Gametogenesis

Question 1

What is the default sex in gametogenesis?

Answer 1

Female.

Question 2

What is the Sry?

Answer 2

The test-determining factor.

Question 3

What happens if Sry is absent?

Answer 3

The sex is female.

Question 4

What does the Sry activate?

Answer 4

Sox9.

Question 5

What is the result of Sry being present?

Answer 5

It induces sex cords that form seminiferous tubules.

Question 6

What do seminiferous tubules contain?

Answer 6

Sertoli cells and leydig cells.

Question 7

What are sertoli cells?

Answer 7

They are cells that secrete anti-Mullerian hormone to prevent female development.

Question 8

What are leydig cells?

Answer 8

Cells that secrete testosterone to promote development of the male reproductive system.

Question 9

What is spermatogenesis?

Answer 9

The process from which haploid spermatozoa develop from germ cells in the seminiferous tubules of the testes.

Question 10

When does spermatogenesis initiate?

Answer 10

Puberty.

Question 11

When does differentiation of spermatozoa occur?

Answer 11

When the threshold of BMP8b is reached.

Question 12

What else happens in mammalian spermatogenesis?

Answer 12

There is anchoring to sertoli cells via N-cadherin.

Question 13

What is the first committed stem cell type in mammalian spermatogenesis?

Answer 13

The intermediate spermatogonia.

Question 14

What is the last mitotic division in mammalian spermatogenesis?

Answer 14

The change from type B spermatogonia to primary spermatocytes.

Question 15

What is differentiation favoured by?

Answer 15

Low concentration GDNF and high concentration SCF.

Question 16

What produces GDNF and SCF?

Answer 16

Sertoli cells.

Question 17

What happens in meiosis?

Answer 17

Secondary spermatocytes form from primary spermatocytes.

Question 18

What happens in spermiogenesis?

Answer 18

Residual bodies are formed from spermatids.

Question 19

What is spermiogenesis?

Answer 19

Post-meiotic generation of sperm.

Question 20

What happens in post-meiotic generation of sperm?

Answer 20

A round spermatid develops to a testicular sperm.

Question 21

What is the starting point of mammalian spermiogenesis?

Answer 21

It begins with a non-flaggelar haploid round spermatid.

Question 22

What happens with the golgi apparatus in spermiogenesis?

Answer 22

It forms the acrosome which covers part of the nucleus. On the basement side, the flagella sticks into the lumen.

Question 23

What are histones replaced in during spermiogenesis?

Answer 23

Protamine.

Question 24

What happens when histones are replaced with protamine?

Answer 24

There is non-nucleosomal chromatin and transcription almost completely shuts down.

Question 25

What is the structure of chromatin at the start of spermiogenesis?

Answer 25

It is nucleosomal.

Question 26

What are histones replaced with in spermatids in sperm chromatin formation?

Answer 26

Transition proteins - tnp1 and tnp2 in round spermatids.

Question 27

What is established in spermiogenesis?

Answer 27

Paternal imprints.

Question 28

What does spermiogenesis result in?

Answer 28

Non-nucleosomal chromatin.

Question 29

What happens to transcription during spermiogenesis?

Answer 29

It almost completely shuts down.

Question 30

What is significant about chromatin at the beginning of spermiogenesis?

Answer 30

It is nucleosomal.

Question 31

What are histones replaced by in spermiogenesis?

Answer 31

Transition proteins TNp1 and Tnp2 in round spermatids.

Question 32

What is the distinction between round spermatids and elongating spermatids?

Answer 32

Round spermatids contain transition proteins that have replaced histones, whereas elongating spermatids

Question 33

How long does spermatogenesis take in humans?

Answer 33

65 days.

Question 34

What happens to cells, in terms of distance from the basal lamina, during differentiation?

Answer 34

They move further away.

Question 35

What transcription factor is essential for spermatogenesis?

Answer 35

TAF4b testis-specific TBP associated transcription factor.

Question 36

What is the epididymis?

Answer 36

A duct behind the testis where sperm passes to the vas deferens.

Question 37

What needs to happen to testicular sperm?

Answer 37

As testicular sperm are not capable of fertilisation (and lack forward motility), this ability needs to be acquired during epidymidal transit.

Question 38

What happens during epididymidal transit?

Answer 38

They undergo extensive membrane changes.

Question 39

What is oogenesis?

Answer 39

Differentiation of the female gamete, the oocyte.

Question 40

What are the two types of oogenesis?

Answer 40

Continuous and finite oogenesis.

Question 41

What is continuous oogenesis?

Answer 41

Ooogenesis from self-sustaining population of mitotically dividing oogonia. It is similar to spermatogonia and occurs in fish, amphibia, sea urchins and insects.

Question 42

What is finite oogenesis?

Answer 42

When it is generated in the embryo and arrested until small numbers resume meiosis. This occurs in birds, mammals and reptiles - only a few eggs are generated until they are released or fertilised.

Question 43

Where does oogenesis occur in mammals?

Answer 43

It occurs in the ovaries and is associated with granulosa cells that become cumulus cells.

Question 44

What are granulosa cells?

Answer 44

A somatic cell of the sex cord closely associated with the developing female gamete.

Question 45

What is the purpose of granulosa cells?

Answer 45

They provide nutrition and support maturation.

Question 46

What are some of the hormones that are involved in oogenesis?

Answer 46

Follicle stimulating hormone and luteinizing hormone.

Question 47

What produces follicle stimulating hormone (FSH)?

Answer 47

The anterior pituatory gland.

Question 48

What is the purpose of follicle stimulating hormone?

Answer 48

It stimulates the growth of ovarian follicles.

Question 49

What is ovulation stimulated by?

Answer 49

A surge in leteinizing hormone.

Question 50

What is luteinizing hormone produced by?

Answer 50

The anterior pituatory gland.

Question 51

What is the structure of FSH?

Answer 51

It is an alpha/beta subunit heterodimer.

Question 52

What is the structure of leutinizing hormone?

Answer 52

It is an alpha/beta heterodimer. The alpha subunit is shared with FSH.

Question 53

What is the zona pellucida?

Answer 53

A unique glycoprotein matrix surround the oocyte.

Question 54

What happens if the zona pellucida is removed?

Answer 54

Infertility.

Question 55

What proteins is the zona pellucida made up of in humans and mice?

Answer 55

3 proteins in mice and 4 in human - ZP1, ZP2, ZP3, (ZP4).

Question 56

What are the glycoproteins linked to in the zona pellucida?

Answer 56

O and N.

Question 57

When are the zona pellucida proteins synthesised?

Answer 57

Oocyte growth phase.

Question 58

What is significant about the ZP2 in the zona pellucida?

Answer 58

It is a receptor for sperm binding.

Question 59

When is meiosis resumed in the oocyte?

Answer 59

It resumes from prophase 1 (check this ?) arrest after follicle growth, which is stimulated by FSH.

Question 60

What is GVBD?

Answer 60

Germinal vesicle breakdown.

Question 61

When does GVBD occur?

Answer 61

The end of prophase 1 - diplotene.

Question 62

What is the polar body a product of?

Answer 62

Asymmetric cytokinesis.

Question 63

When were mouse spermatids produced in vitro?

Answer 63

March 2016. They started from embryonic stem cells.

Question 64

What can spermatids produced in vitro be used for?

Answer 64

Injection into a naturally produced mii oocytes - 1.9-2.7% 2-cell embryos develop to healthy offspring.

Question 65

When were oocytes produced in vitro?

Answer 65

October 2016.

Question 66

How were oocytes produced in vitro?

Answer 66

iPS cells or ES cells.