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Flashcards in Reproduction Deck (60):
1

3 reasons for the 2 sexes

Resource allocation- one gamete instead of 2
Sexual differentiation- avoids over population + physiologically ready
Evolutionary advantage to grandmothers
Reproductivity ends when menopause and a dropsies

2

2 ways animals determine sex
Chromosome combinations
The Y chromosome purpose
How the female X is removed
3 diseases of the chromosomes

Temperatures (turtles) and genic mechanisms (ants)
Chromosomes- XX and XY, ZW and ZZ
The SRY gene on the Y chromosome
One X chromosome in each cell Inactivates and condenses into a clump of nuclear chromatin known as a Barr body. All cells of one tissue have same X.
Klinefelter (XXY) turners (XO) and XYY syndrome

3

3 advantages of sex
3 disadvantages of sex

Accelerates evolution
Reshuffles the genetic composition
Leads to sexual dimorphism

Costly
Time consuming
Expends energy

4

4 key points of Wolfian ducts

Only develops in males
Derived from the embryonic kidney
Becomes epididymis, vas deferens, seminal vesicle
Medulla differentiates into testis

5

3 key points of Müllerian ducts

Develops in females
Becomes Fallopian tube, uterus, cervix and upper vagina
Cortex differentiates into ovarian tissue

6

The 12 stages of embryo development

.

7

What is the purpose of the SRY gene- 4 points

Produces TDF
Binds to DNA
Activates SOX9, WT1, SF1
Protein products then cause medulla to differentiate into testis

8

Purpose of Leydig cells
3 points
1 extra reading point

Produce testosterone and dihydroxytestosterone
Testosterone --> Wolfian duct into accessory structures
DHT --> male genetalia

5a-reductase gene mutation stops conversion of testosterone to DHT. Male genitalia fail to develop.

9

2 points of Sertoli cell hormone release

Secrete anti mullerian hormone
Cause regression of the Müllerian duct

10

GnRH release 4 points

Released by the hypothalamus, gonadotrophin releasing hormone
Causes the anterior pituitary to release FSH and LH
Released 1-3hrs, around 90 minutes
Steady high levels down regulate receptors on the pituitary and will decrease FSH and LH, so pulses are used

11

How does LH act

Causes endocrine cells to secrete steroid and peptide hormones

12

How does FSH act

Combines with sex hormones
Gamete production

13

What do inhibins do?

Inhibit FSH secretion, stop gamete production

14

What do activins do
3 things that activins promote

Stimulate FSH release
Promote spermatogenesis, oocyte maturation, embryonic nervous system development

15

The long and short feedback loop for LH and FSH 4 points

Once certain oestrogen and progesterone reached, negative feedback inhibitis gonadotrophin release
As androgen levels rise, LH and FSH lowers
Rises in oestrogen promote feedback, low levels negative

16

Structure of the testis
6 points

Spermatogonia found on basal membrane of seminiferous tubules
Primary spermatocyte
Secondary spermatocyte
Leydig cells in interstitial
Sertoli cells stretch from basal membrane to the lumen of tubule
Sertoli cells joined by tight junctions, forming the blood testis barrier

17

Penis structure
3 points

Epididymis -> Vans deferens connect to urethra
Urethra runs through column of corpus spongiosum
This is surrounded by corpus cavernosa

18

Male gametogenesis
4 points

At birth the testes contain immature germ cells
At puberty mitosis resumes and some spermatogonia turn into primary spermatocytes
Primary -> 2 secondary -> 4 spermatids
Development moves towards the lumen

19

Sperm structure
4 points

Spermatids embedded in apical membrane of Sertoli until transformation
Mitochondria in mid piece
Microtubules in tail
Nucleus condenses by replacement of Histones with protomenes

20

Purpose of Sertoli cells
3 points

Regulate sperm development
Secrete activin and inhibin, and ABP
ABP binds to testosterone and makes it less lipophillic

21

How does FSH target Sertoli cells
3 points

Male germ cells don't have FSH receptors
Stimulates paracrine factors for mitosis of spermatogonia
Stimulates ABP production

22

How does LH target the leydig cells

Produce testosterone
Testosterone then inhibits LH

23

Purpose of the male accessory glands
3 points

Found in the male reproductive tract
Secrete fluid mixtures that mix with sperm on ejacultion (glucose etc.)
Help protect against infection 'flushing'

24

Male primary characteristics 2
Male secondary characteristics 5

Internal sex organs, external genitalia
Body shape, hair, muscles, vocal chords thicken, libido

25

Capacitation

Glycoproteins layer removed
Acrosome can be used
Takes place in reproduction tract
Done artificially in IVF

26

Fertilisation 5 points

12-24 hours after ovulation
Distal part of Fallopian tube
Acrosome released
Membrane fusion (prevents polyspermy, cortical reaction)
Resumes female meiosis

27

Causes of male infertility
Pre and post testicular

Obesity, drugs alcohol
Duct obstruction, impotence, infection, fibrosis

28

The ovary
5

Oogonia complete mitosis by 5th month of feral development
Each ovary contains 50,000 at birth primary ooycytes
Meiosis resumes at puberty- primary -> secondary and polar body
Second division at fertilisation
2-4cm, small central medulla of blood vessels

29

Oocyte structure
3

Each contained in a primary follicle
Outer layer of granulosa cells
Develops outer layer of cells known as the theca

30

Ovarian cycle
3

Follicular phase (10-21 days)
Ovulation
Luteal phase

31

Uterine cycle

Menses
Proliferation phase- thickening of endometrium
Secrretory phase - thickened endometrium converts to a secretory structure. Corresponds to luteal phase.

32

Early follicular phase
6

FSH acts on granulosa cells -> Oestrogens. Secrete enzymes and hormones into Antrum to promote ovulation
LH -> thecal cells -> synthesise androgens for granulosa cells
Aromatose converts androgens -> oestrogen
One dominant follicle is ovulated
Oestrogen negative feedback to prevent more ovulation
Stops FSH and LH
Menstruation ends, endometrium grows

33

Late follicular phase
6

Granulosa cells secrete
Inhibins
Progesterone
Oestrogen switches to positive feedback
Large LH surge, low FSH surge
Polar body appears, meiosis resumed
High oestrogen to prepare for pregnancy
Stringy mucus to facilitate sperm entry

34

Ovulation
4

16-24hrs after LH peak
Mature follicle secretes collagenase- holds follicle cells together
Antral fluid and egg
Egg swept into Fallopian tube

35

Early to mid luteal
4

Corpus luteum increasing progesterone and oestrogen
Negative feedback on pituitary
Endometrium- glands coil, more blood vessels, more lipids and glycogen
Basal body temp increases 0.3-0.5

36

Late luteal phase and menstruation

Corpus luteum lasts 12 days -> apoptosis
Corpus albicans
Stops negative feedback
Blood vessels contract, menstruation (during follicular phase)

37

Female infertility
6

Age smoking STIs obesity chemotherapy genetic factors

38

4 stages of human sexual response

Excitement- penile and clitoral erection
Plateau- intensification
Orgasm- muscular contraction, increased BP, ejaculation
Resolution- return to normal

39

Erection
7

controlled by higher brain centres
Triggered by mechanireceptors
Sensory -> spinal integration centre
Inhibits vasoconstriction
Increases parasympathetic via nitric oxide
Engorgement of corpus cavernosum
REM sleep

40

Emission
3

Sperm from vas deferens into urethra
Joined by secretions from accessory glands
10ml sperm

41

Ejaculation
3

Semen expelled from urethra
Muscular contractions
Sphincter at base of the bladder contracts

42

Impotence
3

Erectile dysfunction
Physiological / psychological
Postage stamp test during REM sleep

43

Chemical reaction behind vasodilation and erection
4

Neurotransmitters from pelvic nerves
Increases nitric oxide
Activates guanylyl cyclase
cGMP causes vasodilstion

44

Viagra
5

Approved in 1998
Blocks enzyme degrading cGMP
prolongs effect of nitric oxide
Effective in 82%
Most effective 1 hour after

45

Contraceptives

Abstinence, Barrier, sterilisation
IUD, morning after pill
Progesterone and oestrogen pill, inhibits gonadotrophin release
Suppress LH and FSH and therefore ovulation
GnRh agonists

46

Implantation
7

Outer trophectoderm becomes chorion, develops to placenta
Trophectoderm cells secrete enzymes to encase endometrium
Chorionic villi penetrate uterus

Inner cell mass to foetus proper
Amnion -> amniotic fluid
Allantois -> umbilical cord
Yolk sac

47

Hormonal secretions of placenta- human chorionic gonadotropin

Keeps corpus luteum active
Binds to LH receptors
Progesterone still produced
Corpus luteum degrades at 7 weeks
Stimulates testosterone in male foetus

48

Hormonal secretions of placenta- human placental lactogen

Alteration of glucose and fatty acids to support growth

49

Hormonal secretions of placenta- oestrogen and progesterone

Corpus luteum then placenta
Prevents more follicles
O-> milk secreting ducts
P-> maintains endometrium

50

Parturition

Trigger of oxytocin/ corticotrophin releasing hormone (muscle contraction)
Relaxin softens cervix and ligaments holding pelvis bones
Cervical stretch -> uterine contractions
Reinforced by oxytocin secretion
Prostaglandins from oxytocin

51

Mammary glands/ lactation
5

Develop during puberty and pregnancy by oestrogen
Progesterone- -> secretory structure
O and P inhibit milk production
Milk controlled by prolactin and prolactin inhibiting hormone
High PIH, O and P -> colostrum

52

Menopause
5

Ovaries stop responding to gonadotrophin
Gonadotrophin increases, no negative feedback
No oestrogen
HRT
Selective oestrogen receptor modulators

53

Infertility investigations

Semen analysis, pelvic ultrasound, hormone tests, karyotyping

54

Male diagnosis of infertility

Low sperm count
Morphology/viscosity
Chromosomal
Hormonal
Sexual dysfunction

55

Female diagnosis of infertility

Poly unstick ovaries
Too much prolactin
Pelvic inflammatory disease
Endometriosis
Hormonal

56

Male fertility treatment

Donor sperm
IUI, IVF, ICSI
PESA MESA TESE
PGD

57

Female fertility treatment

Donor eggs
Ovulation induction
Timed sex
IUI
IVF
PGD

58

Regulations for donors

18-35
Fit and healthy
Understand implications
Men- 12 month commitment

59

Super ovulation

Used with IUI
Clomiophene or tamoxifen
Timed hormone injections
Aspiration under ultrasound
Insemination 4-5 hours after

60

Embryo grading

Graded on day 4 when morula is formed
Assisted hatching from zone pellucida
Can be screened with
FISH- chromome disorders and sexing
PCR- single gene disorders