Oral Histo 1st Lab Cor

8/7/2019 Oral Histo 1st Lab Cor.

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In the name of Allah mostgrateful most merciful

Embryo rabbit oral slide & coronal sectionslide of embryo's head

Notes:

The doctor started the lecture by saying that this lecture should be

practicaland this course is atwohour credit:2 hours theory and 1

practicalso we only have2 hoursa week .so actually we are going to have

oral histology lab everytwo weeks..

The doctor then told us about how to open the images by connecting the laptopbecause the files that we will see together will be big files and he can't actually

put them inCDand he can't run them on the computer,,,, so that's why heconnected his laptop

The doctor:"" before we start I am going to show you how we can run theprogram to make us able to open the images .. here as you can see there is a

file called oral histology slides this file is about fourGB.let's open this file

these are the slides that we are going to see all these slides are already withyou, we gave theCRtheCDso everyone should have it .because of the files

big size so they require a special program it's calledimage scopeand it'savailable with the slides that you have.

Before opening the image you should first install this file(image scope)toyour computer and by that you will be able to open the program and also u can

open all the images how these images were created??

by using scanning and this way of having the slides enables you to see the

images as if they under the microscope"" .for example (the doctor

opened one an embryo rabbit image to show us how we can use

the program(

The doctor said that" what is in the picture actually asmall rabbitwhich was taken out from the uterus and was sectioned and put under the microscope

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..so this is the embryo rabbit .and notice how I can through the program

zoom in and out the image as if we are seeing it under the microscope.

The doctor asked us to write downthe name of the slideso we can refer to

it(rabbit embryo)it's not very different from human's embryo . Let us seethe different structures

Embryo rabbit:

And the real lecture started from here :p

So this part here is theheadof the embryo and here we see thechestarea

and this is theabdomenand this thetail(here the doctor was pointed on theimage(

Now notice that in thechesthere what we can see? We answered:heart!

And he also pointed on theabdomenand asked us about dark brown area???And we also answered: liver!!! Both answers were true(: .

Notice that theliveris close to thecaudal part.not thecephalic.

Theliverthen theheartthen themouththen thebrainthis is thesequence

The sequence is not the samebefore foldingso this means that this embryo

which you are seeing now isafter folding.!

Of course before folding the liver and actually it's not called liver it's actually

(septum transverse area)is the mostcephalicfollowed by heart, followedby mouth

,followed by brain ..But because of the very fast growth of thebraineverything changes

Let us see now the area which we need (was zoomed in) he pointed again on the

head, the brain, the tongue, the lower jaw and the upper jaw.

And also you can see here cavity or space actually it's the ventricles of the

brain (not important to know).this is thenasal cavity and this is the oral cavity .the tongue again and the tip of the tongue

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Again and again the mandible and the maxilla .we have also what is called

longitudinal cartilage(micelles cartilage)..andlaryngeal cartilages

(form the larynx)and cartilages that form thetrachea.

The doctor ensured that we are interested in one part and he was pointing on

the oral area.and he asked us to draw it in three minutes and we startedcomplaining ..(doctor: every student should have a notebook for

oral histology as the one of the dental anatomy())))unfortunately we took 9 minutes to draw not 3 O.o((((

Back to the lecture


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Moving to the front area so we can see the invagination oforal epithelium, it

gets inside called (primary epithelial band) **don't draw** it this part willdivide into two parts

outer surface and inner surface.

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The outer surface is called thevestibular laminaand the inner surface is

calleddental lamina.then we have 1, 2 is forming in themandible;in fact

we should have more than one but because the line of cut wassagittal sectionso we only saw one tooth but for sure there are other teeth which are forming

on the sides.

We moved to theupper jawwhere the tip of the tongue is located and we

noticed that there is an area from the upper jaw started to have bones (bone

tuberclesand between them there isbone marosphasis..So this is the

initial formation of the bone of thehard palate.

The two shells when they areverticalsbefore they reoriented and fused .

They aremesodermal)no bone in it but once they are fused the bone starts to form, actually when

they are vertically aligned they will formsoft palateand once they are

horizontallyreoriented they fuse together after fusion bone starts to form

inside the palate ; form inside the palate byintra membranous ossificationbecause path is part of the maxilla if the maxilla bone formation is intra

membranous ossificationthat's why I don't see cartilage in hard

palate

We can only see mesenchymaltissue converts into ( I didn't get the nameof the bone: so sry ) bone.

Near the tip of the tongue we can notice a structure as ((C)) shaped structure ;

this is a tooth forming in ((cap stage= because it looks like a cap)), (this picture

is beloved by our doctor in the exams so pay attention while studying) .let ussee the beginnings of the tooth formation ..The tooth starts here and

invaginates (primary epithelial band) then after that this invagination will divide

into two parts:

1.Outer surface (vestibular lamina:(

*Goesbucculy*will have regeneration for the cells to have round space (as I heard(

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2.Inner surface (dental lamina(:*forms lingually.

*at the end of this we have the formation of the tooth.

This tooth has actually gone beyond bud stage now it's in cap stage; what can I

identify in cap stage??? I can identify: theouter cellsand theinner cells.

1.The outer cells (the doctor pointed on the image) calledexternal enamel

epithelium.

2.The inner cells called theinternal enamel epithelium.

3.Inside we havestellate reticulum cells (SR(

***notice that this cap isimpinging (eating something inside it)so thispart which is located in the cavity called(dental papilla)and the whole area

surrounded by called(dental follicle.(

))))The doctor asked us to draw the second image which is the magnified area of

the oral part in the embryo rabbit)))) the doctor said againbriefly

The tooth starts here from the oral epithelium(primary epithelium band)

divides intotwoparts thevestibular lamina (outside(

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**later on it will be emptied from it's contents to be called (oral

vestibule)andthe dental lamina(inside)which gives thetooth budwhich

consists of((enamel organ: forms the enamel of the tooth))surrounded with

condensedectomesenchmal tissue.

Parts of enamel organ; let us see the borders:1.External enamel epithelium.

2.Internal enamel epithelium.

3.In between there arestar-shaped cells(white region) =stellate

reticulum.

Ectomesenchyme: (surrounds only the terminal part of dental lamina(

1.inside the cavity of the cap(dental papilla(.2.Whole area is surrounded bydental follicle.

The doctor asked us who wants to show us again the different structures

..actually I went to the stage and played the role ha-ha I liked it so much

good feeling actually even though I made mistakes ha-ha.. Try it next time guys((((; .

The last thing about this slide ..The most important parts that we should know

are:

*tongue

*upper jaw (bone formation in the palate+ tooth in the cap stage(

*lower jaw (micelle's cartilage+ tooth in the bud stage(

Rabbit embryo Coronal section : (2nd slide for this lecture(

)Coronal section= parallel to the coronal plane which have the coronal suture

between frontal and parietal bones.

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We can see: top of the head chin:

1.Tongue2.Lower jaw

3.Hard palate

4.Alveolar processes which holds the teeth

5.Nasal septum

6.Inferior conchae

7.Middle conchae

8.Eyes

9.Brain

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Let's start with the lower jaw

Sphericalpart of the side of the tongueMicelle's cartilage (spherical mass actually it's a cross section of micelle's

cartilage (white rounded area beside the tongue(

We have bone formation on the lateral side of Micelle's cartilage(two platesof bone)at the outer side of micelle's cartilage =mandible actually the

bodyof the mandible why???

Because we said that micelle's cartilage is associated with the body of the

mandible because the body is formed by theintra membranous ossification

without involvement of cartilage but theramusof the mandible is formed by

endochondrol ossification(have cartilage ; needs no help(

The doctor pointed on theinner plateand theouter plate(we said that

tooth forms between two types of bones) one of them isbucculand the other

is lingual.

)The doctor showed us thedental laminaat the region where the tooth is

going to developed and said whenever you seecondensationarea around it; it's

actuallydental lamina(

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Micelle's cartilage hasinner (lingual) alveolar plateandouter (buccul)

alveolar plate(always on outer side of it(

The mandible is always in the outer surface of micelle's cartilage...it's

impossible for the mandible to form in the inner side of micelle's cartilage the

mandible always forms from the outside and the mandible is from two plates ofbone one of them is close to micelle's cartilage (lingual plate form) and the other

plate far a way from micelle's cartilage called (the buccul plate form).between

the lingual and buccul there is (couldnt hear) that forms

Notice here that we havea nerve(cross section) its spherical; it's a crosssection of a nerve which is a very important nerve in the mandible, what do we

call it? It's of course not facial ,,,,it'sinferior alveolar nervewhich actually

passes throughthe body and the ramus of the mandible and supplies

teeth (the doctor zoomed in the image to show us the nerve).by noticing thisinformation we can see that bones form after nerves .. And after bones

muscles form.

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So again theinferior alveolar nervewhich is located between two plates of

bone (medial and lateral or lingual and buccull(Near thelingualpart ofbone we have micelle's cartilage.

By pointing on the magnified image there is a tooth that will form and this tooth

is going to have innervationsfrom this nerve this is one of the teeth ((((alwaysthe tooth forms in an area where there is a nerve to have innervations. ((((

We were asked to draw the image by the doctor(themicelle's cartilage,

the lingual plates of alveolar bone, the buccul plate of alveolarbone, the inferior alveolar nerve and dental lamina of one of the

teeth.

The doctor wanted again a student to show us the parts on the image . Our

colleague (yara 8ablan) showed us again the parts thank you for your

participation

The doctor also showed us the nerve which located inferiorly to the eye called

(infra orbital eye)as an extra information

And also the doctor pointed into topalatine shellsdivided byfusion line.

The muscle which is in the floor of the mouth called

MylohyoidDr. Ashraf wanted us to draw

Threeimages and see you enshalla on Wednesday with your seat numbersplease.

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That's set(;(;

Forgive me for any mistake; I did my best ..With love

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Oral Histo 1st Lab Cor