Prenatal Development Flashcards

(38 cards)

1
Q

When is genetic sex determined?

A

At the time of fertilization

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

First step in prenatal development

A

Primordial germ cells from the yolk sac/ allantois migrate into the gonadal ridge in the first trimester

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the gonadal ridge classified as?

A

Bipotential (decides on sex based on genetic info)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How is the embryo a male?

A

Sperm with Y chromosome with SRY gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What cells are present on the gonadal ridge?

A

Precursor cells (2)
Primordial germ cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What do the precursor cells in the male become?

A

Sertoli cells that secrete desert hedgehog and anti-mullarian hormone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Desert Hedgehog

A

Tells the second precursor cells to become Leydig cells that produce Testosterone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What do the primordial germ cells in the male become?

A

Gonacytes that produce sperm throughout the male’s life

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Mesonephric Duct (wolffian duct) in males

A

Gives rise to male internal genitalia
Testosterone is essential for development

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Paramesophric duct (Mullarian duct) in males

A

Degernerates due to AMH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What happens after Leydig cells secrete testosterone?

A

Development of testis and regression of the mesonephros (temporary version of the kidney)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What does the remnant mesonephros give rise to in males?

A

Future efferent duct after combining with epithelial cords (future seminiferous tubules)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What does the mesonephric duct generate in males?

A

Epididymus and vas deferens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Dihydrotesterone

A

5a-reductase will convert testosterone into dihydrotesterone to develop into external genitalia because it’s 100 times more potent than testosterone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What does the genital tubercle become in males?

A

Glans penis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What does the urogenital/ genital folds become in males?

A

Fuse to form the ventral aspect of the penis

17
Q

What does the labioscrotal/genital swelling do in males?

A

Become the scrotum

18
Q

How is the female embryo developed?

A

Egg is fertilized with sperm with the XX genotype (SRY gene absent)- default pathway

19
Q

For the female, what does the primordial germ cells give rise to?

20
Q

For the female, what do precursor cells become?

A

Granulosa (follicle cells) that secrete theca cells that secrete estrogen

21
Q

Which structures regress in the female?

A

Mesonephros tubules and epithelial cords
Mesonephric duct as well because no testosterone

22
Q

What does the Coelomic epithelium become?

A

Future cortex

23
Q

What does the Paramesonephric duct become in females?

A

Develop into internal female genitalia (uterus, cervix, part of the vagina, oviduct) due to the absence of the AMH

24
Q

For the female what does the Cranial and caudal urogentical sinuses develop into?

A

Bladder and vestibule respectively

25
In females, what does the genital tubercle become?
Clitoris
26
In females what does the urogentical fold do?
Remain separate as the labia minora
27
In females, what does the labioscrotal swelling become?
The labia majora where the remain fused
28
Karyotype XY-SRY Mutation
No desert hedgehog, leydig cells, T, DHT--> mesonephric duct generateates and male system doesn't develop --> external genitalia of the female No Sertoli cells, AMH -->Mullerian ducts develop producing female genitalia
29
What happens to animals with the XY-SRY mutation?
Dysfunctional ovary with female internal and external genitalia Common in horses
30
Persistent Mullerian Duct Syndrome
Sertoli cells form but don't secrete AMH (mutation in the AMH gene) The individual will have internal female and male genitalia and external male genitalia
31
Complete Androgen Insensitivity Syndrome
Mutation in the androgen receptor so T and DHT can't activate downstream signaling
32
What is the outcome of androgen insensitivity syndrome?
Abnormal development of the male duct system Female external genitalia will develop
33
Freemartin statistics in cattle
92% of heterosexual twins result in freemartin heifer 86,000 freemartin calves born annually in the US
34
Twins in cattle
Common blood supply between two fetuses due to fusion of chorio-allantois portion of the placenta 5% twinning rate i Holstein cattle
35
What happens to the females during freemartin?
Due to shared blood supply with male, female fetus is exposed to AMH and testosterone Wide variation in external genitalia, maldevelopment or no development of internal genitalia
36
Transabdominal Phase of Testicular Descent
Enlargement of the distal gubernaculum, making it short and fat (swelling) Regulated by insulin-like 3 (ligand) protein secreted by leydig cells and pancreas
37
Inguinal-Scrotal phase of Testicular Descent
Testis moves through inguinal region because gubernaculum shrinks Shrinks and pull testis deeper into the scrotum Controlled by T (androgen receptor)
38
What are the testicular descent abnormalities?
Cryptorchidism Inguinal Hernia