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Male gametogenesis Flashcards

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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
when dothe testis decend\>
jus tbefore birth
26
why are the testis located outside the body
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
wat is poor decent of the testis assocaited with
• Maldescent (cryptorchidism) associated with teratocarcinoma, reduced spermatogenesis and subfertility
28
testis has ___ lobes
250
29
how many seminiferous tubules does each lobule contain
1-4
30
shape of the seminiferous tubules?
hourse shoe shaped
31
what the seminiferous tubules connected to?
* 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
• Maturation and storage of sperm takes place in the \_\_\_\_\_
• Maturation and storage of sperm takes place in the epididymis
33
•Seminiferous tubules are developed during the ...... when are they activateD?
•Seminiferous tubules are developed during the fetal period but inactive until puberty
34
what effect do FSH and LH have on the seminiferous tubules?
• Once FSH and LH rise at puberty the testis enlarges as the Leydig cells and seminiferous tubules expand, and spermatogenesis starts
35
the wall of the seminiferous tubule is how thick?
Sertoli cells make up the wall of the tubule, which appears multilayered but is only 1 cell thick
36
Whether sperm are present in the smeiniferous tubule lumen depends on ?
Whether sperm are present in the lumen depends on the stage of the spermatogenic cycle of that particular profile
37
Blood vessels and lymphatics are confined to the \_\_\_\_\_\_\_\_\_, and the tight junctions between Sertoli cells constitute the \_\_\_\_\_\_\_\_\_\_\_\_
Blood vessels and lymphatics are confined to the interstices, and the tight junctions between Sertoli cells constitute the blood-testis barrier
38
the basal testicular compartment is high in?
testosterone
39
teh apical testis compartment is ?
immunologically provilages - to stop immune cells repsonding to new spermy bois
40
The tubules are lined by Sertoli cells attached to a ....
The tubules are lined by Sertoli cells attached to a basement membrane
41
Spermatogonia are also attached to the .....
Spermatogonia are also attached to the basement membrane
42
Tight junctions between the Sertoli cells divide the testis into .....
Tight junctions between the Sertoli cells divide the testis into basal and apical (adluminal) compartments
43
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
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
problems if teh tight junctions in the basement membrane in the testis break down
If tight junctions break down can develop an autoimmune reaction, and anti- spermatozoal antibodies, leading to subfertility
45
3 stages of spermatogenesis
1. mitotic proliferation 2. Meiotic division 3. Cytodifferentiation (spermiogenesis)
46
what is spermiation?
Spermatozoa are released luminally into testicular fluid in a process called spermiation
47
describe 1: mitotic proliferation
Numbers of sperm produced depend on mitotic activity of spermatogonia from stem cells in basal compartment (5-7 division rounds)
48
descxribe 2: meiotic division
Meiosis occurs in spermatocytes, and they move from the basal to the apical compartment as they divide
49
describe 3: cytodifferentiation
Post-meiotic haploid spermatids transform their phenotype from round spermatid through elongating spermatid to a spermatozoon
50
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52
53
in sperm - histones are replaced by
protamines high condensation = loss of transcription in late spermatids and spermatozoa
54
55
human spermatogenic cycles last for?
In the human the cycle lasts for 16 days, and spermatogenesis for 64 days
56
describe the Transport of spermatozoa
**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
Maturation and storage of spermatozoa in the epididymis; describe
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
Epididymal function, prostate and seminal vesicles all dependent on \_\_\_\_\_\_
Epididymal function, prostate and seminal vesicles all dependent on androgens
59
Normally produce ~\_- million spermatozoa per day
Normally produce ~30 million spermatozoa per day
60
Reduced sperm count may be associated with:
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
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