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Year 2 RE > The Role of Sperm > Flashcards

The Role of Sperm Flashcards

1
Q

Gonadotrophin releasing hormone (GnRH) is secreted by the hypothalamus, which then goes on to stimulate gonadotrophin cells within the anterior pituitary gland that release leutenising hormone (LH) and follicular stimulating hormone (FSH). Which cells do LH and FSH then go on to stimulate in the testes?

A
  • LH = leydig cells

- FSH = sertoli cells

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2
Q

Gonadotrophin releasing hormone (GnRH) is secreted by the hypothalamus, which then goes on to stimulate gonadotrophin cells within the anterior pituitary gland that release leutenising hormone (LH) and follicular stimulating hormone (FSH). LH and FSH then go on to stimulate leydig cells and sertoli cells respectively. What does LH trigger in the leydig cells once it binds to leydig receptors?

A
  • production and secretion of androgens, specifically testosterone
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3
Q

Once LH has bound to leydig cells it stimulates the production and secretion release androgens, such as testosterone. This testosterone is able to provide positive and negative feedback. What negative and positive feedback does testosterone induce?

A
  • positive = stimulates sertoli cells to induce spermatogenesis
  • negative = inhibits hypothalamus and anterior pituitary gland reducing gonadotrophin releasing hormone, LH and FSH
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4
Q

FSH stimulates the sertoli cells of the testes. What does this stimulation then do to sperm?

A
  • weak stimulation of spermatogenesis

- need testosterone from leydig cells and FSH for strong stimulation

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5
Q

FSH stimulates the sertoli cells of the testes and provides a weak stimulation of spermatogenesis. In addition, what protein do sertoli cells secrete that has a negative feedback on the anterior pituitary gland?

A
  • inhibin
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6
Q

What is spermatogenesis, and what 2 stages does it include?

A
  • mitotic divisions of spermatogonia and the meiotic divisions of spermatogonia
  • process includes bothspermatocytogenesisand spermiogenesis
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7
Q

Spermatogenesis is a sequence of events that leads to the maturation of spermatogonia into spermatozoa (mature). What are spermatogonia and are they diploid or haploid cells?

A
  • immature sperm cells

- diploid cells (46 chromosomes, 2 pairs of 23 chromosomes)

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8
Q

Spermatogenesis is a sequence of events that leads to the maturation of spermatogonia into spermatozoa (mature). Spermatogonia are immature sperm cells that are diploid cells (46 chromosomes, 2 pairs of 23 chromosomes). What is the first process that occurs to the spermatogonia during spermatogenesis?

A
  • spermatogonia undergo mitosis creating 2 identical daughter cells
  • each daughter cell contains 46 chromosomes, 2 pairs of 23 chromosomes
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9
Q

Spermatogenesis is a sequence of events that leads to the maturation of spermatogonia into spermatozoa (mature). Spermatogonia are immature sperm cells that are diploid cells (46 chromosomes, 2 pairs of 23 chromosomes). The first process that occurs to the spermatogonia during spermatogenesis is mitosis creating 2 identical daughter cells, where each daughter cell contains 46 chromosomes, 2 pairs of 23 chromosomes. What happens to these 2 cells?

A
  • 1 cell becomes a spermatogonia to keep the pool of sperm constant
  • 1 cell becomes a primary spermatocyte
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10
Q

Once a spermatogonia becomes a primary spermatocyte, what happens to this cell?

A
  • moves towards lumen of the seminiferous tubules nourished by sertoli cells
  • undergoes meiosis 1
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11
Q

Once the primary spermatocyte undergoes meiosis I, what cells are left?

A
  • 2 daughter cells each containing 23 chromosomes (not a pair)
  • cells are not identical
  • these are called secondary spermatocytes
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12
Q

Once the primary spermatocyte undergoes meiosis I, 2 daughter cells are created which both containing 23 chromosomes (not a pair), these are called secondary spermatocytes. What is then left following meiosis II?

A
  • 4 cells each containing 1 lot of 23 chromosomes so haploids
  • all unique
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13
Q

Following meiosis II, what happens to the 4 haploid cells?

A
  • enter the seminiferous tubule and undergo spermiogenesis

- this is the process where they acquire a tail, and turn into mature sperm

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14
Q

What is spermatocytogenesis?

A
  • refers to the mitotic and meiotic stages of spermatogensis
  • refers to the meiotic stages of spermatogenesis
  • meiosis I spermatogonia (diploid 2n) develop into primary spermatocytes (diploid 4n)
  • meiosis II secondary spermatocytes (haploid 2n), and then finally into spermatids (haploid 1n)
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15
Q

What is spermiogenesis?

A
  • refers to the maturation of spermatids (haploid 1n) to mature spermatozoa
  • no cell division
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16
Q

What is spermiation?

A
  • mature spermatids are released from Sertoli cells into the seminiferous tubule lumen prior to their passage to the epididymis
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17
Q

What is sperm capacitation?

A
  • physiological changes spermatozoa must undergo in order to have the ability to penetrate and fertilise an egg
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18
Q

What are the 2 main products of the tests?

A 
1 = spermatoza
2 = hormones
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19
Q

The testes has 2 basic compartments, what are they?

A
  • interstitial (intertubular) compartment

- seminiferous tubule compartment

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20
Q

The testes are contained within the scrotum outside of the human body. What is one key reason for this?

A
  • helps maintain a lower temperature that human core temperature
  • optimal temperature for sperm development is 2 degrees less than 37 degrees
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21
Q

Sertoli cells are cells that nourish the sperm as they develop. How do they appear on histology?

A
  • large cells

- contain oval and dark nucleus

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22
Q

Where does spermatogenesis occur?

A
  • in seminiferous tubules

- this includes the maturation of spermatocytes via spermiogenesis

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23
Q

Spermatogonia are immature sperm cells that have yet to undergo mitosis and are located in the peripheries of the seminiferous tubules. There are type 2 type A and 1 type B spermatogonia. What is the difference?

A
  • type A dark cells do not undergo mitosis (act as reserve spermatogonia)
  • type A pale cells undergo active mitosis
  • type B cells undergo growth forming primary spermatocytes in seminiferous tubules
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24
Q

The leydigs cells located around the seminiferous tubules within the interstitial (intertubular) compartments main function is to synthesise testosterone. How much testosterone do they produce daily and what immune function do they have?

A
  • 4-10mg/day

- testes immunity

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25
Q

Testosterone is an androgen. What 2 important components are used to synthesise testosterone?

A

1 - cholesterol

2 - acetate

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26
Q

There are a number of androgens, but what are the 2 most important in sperm development?

A

1 - testosterone

2 -5α-dihydrotestosterone.

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27
Q

At puberty spermatogenesis begins. In order for this to occur what must increase in synthesis and release?

A
  • androgens

- specifically testosterone

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28
Q

Label the seminiferous tubules using the labels below:

leydig cells
sertoli cells
myoid cells (smooth muscle cells)
spermatogonium
basal lamina
lumen
A 
1 = sertoli cells
2 = leydig cells (located in interstitial compartment)
3 = myoid cells (smooth muscle cells)
4 = basal lamina (basement membrane)
5 = spermatogonium
6 = lumen
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29
Q

Sertoli cells within the seminiferous tubules sit side by side and are connected to one another and are able to communicate through direct communication. What 4 proteins between the sertoli cells facilitate the direct communication between sertoli cells?

A

1 - tight junctions
2 - gap junctions
3 - adheren junctions
4 - desmosomes

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30
Q

Sertoli cells within the seminiferous tubules sit side by side and are connected to one another and are able to communicate through direct communication. Tight junctions, gap junctions, adheren junctions and desmosomes facilitate the direct communication between sertoli cells? Why is this important?

A
  • transfer molecules or anything needed between cells

- helps maintain sertoli cell function

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31
Q

What are the 3 basic steps of spermatogenesis?

A

1 - mitosis to increase cell number
2 - meiosis to create genetic diversity
3 - cell modelling to package chromosomes into sperm to deliver to oocyte

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32
Q

What are the 3 key parts of a sperm?

A

1 - head
2 - mid piece
3 - tail

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33
Q

What is the function of the tail in a sperm?

A
  • propulsion
34
Q

What is contained within the mid piece in high concentrations?

A
  • mitochondria

- crucial for energy so the sperm can migrate towards the oocyte

35
Q

Where are the chromosomes (haploid) contained within the sperm?

A
  • chromosomes within the nucleus

- nucleus is contained within the head

36
Q

The acrosome appears like a helmet on the head of the sperm. What is the function of the acrosome?

A
  • important for ensuring the sperm can penetrate the oocyte
37
Q

Is spermatogenesis similar to ovulation and occur at a regular timed event?

A
  • no
  • occurs continually between puberty and death
  • millions of sperms formed every day
38
Q

Where in the testes do sperm wait and eventually mature to their final maturation point which provides the sperm with motility?

A
  • epididymis
39
Q

How long does it take on average for spermatogonia A to undergo mitosis?

A
  • 16 days
40
Q

How long does it take on average for spermatocytes I to undergo meiosis I?

A
  • 24 days
41
Q

How long does it take on average for spermatocytes II to undergo meiosis II?

A
  • several hours

- a spermatid is created following meiosis II

42
Q

How long does completion of spermatogenesis take?

A
  • 64-74 days
43
Q

The process of spermatogenesis is highly sensitive to fluctuations in the environment, particularly hormones and temperature. Any change in these variables can lead to what?

A
  • ectopic fertility

- random continuous production of sperm

44
Q

What is meant by spermatogenic cycle?

A
  • time it takes for the reappearance of the same stage within a given segment of the seminiferous tubule
  • distance between the same stage is called the spermatogenic wave
45
Q

The spermatogenic cycle is the time it takes for the reappearance of the same stage within a given segment of the seminiferous tubule. What term is used to measure the distance between the same stages of the spermatogenic cycle?

A
  • spermatogenic wave
46
Q

What is the mature sperm cell called?

A
  • spermatozoa
47
Q

Once the spermatozoa (mature sperm cell) has been formed in the seminiferous tubules, what is its pathway before it reaches the epididymis?

A
  • seminiferous tubules form the straight tubules
  • straight tubules form rete testes
  • rete testes enter the efferent ductules
  • efferent ductules enter the epididymis
48
Q

The final maturation of the spermatozoa occurs in the epididymis. What occurs in the epididymis that allows them to become motile?

A
  • fluid is absorbed and the sperm become concentrated

- following this stage they will be able to swim

49
Q

The final maturation of the spermatozoa occurs in the epididymis is dependent on what?

A
  • androgens
50
Q

Label the testes using the labels below:

head of epididymis
tail of of epididymis
body of epididymis
efferent ductule
ductus deferens
rete testis
straight tubule
seminiferous tubule 
tunica albuginea
A 
1 = efferent ductule
2 = body of epididymis
3 = ductus deferens
4 = rete testis
5 = straight tubule
6 = head of epididymis
7 = seminiferous tubule 
8 = tunica albuginea
9 = tail of of epididymis
51
Q

In addition to sperm cells contained within semen, what other cells can often be found within semen?

A
  • urogenital cells of urogenital tract
  • leukocytes (risk of HIV through this)
  • immature germ cells
52
Q

What tissues/organs secrete acellular components into the semen?

A
  • testes
  • epididymis
  • seminal vesicles
  • prostate
  • bulbourethral gland/cowpers gland (below prostate, secretes mucin)
53
Q

Is the fluid contained with semen essential for fertilisation?

A
  • no
54
Q

The fluid contained with semen is not essential for fertilisation, however, it does have 3 important functions, what are they?

A 
1 = nutrition (fructose, sorbitol)
2 = buffer (to protect against vaginal acidity)
3 = antioxidants (ascorbic acid, hypotaurine, help sperm survive uterus)
55
Q

The endocervix is the opening of the cervix that leads into the uterus. What do the hormones estrogen and progesterone do to assist sperm entering the uterus?

A
  • secrete watery thin mucus

- inhibit secretory activity that may wash away sperm

56
Q

The endocervix is the opening of the cervix that leads into the uterus. What are located in the endocervix that helps guide the spermatozoa?

A
  • macromolecular network of mucin fibrils
57
Q

When can sperm generally penetrate the endocervix?

A
  • from day 9 has a an ok enviroment

- peak time for entry is ovulation

58
Q

Although the endocervix, the opening of the cervix that leads into the uterus tries to assist sperm in the journey to the oocyte in the fallopian tubes, what % of sperm do not make it past the endocervix?

A
  • 99%
59
Q

Once inside the uterus, what else can the endocervix do to support the sperm in the journey to the oocyte in the fallopian tubes?

A
  • ensure sperm are not phagocytosed
  • provide nutrition
  • initiate capacitation (increased motility)
60
Q

How long can sperm survive in the uterus?

A
  • 72 hours
61
Q

The final step of spermatozoa maturation occurs and is facilitated by the uterus, what is the stage called?

A
  • capacitation
62
Q

What does a dry or sticky cervical mucus indicate?

A
  • no ovulation
63
Q

What does a wet or watery cervical mucus indicate?

A
  • ovulation is very close
64
Q

What does a creamy cervical mucus indicate?

A
  • ovulation may be coming
65
Q

What does a very wet, stretchy, similar to egg white cervical mucus indicate?

A
  • ovulation is occuring
66
Q

What is the spinnbarketi test?

A
  • a biomedical rheology test to assess the stringy or stretchy property found to varying degrees in mucus, saliva, albumen and similar viscoelastic fluids, especially cervical mucus
67
Q

The spinnbarketi test is a biomedical rheology test to assess the stringy or stretchy property found to varying degrees in mucus, saliva, albumen and similar viscoelastic fluids, especially cervical mucus. What is this test used to assess?

A
  • assess infertility in couple with no obvious anatomical or physiological issues
68
Q

What is the Ferning test?

A
  • detection of a characteristic ‘fern like’ pattern of vaginal secretions when a specimen is allowed to dry on a glass slide and is viewed under a low-power microscope
  • can be used to detect early labour
69
Q

If sperm are collected upon ejaculation, would they be able to fertilise an oocyte in-vitro?

A
  • no

- they haven’t undergone capacitation which is required

70
Q

Capacitation is the final stage of maturation of the spermatozoa. What 3 things happens to the spermatozoa during capacitation to facility penetration of the oocytes membrane?

A
  • loss of cholesterol
  • destabilisation of the sperm membrane
  • activation of phospholipases
71
Q

Capacitation is the final stage of maturation of the spermatozoa. During capacitation the spermatozoa undergo:

  • loss of cholesterol
  • destabilisation of the sperm membrane
  • activation of phospholipases

What 3 key things does then facilitate to allow the sperm to fertilise the oocyte?

A

1 - hyperactivity motility of the sperm
2 - increases responsiveness of the sperm to signal from oocyte
3 - allows spermatozoa to penetrate oocyte

72
Q

The acrosome of the sperm upon coming into contact with the oocyte as able to do what that facilitates the digestion of the zona pellucida?

A
  • release enzymes (hyaluronidase and acrosin)
73
Q

When we want to look at male infertility or to determine if a vestectomy was successful, we need to look at sperm. What are the 3 measurements of the sperm we would use?

A

1 - concentration
2 - motility
3 - morphology

74
Q

What is a vasectomy?

A
  • surgical procedure for male sterilisation or permanent contraception
  • vasa deferentia are cut and tied or sealed
75
Q

What is the cut off for a normal semen ejaculation volume?

A
  • 1.5ml (normal range =1.5-6ml)
  • low can be retrograde ejaculation
  • high can be due to abstinence
76
Q

How is sperm concentration and vitality measured?

A
  • number of sperm/ml in total ejaculate
77
Q

What is the normal sperm concentration and vitality?

A
  • 15 million/ml

- 58% or more live spermatozoa

78
Q

How is sperm motility defined?

A
  • % of progressively motile sperm in ejaculate

- progressively motile means they move everywhere not just in circles

79
Q

Sperm motility is defined as the % of progressively motile sperm in ejaculate, where progressively motile means they move everywhere not just in circles. What is the lower cut off for normal progressive motility?

A
  • 32%
80
Q

When we look at the morphology of the sperm visually, what can be affected?

A
  • head including acrosome
  • mid piece
  • tail
81
Q

When we look at the morphology of the sperm visually, we can see changes in the head including acrosome, mid piece and tail. What is the WHOs guidelines to normal morphology?

A
  • > 4%

- 4-14% is the normal, with lots of other morphologies

Year 2 RE (53 decks)

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