Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Reproduction > Embryology > Flashcards

Embryology Flashcards

1
Q

What occurs in gastrulation

A

The embryo forms 3 layers

Called the trilaminar disc

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

When does gastrulation occur

A

Week 3 of gestation

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

Where is the urogenital system derived from

A

The intermediate mesoderm

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

How are the endoderm and mesoderm formed

A

Invagination of epiblast cells through the primitive streak

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

How does cranial-caudal folding affect the embryo

A

It rolls up like a scroll from each end to give the foetal position

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

Describe the function of the pronephros, mesonephros and metanephros

A

The pronephric system will eventually disappear – doesn’t function in humans
Mesonephros is not the end kidney but does have some functional capability in the foetus – some urine production
Metanephric system is the end kidney

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

Where do the excretory ducts of the forming UG system enter

A

They join with the cloaca to eventually form an output

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

Which cells will go on to form gametes

A

Primordial germ cells

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

Describe the progression of the primordial germ cells

A

They form in the yok sac
They work their way into the embryo into the developing gonads (intermediate mesoderm)
When they get in, they stimulate epithelium to start proliferating – forms a gonadal/genital ridge
The proliferating epithelium will form somatic support cells which envelop to the germ cells
These support cells will eventually become the follicular cells or Sertoli cells

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

Which two ducts form the urogenital system

A

Mesonephric (Wollfian) duct

Paramesonephric (Mullerian) duct

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

Where is the mesonephric duct found

A

Connects to the posterior wall of the urogenital sinus and the cloaca
Joins the paramesonephric duct at the urogenital sinus

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

Where is the paramesonephric duct found

A

It is blindly open at the top and opens into the peritoneal cavity
Joins the mesonephric duct at the urogenital sinus at the caudal end of the foetus

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

When does sexual differentiation occur

A

From week 7 of gestation onwards

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

What triggers the differentiation into a male

A

The presence of the SRY protein transcription factor

This is the sex determining region of the Y chromosome

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

Describe the effect of SRY on the early gonads

A

Triggers the somatic support cells to become Sertoli cells and they form medullary cords
These cords engulf the PGCs
Rete testis connect the mesonephric tubules to the testis cords

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

What happens to the paramesonephric duct in males

A

It disappears

Sertoli cells secrete anti-Mullerian hormone to cause the degeneration of the paramesonephric duct

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How is testosterone production started in the early male

A

The Sertoli cells stimulate the formation of Leydig cells which secrete testosterone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the role of testosterone in the developing male gonads

A

influences the mesonephric duct to form the structures of the male repro system – epididymis , vas deferens etc

Dihydrotestosterone (DHT) is more potent and stimulates formation of external genitalia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is persistent Mullerian duct syndrome

A

When part of the female reproductive tract is present in a biological male
Due to a failure of the anti-Mullerian hormone or its receptors
The paramesonephric duct doesn’t regress

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is cryptorchidism

A

Failure of descent of one or both testes

21
Q

Where do the testes originate

A

Level of T10 on the abdominal wall

22
Q

How do the testes move down to the scrotum

A

Tissue called the gubernaculum shortens and pulls the testes down and through the body wall
Should be in scrotum by birth - sitting high up

23
Q

What is the vaginal process in men and its significance

A

Vaginal process is a small pocket in front of the descending testes
It should close off and form a space that allows for testicular movement
If it stays open you are at increased risk of inguinal hernias

24
Q

How do the seminal vesicles develop

A

They are outpouchings of the mesonephric ducts

25
Q

How do the bulbourethral glands and prostate develop

A

Form from endodermal invaginations from the urethra

26
Q

What triggers the embryo to develop into a female

A

The absence of SRY transcription factor = no Y chromosome

27
Q

How are the ovaries formed

A

Germ cells differentiate into oogonia and then into primary oocytes.
Somatic support cells differentiate into granulosa cells and surround the primary oocytes.
This forms primordial follicles in the ovary.

28
Q

What does the paramesonephric duct go on to form in females

A

Uterine tubes
Uterus
Superior vagina

29
Q

What is the role of oestrogen in the early development of a female foetus

A

Stimulates the formation of the external female genitalia and the development of the paramesonephric ducts

30
Q

How do the paramesonephric ducts form the uterine cavity

A

Ducts from each side fuse together
The bits that are touching (middle) will regress to form the bigger cavity
Still have an independent uterine tube coming from either side

31
Q

Describe the hymen

A

Thin tissue that closes off the vaginal opening

At birth there are little holes in the hymen and it degrades with activity

32
Q

How does the uterus connect to the vagina

A

Forms a tubercle when it meets the urogenital sinus

Starts to elongate and forms a plate with sinovaginal bulbs

33
Q

What can happen if the paramesonephric ducts don’t join properly

A

Double uterus/vagina if they completely fail to meet
Double uterus – they have come together at the bottom (one vagina) but middle of cavity hasn’t regressed so get 2 uteruses

34
Q

What is cervical atresia

A

Where the uterus and vagina are not connected

Cannot get fertilisation with cervical atresia as there is no way for sperm to meet eggs

35
Q

What causes hypospadias

A

Malfunctioning in the zipping mechanism on the ventral surface (underneath) of the penis
The urethral groove doesn’t close up properly leading to the outlet being in an abnormal place

36
Q

What is hypospadias

A

When the urethral opening lies in an abnormal position on the penis
Usually underneath (ventral surface)
Comes in various severity - on glans, shaft or even scrotum
Can be fixed surgically

37
Q

How do the external genitalia develop - prior to sex differentiation

A

The cloaca forms a general outlet
Septum (from mesenchyme) splits the cloacal area into a urogenital sinus and anorectal sinus
Separates anus from the UG system
Mesenchymal cells at the top of the urogenital sinus proliferate and form the genital tubercle

38
Q

What does the genital tubercle go on to form in males and females

A

Males - penis

Females - clitoris

39
Q

How does the penis form

A

Growth of th genital tubercle
The urethral groove starts to ‘zip up’ towards the tip of the phallus - forms the spongy urethra
should have a outlet on the glans
A circular ingrowth of ectoderm around the glans forms the foreskin

40
Q

What is meant by monozygotic twins

A

Develop from one egg and therefore will be identical

41
Q

What is meant by dizygotic twins

A

Develop from two eggs and therefore will be non-identical

42
Q

What is the most common subtype of monozygotic twins

A

Dichorionic

43
Q

What are dichorionic monozygotic twins

A

Twins which develop from the same egg but cleavage occurs before implantation
Each twin has it’s own placenta

44
Q

What are monochorionic diamniotic twins

A

Twins which develop from the same egg (monozygotic) but cleavage occurs between day 6-8
The twins share a placenta but have separate amniotic sacs

45
Q

What are monoamniotic twins

A

Twins which develop from the same egg (monozygotic) but cleavage occurs after day 8
The twins share an amniotic sac

46
Q

In the development of twins, what is the latest form of cleavage

A

Conjoined twins - separate very late

Rarest form

47
Q

List risk factors for dizygotic twins

A 
Aged 35-40,
Family history
Previous multiple birth
High BMI
Smoking
Summer and autumn conceptions.
induced ovulation and in-vitro fertilisation
race e.g. Afro-Caribbean
48
Q

Monoamniotic monozygotic twins are associated with which poor outcomes

A

ncreased spontaneous miscarriage, perinatal mortality rate
increased malformations, IUGR, prematurity
twin-to-twin transfusions: recipient is larger with polyhydramnios

Reproduction (16 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions