The causes of a reduced reproductive function (hypogonadism) may be
classified according to the origin of the disease. Pre-testicular factors are due to
alterations in the central regulation and the hypothalamic-pituitary-testis axis, while
testicular factors (from primitive testicular alterations) manifest themselves as
hypergonadotropic hypogonadism and are a major cause of azoospermia and
oligozoospermia. When post-testicular factors are present, the reproductive and
endocrine functions are normal but there is an obstacle to semen outflow because of
occlusions, infections and inflammation of the genital tract. Genetic factors such as
karyotype abnormalities, microdeletions of the Y chromosome mutations and
polymorphisms are discussed extensively.
Keywords: Anejaculation, Anorchia, Cryptorchidism, Cystic Fibrosis, Endocrine
Disruptor, Germinoma, Hypogonadism, Kallmann Syndrome, Klinefelter
Syndrome, Laurence-Moon Syndrome, Lowe syndrome, Microdeletions of the Y
Chromosome, Obstructive Azoospermia, Papillomavirus, polymorphism, Prader-
Willi Syndrome, Retrograde Ejaculation, Robertsonian Translocation, Testicular
Dysgenesis, Varicocele.
