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Physiology of Reproduction > T3: Gamete Transport > Flashcards

T3: Gamete Transport Flashcards

1
Q

what is the overview of sperm challenges

A
  1. transport
  2. capacitation
  3. hyperactivation
  4. chemotaxis/recognition
    5.cumulus penetration
  5. sperm-zona binding
  6. acrosome reaction
  7. egg penetration
  8. fertilization
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2
Q

how long does sperm transport through bovine and oviduct take

A

4-16 hours

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3
Q

how long does it take dead/defective spermatozoa to pass through the oviduct

A

15 mins

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4
Q

what are some barriers for the sperm

A
  • vagina/cervix/uterus
    -uterotubal junction
    -isthmus/ sperm reservoir
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5
Q

what are some barriers to the oocyte

A

-follicle wall
-infundibulum
-ampulla

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6
Q

what are the semen depositions for species

A

vagina: cow, sheep, primates
cervical: mouse
intrauterine: sow, mare

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7
Q

what happens with the sperm in the cervix

A

spermatozoa migrate along the walls/ folds, not through the lumen

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8
Q

name the challenges for sperm deposition

A

-acidic PH in vagina (high lactate secretion)
-retrograde/backflow of semen
-long uterine body and horns
-leukocytic infiltration of uterus

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9
Q

what are the solutions to the challenges of semen deposition

A

-alkaline ph of seminal plasma
-cervical mucus serves as a vehicle for sperm and a filter for seminal plasma
-uterine muscle contractions increase in the late follicular phase
-timing of immune response to sperm is delayed (leukocyte infiltration occurs only after coitus)

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10
Q

what is included in immediate transport

A

-retrograde loss
-phagocytosis
-entrance into cervix/uterus

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11
Q

what is included/processes in the cervix

A

-privileged pathways
-removal of non-motile sperm
-removal of some abnormalities

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12
Q

what is included/processes in the uterus

A

-capacitation initiated
-phagocytosis

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13
Q

what is included/processes in the oviduct

A

-capacitation completed
-hyperactive motility

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14
Q

what is included/processes in fertilization

A

-acrosome reaction
-spermatozoon penetrates oocyte
-male and female pronuclei form

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15
Q

what are the two phases of sperm transport

A

rapid and sustained transport phase

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16
Q

what is included in the rapid transport phase

A

-within a few minutes sperm can be found in oviduct
-these sperm are non-viable and do not result in fertilization

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17
Q

what is included in the sustained transport phase

A

-trickle like delivery over hours
-these are the capacitated sperm that do not result in fertilization

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18
Q

what are the two types of mucous in cow

A

sialomucin: low viscosity and helps forward movement( helps create a privileged pathway: basal cells/ crypts
sulfomucin: high viscosity and washes sperm out: apical cells, cervical

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19
Q

what king of environment is important for the privileged pathway?

A

low viscosity environment in the valley of the cervix creates a “privilege pathway” for healthy spermatozoa

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20
Q

what are the challenges for the uterotubal junction/ solution

A

fold in mucosa (dead ends), viscous fluid, removal of seminal plasma, removal of defective/slow spermatozoa

solution: waves of contractions

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20
Q

what is the oviductal sperm reservoir and where is it present

A

binding of spermatozoa to oviductal epithelium in utero-tubal junction or isthmus
- present in cows, pigs, hamsters, sheep, mares

21
Q

what are the proposed functions of the oviductal sperm reservoir

A

-maintenance of spermatozoa between the onset of oestrus and ovulation
-synchronization of sperm/ egg transport in oviduct
-prevention of polyspermy
-capacitation and hyperactivation

22
Q

in cattle, earlier _____ reduces ______

A

earlier insemination reduces fertilization rates but increase embryo quality (timing difference between mating and ovulation

23
Q

describe the binding of spermatozoa to oviductal sperm reservior

A

carbohydrate recognition is the mechanism, oviductal mucosa protects spermatozoa against aging and damage

24
Q

release from the oviductal sperm reservoir

A

a change in the sperm surface, rather a change in oviductal epithelium
-only hyperactivated spermatozoa can detach

25
Q

what process is reversible and which is not

A

capacitation id not fully reversible
hyperactivation is reversible

26
Q

what is capacitation

A

set of changes in the sperm plasma membrane that enables a cell to acquire fertilizing potential/ undergo acrosome reaction

27
Q

what does capacitation require

A

requires the removal of seminal fluid (has decapacitating activity)

28
Q

how is capacitation asynchronous and continuous

A

only a percentage of spermatozoa are capacitated and those are continuously replaced

29
Q

how long does the capacitated state lasts how long

A

50-240 minutes, post capacitated cells die unless they undergo acrosome reaction

30
Q

how is capacitation initiated

A

initiated in the cervix by seminal plasma removal, completed in the isthmus during detachment from sperm reservoir by female-derived factors

31
Q

which factors during capacitation are not species specific

A

female factors

32
Q

explain the process of capacitation

A

-the plasma membrane of epididymal spermatozoa contains a complement of surface molecules (proteins and carbs) are attached to the head of the sperm (epididymal +seminal plasma)

-the surface molecules in epididymal sperm becomes coated with seminal plasma proteins that mask portions of the membrane molecules
(Ejaculated +female tract)

-When sperm are exposed to the female repro tract environment, these seminal plasma coating along with some surface molecules are removed, this exposing portions of the molecules that can bind to the zona pellucida of the oocyte
(capacitated)

33
Q

what are some of the sperm changes after capacitation

A

-cholesterol increase
-acrosome is altered
-increase in intracellular calcium and levels of PH
-tyrosine phosphorylation

34
Q

what do we need both of so that the sperm can be released from the oviductal sperm reservoir

A

both capacitation and hyperactivation

35
Q

describe the process of hyperactivation

A

-increase in the flagellar bend amplitude and asymmetry lateral head displacement (tail movement is bigger and faster)
-enhances release from sperm reservoir, progressive motility and sperm penetration of cumulus ECM
-is accompanied by calcium oscillations in sperm head and midpiece, regulated by CAMP
-reversible process

36
Q

what is the start of oocyte transport

A

capture by the infundibulum fasclitated by expanded cumulus fimbria and mesosalpinx contractions

37
Q

what is oocyte transport facilitated by

A

oviductal muscle contractions (low amplitude and high frequency during estrus)
-cilia =: FACILITATE TRASNPORT (back and forth movement)

38
Q

describe what happens when the penis becomes erect

A

when erotogenic stimuli are present the NANC neurons fire and release nitric oxide from their terminals.
-when NO is released it activates an enzyme called guanylate cyclase. This enzyme convertrs GTP to CGMP and causes the smooth muscle of the corporal sinusoids to relax (vasodilation)

the sinusoids engorge with blood and intracorporal pressures increases.

GTP–NO acting on guanylate cyclase—–cGMP sinusoid smooth muscle relaxes = erection

cGMP—-PDEs—–GMP (sildenafil blocks the action of PDE)

39
Q

describe the day length/ hormone dependence for the ovary

A

Day 1: Estrogen (LH surge)
-cilia beat moves egg to AIJ against flow of secretion
-counter current of secretion is more effective than cilia
Day 3: Progesterone
-more cilia beat
-less secretion in isthmus
-embryo should be able to pass

40
Q

how long is the embryo in the oviduct till

A

day 4

41
Q

when does the control of ovum transport start

A

occurs under estrogen dominance

42
Q

describe the control of ovum transport

A

distal isthmus and uterus are richly supplied with sympathetic nerves
-both A(stimulating) and B(inhibiting) adrenergic receptors are present

43
Q

what enhances the activity of alpha receptors

A

estrogen= contraction of the isthmus

44
Q

what enhances the activity of B receptors

A

progesterone= relaxation of the isthmus to allow embryo transport into the uterus

45
Q

what drives sperm-oocyte recognition

A

chemotaxis: sperm recognizes the egg
thermotaxis: 2 degree Celsius difference between isthmus and ampulla

46
Q

exposure to what alters sperm motility

A

cumulus cells

47
Q

when do spermatozoa acquire chemotactic responsiveness

A

during capacitation

48
Q

what is the overview of gamete transport part 1

A
  1. deposition of spermatozoa and sperm protective seminal plasma
  2. acquisition of motility and rapid swimming through cervix
  3. sperm movement through uterine cavity assisted by muscle contraction
  4. slowing of the sperm in uterotubal junction or isthmus
49
Q

what is the overview of gamete transport part 2

A
  1. binding to oviductal epithelium sperm reservoir
  2. capacitation, hyperactivation and sperm release induced by ovulation
  3. oocyte picked by cilia on fimbria, moved down ampula by cilia and contractions
  4. fertilization occurs in ampullary-isthmic junction
50
Q

what does sulfomucin corresponds to

A

high viscosity and washes sperm out
-from apical portions of cervical mucosa

51
Q

what does sialomucin corresponds to

A

low viscosity and helps movement
-inside with the basal cells/ crypts

Physiology of Reproduction (22 decks)

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