Spermatogenesis & male infertility Flashcards
What determines gender?
Chromosomal sex (XY chromosome pair) Gonadal sex (foetus with ovaries/testes) Genital sex (testes secrete hormones/are absent) Gender (perceived genital sex + upbringing)
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
- 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
what controls the differentiation of the external genitalia?
Dihydrotestosterone which stimulates the development of the male external genitalia
see diagram of development of the internal and external genital tracts pls
look at the thing yes
- what is Androgen insensitivity syndrome?
- presentation
- features?
-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
Descent of the testes
- what is descent dependent on?
- importance of descent?
- clinical name?
- management
- 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
What is the function of the testis?
-where do these functions occur
Spermatogenesis & production of testosterone
-spermatogenesis- seminiferous tubules
production of testosterone- Leydig cells
- name of a single mature sperm?
- where is the acrosome and what does it contain?
a spermatozoon
-under the plasma membrane at the head of the sperm
contains enzymes to penetrate the zona falicuda and into the ovum
sertoli cells
give the 6 functions of sertoli cells
-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)
how is GnRH released in the male?
- what does FSH stimulate in the male?
- What does LH stimulate in the male?
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
GRH
- type of molecule?
- pattern of release?
- action?
- feedback control?
- 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
LH & FSH
- what does LH do?
- What does FSH do?
- pattern of production?
- acts on leydig cells- regulates testosterone secretion
- acts on sertoli cells and enhances spermatogenesis, neg feedback from inhibin
- non-cyclical
testosterone
- produced where?
- derived from what?
- secreted where?
- has what effect? (before birth, at puberty, adulthood)
- 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
inhibin & Activin
- secreted by what?
- what hormone do they control?
- sertoli cells
- feedback on FSH, inhibit inhibits and action stimulates
describe what happens to spermatozoa after ejaculation?
- 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)
give the functions of:
- Epididymis & vas deferens
- Seminal vesicles
- prostate gland
- Bulbourethral glands
- 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
describe the route sperm takes to exit the male?
- what controls an erection?
- what controls ejaculation
Testes, epididymis, vas deferens, ejaculatory duct, urethra
- the PS
- the sympathetic NS
definition of male infertility?
-name the different causes of male infertility (obstructive (4)/non-obstructive (8))
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
Name the endocrine causes of male infertility? (7)
-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
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?
-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
Obstructive infertility
- clinical features
- endocrine features
-normal testicular volume
normal secondary sexual characteristics
vas deferens might be absent
-normal LH, FSH & testosterone
Non-obstructive
- clinical features
- endocrine features
-low testicular vol
reduced secondary sexual characteristics
vas deferens present
-high LH, FSH & low testosterone
Treatment of male infertility:
what lifestyle areas should be addressed? (9)
- 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)
treatment of male factor infertility? (4)
- 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)
