage

Fibrocartilage

This is a picture of Fibrocartilage and you can see the chondrocytes which are arranged in rows surrounded by thick bundles of collagen cartilage and the extra cellular

matrix.

Connective Tissue

This is a picture of connective tissue and the main cells you can see here are Fibroblasts so all of the nuclei you can see are fibroblasts and there are the extracellular matrix and collagen bundles .

As we said before, Collagen present in tissues as bundles .

Reticular Fiber

This is a picture you can see in the cardiovascular system and here when you stain the elastin component it takes a black color you can see over here also you can see the Tunica Intima Media of the artery and another layers

of elastin fibers .

This is a very typical picture of loose connective tissue.The Fibroblasts, the elastic fibers and the extra cellular

matrix are shown.

Loose connective tissue

Again this is the same picture, but this is a caillary as you can see.

This is about the Dense connective tissue you can see the Fibrocytes and collagen

bundles present there.

This is the dense irregular connective tissue .It’s taken from the breast , you can see the collagen bundles running in different directions , we see blood vessels so these are like arterioles

or capillaries because all you can see here are

The simple endothelium , but in the blood vessels we don’t see any wall like tunica media , tunica external .So what we are talking about here is a capillary because in the level of capillaries most of these layers which are in the tunica media and tunica externa will not be present

over there at the level of capillary we have exchange .So we just need to have the structure that

make up the wall of the capillarywhich are simple endothelium cells, so this is a capillary.

1 2

Renal system

Now that was a picture taken from the renal system which you have covered , showing the different structures , the different views .And you have to differentiate between them .For example looking at pic.1 ( large lumen ) the nuclei is almost tall cuboidal or low columnar so this is something like Collecting Duct .Now looking at pic.2 it’s much likely a proximal

convoluted tubule.

-And you have to differentiate between collecting ducts , proximal tubules (PT) and

distal tubules (DT).

-Collecting Ducts : Columnar epithelium , larger than the rest with wide lumen

-Distal Convoluted Tubules : lined by Cuboidal epithelium , no microvilli and smaller cells so more cells in

cross section.

-Proximal Convoluted Tubules : lined by cuboidal to low columnar epithelium , acidophilic cytoplasm , have microvilli and 3-5

cells in cross section.

Simple cuboidal / squamous epithelium

Now the first picture is from the small intestine from the duodenum , you can see the simple columnar epithelium and the goblet cells .

In the second picture you can see the simple squamous epithelium from a blood vessel .

- To differentiate between an artery and a vein we can say that the arterys’ outline is circular .But the outline of the vein as you can see is

collapsed.

Here are different types of epithelium and I put them together so you can differentiate between them , for example in pic.1 you can see the stratified squamous epithelium .We see the basal layer and as we go up the cells try to become flatter and eventually when we reach the top most layer they

become completely squamous.

Now pic.2 it could be stratified cuboidal or even stratified columnar .So all you have to do is to look at the wall over there and you can see 2 layers ( 2 nucleus ) and the shape of the nuclei is rounded so it’s Stratified cuboidal .It could be columnar , but the nuclei don’t look elongated in the picture they look more oval

and rounded so it’s stratified cuboidal .

Now here we have the stratified epithelium and next to it you can see the transitional epithelium to differentiate between them .In the stratified type usually we have 2 layers ( 2 nuclei ), but in the Transitional you can see more .The second thing , look at the top most layer (in pic.2) its dome

shaped , and that’s a typical feature of transitional epithelium .

We’ve talked about cuboidal and columnar .And here pic.1 is the Pseudostratified ciliated columnar epithelium and pic.2 is about cuboidal epithelium .To differentiate you can see that the nuclei in pic.1 are columnar in addition to that we have two more features

here you can see goblet cells and on top you can see cillia .

It’s a bronchiole taken from a section of lung tissue of course the structure over her we are talking about is alveoli .The features of bronchiole that we’ve talked about are : the type of epithelium , the presence of cartilage within the wall , the transition and we said that the last level where you expect to see cartilage is the tertiary bronchi , after that we don’t need cartilage . Also cillia and goblet cells decrease as you can see and so we end up having rounded nucleus . This has to be

Terminal Bronchiole .

lungs

Here is another section from the lung .

We can see the alveolar duct surrounded by alveoli .

In GIT system we have different layers like mucosa , submucosa …and you must know that the top most layer is always the epithelium and here it’s the stratified squamous epithelium which I find in the pharynx and esophagus or down there in the anorectal junction .Now in the other structure I see mucosa and submucosal glands

and in the muscularis layer I can see different layers of muscles …

…In the Esophagus you can see that the mucosa is thrown into villi (projections ) .Now looking at the villi I see submucosal glands .. Which are structurally the same as those in the esophagus , but I can tell the difference by knowing that there in the esophagus we have stratified squamous epithelium , but here in the duodenum we have villi + large accumulation of submucosal

glands .

Now in pic.1 I can see a very long and numerous villi so this is the Jejunum which is almost obstructing the lumen , the submucosa has got no glands so it has to be the main sight of absorption ( the jejunum – Small intestine ) .In pic.2 I can see the mucosa doing invasion downward . Also I can see that the majority of the lining cells are goblet cells .

So this is a part of the large intestine (Colon) .

here we can see the Plicae ciculares ( folds ) of the Jejunum . The mucosa and submucosa of the small intestine form distinct projecting folds called plicae which encircle around the inner

circumference developed in the jejunum.

Again I have different layers and the top most layer is the mucosa also I have submucosa and the muscularis layer …the features I can see here , the mucosa is thrown into pits like so it’s the stomach , In addition to the presence of gastric cells that

present along these pits ( parietal cells and chief cells ). Now the second picture with a higher magnification to show the differences between the parietal cells, which take a lighter stain and present at higher levels.. and chief cells, which takes more

stain and present downward the bottom.

Here we have villi like projections ( villus ) and I have aggregates of lymphoid tissue ( lymphoid follicles ) and this is

taken from the ileum .

Here is the appendix , you can see the crypts of lieberkuhn and invasionations in large intestine also you can see the aggregations of lymphoid tissue .In the cross section notice the crypts of lieberkuhn , the

invasionations and the lymphoid follicles .

This is the anorectal junction , above here we can see invasionation crypts of lieberkuhn so this is a part of large itestine , down there you can see stratified squamous epithelium and no crypts .Also notice the stratified squamous epithelium and the central

columnar so it’s a junction .

Here is another junction between the stomach and esophagus .Here you will never see abrupt changes .. There are gradual changes .As you can see here in the upper part of the stomach we still have

some stratified squamous epithelium . Which means that we never go immediately from the stratified squamous epithelium to the

simple columnar .

Blood – WBC’s

Neutrophils :multinucleated (3-5 lobes),

Neutral (not stained nucleus) .

Eosinophils : nucleus made of 2 lobes,

eosinophilic red granules.

Basophils : nucleus made of 2-3 lobes,

basophilic dark blue granules .

Monocytes : kidney shaped nucleus,slightly larger than graulocytes , sky

clear blue color.

Lymphocytes : large oval nucleus fills the entire cell , vary in size fom

small as RBC’s to large.