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Reproduction > Spermatogenesis & male infertility > Flashcards

Spermatogenesis & male infertility Flashcards

1
Q

What determines gender?

A 
Chromosomal sex (XY chromosome pair)
Gonadal sex (foetus with ovaries/testes)
Genital sex (testes secrete hormones/are absent) 
Gender (perceived genital sex + upbringing)
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2
Q

internal reproductive tract development

  • what chromosome has the sex determining region?
  • name the 2 primitive genital tracts
  • what causes the development of the male tract
  • name the ducts in a male and a female
A
  • Y chromosome, causes development of testis from the biopotential gonad
  • Wolffian & Mullerian ducts
  • Testosterone and Mullarian inhibiting factor cause the development of the male internal genital tract

-Male- Wolffian
Mullarian- Mullerian

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3
Q

what controls the differentiation of the external genitalia?

A

Dihydrotestosterone which stimulates the development of the male external genitalia

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4
Q

see diagram of development of the internal and external genital tracts pls

A

look at the thing yes

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5
Q
  • what is Androgen insensitivity syndrome?
  • presentation
  • features?
A

-congenital insensitivity to androgens
X-linked recessive disorder

-primary amenorrhoea and lack of pubic hair

-Male karyotype, testis develop but do not descend
Androgen induction of the Wolffian duct does not occur but Mullarian inhibition does occur:
born phenotypically external genitalia female but with absence of the uterus and ovaries, with short vagina

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6
Q

Descent of the testes

  • what is descent dependent on?
  • importance of descent?
  • clinical name?
  • management
A
  • androgen dependent, they develop in the abdominal cavity and drop into scrotal sac before birth
  • lower temp outside body to stimulate spermatogenesis
  • Cryptorchidism
  • perform orchidopexy if below age 14 to minimise cancer risk
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7
Q

What is the function of the testis?

-where do these functions occur

A

Spermatogenesis & production of testosterone

-spermatogenesis- seminiferous tubules
production of testosterone- Leydig cells

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8
Q
  • name of a single mature sperm?

- where is the acrosome and what does it contain?

A

a spermatozoon

-under the plasma membrane at the head of the sperm
contains enzymes to penetrate the zona falicuda and into the ovum

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9
Q

sertoli cells

give the 6 functions of sertoli cells

A

-form blood testes barrier
(protects sperm from antibody attack and provides suitable fluid composition which allows later stages of development of sperm)

-provide nutrients
(for the developing cells)

-phagocytosis
(Remove surplus cytoplasm from packaging process & destroy defective cells)

-secrete seminiferous tubule fluid
(used to carry cells to the epididymus)

-secrete androgen binding globulin
(binds testosterone so Conc remains high in the lumen and is essential for sperm production)

-secrete inhibit & activin hormones
(regulates FSH secretion and controls spermatogenesis)

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10
Q

how is GnRH released in the male?

  • what does FSH stimulate in the male?
  • What does LH stimulate in the male?
A

in a pulsatile fashion

  • stimulates spermatogenesis and the sertoli cells to produce Androgen binding globulin which binds to testosterone
  • testosterone secretion (leydig cells) which reduces release of GnRH & LH
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11
Q

GRH

  • type of molecule?
  • pattern of release?
  • action?
  • feedback control?
A
  • decapeptide
  • released from hypothalamus in bursts every 2-3 hrs from age 8-12
  • stimulates ant pit to produce LH and FSH
  • under negative feedback control from testosterone
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12
Q

LH & FSH

  • what does LH do?
  • What does FSH do?
  • pattern of production?
A
  • acts on leydig cells- regulates testosterone secretion
  • acts on sertoli cells and enhances spermatogenesis, neg feedback from inhibin
  • non-cyclical
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13
Q

testosterone

  • produced where?
  • derived from what?
  • secreted where?
  • has what effect? (before birth, at puberty, adulthood)
A
  • Produced in Leydig cells
  • cholesterhol- steroid hormone
  • into blood and seminiferous tubules for sperm production

-Negative feedback on hypothalamus and pituitary gland
Before Birth:
masculinises repro tract and promotes descent of testes
Puberty:
promotes puberty and male characteristics
Adult:
controls spermatogenesis, secondary sexual characteristics, lipido, penile erection, aggressive behaviour

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14
Q

inhibin & Activin

  • secreted by what?
  • what hormone do they control?
A
  • sertoli cells

- feedback on FSH, inhibit inhibits and action stimulates

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15
Q

describe what happens to spermatozoa after ejaculation?

A
  • liquified
  • Capacitation (this is a series of biochemical and electrical events before fertilisation
  • chemoattraction to oocyte and bind to zona pellucida of oocyte
  • acrosome reaction
  • hyperactivated motility
  • penetration and fusion with oocyte membrane
  • zonal reaction (thickening)
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16
Q

give the functions of:

  • Epididymis & vas deferens
  • Seminal vesicles
  • prostate gland
  • Bulbourethral glands
A
  • exit route from testes to urethra, concentrate & store sperm, site for sperm maturation
  • produce semen into the ejaculatory duct, supply fructose, secrete prostaglandins (motility), secrete fibrinogen (clot precursor)
  • produces alkalin fluid (neutralises vaginal acidity), produces clotting enzymes to clot semen with female
  • secrete mucus to act as lubricant
17
Q

describe the route sperm takes to exit the male?

  • what controls an erection?
  • what controls ejaculation
A

Testes, epididymis, vas deferens, ejaculatory duct, urethra

  • the PS
  • the sympathetic NS
18
Q

definition of male infertility?

-name the different causes of male infertility (obstructive (4)/non-obstructive (8))

A

due to failure of a sperm to normally fertilise an egg
usually assoc with abnormalities in semen analysis
Common cause of infertility

-Idiopathic- most common

Obstructive- CF, vasectomy, infection

Non-obstructive- 
Congenital (cryoptorchadism)
Infection (mumps, orchitis)
Iatrogenic (chemo/radio)
Pathological (testicular tumour)
Genetic (chromosomal e.g. Klinefelter's, robertsonian)
Specific semen abnormality
Systemic disorder
Endocrine
19
Q

Name the endocrine causes of male infertility? (7)

A

-Pituitary tumours
acromegaly, Cushing’s, hyperprolactinaemia

Hypothalamic causes
idiopathic, tumours, Kallman’s, anorexia

Thyroid disorders
hyper/hypothyroidism

Diabetes

CAH

Androgen insensitivity

Steroid abuse
gives decreased LH, FSH and test

20
Q

Assessment of male infertility

  • examination (general & genital)
  • what is normal testicular volume & measured with?
  • semen analysis components?
  • what external factors effect semen analysis?
  • further assessment?
A

-General:
secondary sexual characteristics & presence of gynaecomastia
Genital:
testicular vol
presence of vas deferens & epididymis
Penis
presence of varicocele/other scrotal swelling

-Pre pubertal: 1-3mls
Adult: 12-25 mls
orchidometer

-volume
Density (no. sperm)
Motility (what proportion are moving)
Progression (how well they move)
Morphology
-completeness of sample
period of abstinence
Condition during transport
time between production and assessment 
natural variations between samples
health of man 3 months before production

-semen analysis 6 wks later
endocrine profile
chromosome analysis
possible testicular biopsy & scrotal scan

21
Q

Obstructive infertility

  • clinical features
  • endocrine features
A

-normal testicular volume
normal secondary sexual characteristics
vas deferens might be absent

-normal LH, FSH & testosterone

22
Q

Non-obstructive

  • clinical features
  • endocrine features
A

-low testicular vol
reduced secondary sexual characteristics
vas deferens present

-high LH, FSH & low testosterone

23
Q

Treatment of male infertility:

what lifestyle areas should be addressed? (9)

A
  • frequency of sexual intercourse (2-3 times per wk)
  • alcohol < 4 units per day
  • Smoking: dec sperm quality
  • caffeine?
  • BMI <30
  • aviod tight fitting underwear & hot baths or saunas
  • certain occupations:chemical exposure
  • complimentary therapies and OTC/recreational drugs
  • antioxidants (good)
24
Q

treatment of male factor infertility? (4)

A
  • intra uterine insemination (for mildly educed sperm count)
  • ICSI (for a very low sperm count)
  • surgical sperm aspiration (in azoospermia)
  • donor sperm insemination (in azoospermia or very low sperm count, genetic conditions, infective conditions)

Reproduction (48 decks)

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