5.1 Getting Pregnant

Question 1

Where are Leydig cells found?

Answer 1

In interstitium of testes

Respond to LH

Question 2

Describe the epididymal maturation of sperm

Answer 2

Immobile on entry
Capable of movement and fertilisation at tail
Addition of secretory products to the surface of sperm

Question 3

What is the maturation of sperm dependent on?

Answer 3

The support of the epididymis by androgens

HPT axis

Question 4

What is semen made up of?

Answer 4

Spermatozoa and seminal plasma

Question 5

Where is seminal plasma derived from?

Answer 5

Accessory glands of the male reproductive tract

Question 6

What are the functions of semen?

Answer 6

Transport
Nutrients
Buffering capacity
Prostaglandins stimulate muscular activity in female reproductive tract

Question 7

What contributes to the seminal plasma?

Answer 7

Seminal vesicles
Prostate gland
Bulbourethral glands

Question 8

Describe what the seminal vesicles produce

Answer 8

60% of volume
Alkaline
Fructose, prostaglandins, clotting factors (semenogelin)

Question 9

Describe the secretions of the prostate gland

Answer 9

25% volume 
Milky
Slightly acidic 
Proteolytic enzymes 
Citrate, acid Phosphatase

Question 10

Describe the secretions of the bulbourethral glands

Answer 10

Small volume
Alkaline
Produces a mucus that lubricates the end of the penis and urethral lining

Question 11

What is the normal volume of ejaculate?

Answer 11

2-6ml

Question 12

What is the normal value for motility in semen analysis?

Answer 12

50% or more

Question 13

What is the value for normal morphology in semen analysis?

Answer 13

60%

Question 14

What stimulants are involved in erection?

Answer 14

Psychogenic

Tactile from sensory afferents of penis and perineum

Question 15

What efferents are involved in erection?

Answer 15

Somatic and autonomic efferents
Pelvic nerve
Pudenal nerve

Question 16

What 3 things does erection require?

Answer 16

Sinusoidal Relaxation
Arterial dilation
Venous compression

Question 17

Describe the parasympathetic innervation to the male genital system

Answer 17

Fibres - lumbar and sacral spinal Levels
Pelvic nerve and pelvic plexus
Cavernous nerve to corpora and vasculature

Question 18

Describe the neurophysiology of erection

Answer 18

Inhibition of sympathetic vasoconstrictors
Activation of PNS
Activate non adrenergic, non cholinergic autonomic nerves to arteries
Releases NITRIC OXIDE

Question 19

How is nitric oxide produced in erection?

Answer 19

Post ganglionic fibres release Ach 
Ach acts on M3 receptors on endothelial cells
Increase in intracellular calcium
Activation of nitric oxide synthase 
Increase in NO 

NO also released from nerves directly

Question 20

What is the role of nitric oxide in erection?

Answer 20

Diffuses into vascular smooth muscle

Relaxation = Vasodilation

Question 21

What are 4 causes of erectile dysfunction?

Answer 21

Psychological - descending inhibition of spinal reflexes
Tears in fibrous tissue of corpora cavernosa
Vascular
Drugs

Question 22

Define emission

Answer 22

Movement of semen into prostatic urethra

Contraction of smooth muscle in prostate, vas deferens and seminal vesicles

Question 23

Define ejaculation

Answer 23

Expulsion of semen

Question 24

What happens during ejaculation?

Answer 24

Contraction of smooth muscles of glands and ducts
Contraction of bladder internal sphincter
Rhythmic striatal muscle contractions

Question 25

Why does the bladder internal sphincter contract during ejaculation?

Answer 25

To prevent retrograde ejaculation | So sperm doesn't enter the bladder

Question 26

What innervation controls erection?

Answer 26

Parasympathetic

Question 27

What innervation control ejaculation?

Answer 27

Sympathetic

Question 28

What effect does oestrogen have on cervical mucus?

Answer 28

Thin and stretchy

Question 29

What effect does oestrogen and progesterone have on cervical mucus?

Answer 29

Thick and sticky | Forms a plug

Question 30

What happens during capacitation?

Answer 30

``` Final maturation of sperm Takes 6-8hrs Sperm membrane changes - removal of non covalent things Movement to whip like Can undergo acrosome reaction ```

Question 31

How long do spermatozoa and oocytes stay viable for?

Answer 31

Spermatozoa 48-72hrs | Oocyte 6-24hrs

Question 32

How are oocytes and sperm transported?

Answer 32

Oocyte - Beating cilia and peristalsis of uterine tubes Sperm - Own propulsion

Question 33

Where is the acrosome derived from and what does it contain?

Answer 33

Derived from golgi region of developing spermatid Contains enzymes Hyaluronidase is important as granulosa cells are held together by hyaluron

Question 34

What happens during the acrosome reaction?

Answer 34

Sperm pushes through corona radiata Binding of sperm surface receptor to ZP3 glycoprotein of zona pellucida Triggers acrosome reaction Digestion of zona pellucida

Question 35

What happens in the cortical reaction?

Answer 35

Happens once a sperm penetrates leading to fusion of plasma membranes Prevents more sperm binding Preventing polyspermy There are a series of calcium spikes Meiosis II can resume

Question 36

At which stage of development are cells totipotent?

Answer 36

Morula

Question 37

Define totipotent

Answer 37

Has the capacity to become any cell type

Question 38

Briefly describe the process of assisted reproductive technology

Answer 38

Oocyte fertilised in vitro Allowed to divide to 4 or 8 cell stage Morula transferred to uterus Remember capacitation needs to be mimicked

Question 39

What is PGD?

Answer 39

Pre-implantation Genetic Diagnosis One cell removed from morula Tested for serious heritable diseases before transfer of embryo to mother

Question 40

What does the first differentiation after fertilisation create?

Answer 40

Inner cell mass - becomes body cells | Outer cell mass - becomes placenta

Question 41

What is hatching and why must it occur?

Answer 41

When blastocyst hatches from the zona pellucida Means that the blastocyst is no longer constrained so can begin to increase in size Blastocyst can then interact with the uterine surface and implant

Question 42

What happens during implantation?

Answer 42

Outer cell mass (trophoblast) interacts with endometrium | Endometrium controls degree of invasion

Question 43

What is the trophoblast?

Answer 43

The outer cell mass

Question 44

What is ectopic implantation?

Answer 44

Implantation at sites other than the endometrium lined uterine cavity The invasion is not controlled

Question 45

What is placenta previa?

Answer 45

Implantation in lower uterine segment | Causes problems at point of delivery