Embryology

Question 1

What is the name of the protein coat that surrounds the oocyte that dissapears by blastocyst stage to allow it to penetrate the endometrial wall?

Answer 1

Zena Pellucida

Question 2

3 Components of an early blastocyst?

Answer 2

Outer layer of trophoblasts
Inner cell mass
Blastoceale - cavity

Question 3

The trophoblasts will give rise to what and secrete what after implantation?

Answer 3

Placenta, secrete HCG

Question 4

The inner cell mass will form a bilaminar disc composed of which two layers?

Answer 4

Epiblasts and hypoblasts

Question 5

What is the process which includes the differentiation of this bilaminar disc to a trilaminar disc, and when does it occur?

Answer 5

Gastrulation. Begins immediately after implantation trilaminar disc is formed by 4 weeks.

Question 6

Main steps of gastrulation?

Answer 6

Epiblasts invaginate through primitive streak
Bury into hypoblasts layer and differentiate
3rd middle layer formed –> mesoderm.
Epiblasts –> ectoderm
Hypoblasts –> endoderm.

Question 7

After gastrulation is complete what process begins?

Answer 7

Nuerolation

Question 8

In neurulation cells of the Mesoderm differentiate to form ____A____ and the Ectoderm thickens to form ___B___?

Answer 8

A. Notocord

B. Nueral plate

Question 9

How does the nueral tube form from the nural plate?

Answer 9

Nueral groove (of plate) invaginates (dives towards notocord) and then seals as a tube in mesoderm

Question 10

Ectoderm will become…?

Answer 10

Epidermis & Nervous system

Question 11

Endoderm will become?

Answer 11

Lining of - gut, RT, bladder and urethra

Question 12

Mesoderm differentiates into which 3 groups either side of notochord?

Answer 12

(from medial to lateral)
Paraxial
Intermediate
Lateral

Question 13

Visceral mesoderm laterally folds to form?

Answer 13

Gut tube

Question 14

Somatic mesoderm folds laterally and zips anterior to form?

Answer 14

Somatic body

Question 15

Space inbetween these that gives rise to pericardium, plueral cavity and peritoneal cavity is called?

Answer 15

Intra-embryonic coeleum

Question 16

Urogenital system arises from which group of mesoderm?

Answer 16

Intermediate mesoderm.

Question 17

During weeks 4-6 what migrates to teh intermediate mesoderm to start the sexual gonadal development?

Answer 17

PGCs - Primordial germ cells.

Question 18

coelemic epithelium (covers intermediate mesoderm) thickens and gives rise to?

Answer 18

genital ridges

Question 19

Which cells are formed during proliferation of coelomic epithelium which surround primordial germ cells?

Answer 19

Somatic support cells.

Question 20

The ambisexual phase gives rise to the development of which two ducts?

Answer 20

Wollfian duct & Mullerian.

Question 21

Where do these ducts connect?

Answer 21

Posterior abdominal wall

Question 22

Sexual differentiation occurs from which week onwards?

Answer 22

Week 7

Question 23

Which part of the Y chromosome is sex defining?

Answer 23

SRY region. –> male development.

Question 24

The PGCs mirgrate to intermnediate mesoderm and become enveloped in somatic supporting cells with proliferating epithelium around it this is now referred to as?

Answer 24

Primitive sex cords. - become either testis cords or cortical cords in female.

Question 25

In males somatic support cells develop into?

Answer 25

Sertoli cells

Question 26

what connects the mesonephric tubules to the testis cords?

Answer 26

Rete testis

Question 27

what is the name given to the thickened layer of connective tissue that forms between the coelomic epithelium and the testis cords (white coat over testes)?

Answer 27

Tunica albuginae

Question 28

what 2 things occur as a result of the sertoli cells that ensure internal MALE genital tract develops?

Answer 28

1. AMH produced --> degeneration of mullerian (female duct) | 2. Stimulation of leydig cell formation. Leydig cells secrete testosterone.

Question 29

How will those with persistant mullerian duct syndrome present?

Answer 29

Internal genital tract develops femal - Uterus, vagina and uterine tubes. Testes in ovarian location Male external genitalia

Question 30

What hormone must be secreted for A) internal male genitalia B) external male genitalia ???

Answer 30

A) AMH | B) DHT

Question 31

Testosterone acts on mesonephric (wollfian duct )to form which 3 structures? /

Answer 31

- Epididymis - Vas deferans - seminal vesicles

Question 32

Testes develop at which thoracic level?

Answer 32

10th

Question 33

Muscle layer which doesnt contribute to spermatic cord?

Answer 33

transverse abdominus.

Question 34

Name given to undescended testes?

Answer 34

cryptorchidism

Question 35

Which 3 accessory glands arise near junction of wollfian duct and urethra?

Answer 35

- Prostate Bulbourethral Seminal Vesicle

Question 36

Female development occurs in the absence of ?

Answer 36

SRY transcription factor

Question 37

In female development somatic support cells differentiate into?

Answer 37

Granulosa cells.

Question 38

Granulosa cells secrete oestrogen which stimulates devlepment of mullerian ducts into ?

Answer 38

Uterine tubes Uterus Superior vagina

Question 39

3 parts of mullerian duct?

Answer 39

- Cranial - Caudal - Horizontal

Question 40

which portion of the mullerian duct opens into developing peritoneal cavity?

Answer 40

Cranial

Question 41

What is hypospadius?

Answer 41

External urethral opening lies abnormally along ventral aspect of penis.