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ANS3319C Reproductive Physiology and Endocrinology > Spermatogenesis Part 1 > Flashcards

Spermatogenesis Part 1 Flashcards

1
Q

What are the endocrine requirements necessary for sperm production?

A
  1. Adequate GnRH secrewtion from hypothalamus
  2. FSH and LH secretion from the anteiror lobe of the pituitary
  3. Secretion of testosterone and estradiol from the gonads
  4. Low testosterone in blood (much higher in testes)
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2
Q

What do males not have ? what does it do?

A
  1. Males do not have a surge center
  2. GnRH is frequent and intermittent (no bursts)
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3
Q

In spermatogenesis where does it take place and what do it require?

A
  1. Takes palce entirely within the seminiferous tubules
  2. Requires cell divisions and morphologic changes of developing germ cells to product mature spermatozoa
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4
Q

How often are the GnRH pulses in males due to no surge center?

A
  1. 4-8 GnRH pulses/day
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5
Q

How does FSH differ compared to female?

A
  1. FSH is lower
  2. Pulses are longer than in female due to constant inhibin production from Sertoli cells
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6
Q

What occurs in LH for males?

A
  1. LH acts on the Leydig cells to synthesize P4 which is converted to testosterone
  2. Pulses of LH prevent the cells from becoming refractory
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7
Q

What does refractory mean in spermatogenesis?

A
  1. Means no testosterone production
  2. No muscle
  3. No spermatogenesis
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8
Q

What is pulsatile LH necessary for? What does it do?

A
  1. Needed for proper biological function of spermatogenesis
  2. Increases testosterone in seminiferous tubules essential for spermatogenesis
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9
Q

What occur when there is Chronic & high LH?

A
  1. Leydig cells become refractory
  2. Severe down regulation GnRH & LH feedback system
  3. Testosterone secretion and spermatogenesis essentially stop
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10
Q

How is testosterone secretion? what does it remove?

A
  1. It is pulsatile (short lived)
  2. Removes the -ve feedback on FSH
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11
Q

FSH acts on ?

A

Act on Sertoili (nurse) cells to produce inhibin

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12
Q

What does inhibin do?

A

Blocks FSH by producing negative feedback on the GnRH production in the hypothalamus

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13
Q

How long is LH elevated for? How is Testosterone?

A
  1. Elevated for about 1 hour in blood
  2. Testosterone elevation is simialr to LH
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14
Q

From the Hypothalamus/pituitary what does FSH interact with ? What does LH interact with?

A

1.FSH interacts with Testis and Serotli cells
2.LH interacts with Testis and Leydig cells

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15
Q

When FSH interacts with sertoli cells what occurs?

A
  1. Sertoli cells interact with Inhibin which causes negative feedback
  2. Sertoli cells interacts with spermatogonia
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16
Q

When LH interacts with Leydig cells what occurs?

A
  1. Interacts with testosterone
  2. Then interacts with Spermatogonia
17
Q

Testosterone secreted by Leydig cells is transported to sertoli cells and then what occurs?

A

They are converted to DHT and E2

18
Q

How are Testosterone and E2 transported?

A

Transported by blood to hypothalamus to exert negative feedback on GnRH

19
Q

In what order does FSH go in order for spermatogenesis?

A

1.FSH targets Serotil cells
2.Converting testosterone into Estradiol

20
Q

What do sertoli cells secrete?

A

Sertoli cells secrete inhibi to product negative feedback directly on FSH

21
Q

What is the are the goals of spermatogenesis?

A
  1. Continual gamete supply via stem cell renewal
  2. DNA crossig over (recombination) to provide genetic diversity
  3. Produce billions sperm/day to maximize reproduction
  4. Provide an immunologically privileged site where germ cells are not destroyed by immune system
22
Q

How does the order of Mitosis go?

A
  1. Comes from parent cell ->
  2. Chromosome duplication->
  3. Enters prophase which is duplicated chromosome (two sister chromatids)->
  4. Enters Metaphase (chromosomes align at the metaphase plate ->
  5. Enters Anaphase Telophase (sister chromatids separate during anaphase) called Daughter cells of Mitosis
23
Q

How does the process of Meiosis go in?

A

Starts with parent cell -> Chromosome duplication -> Enters Meiosis 1 prophase 1 -> Metaphase 1 -> Anaphase 1 Telophase 1 -> Meiosis 2

24
Q

What occurs during prophase 1?

A
  1. Tetrad formed by synapsis of homologous chromosomes
  2. Tetrads align at the metaphase plate
  3. Homologous Chromosomes seperate (anaphase 1) sister chromatids remain together
  4. No further chromosomal duplication; sister chromatids seperate (anaphase 2)
25
Q

Spermatogenesis can be divided into 3 phase:

A
  1. Proliferation-mitotic divisions of spermatogonia (Basal Section)
  2. Meiotic (Adluminal section)
  3. Differentiation (Adluminal section)
26
Q

What occurs under proliferation?

A
  1. A- spermatogonia divides several times to make B-Spermatogonia
  2. Stem cell renewal takes place by loss of intracellular bridges for a continual supply so that more spermatogonia can develop
  3. Mitotic divisions of spermatogonia (2n)
  4. Stem cell renewa, replacement of A1 spermatogonia
27
Q

What occurs in Meiotic?

A
  1. Begins with 1° spermatocytes (Lifespan 18-19 days in bull)
    * initiates first meiotic divisions
    * DNA replication & recombination -> genetic diversity
    2 . 2° spermatocytes
    * Conclusion of second meitotic division
    * Final product: 1n spermatids
    3 . Provides genetic diversity (no two sperm are same)
    4 . The 2nd meiotic division = haploid (1N) spermatids
28
Q

What occurs during Differentiation (spermiogenesis)?

A
  1. Round to elongated spermatid
  2. No further dell divisions
  3. Spermatids -> spermatozoon (single sperm)
  4. Development of head, midpiece, principles piece (tail)
29
Q

In what order does the basement mebrane occur?

A

Starts with proliferation and contains spermatogonia -> Enters Meiosis containing spermatocytes-> Enters Meiosis 2 contains secondary spermatocytes-> Goes into differentiation containing spermatids

30
Q

How long does
1. Spermatogonia,
2. Primary spermatocytem
3. Secondary spermatocyte,
4. Spermatid occur for
5. Traveling to through epididymis
Last for?

A
  1. 15 days
  2. 15 days
  3. 29 days
  4. 1 day
  5. 10 days

ANS3319C Reproductive Physiology and Endocrinology (13 decks)

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