Repro Week 7

Question 1

What are the six functions of the placenta?

Answer 1

1) Transporting nutrients from maternal circulation to foetus, direct contact with the maternal blood
2) Oxygen and carbon dioxide are exchanged between the foetus and mother
3) Foetal waste is excreted into the maternal compartment
4) Making sure the fetus is not recognized as a pathogen
5) Passive immunity: transferring the mother’s antibodies to the foetus
6) Produce hormones that play an role on foetal organ development

Question 2

Describe the three phases of development in the formation of the Chorionic Villi

A) Primary stem villi
B) Secondary stem villi
C) Tertiary stem villi

Answer 2

1) Primary stem villi (11-13 days after fertilization): cytotrophoblast expands into syncytiotrophoblast
2) Secondary stem villi (16 days): extraembryonic mesoderm proliferates into projection
3) Tertiary stem villi (21 days): mesoderm differentiates into connective and blood vessels

Question 3

What are the four things separated by maternal and foetal blood?

Answer 3

1) Syncytiotrophoblast, cytotrophoblast, villus connective tissue and foetal capillary endothelium

Question 4

Differentiate between pre-implantation and post-implantation

Answer 4

1) Pre-implantation (up to blastocyst-stage)
• Uptake of nutrients from the uterus (Histotrophic nutrition)

2) Post-implantation (up to 3.2 kg foetus)
• Uptake of nutrients from the maternal blood (Haemotrophic nutrition), plugging directly into the blood supply, achieved in humans
• The haemochorial placenta allows direct contact with the blood
• Development starts at the beginning of Week 2
• After fertilization, it becomes fully functional by the end of Week 12 (nutritive, respiratory, excretory, immunological, endocrine functions are established)

Question 5

Describe the Maturation of the Placenta

a) What are the three things that the Chorion and Chorionic Villi is made up of?
b) What are the three things that the true placenta is made up of?

Answer 5

Chorion and Chorionic Villi = Extra-embryonic mesoderm + Cytotrophoblast + Syncytiotrophoblast

True Placenta = chorion and chorionic villi + maternal decidua basalis (stratum functionalis of endometrium)

 Villi become highly vascularized and project into maternal blood supply
 The maternal and foetal blood separated by syncytiotrophoblast, cytotrophoblast, villus connective tissue and foetal capillary endothelium
 Chorion in decidua capsularis compressed (discoidal haemochorial placenta)
 Placenta is fully functional by end of the week 12 after fertilization

Question 6

Name the functions of the placental hormones

A) hCG (2) 
B) oestrogen (3) 
C) relaxin (1) 
D) progesterone (3) 
E) hCS/hPL (2) 
F) hCT (1) 
G) CRH (1)

Answer 6

A) hCG: maintains corpus luetum, supresses the immune system of the mother
B) oestrogen: enlarges uterus, relax pelvic ligaments breast development
C) Relaxin: relax pelvic ligaments and pubic symphysis
D) Progesterone: maintains functional endometrium, quietens uterus, develops breast, increase respiratory tidal volume
E) hCS/hPL: inhibits glucose metabolism, increase fatty acid metabolism, breast development
F) hCT: increasing maternal metabolism
G) CRH: stimulates cortisol production through the foetal HP adrenal axis

Question 7

Describe the five anatomical changes in Pregnancy

Answer 7

• increase vascularisation of reproductive organs
• Breast Development and Milk Synthesis (Prolactin)
• Uterine Enlargement
• Relaxation and widening of the pelvis and ligaments
• Considerable weight gain (13kg)

Question 8

Describe the four metabolic changes in Pregnancy

Answer 8

• appetite increases because of cortisol
• increase in fatty acid metabolism
• There might be a 10% risk of diabetes
• hCT elevates calcium for foetal bone development

Question 9

Describes the physiological changes in Pregnancy

a) Gastrointestinal system
b) Urinary/renal system
c) Respiratory System
d) Cardiovascular System

Answer 9

Gastrointestinal system: inhibit smooth muscle contraction

Urinary/renal system: increasing frequency and urine volume

Respiratory system: greater need of oxygen

Cardiovascular system: increased blood volume and cardiac output

Question 10

Describe the function of the SRY gene

Answer 10

determines the sex and controls the maleness

The sex is determined by the sperm

Question 11

Define each:

A) Genetic sex
B) Gonadal sex
C) Phenotypic sex

Answer 11

A) XY and XX

B) testis and ovary

C) internal and external genitalia

Question 12

1) Describe the development of the Reproductive Tract

A) Gonadal ridge
B) Primordial germ cells

2) Name the order of development

Answer 12

A) Gonadal ridge:
• Precursor to the gonads
• Gives rise to the primarily reproductive system

B) Primordial germ cells
• Common origin of spermatozoa and oocytes

2) SRY —> Testis determining factor (TDF) —> Testis and Sertoli cells —> Mullerian Inhibitory Factor/ Anti-mullerian hormone (MIF/AMH) —> Leydig cells —>Testosterone

Question 13

Describe the functions of Testosterone, Dihydrotestosterone and MIF/AMH in embryo development

A) Males
B) Females

Answer 13

A) Testosterone which is released from Leydig cells (differienated by MIF/AMH), helps the epididymis to grow

Dihydrotestosterone, development of penis, scrotum, accessory sex glands

MIF/AMH is secreted from Sertoli cells and destroys the paramesonephric (Mullerian) duct

B) No Testosterone and MIF/AMH is secreted, paramesonephric forming the uterine tube