Sperm Transport and Maturation in the Female Reproductive Tract Flashcards Preview

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Flashcards in Sperm Transport and Maturation in the Female Reproductive Tract Deck (35):
1

Characteristics of the phallus in birds

1. mechanism of erection is lymphatic rather than vascular
2. semen is transfered via a groove along the outside of the phallus rather than a tube in the middle

2

What are the two types of penises in mammals?

musculocavernous
fibro-elastic

3

Describe the musculocavernous penis

-large amount of erectile tissue
-found in horse, dog, cat, and human

4

Describe the fibro-elastic penis

-fibroelastic tissue with smaller amounts of erectile tissue
-tends to have a sigmoid flexure
-found mostly in artiodactyls (ruminants, pigs)

5

What other components are found within the penis?

-paired corpora cavernosa enclosed in tunica albuginea
-os penis in some species (dogs, raccoons, seals)
-barbs on the glans in some species (rabbit, cat, ferret)
-corpus spongiosum (surrounds urethra)

6

What is the purpose of the retractor penis muscle? (not in all species)

keeping the non-erect penis within the prepuce

7

What are the 4 phases of erection?

flaccid
tumescence
stable erection
detumescence

8

Describe the flaccid state

maintained by tonic contraction of s.m. in the corpora and arteries supplying them under the influence of sympathetic adrenergic input

9

Describe erection

-psychic stimuli acting on the brain and tactile stimuli on the penis result in decreased sympathetic tone and increased parasympathetic tone causing relaxation of penile arterioles and smooth muscle of the cavernous sinuses
-NO and cGMP mediate relaxation and blood flows into the erectile corpora
-venous drainage is then compressed

10

Describe detumescence

-sympathetic tone increases and parasympathetic tone decreases
-synthesis of NO and cGMP ceases
-venous outflow is re-established and blood expelled from the cavernous sinuses returns the penis to a flaccid state

11

Ejaculation consists of what 2 components?

emission
expulsion

12

What is the function of the spinal ejaculation generator?

integrate sensory inputs from the genitalia that will trigger ejaculation with the autonomic and motor outputs required to generate the ejaculatory response

13

Where are sensory receptors located on the penis?

penile skin
glans
urethra
within the corpus cavernosum

14

What is involved in emission?

getting all the components of ejaculation into the pelvic urethra

15

What happens during emission?

1. secretion of fluids from the accessory glands
2. contraction of the cauda epididymis and vas deferens containing the sperm
3. closure of the sphincter at the bladder neck and the external urethral sphincter

16

What does parasympathetic supply stimulate in emission?

secretion of fluids by the epithelial lining of the accessory glands

17

What does sympathetic supply stimulate in emission?

-muscle contraction of the accessory glands to expel the fluid
-cauda epididymis and vas deferens to move sperm
-contracts the bladder neck and external urethral sphincters

18

What is the order of contraction of the gland systems?

bulbourethral or prostatic fraction first
sperm-rich fraction next
gland fraction last

19

What is expulsion?

rhythmic contractions of urethral smooth muscle and the striated bulbospongiosus muscle that expel semen from the urethra

20

What follows expulsion?

refractory period where sexual arousal is inhibited

21

When is sperm motility activated?

during the process of emission and ejaculation when they are mixed with the accessory sex gland fluids

(show progressive motility at this stage)

22

What is progressive motility?

when the sperm show relatively low-amplitude wave motion of the tail which gives little lateral head movement and fairly straight line motility

23

When do sperm develop hyper-activated motility?

at the time of capacitation

24

Name some factors that can influence the mechanisms and speed of sperm transport to the site of fertilization

1. species variation in size and morphology of sperm
2. duration of estrus and the timing of ovulation in relation to estrus
3. anatomical site of sperm deposition
4. the life span of sperm within the female tract

25

What are the barriers to sperm that deposit in the vagina?

-need first to negotiate the vagina then cervix and cervical mucous
-second need to get past the uterotubal junction (UTJ)

26

What are the barriers to sperm that deposit in the uterus?

only the uterotubal junction (UTJ)

27

How does rapid sperm transport occur?

-due to contractions of the female tract and changes in intraluminal pressures
-can be found in the upper oviduct within minutes of mating (non-viable sperm though)

28

What is the prolonged phase of sperm migration?

distributes competent sperm throughout the tract and it is during this phase that the fertilizing population of sperm arrive near the site they will encounter the egg

29

How do sperm transport through the cervix?

mucus prevents passage of appreciable amounts of seminal plasma into the upper tract, so the sperm swim deep into the cervical crypts of the cervical folds

30

How do sperm transport through the uterus and into the oviducts?

-uterine contractility distributes sperm throughout the uterus
-viable sperm temporarily bind to uterine epithelial cells to avoid discharge back through the cervix
-sperm accumulate at the uterine side of the UTJ and only viable sperm can move past it

31

Where does sperm storage occur?

in sperm reservoirs, usually the caudal isthmus of the oviduct

32

What is the purpose of sperm storage sites?

1. maintain sperm viability
2. serve as the site of sperm capacitation
3. synchronize final sperm maturation with ovulation
4. selection of the highest quality sperm

33

Binding of sperm to the oviduct is mediated by what?

mediated by glycans on the surface of ciliated oviductal epithelial cells that interact with surface proteins on the sperm plasma membrane

(binding prevents capacitation)

34

Name some sites of sperm selection

1. cervix
2. uterine epithelium
3. UTJ
4. oviductal sperm storage area

35

The oviductal binding site selects sperm that are what?

-not capacitated
-not acrosome reacted
-morphologically superior
-chromatin intact