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BMSc Repro > Spermatogenesis > Flashcards

Spermatogenesis Flashcards

1
Q

What is the main reproductive organ in the male?

A

Testis

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2
Q

What is the function of the testis

A

-To produce sperm
-To produce hormones (androgens, oestrogens, inhibin, activin, relaxin-like factor)

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3
Q

Which cells live in the semimiferous tubules?

A
  • Sertoli cells
    -Germ cells

(myoid cells)

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4
Q

Where do myoid cells live in the testis?

A

They surround the seminiferous tubules in a thin layer

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5
Q

What is present in the interstitial compartment?

A
  • Leydig cells
  • capillaries and lymphatic vessels
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6
Q

When does the blood testis barrier develop

A

During puberty

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7
Q

What is the function of the BTB?

A
  • Avoids sperm passing into the interstitum
  • protects sperm from the immune system
    -retains hormones within the ST
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8
Q

What makes up the BTB?

A

Sertoli cells with tight gap junctions

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9
Q

What is spermatogeneis?

A

The whole process going from an undifferentiated germ cell to spermatozoa. The process takes 74 days.

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10
Q

What are the 3 phases in spermatogenesis?

A

-Mitosis
-meiosis
-Spermiogenesis

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11
Q

What is spermiogenesis?

A

where spermatids acquire the morphology of specialised cells

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12
Q

Where do primordial germ cells originate?

A

They originate in the yolk sac during the first few weeks of gestation

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13
Q

Where do primordial germ cells migrate to?

A

They migrate to the genital ridges, and once they are here they are called gonocytes. They proliferate by mitosis

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14
Q

Initially there is no sex differentiation in primordial germ cells/ gonocytes. Describe the sex differentiation process

A

In XY embryos, around week 5/6 pre-sertoli cells enter the genital ridges. They express SRY genes which drives the differentiation of the male gonads.

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15
Q

What are seminiferous cords?

A

Pre-sertoli cells surround the gonocytes and produce cords. Until a lumen is formed they are described as seminiferous cords.

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16
Q

When are gonocytes called stem cells

A

When they move to the basement membrane of the seminiferous cords

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17
Q

Why is the stem cell niche important

A

Because it keeps the stem cells in an undifferentiated state so that men can produce sperm their whole life

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18
Q

how many germ cells can a sertoli cell support and why is this important

A

30-50 germ cells
If a sertoli cell is damaged then there are less germ cells and so less spermatogenesis can occur

19
Q

What is the first step of of spermatogenesis?

A

Stem cells undergo mitosis to produce spermatogonia, and these undergo several rounds of mitosis to produce more spermatogonia (one spermatogonia A1 can produce 16 spermatogonia B)

20
Q

What is the second step of spermatogenesis?

A

Spermatogonia undergo mitosis to produce primary spermatocytes.

21
Q

What is the third step of spermatogeneis?

A

Primary spermatocytes undergo meiosis I to produce secondary spermatocytes.

This process involves crossing over, random assortment and produces 2 haploid cells from one progenitor cell.

CHECK W STEVE

22
Q

What is the fourth step of spermatogenesis?

A

Secondary spermatocytes undergo meiosis II to produce spermatids

CHECK W STEVE

23
Q

What is the fifth step of spermatogenesis

A

round spermatids become spermatozoa through cytodifferentiation (spermiogenesis)

Note: round spermatids develop into elongated spermatids during this process before becoming spermatozoa

24
Q

what are myoid cells?

A

Contractile cells that help release sperm into the lumen

25
Q

Describe the formation of the acrosomal vescile

A

the golgi apparatus produces lysosomes that will form the acrosomal vescile.
The spermatocyte rotates so that this is facing down the way - and so the tail will grow out of the other end.
Cytoplasm is removed and droplets phagocyted by sertoli cells

26
Q

What is spermiation

A

The final release of sperm into the lumen of the seminiferous tubules

27
Q

Why would we use a machine to determine whether X or Y sperm (X is bigger)

A
  • avoid genetic sex linked diseases
    -large animal production
    -endangered species
    -risk of shifting sex ratio - e.g. china
28
Q

What is the spermatogenic wave?

A

The process by which a stem cells starts division and differentiation occurs every six days - this is controlled by sertoli cells.

29
Q

What stimulates Leydig cells?

A

LH

30
Q

What stimulates Sertoli cells?

A

FSH

31
Q

What do leydig cells produce?

A

-Testosterone
-oestrogen
-Oxytocin

32
Q

What do sertoli cells produce?

A

-Anti-mullarin hormone
-Inhibin B
- Androgen binding protein

33
Q

What effect does Testosterone have on sertoli cells?

A

-helps them maintain BTB
-Helps them support meiosis
- helps then support spermatid elongation
-Essential for spermiation

34
Q

What stimulates myoid cells

A

-Testosterone
-oestrogen
-oxytocin

35
Q

What is azoospermia?

A

Absence of any sperm in the ejaculate

36
Q

What are the two classifications of Non-obstructive azoospermia?

A
  • Pre-testicular (secondary hypogonadism)
    -testicular (primary hypogonadism)
37
Q

What histological feature is seen in NOA

A

Sertoli cell only syndrome

38
Q

Name some causes of pre-testicular NOA

A

-Kallman’s syndrome
- pituitary tumours

39
Q

Name some causes of testicular NOA

A
  • Infection (mumps)
  • Klinefelters syndrome
    -Iatrogenic (cancer treatments)
    -Ischaemic - testicular torsion
    -Idiopathic
40
Q

Describe causes of obstructive azoospermia

A
  • Vasectomy
  • Congenital anomalies
    -iatrogenic injury
    -Infection
41
Q

What requirements are necessary for a man to be classed as fertile

A
  • 1.5ml of ejaculate
  • 15 million sperm per ml of semen
  • 32% of the sperm need to swim forwards
    -4% need to be morphologically normal
42
Q

Define the classification of olgiospermia

A

Mild: 10-15 million
Moderate: 5-10 million
Severe: <5 million

43
Q

List some environmental and lifestyle causes of reduced spermatogenesis

A
  • Obesity
  • Diabetes
  • Temperature
  • Alcohol
  • Smoking
  • Chemo/radiotherapy
  • Endocrine distributors
  • Cadmium
  • Dioxin

BMSc Repro (9 decks)

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