Session 3- Gametogenesis/Puberty

Question 1

How many oocytes are formed from meiosis II

Answer 1

1 mature oocyte, 3 polar bodies

Question 2

How many eggs are produced in lifetime

Answer 2

400

Question 3

How many sperm a day

Answer 3

200 million

Question 4

Sources of genetic variation

Answer 4

Crossing over, random segregation, independent assortment

Question 5

Stages of sperm production

Answer 5

Spermatogonia, primary spermatocyte, secondary spermatocyte, spermatid, spermatozoa

Question 6

What is spermiogenesis

Answer 6

Spermatid - spermatozoa

Question 7

What is spermiation

Answer 7

Release of spermatids into tubule of seminiferous tubule

Question 8

What is spermatogenic cycle versus wave

Answer 8

Cycle is how long it takes for one segment of seminferous tubule to see the same stage of sperm development (16 days), wave is the distance between the same stage in a tubule

Question 9

% and purpose of each component of ejaculate

Answer 9

60% seminal vesicles- food (citrate, fructose, amino acids, PGs)
25% prostate- proteolytic enzymes and zinc (motility)
10% bulbourethral- lube and alkaline
5% sperm

Question 10

Final maturation stage of sperm?

Answer 10

Sperm capacitation in female reproductive tract, glycoproteins and cholesterol removed from sperm membrane and can now undergo acrosome reaction

Question 11

Stages of oocytes

Answer 11

Oogonia, primary oocytes, primordial follicles, primary follicles, secondary follicles (antrum), tertiary follicles (graafian)

Question 12

When does an oocyte enter meiosis I

Answer 12

Between primary oocytes and primordial follicles

Question 13

When does an oocyte enter meiosis II

Answer 13

When it’s a graafian (tertiary) follicle. Arrests at meiosis II 3 hours pre-ovulation

Question 14

When does oocyte arrest at meiosis II and when does it continue

Answer 14

Arrests 3 hours before ovulation and continues only if fertilised

Question 15

How soon will the graafian follicle degenerate if not fertilised

Answer 15

24 hours

Question 16

At what stages do oocytes undergo atresia

Answer 16

Between 4-7months gestation and again during childhood, then some primordial follicles degenerate of the 15-20 chosen for each ovulation

Question 17

What stimulates primordial follicular growth

Answer 17

FSH

Question 18

What stimulates primordial follicular maturation

Answer 18

FSH and LH

Question 19

Why is LH key for ovulation

Answer 19

Increases collegenase activity so that ovary can rupture

Question 20

What is the role of PGs in ovulation

Answer 20

Ovarian wall contractions to help oocyte leave ovary

Question 21

What is the corpus luteum made of

Answer 21

Remaining granulosa and theca interna cells

Question 22

What do the granulosa and theca interna cells become in the corpus luteum

Answer 22

Lutein cells, make oestrogen and progesterone

Question 23

How soon will the corpus lutuem die if no hCG

Answer 23

14 days

Question 24

For how long in pregnancy does the corpus luteum provide progesterone

Answer 24

4 months

Question 25

Describe egg transport

Answer 25

Fimbriae sweep over the ovary and the uterine tube contracts rhythmically

Question 26

How long will a fertilised oocyte take to reach uterus

Answer 26

3-4 days

Question 27

When does spermatogenesis and oogenesis start?

Answer 27

Sperm at puberty, oogenesis in fetus

Question 28

Location of spermatogenesis completion?

Answer 28

Testes. Although maturation continues for final stage (capacitation) in female tract

Question 29

Location of oogenesis completion?

Answer 29

Last stage in oviduct- meiosis II only completed if fertilised

Question 30

When do sperm become motile

Answer 30

In epididymis. Before then moved via sertoli cell secretions and peristaltic contractions

Question 31

Critical weight for female puberty

Answer 31

47kgs

Question 32

average age for M and F puberty

Answer 32

M 10-14, average 12.5 | F 9-13, average 11.5

Question 33

Average length of puberty in M and F

Answer 33

2.4 for F, 3.2 for M

Question 34

Height growth per year in puberty

Answer 34

9cm for F, 10.3 for M

Question 35

First sign of puberty in M and F

Answer 35

M G2 stage- testicular volume 4ml | F B2 stage- breast buds

Question 36

Word for breast buds

Answer 36

Thelarche

Question 37

Word for pubic hair beginning

Answer 37

Adrenarche

Question 38

What initiates pubic hair growth in both sexes

Answer 38

Testosterone

Question 39

What drives genital growth in males

Answer 39

Testosterone

Question 40

What is the staging scale for puberty called

Answer 40

Tanner stage

Question 41

Why are men taller than women

Answer 41

Puberty is longer

Question 42

What does puberty end with

Answer 42

Epiphyseal fusion

Question 43

What is GnRH release from the hypothalamus affected by

Answer 43

Leptin and photoperiod

Question 44

Describe GnRH release

Answer 44

Pulsatile, every 1-3hours | Sleep related GnRH increase

Question 45

At what time does oestrogen/testosterone/LH increase

Answer 45

At night

Question 46

When is testosterone highest

Answer 46

Early am

Question 47

How long before puberty can noctural GnRH pulsatility be seen

Answer 47

a few years

Question 48

Tell me about growth hormone

Answer 48

Needed for somatic growth in puberty, stimulated by GHRH from hypothalamus. Acts on liver to produce IGF-1 for bone growth, acts on lots of tissues to stimulate growth

Question 49

Targets of FSH and LH in M and F

Answer 49

M- FSH to sertoli, LH to leydig | F- FSH to granulosa, LH to theca cells

Question 50

What do sertoli and leydig cells produce

Answer 50

Leydig makes testosterone, sertoli makes inhibin

Question 51

What do granulosa and theca cells produce

Answer 51

Granulosa makes oestrogen and inhibin, theca makes androgens