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MVST1B HR > Male gametogenesis > Flashcards

Male gametogenesis Flashcards

1
Q

what is fecundity?

A

The potential for reproduction: gamete production, fertilisation and ability to carry a pregnancy to term

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2
Q

what is fertility?

A

A measure of reproductive outcome: the number of children born per person, couple or population

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3
Q

what is the fertiltiy rate?

A

The number of births per time period per person, couple or population

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4
Q

is fecundity afffected by age?

A

yes.

males - constant / then gradual decline

females = monthly / sharp drop off at menopause

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5
Q

peak fertility rate – _____ years

A

peak fertility rate – 20-24 years

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6
Q

menopause: ___ years old average

A

menopause: 51 years old average

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7
Q

male fertility is lost in later life due to?

A

many factors

Vascular disease Erectile dysfunction Diabetes

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8
Q

describe the HPG axis

A
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9
Q

the hypothalsmus releases what?

A

gonadotrophic releasing hormone

GnRH. into pituitarty portal system - stimulates release of FSH LH and prolactin from anterior pituitary

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10
Q
  • Release controlled by hypothalamus – GnRH – release is ______ – peaks hourly – important for function
A
  • Release controlled by hypothalamus – GnRH – release is. Pulsatile – peaks hourly – important for function
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11
Q

when hormones provide feedback from the gonads to the brain?

A

Inhibin oestrogen and testosterone

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12
Q

•FSH and LH are secreted by …

A

•FSH and LH are secreted by gonadotroph cells in the anterior lobe of the pituitary gland

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13
Q

•Prolactin secreted by ____

A

•Prolactin secreted by lactotrophs

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14
Q

acidophiles in the ant pituitaery produce?

what about basophils?

A

acidophils: Growth hormone or prolactin
basophils: TSH, ACTH, FSH or LH

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15
Q

Secretion of FSH and LH is regulated by ….

A

Secretion of FSH and LH is regulated by gonadotrophin-releasing hormone (GnRH) produced by neurons in the hypothalamus and

the

released into the pituitary portal vein

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16
Q

Release of GnRH is ….

A

Release of GnRH is pulsatile, peaking approximately hourly

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17
Q

role of LH

A

•LH stimulates thecal cells in ovary to produce oestradiol, and Leydig cells in testis to produce testosterone

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18
Q

are oestradiol and testosterone negative feedback mediators?

A

yes

expect oestrdiol is a positive feedback mediator in high concentrations. = LH surge

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19
Q

describe FSH

A

•FSH stimulates granulosa cells in ovary and Sertoli cells in testis to produce inhibin

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20
Q

does Inhibin exert negative feedback

A

•Inhibin exerts –ve feedback on FSH secretion by gonadotrophs

only FSH release.

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21
Q

Functions of prolactin?

A
  • diverse unclear actions
  • potentiates actions of FSH and LH through actions on receptors and enzymes e.g. 5 alpha reductase
    *
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22
Q

•Hyperprolactinaemia is associated with ________ in both men and women

A

•Hyperprolactinaemia is associated with infertility in both men and women

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23
Q

how is prolactin regulated?

and so hwo do we treat hyperprolactinaemia?

A

Regulated primarily by negative action of dopamine released from TIDA neurons

•Hence, treated with bromocriptine, a dopamine D2

receptor agonist

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24
Q

TIDA neurones are located where?

A

the arcuate nucleus

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25
Q

when dothe testis decend>

A

jus tbefore birth

26
Q

why are the testis located outside the body

A

This position, plus the countercurrent heat exchange between the testicular artery and the pampiniform plexus of veins lowers the temperature by a few degrees centigrade

27
Q

wat is poor decent of the testis assocaited with

A

• Maldescent (cryptorchidism) associated with teratocarcinoma, reduced spermatogenesis and subfertility

28
Q

testis has ___ lobes

A

250

29
Q

how many seminiferous tubules does each lobule contain

A

1-4

30
Q

shape of the seminiferous tubules?

A

hourse shoe shaped

31
Q

what the seminiferous tubules connected to?

A
  • Tubules are horse-shoe shaped and both ends connect with the rete testis and hence to the efferent ductules
  • Released sperm are non-motile at this point, and so movement by bulk- fluid flow
32
Q

• Maturation and storage of sperm takes place in the _____

A

• Maturation and storage of sperm takes place in the epididymis

33
Q

•Seminiferous tubules are developed during the ……

when are they activateD?

A

•Seminiferous tubules are developed during the fetal period but inactive until puberty

34
Q

what effect do FSH and LH have on the seminiferous tubules?

A

• Once FSH and LH rise at puberty the testis enlarges as the Leydig cells and seminiferous tubules expand, and spermatogenesis starts

35
Q

the wall of the seminiferous tubule is how thick?

A

Sertoli cells make up the wall of the tubule, which appears multilayered but is only 1 cell thick

36
Q

Whether sperm are present in the smeiniferous tubule lumen depends on ?

A

Whether sperm are present in the lumen depends on the stage of the spermatogenic cycle of that particular profile

37
Q

Blood vessels and lymphatics are confined to the _________, and the tight junctions between Sertoli cells constitute the ____________

A

Blood vessels and lymphatics are confined to the interstices, and the tight junctions between Sertoli cells constitute the blood-testis barrier

38
Q

the basal testicular compartment is high in?

A

testosterone

39
Q

teh apical testis compartment is ?

A

immunologically provilages - to stop immune cells repsonding to new spermy bois

40
Q

The tubules are lined by Sertoli cells attached to a ….

A

The tubules are lined by Sertoli cells attached to a basement membrane

41
Q

Spermatogonia are also attached to the …..

A

Spermatogonia are also attached to the basement membrane

42
Q

Tight junctions between the Sertoli cells divide the testis into …..

A

Tight junctions between the Sertoli cells divide the testis into basal and apical (adluminal) compartments

43
Q

Basal compartment has a high _________ concentration secreted by Leydig cells in response to ___, and bound by androgen binding protein secreted by Sertoli cells in response to FSH

A

Basal compartment has a high testosterone concentration secreted by Leydig cells in response to LH, and bound by androgen binding protein secreted by Sertoli cells in response to FSH

44
Q

problems if teh tight junctions in the basement membrane in the testis break down

A

If tight junctions break down can develop an autoimmune reaction, and anti- spermatozoal antibodies, leading to subfertility

45
Q

3 stages of spermatogenesis

A
  1. mitotic proliferation
  2. Meiotic division
  3. Cytodifferentiation (spermiogenesis)
46
Q

what is spermiation?

A

Spermatozoa are released luminally into testicular fluid in a process called spermiation

47
Q

describe 1: mitotic proliferation

A

Numbers of sperm produced depend on mitotic activity of spermatogonia from stem cells in basal compartment (5-7 division rounds)

48
Q

descxribe 2: meiotic division

A

Meiosis occurs in spermatocytes, and they move from the basal to the apical compartment as they divide

49
Q

describe 3: cytodifferentiation

A

Post-meiotic haploid spermatids transform their phenotype from round spermatid through elongating spermatid to a spermatozoon

50
Q
A
51
Q
A
52
Q
A
53
Q

in sperm - histones are replaced by

A

protamines

high condensation = loss of transcription in late spermatids and spermatozoa

54
Q
A
55
Q

human spermatogenic cycles last for?

A

In the human the cycle lasts for 16 days, and spermatogenesis for 64 days

56
Q

describe the Transport of spermatozoa

A

From testis through vasa efferentia

  • passively in bulk fluid flow
  • non-fertile and immotile

Through the epididymis to vas deferens

  • 90% fluid absorbed so spermatocrit rises
  • muscular contractions move the sperm along
57
Q

Maturation and storage of spermatozoa in the epididymis;

describe

A

Maturation and storage of spermatozoa in the epididymis; stiffening of outer dense fibres in tail, addition of glycoproteins, change in lipid composition of membranes (lectures on fertilisation)

58
Q

Epididymal function, prostate and seminal vesicles all dependent on ______

A

Epididymal function, prostate and seminal vesicles all dependent on androgens

59
Q

Normally produce ~_- million spermatozoa per day

A

Normally produce ~30 million spermatozoa per day

60
Q

Reduced sperm count may be associated with:

A

Reduced sperm count may be associated with:

  • Cryptorchidism
  • Overheating of the testis e.g. varicocoele
  • Drugs e.g. anti-mitotic drugs, alcohol, xenobiotics, bisphenol A
  • Hyperprolactinaemia
  • Obstructive pathology of the epididymis or vas e.g. congenital or post-infective
61
Q

fat

A

mamba

62
Q
A

MVST1B HR (13 decks)

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