Reproductive Biology

Question 1

What is Kleinfelter’s syndrome?

Answer 1

An individual with the sex chromosomes XXY

Question 2

What is Turner’s syndrome?

Answer 2

An individual with the sex chromosomes XO

Question 3

What is SRY and what does it do? (long explanation)

Answer 3

SRY stands for sex-determining region Y. Following fertilisation, it is active for a few hours and determines whether the foetus will become a male or female through the activation of transcription factors such as SOX9 leading to the development of the testes.

Question 4

What can inactivation or loss of SRY cause?

Answer 4

Inactivation or loss can result in a female with the XY chromosomes and a male with XX chromosomes

Question 5

During development, if SRY is absent, what happens?

Answer 5

The foetus will be female and ovarian factors will take over

Question 6

What is the average volume of semen produced and its pH?

Answer 6

2-5ml with a pH between 7.2-7.8

Question 7

What happens to sperm after deposition into the cervix?

Answer 7

It coagulates and liquefies again 30 minutes later

Question 8

How does the female’s genitalia affect the sperm?

Answer 8

Only morphologically normal sperm will be able to enter the uterus, those abnormal will be killed by the acidic conditions and macrophages present

Question 9

Prior to fertilisation, what happens to sperm? (long explanation)

Answer 9

Sperm will undergo capacitation, a cholesterol efflux with a calcium and bicarbonate influx. This causes hyperactive movement of the tail. When the sperm approaches the cumulous cells surrounding the egg, progesterone secreted from them will bind to the CatSper channels on the cell membrane of the sperm causing a further influx of calcium, causes the tail to have faster hyperactive movements (hyperactivation)

Question 10

How do the sperm break through the cumulous cells apart from capacitation and hyperactivity?

Answer 10

The spermatozoon will undergo an acrosome reaction releasing enzymes into the cumulous cells matrix, in particular, hyaluronidase, which will break down the hyaluroninan (no-sulphate GAG) embedded into the protein and carbohydrate extracellular matrix

Question 11

What unusual condition can women possess in regards to semen? and what does it do?

Answer 11

Hypersensitivity, which can cause anaphylaxis. It is IgE mediated and can cause local and systemic reactions

Question 12

How would you treat HHS?

Answer 12

Can be treated with antihistamines and steroids, as well as desensitisation

Question 13

What is Postorgasmic illness syndrome?

Answer 13

Semen allergy in men causes systemic flu-like syndrome and can last for days. Can be treated with antihistamines

Question 14

Name some constituents in the semen

Answer 14

Nitric oxide (vasodilator), dihydrotestosterone (development of scrotum), serotonin, oxytocin and prostaglandin

Question 15

GnRH stimulates the release of FSH and LH, what does this lead to in males?

Answer 15

It promotes the production of testosterone through the hypothalamic to pituitary-gonadal axis

Question 16

What converts testosterone into dihydrotestosterone?

Answer 16

5-alpha-reductase

Question 17

Explain what LH and FSH separately do for male development

Answer 17

Upon secretion, LH binds to Leydig cells, which secrete testosterone. FSH stimulates Sertoli cells to activate spermatogenesis

Question 18

GnRH stimulates the release of FSH and LH, what does this lead to in females?

Answer 18

GnRH is released every hour normal and stimulate the release of FSH and LH, which bind to produce estradiol and progesterone, which have a negative feedback loop on the secretion of more FSH and LH