ARTS repro

Question 1

the gonads are indifferent in the

Answer 1

first 5 weeks of gestational life

Question 2

phenotypic sex (external genitalia) in M vs F

Answer 2

Male
1. penis
2. scrotum
3. penile urethra

Female
1. clitoris
2. labia majora/ minora
3. lower 1/3 of vagina

Question 3

2 important facts about the Y chromosome (SRY gene)

Answer 3

1. Contains the SRY (sex region Y) gene
2. SRY gene encodes the TDF (testes determining factor), which is a nuclear transcription factor

Question 4

what is the relationship between testosterone and testes determining factor

Answer 4

SRY gene encodes for TDF
= TDF causes development of testes in embryogenesis
= testes produce testosterone

Question 5

what is the role of TDF in males (in relation to the 2 types of cells)

Answer 5

TDF produces
1. SERTOLI cells
= produce MULLERIAN inhibiting substance
= no mullerian duct development

2. LEYDIG cells
   = produce testosterone
   = development of WOLFFIAN duct
   = give rise to INTERNAL genitalia

LEYDIG CELLS
= produce testosterone
= converted to DHT via 5 alpha reductase enzyme
= give rise to EXTERNAL genitalia

Question 6

what is the significance of the lack of TDF in females? (3 roles)

Answer 6

No TDF means…
1. no MIS
= production of mullerian duct
= give rise to internal genitalia

2. estradiol production
   = give rise to external genitalia
3. no testosterone
   = no wolffian duct

Question 7

what is the internal vs external genitalia of F

Answer 7

Internal
1. uterus
2. oviduct
3. upper vagina

External
1. clitoris
2. labia majora and minora
3. lower vagina

Question 8

what is the internal vs external genitalia of M

Answer 8

Internal
1. Vas deference
2. Epididymis
3. Seminal Vesicles

External
1. Penis
2. Penile Urethra
3. SCROTUM

Question 9

function of the SERTOLI cells

Answer 9

1. provide nutrients to differentiating sperm
2. blood testes barrier
3. secrete aqueous fluid to aid transport into epididymis
4. secrete ABP (androgen binding protein) into semiferous tubule = keep testosterone levels high

Question 10

what are the 2 functions of the testes

Answer 10

1. spermatogenesis
2. testosterone secretion

Question 11

how does the testes maintain its temperature?

Answer 11

lower temperature:
countercurrent arrangement of pampiniform plexus
= facilitate heat exchange

Question 12

what is the functional unit of the testes?

Answer 12

seminiferous tubules

Question 13

what are the 4 functions of the sertoli cells?

Answer 13

1. provide nutrients to differentiating sperm
2. tight junctions between sertoli cells of seminiferous tubules = blood-testes-barrier
3. secretes aqueous testicular fluid
   = easier transportation of sperm into epidiymis
4. secrete ABP (androgen binding protein) into semiferous tubule
   = allows for transport of testosterone and maintained concentration of testosterone

Question 14

what is the importance of the blood-testes-barrier?

Answer 14

1. prevent toxins from entering seminiferous tubules
2. maintain the unique chemical composition of seminiferous tubule fluid

funfact: blood testes barrier only forms at early stages of puberty in humans

**ANY DISRUPTION TO THIS BARRIER CAN RESULT IN INFERTILITY

Question 15

what is the blood-testes-barrier made out of?

Answer 15

tight junctions of sertoli cells

Question 16

where are ABPs found and what is their function

Answer 16

ABPs circulate around the testes

function:
1. transport testosterone from seminiferous tubules and epididymis
2. bind to testosterone
= prevent premature breakdown/ metabolism of testosterone

Question 17

how is testosterone linked to the development of the internal & external male genitalia?

Answer 17

testosterone –> internal

testosterone – 5 alpha reductase –> DHT –> external

Question 18

what are the 3 stages of spermatogenesis

Answer 18

PGD

1. proliferation (spermatogonia –mitosis–> spermatocyte)
2. growth (spermatocyte –meiosis–> spermatids)
3. differentiation (spermatid –> mature sperm)

Question 19

what happens during the differentiation stage of SPERMATOgenesis

Answer 19

SPERMIOgenesis:

1. loss of cytoplasm
2. development of flagella

spermatids (haploid) –> spermatozoa/ mature sperm

Question 20

what is the route of the sperm during sexual arousal?

Answer 20

epididymis –> vas deferens –> urethra

Question 21

what nutrients does the vas deferens provide, and what is the purpose of it?

Answer 21

CITRATE AND FRUCTOSE
= nourish ejaculated sperm

1. increase sperm motility (give it energy)
2. increase sperm viability

Question 22

what is the seminal vesicle fluid rich in?

Answer 22

1. fructose
   - give sperm energy to move
2. prostaglandins
   - make cervical mucus more penetrable to sperm
   - induce peristaltic contraction in uterus and fallopian tube (allow egg to move)
3. fibrinogen
   - liquifies the semen
   = coagulating agent when semen is deposited in female reproductive tract

Question 23

what does the prostate gland add to the ejaculate?

Answer 23

adds a milky aqueous solution
- citrate
- enzymes
- calcium

Question 24

semen vs vaginal fluid alkaline or acidic?

Answer 24

semen: alkaline
vaginal fluid: acidic

= neutralises each other
= increase sperm motility

Question 25

what is capacitation?

Answer 25

penultimate step in maturation of mammilian spermatozoa - allows the sperm to penetrate the egg

cholesterol an other inhibitory substances on the head of sperm are removed by secretion from female repro tract
= sperm can release acrosomal enzymes

Question 26

what are acrosomal enzymes known as, and what is their function?

Answer 26

acrosome located in the sperm head contains proteolytic enzymes
= break down proteins at zona pellucida
= allows for sperm to penetrate the egg

Question 27

what are some of the key acrosomal enzymes?

Answer 27

1. hyaluronidase –> breaks down hyaluronic acid, which holds the zona pellucida together
2. acrosin –> serine protease enzyme that digests proteins in the zone pellucida

Question 28

where is GnRH released from?

Answer 28

hypothalamus