Embryo: Development of Organs and Sex

Question 1

What is Diverticule de Meckel ?

Answer 1

Prolongement de la vésicule vitelline en continuité avec l’intestin grêle qui ne s’est pas refermé par apoptose.

Regle 2-3:
présents dans 2-3 % de la population,
mesurent 2-3 pouces,
et sont localisés 2-3 pieds en amont de la valve iléo-caecale in intestin grele (exam bro exam exam)
Chez les individus avec un diverticule de Meckel,** 2-3 % ont une complication reliée à leur Meckel **

Question 2

What is a kyste de duplication?

Answer 2

1. Digestive system formation in an embryo involves creating a lumen (light) inside the stomach through a process called apoptosis.
2. If apoptosis does not occur properly, it can lead to atresia, which results in a blockage in the digestive system.
3. Sometimes, the clearing of the tube is incomplete, or two separate tubes may form, a condition known as intestinal duplication.
4. In cases of intestinal duplication, one tube functions normally while the other is closed on itself.
5. The closed tube constantly releases molecules, causing it to enlarge over time.
6. In some instances, the enlarging closed tube, known as a duplication cyst, can block the normal passage.

Question 3

Omphalocoele géante vs Diverticule de Meckel

Answer 3

Both are congenital conditions, but they involve different parts of the body and have different implications.

Omphalocele involves the abdominal organs protruding through an opening in the abdominal muscles, while Meckel’s Diverticulum involves a small pouch in the lower part of the small intestine.

Question 4

Maladie de Hirschsprung

Answer 4

Normally, our intestines have nerve cells that help move food and waste through them. In embryo, neural crest cells migrate and colonize the gut, forming a network of neurons that govern the function of the gastrointestinal tract.

But in Hirschsprung’s disease, some of these nerve cells are missing in parts of the large intestine. This means that the muscles in those parts can’t contract and relax properly to move the stool (or poop) along, which can cause a blockage.

This is known as Hirschsprung

Question 5

Gastroschisis

Answer 5

rupture de la paroi intestinale péri-ombilicale suite a une nécrose anoxique de cette région

This happens due to hypoxia of the right side of the stomach which prevents the proper closing of the abdomen the reason why it doesn’t happen on the left side is because there’s an artery on the left side that always feeds this is why it’s important to not take Visa constrictions during this time

Question 6

Fistules trachéo-oesophagiennes (FTE)?

Answer 6

Missfolding in the lung tube formation

This causes respiratory problems and ingurgitation (swallowing)

For example, a baby that tries to eat, the food cannot pass, it will literally get blocked and the child will sufficate

Question 7

What part of the emryo is responsible for the formation of the organs of GI tract?

Answer 7

The ENDODERM

Question 8

What is vitaline duct?

Answer 8

It is the narrow connection between the midgut and the hindgut that is present during the folding embrio.

Question 9

What is Blasteme métanephrique (metanephros) ?

Answer 9

IT is mesenchyme tissue that will generate the definitive kidneys!!

Question 10

What is Ouraque?

Answer 10

Projection of the allantoide towards the cordon ombilical

Question 11

What is Septum
uro-rectal?

Answer 11

This is what will split the Cloaque and allantoide such that the allantoide will become the vessie and the cloaque will become the rectum.

Question 12

Anomalie loacale avec fistule recto-vesicale (septum uro-rectal is not closed properly)

Answer 12

This causes the bladded to be in continuum with the rectum. Becasue there are bacteria in the rectum, they can go in the bladder and go up the kidneys and cause an infection

Very lethal

Question 13

Describe pronephros all the way to the end for male and female. Draw it

key words, pronephros, mesonephros, canal mesonephrique, allantoide, bourgeon uretal, metanephros, gonades, muller and male vs female

Answer 13

The Pronephros, a non-functional primitive kidney, is present around the 4th week.

The ** Mesonephric canal** and the Mesonephros develop and begin to migrate in the fetus.

The ** Mesonephric canals** migrate all the way to the allantois.
Before the Mesonephros migrates, ureters emerge from the allantois.
At the end of the ureters, the Metanephros begins to develop. This will become the definitive kidney.
Simultaneously, the paramesonephric canals (also known as Müllerian canals) and the indifferent gonads migrate towards the allantois.
The kidneys develop and the Müllerian canals merge into the allantois, which now becomes the bladder.
Up to this point, the development is the same for both males and females.
___________________________________
Depending on the sex of the individual, certain developments occur:
In females, the Mesonephric canals disappear, the Müllerian canal becomes the uterus, and the gonads become the ovaries.
In males, the Müllerian canal disappears, the Mesonephric canal matures, and the gonads become testicles.

Question 14

Describe male vs female develoment based on Y chromosome

Answer 14

1. The indifferentiated gonads have a cortex and medulla, and a cellular cord which is the mesothelium.
2. If there is a Y chromosome, there will be SRY gene production. The SRY gene allows males to produce TDF, which then produces SOX9.
3. In females, there is no Y chromosome, therefore there is no SRY being produced, and consequently no TDF and no SOX9.
4. In males where there is SOX9, the cortical area of the gonad undergoes atrophy and the medulla becomes the testicle.
5. The presence of SOX9 in males leads to testicular development. The mesothelium creates Sertoli cells and the seminiferous tubules, which produce anti-Müllerian hormone (AMH). This makes the Müllerian canal disappear.
6. Leydig cells are produced, leading to testosterone production and DHT production, leading to the development of male organs as well as the growth of the Wolffian structures.
7. On the female side, the lack of SOX9 leads to ovarian development, atrophy of the medulla, and growth of the cortex.
8. The lack of AMH is what leads to the growth of the Müllerian canals, leading to the development of the uterus, vagina, etc.

Question 15

True or False,

an individual with an ovotestis must have SRY gene

Answer 15

True

Ovotestis is the presence of ovaries and testicles

The presence of SRY is MANDATORY for testicle formation

In fact, it is the inbalance or insufficient levels of SRY gene that can lead to ovotestis

Question 16

What does a lack in testosterone receptor in the hypophyse lead to?

Answer 16

L’absence de rétroaction de la testostérone sur l’hypophyse engendre une surproduction de LH qui stimule les cellules de Leydig

overall this leads to a huge production of testosterone since the hypophyse will continue to secrete LH as it does not sense testosterone

Question 17

insensibilité aux androgénes

Answer 17

Example a girl that has absence of testosterone receptors (46 XY; genetic male but female phenotype)

Question 18

What would be the phenotype of a 46 XX individual who was overexposed to androgens?

Answer 18

An individual with a 46,XX karyotype who is overexposed to androgens may develop XX male syndrome. This condition is characterized by the presence of male phenotypic characteristics in an individual with a typically female karyotype.

Question 19

TSPY gene and clinical relevance

Answer 19

The TSPY gene is a gene in the human Y chromosome.
TSPY gene is considered a proto-oncogene, meaning it has the potential to cause cancer when it is mutated or expressed at high levels

In males with not well developed testiculse, the probability of having germinal cancer