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Gametes & Embryos > Sperm Transport & Capacitation > Flashcards

Sperm Transport & Capacitation Flashcards

1
Q

From what structure does the epididymis develop?

A

An enlarged Wolffian duct which was reorganized into vas efferent, epididymis, and the vas deferens

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2
Q

What is the length of the uncoiled tubes of the epididymis?

A

23 feet

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3
Q

What lines the tubules of the epididymis?

A

Stereociliated columnar epithelium

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4
Q

What are the two types of epithelium in the epididymis?

A
  1. Principle cells with ciliated absorptive/secretory surface
  2. Basal cells (close to lumen and have clear cytoplasm usually)
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5
Q

The function and maintenance of the epididymis epithelium is dependent on what hormone?

A

Testosterone

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6
Q

What are the three anatomical areas the epididymis is divided into?

A
  1. Caput (Head)
  2. Corpus (Body)
  3. Cauda (Tail)
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7
Q

What is the vas efferentia

A

Small ducts that carry semen from the testis to the epididymis

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8
Q

Where is the epididymis found?

A

Posterior to each testes

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9
Q

From the epididymis where do spermatozoa g?

A

Vas deferens

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10
Q

Connective tissue between the epididymis and testes is called..?

A

Tunica albuginea

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11
Q

What are two functions of the epididymis?

A
  1. Secrete spermatozoa (pass on to vas deferens by contracting smooth muscle around testes and fluid pressure build-up)
  2. To secrete energy and protective coating around spermatozoa
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12
Q

What are three ways in which the epididymis provides a nutritional and protective coating for spermatozoa?

A
  1. Converting testosterone into DHT (potent form)
  2. Secreting glycerolphosphorocholine (which will feed spermatozoa in female tract)
  3. Producing sialic acid (part of the mucupolysach. coating on sperm)
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13
Q

Can sperm produce its own protein?

A

No

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14
Q

Can fertilization via ICSI be affected using sperm from the epididymis?

A

Yes because of in vitro capacitation

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15
Q

What are the three male accessory sex glands?

A
  1. Seminal Vesicles
  2. Prostate
  3. Bulbourethral (Cowper’s) glands
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16
Q

What is the function of the seminal vesicles?

A

Produces nourishment and protection for sperm (fructose, prostaglandins, and clotting proteins) and makes up ~60% of semen

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17
Q

What is the function of the prostate gland?

A

Produces substances to aid in sperm motility (citric acid, acid phosphatase, and protein-digesting enzymes) and makes up ~25% of semen

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18
Q

What is the function of the bulbourethral glands?

A

Lubricates the end of the penis with mucus and also secretes an alkaline substance to neutralize any urine acidity remaining in the urethral tract

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19
Q

What is semen made of?

A
  1. sperm
  2. Sertoli cell secretions
  3. Accessory gland secretions
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20
Q

Volume of typical semen ejaculation is..?

A

2.5-5mL

21
Q

What happens to spermatozoa upon ejaculation?

A
  1. Moves from epididymis –> vas deferens –> urethra via muscle contractions
  2. Deposited through vagina –> cervix –> uterus –> utero-tubule junction –> Fallopian tubes for fertilization
22
Q

Is the transport of spermatozoa the same for all species?

A

No, in rabbits sperm passes through external OS (wtf is that) —> endocervical canal and in dogs, pigs, horses, and rodents, it goes directly to the uterus

23
Q

How long can sperm survive in the vagina?

A

~ 6 hours (unless it’s during an infertile time, where it will only survive ~1 hr due to antibacterial acidity of vaginal secretions)

24
Q

How long does it take for sperm to make it through the female tract?

A
  1. 6-12 hours = cervix, uterus
  2. 18-24 hours = isthmic sperm reservoir
  3. At ovulation = moves up isthmic sperm reservoir
25
Q

How many sperm is deposited in the female tract on average and how many make it to the Fallopian tubes?

A

10^7 vs. 100-200 sperm

26
Q

In IVF how many mL of medium is there and how many sperm in medium?

A

10^5 - 10^6 with 5% being sperm?

27
Q

What are the six causes for sperm loss in the female tract?

A
  1. Retrograde flow
  2. Phagocytosis from neutrophils (stimulated by insemination)
  3. Loss from vagina
  4. Holding in storage sites (cervical crypts, oviducts)
  5. Binding to epithelium (endosalpinx)
  6. Loss of motility
28
Q

What does the cervix secrete to help sperm survive and reach the ovum?

A

Water, proteins, lipids, enzymes, salts in a mucus

29
Q

Why (3 reasons) are cervix secretions important for fertilization success?

A
  1. Gives them energy for transport
  2. Protects against vaginal environment and phagocytes
  3. May possibly help capacitate sperm
30
Q

How long can sperm survive in the Fallopian tubes?

A

Usually 3-4 days but up to 7

31
Q

During what phases in the female cycle are sperm likely to be blocked?

A

luteal phase and pregnancy (high progesterone = viscous mucus which blocks sperm)

32
Q

Pregnancy will typically not occur more than how many days pre- or post-ovulation?

A

6

33
Q

What two types of changes occur to immature sperm after ejaculation?

A
  1. Hyperactivation (physiological changes affecting its ability to bind to zone pellucida)
  2. Acrosome reaction (morphological changes that prepare it to penetrate the oocyte)
34
Q

What are the 8 molecular factors of mammalian sperm capacitation?

A
  1. Loss of membrane cholesterole
  2. Less zinc in membrane
  3. Increased membrane fluidity (b/c of 1&2)
  4. Increased intracellular pH
  5. Increased cytoplasm Ca2+ and ATP
  6. Protein/carb surface removed for sperm binding
  7. Plasma membrane becomes more (-) charged
  8. Surface protein phosphorylation
35
Q

What does GAG (glycosaminoglycan) do for sperm capacitation?

A

phosphorylates sperm surface proteins using tyrosine kinase and cAMP

36
Q

Once hyperactivation is expressed in sperm, how does the motility of sperm change?

A

Increase in cAMP = increase in power output of flagellum = increased motility (no physical changes occur)

37
Q

What culture conditions are required for sperm capacitation in vitro for mammals?

A
  1. Albumin
  2. Glucose for humans and hamsters, not bulls or guinea pigs
  3. Caffeine helps with monkeys
  4. Epinephrine helps with hamsters
38
Q

How do culture media conditions help capacitation of sperm ex vivo?

A
  1. Promote tyrosine phosphorylation of proteins with molecular weights of 40kD to 120kD
  2. This phosphorylation depends on serum albumin (BSA), Ca2+ and sodium bicarbonate
  3. They think BSA helps remove cholesterol from sperm plasma membranes in vitro
39
Q

How long does it take for capacitation to occur?

A

It varies but less than 30min in mice and a few hours for primates.

40
Q

Why is cholesterol removal important from sperm membranes?

A

intracellular signalling

41
Q

Why is Ca2+ and sodium bicarbonate movement during capacitation important?

A

regulates sperm cAMP metabolism

42
Q

Capacitation affects the polarization of the plasma membrane by…

A

Increasing polarity of charges (hyper polarization)

43
Q

How do sperm find the egg?

A

Chemotaxis (egg releases pheromones and this results in a chemical stimulant gradient that the sperm move towards)

44
Q

What happens during the FINAL phase of sperm migration (to contact the cumulus oocyte complex)?

A

Self propulsion

45
Q

How do sperm behave within the ovulating and non-ovulating fallopian tubes?

A
  1. Roughly same concentration of sperm in each

2. However, in ovulating tube more sperm found in ovulatory tubal ampulla than the contralateral tubal ampulla

46
Q

What happens when sea urchin sperm come within 1mm to the egg?

A

They swim in little circles to get closer (indicating chemotaxis is present via a Ca2+ GMP mechanism)

47
Q

Is there anything in follicular fluid that attracts sperm?

A
  1. Scientists thought progesterone but were wrong

2. Maybe heparin, natriuretic factors?

48
Q

Why was the discovery of olfactory receptors in sperm important and puzzling?

A

They are attracted to a ligand which releases Ca2+ and studies have yet to show if the egg/female tract releases this ligand, but it may further indicate chemotaxis in vivo and not just in vitro.

49
Q

What does the 2004 study on sperm chemotaxis suggest?

A

That the oocyte AND cumulus complex secrete chemoattractants both prior to and post ovulation.

Gametes & Embryos (15 decks)

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