Tuesday, May 20, 2008

sheet no.37

Notes for the last lecture:

-Outer cell (trophoblast) mass is nutritious.

-blastocyst cavity is the pool that allows the embryo to grow the way he wants freely.



Implantation


-Pregnancy starts when the Blastocyst loosely attached to the endometrium at Day 6(from fertilization)---->anchored implantation.

-Trophoblastic cells above inner cell mass attached to uterine wall by invading its epithelium and underlying stroma.



-At Day 7 implanted Blastocyst interrupted the regular sexual cycle affected by hCG hormone production from trophoblastic cells of the implanted Blastocyst.

*hCG---> (human Chorionic Gonadotropin)

-Chorion: Fetal portion of placenta.

-Gonad : sex organ (ovary here).

This hormone prevents degeneration of corpus luteum (C.L.)--->in the first 3 months, and maintains it as C.L. of pregnancy.

*Remember that C.L. will degenerate at Day 28 (from ovulation) and become corpus Albicans if no fertilization occurs.

-So we can detect pregnancy at Day 7.



At Day 8:

The trophoblastic cells differentiate into 2 layers:

Inner layer: Cytotrophoblast (mononucleated distinct cells).
Outer layer: Syncytiotrophoblast (multinucleated protoplasmic mass lacking cells) which is highly energetic.
Both 2 layers become part of the chorion.



The inner cell mass (Embryoblast) differentiates into 2 layers:

1- Hypoblast (with cuboidal cells) àendoderm to be.

2-Epiblast (with columnar cells) àectoderm to be.

Both layers form the Bilaminar embryonic disc.

A small cavity appears within epiblast then enlarges to be the Amniotic cavity.

Notes:

-The embryo has 3 layers:

Ectoderm (outermost).
Mesoderm (middle).
Endoderm (innermost).


-In Day 8 it will forms 2 layers & 2 cavities (Weak 2 loves no. 2).

-Until now there is no complete implantation.



Day 9:


Notice that:

-Syncytiotrophoblast will spread around(beldozer).

-Blastocyt embedded deeply in endometrium.

-Sycytium show small fluid-filled cavities (vacuoles)àfuseàto form trophoblastic lacunae.

* Lacunae mean---->cavities / small lakes.


Days 11 & 12:---->complete implantation


Trophoblastic lacunae fused to form lacunar network which communicate with maternal sinusoids to establish the Uteroplacental circulation which is the first communication between the mother & the embryo.



Day 13:


It has 3 main events:

Endometrial implantation defect healed.
Bleeding occasionally occurs at implantation site at Day 28 (from ovulation) of normal cycle?
*The bleeding may fool the lady and make her think that she is having her period.


Cellular columns from Cytotrophoblast invading Syncytiotrophoblast forming Primary Villi which is the beginning of placenta.
Cytoplast will form finger like pillar & penetrate inside forming Primary Villi.

*Now we have completely implantation (implantation ends at day 13).


Note: Fertilization occurs at Day 13 of ovulation so when we want to do the math we add 13.

e.g.: Day 8 from fertilization = (8+13=21) Day 21 from ovulationàsecretory phase of uterine cycle.


-so by day28(13 from fertilization) the embryo differentiates into 2 layers(endoderm-ectoderm) and placenta will have started then.


"Two little mice fell in a bucket of cream. The first mouse quickly gave up and drowned. The second mouse, wouldn't quit. He struggled so hard that eventually he churned that cream into butter and crawled out. As of this moment, I am that second mouse."


I want to dedicate this sheet to:

Children of Palestine, Iraq & Lebanon (You are the real men).


And to all my friends who:

-Study on medicine faculty:

5aled 7ajeer(Mr.”bla 10 3la al shagarah”),Ebraheem Abo Dya, M2moon sha3ban, Ahmad Abo Hallawah, Osamah 5aleel, Ahmad Abo Khadeegah ,5aled Daye3, Yazeed Al-naif , Yazeed Qaisyah , M2yad Ketaneh,7amzeh jassar , Qosay 3zzam ,Moh. Tamimy, Moh. Momany , Yazan 3toom(y36eek el 3afyeh) ,3dnan Al-3aref (ya 7ram Chelsea) , mo2men K7aleh , Abd Allah Tayyem ,Ebraheem Al-Sa3eedy , Moh. Al-quasmeh ,Moh. Abo 3rjah, Ahmad 7ra7shah , Ahmad 7na6y , 9ohayb Al-3bady , samy 3bdeen , Ahmad Al-shalabi, Moh sbo3, Zaid mal7ees .

-Study on other faculties:

Sa2ed kharoob, Moh. Bdar, J3fary (The tall) ,Ahmad (Sokkar) , Mahmood & ahmad Abo Znai6, Monther, Ahmad hamshary , 6ohayb, shukri, 30mar semreen,Wael 3lawneh,Muhannad,Nusaiba .

-Study on other Universities:

3la2 mara3’y, Wael Abo Hassan, Fat7y, Moh. Faroq, 7osam.

-Study on other countries:

Abo hmade (King kong) , Marwan 5amees.((In Egypt)).

J3fary”the short” (sht2nalak wala) ((In U.S.A.)).

-And to Dr. Maher Al-Hadidi.

-And to my little brother Hashem Al-Faqih.


*And to people who are special to my heart*

Mohammad Al-Faqih

2 comments:

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