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Flashcards in Reproductive Embryology Deck (51)
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1

Give a brief summary of development from 1-9 weeks

Week 1 and 2 - implantation and cell proliferation

Week 3 - gastrulation, neuralation and somite formation

Week 4-8 - organogenesis

Week 9 onwards - maturation of organ systems

2

How is reproductive organogenesis different fro normal embryology?

It extends beyond 8 weeks and even the post-natal period

3

Urinary recap:

What three sets of kidneys form during foetal development?

Pronephros

Mesonephros

Metanephros

4

Urinary recap:

Describe the location of each sets of kidneys and their functionality during development

Pronephros - cervical region - vestigial (not functional)

Mesonephros - thoracic-lumbar region - briefly functional

Metanephros - pelvic region (functional)

5

Urinary recap:

What is the predecessor structure to the metanephros?

Ureteric bud

6

What is the cloaca?

The terminal part of the foetal gut tube

7

The cloaca divides to outline what two cavities

Anteriorly: urogenital sinus

Posteriorly: rectum

8

Where does the cloaca drain?

Maternal systemic circulation

9

What duct drains into the urogenital sinus?

Mesonephric duct

10

What week does genital development begin?

5th-6th

11

What happens to the mesonephros to kick off genital development?

Long ovoid structure (mesonephric ridge develops) - the medial part of this becomes thickened into the genital/gonadal ridge

12

Describe the epithelium of the gonadal ridge; what structure does it form

Formed from intermediate mesoderm and forms the primary sex cords

13

What type of cells migrate into genital ridge to form the indifferent gonad?

Germ cells from the yolk sac (itself formed from outer lining of the blastocyst and therefore undifferentiated)

14

The epithelium of what structure invaginate to form a tube?

Mesonephros

15

What structure is formed from the invagination of the mesonephric duct?

Paramesonephric duct

16

What are the alternative names for the paramesonephric and mesonephric ducts?

PMN duct = Mullerian duct

MN duct = Wolffian duct

17

The PMN duct develops on what side of the gonads/MN duct

Lateral

18

The funnel shaped cranial end of the PMN duct opens into what cavity?

Peritoneal cavity

19

The PMN duct crosses the MN duct on what side and drains into the dorsal wall of what cavity?

Ventrally crosses the MN ducts and projects into the urogenital sinus

20

In males the gonads form what?

Testes

21

In males, what are the fates of the MN duct, PMN ducts and urogenital sinus

MN duct - epididymus, vas deferens and seminal vesicles

PMN duct - degenerates

Urogenital sinus - bladder, urethra and prostate

22

In females what do the gonads form?

Ovaries

23

In famles, what are the fates of the MN duct, PMN duct and the urogenital sinus?

MN duct - degenerates

PMN duct - fallopian tubes, uterus, cervix

Urogenital sinus - bladder and lower vagina

24

OSPE help:

If there is a pin in the interstitium of the testes, what is the answer?

Leydig cells (testosterone producing)

25

How does the indifferent gonad know to develop into testes?

Y chromosome SRY codes for TDF (testis determining factor)

26

What other sex determining functions does SRY code for?

Primordial supporting cells express SRY

Transforms them into Sertoli cells

S cells secrete MIS (Mullerian-inhibiting-substance) - further develops male genitalia

27

What are the functions of MIS?

Cause PMN duct to degenerate and transforms mesenchymal cells between sex cords into Leydig cells

28

What gestational week are gonads differentiated in the male foetus?

7th week

29

What is the action of TDF?

Stimulates primary sex cords which extend into the medulla and form seminiferous tubules branching into the rete testes

30

What are the rete testes?

The rete testis is an anastomosing network of delicate tubules located in the hilum of the testicle

31

Describe the change of epithelium in the developing testis

Surface epithelium (mesothelium) is lost when thick capsule forms (tunica albuginea)

32

What are the three male sex glands?

Seminal vesicles, prostate, external male genitalia

33

How are seminal vesicles formed?

Outgrowth from caudal end of the MN duct

34

How is the prostate formed?

Outgrowths from urethra from urogenital sinus

35

What substance causes the external male genitalia to be developed?

Formed under the influence of testosterone

36

How does female gonadal development differential from male development?

No Y chromosome, no SRY region therefore no TDF and gonads develop into ovaries

37

What are the two distinct phases of development of the ovaries?

Pre-natal and Pubertal

38

Outline the pre-natal ovaries development

Primary sex cords degenerate and primary germ cells remain

Secondary sex cords develop and are incorporated around the germ cells


Meiosis is arrested and waits for puberty

39

Approx how many follicles is a woman born with?

Approx. 2 million

40

What is the fate of many of a woman follicles before puberty?

Many become atretic

41

After puberty, what happens to these follicles?

Hormonal influences causes maturation of 12-15 of these follicles per 28 day cycle

42

How many of the stimulated follicles are ovulated?

One (normally)

43

Outline the development of the tubular components to the female reproductive system

Absence of testosterone causes degeneration fo MN and MN duct

PMN duct develop into female genital tract

44

What is the fate of the cranial end of the PMN duct?

Open funnel end becomes associated with the ovary

45

What is the fate of the caudal end of the PMN duct?

Otherwise known as the uterovaginal primoridium, becomes the uterus and superior part of the vagina

46

Outline the descent of the testes

Week 7 - T10 (diaphragm undescended)

Week 12 - level of deep inguinal ring (remains until 7th month)

Enters scrotum just prior to birth (39 weeks)

47

Outline the descent of the ovaries

Week 7 - T10

Week 12 - Broad ligament forms

Round ligament drawn through inguinal canal to attach to the labrum majorum

48

What is cryptorchidism?

Absence of testis in the scrotum

49

What are the causes of cryptorchidism?

1. Undescended
2. Ectopic
3. Retractile testes
4. Absent testes

50

What are the complications of cryptorchidism?

1. Infertility
2. Malignant transformation (germ cell tumours)
3. Testicular torsion

51

List some anomalies of the female reproductive tract

1. Complete duplication
2. Septate uterus
3. Bicornuate uterus
4. Arcurate uterus