Male reproductive tract Flashcards
For conception to occur:
spermatogenesis must be normal
seminal accessory glands must produce seminal fluids
Ducts for sperm transport must be unobstructed
Ejaculation must occur
Spermatozoa must be able to travel to the uterine tubes
Spermatozoa must be capable of functional changes allowing them to fuse with the oocyte
infertility =
Inability of a male and female to achieve pregnancy despite unprotected intercourse for a period of more than 12 months
~15% of all couples are infertile = it’s estimated to be 50/50
Male infertility =
Pretesticular
Testicular
Post-Testicular
Pretesticular Male infertility =
Originate in either the hypothalamus (GnRH) or the pituitary (LH and FSH)
Endocrinopathies most often caused by mutations in genes involved in biosynthesis of hormones, growth factors or receptors
Hormones deficiencies result in loss of intratesticular testosterone production = cessation of spermatogenesis
Hypogonadotropic hypogonadism =
Uncommon cause, however, efficiently treated with hormone replacement therapy
Reduced GnRH production = deficient androgen secretion = deficient spermatogenesis
Pretesticular syndromes:
Prader-Willi Syndrome
Genetic Mutations of X-linked Dax1 or PC1 gene
Biologically inactive LH or FSH due to genetic mutations
Pituitary Mass Lesions
Anabolic steroid abuse
Prader-Willi Syndrome =
Mutations or deletion of a specific locus within paternal chromosome 15 or by maternal uniparental disomy of this locus
Symptoms: obesity, mild or moderate mental retardation, infantile hypotonia, and hypogonadotropic hypogonadism
Anabolic steroid abuse =
Negative feedback at the level of the hypothalamus and pituitary
Reduction in LH and FSH release
Disables endogenous testosterone production and spermatogenesis
Testicular Causes
Varicoceles: abnormally dilated scrotal veins
Klinefelter Syndrome
Cryptorchidism
Epididymitis
Torsion of the spermatic cord
Varicoceles =
are considered the most common cause of subfertility in men
Present in about 15% of male normal male population = ~40% of men presenting with infertility
Varioceles associated with impaired spermatogenesis by one of several mechanisms:
Increased scrotal temperature
Alterations in testicular blood flow
Reduced testicular size
Over production of adrenal steroid metabolites
Increased oxidative stress
Alterations in the hypothalamic-pituitary-gonadal axis
Klinefelter Syndrome =
Most common chromosomal disorde = severely oligospermic (low sperm count)
Increased serum FSH, normal or increased serum estradiol, and normal to low testosterone
Cryptorchidism:
testicular descent does not proceed normally during development = testis remains in the abdominal cavity or groin
3% of full-term newborns, 1-2% by age 6 months
85% of all cases are unilateral
Impaired spermatogenesis in 50-575 of unilateral cases
Exposure to toxins
numerous substances and occupations have been suspected, inadequate study sample size and confounding factors make a casual relationship difficult to confirm
Cigarette Smoking:
associated with a reduction in sperm count and motility and increase in abnormal forms
Lower sperm concentration suspected = spermatogenic outcome uncertain