Spermatogenesis, oogenesis & fertilisation

Question 1

What are the testes

Answer 1

Male reproductive glands, suspended in the scrotum
Size- 4.5 cm x 2.5cm x 3cm
3 layers

Question 2

What is the tunica vaginalis in the testes

Answer 2

Outer covering of membrane formed from peritoneum

Question 3

What is the tunica albuginea of the testes

Answer 3

Fibrous covering, forms septa which divides testes into lobes

Question 4

What is tunica vasculosa of the testes

Answer 4

Network of capillaries

Question 5

What are the internal structures of the testis

Answer 5

Seminiferous tubules, leydig cells, epididymis and vascular deferens

Question 6

What are the seminiferous tubules of testis

Answer 6

Convoluted loops of germinal epithelium, produce spermatozoa

Question 7

What is leydig cells of the testis

Answer 7

Lie between seminiferous tubules, produce testosterone after puberty

Question 8

What is epididymis of the testis

Answer 8

Single highly convoluted tubule forming a mass at upper pole of testis - 6cm long

Question 9

What is a vas deferens of the testis

Answer 9

Duct formed from epididymis as it leaves the scrotum

Question 10

What is spermatic cord of the testis

Answer 10

Suspend testes in scrotum contains vas deferens, blood, lymph vessels and nerves

Question 11

What is the blood supply to testis

Answer 11

Testicular arteries and veins

Question 12

What is the nerve supply to testis

Answer 12

Branch of 10th/11th thoracic nerve- ilioinguinal nerve

Question 13

What are seminal vesicles

Answer 13

2 fibromuscular pouches, 5cm long
Lie at posterior base of the bladder
Join vas deferens by small duct to form ejaculatory duct which then joins urethra
Secrete seminal fluid ( alkaline)
Neutralises acidic environment of female reproductive tract of intercourse
Provide energy for sperm and assists coagulation of semen after intercourse

Question 14

What is the prostate

Answer 14

Doughnut shaped gland - 4cm x 3cm x 2cm
Inferior to bladder and surrounds urethra

Question 15

What is the function of the prostate

Answer 15

Produces milky coloured prostatic fluid composing 30% of volume of semen
Slightly acidic nature helps semen coagulate after intercourse then breaks down this clot

Question 16

What are the bulbourethral glands associated with the prostate

Answer 16

Pea sized glands inferior to prostate alkaline fluid to protect sperm and secrete mucus to lubricate penis prior to intercourse

Question 17

What is the penis

Answer 17

External male sex organ
Passage for ejaculation of semen and excretion of urine
Root and body- root in perineum- body surrounds urethra
Composed of 3 columns of erectile tissue

Question 18

What is the corpora cavernosa

Answer 18

2 lateral columns

Question 19

What is the corpus spongiosum

Answer 19

Midventral column containing urethra

Question 20

What is a glans penis

Answer 20

Expanded triangular distal end covered with retractable foreskin- prepuce

Question 21

What two ligaments support penis

Answer 21

Fundiform and supensory ligaments

Question 22

What is the blood supply to penis

Answer 22

Branches of internal pudendal arteries and veins

Question 23

What is the nerve supply to penis

Answer 23

Autonomic and somatic nerves

Question 24

What is erection of sexual inercourse

Answer 24

Caused by parasympathetic stimulus resulting in massive increase of blood to fill the corpus cavernosa and corpus spongiosum

Question 25

What is ejaculation in sexual intercourse

Answer 25

Sympathetic reflex, bladder sphincter closes, peristaltic action of vas deferens, seminal vesicle, ejaculatory ducts and prostate propel semen into the penile urethra Has two phases

Question 26

What happens in 1st phase in ejaculation

Answer 26

The vas deferens contract to squeeze the sperm toward the base of the penis and the prostate gland and seminal vesicles release secretions to make semen

Question 27

What happens in. 2nd phase of ejaculation

Answer 27

Muscles at the base of the penis contract every 0.8 seconds and force the semen out of the penis in up to 5 spurts

Question 28

What is male puberty

Answer 28

Average onset age - 12/13 yrs Influenced mainly by body mass Triggered by gonadotrophin releasing hormone (GnRH) from hypothalamus stimulating release of FSH and LH Causes considerable body change LH from anterior pituitary gland stimulates production of testosterone from the interstitial cells in the testes, which stimulates the development of secondary sexual characteristics

Question 29

What are the secondary sex characteristics of male puberty

Answer 29

Growth of muscle and bone Increase in height and weight Growth of hair on the face,axillae,chest,abdomen and pubis Enlargement of the penis,scrotum and prostate gland Maturation of seminiferous tubules and production of spermatozoa Thickening of skin, becomes oilier

Question 30

What is spermatogenesis

Answer 30

Process of the formation of male gametes in the testes In early foetal development primordial germ cells differentiate into spermatogonia Spermatogonia remains dormant until puberty Males will develop approx 500 billion sperm in their lifetime with up to 1 billion shed a month

Question 31

What is spermatozoa

Answer 31

Produced by spermatogenesis in the seminiferous tubules of the testes and mature as they pass through the long and convoluted epididymis where they are stored FSH can stimulate sperm production

Question 32

What does a mature spermatozoon have

Answer 32

Has a head, a body and a long whip-like tail used for mobility Head - almost completely filled by nucleus which contains DNA, as contains enzymes required to penetrate outer layers of the ovum to reach and fuse with nucleus Body- packed with mitochondria to fuel the propelling action of the tail that powers it along

Question 33

Explain the head of the sperm

Answer 33

Acrosome- contains enzymes required for penetration of oocyte Nucleus- contains chromosomes

Question 34

Explain midpiece of the sperm

Answer 34

Contains mitochondria which supply energy to the sperm

Question 35

Explain the tail of the sperm

Answer 35

Flagellum to transport sperm

Question 36

What is the 1st stage of spermatogenesis

Answer 36

Differentiation - primordial germ cell to spermatogonium Mitosis- spermatogonium to primary spermatocytes

Question 37

What is 2nd stage of spermatogenesis

Answer 37

Meiosis 1 - primary spermatocyte to secondary spermatocytes Meiosis 2 - secondary spermatocytes to spermatids Spermiogenesis - spermatids to spermatozoa

Question 38

What are the stages of fertilisation

Answer 38

1) sperm deposition 2) capacitation 3) penetration of corona radiata- granules a cells, occurs by acrosome reaction 4) penetration of zona pellucida- glycoprotein layer between corona radiata and oocyte membrane 5) fusion of sperm cell membrane with oocyte cell membrane 6) oocyte competes meiosis 2 ( becomes ovum) 7) gamete fusion ( becomes zygote)