Download HUMAN REPRODUCTION BIOLOGY 269

So far, we have discussed sexual anatomy and physiology, sexual
response, fertilization, and early development with the assumption that
everything works correctly. That is often not the case.
Overall, with frequent unprotected sexual intercourse:
50% of couples will conceive within three months
70% of couples will conceive within six months
Failure to conceive within one year of
unprotected intercourse is clinically
defined as infertility
May involve one or both partners
Men and women involved ~ equally
10 - 15% of couples in US have fertility problems
Disorders of sperm production:
No sperm produced
Defects in testes
Undescended testes (cryptorchidism)
Pituitary fails to stimulate spermatogenesis
Infection or inflammation destroys seminiferous tubules
Insufficient number of sperm produced
Damage to testes
Insufficient stimulation by pituitary
Infection or inflammation of testes
Stress
Obesity
Increased temperature of testes
Damage to nerve or blood supply to testes
(most common cause is varicocele)
Some drugs used in treating tumors or infections
Aging
Disorders of male reproductive tract:
Abnormal function of epididymis
Usually due to hormonal disorders
Abnormal function of prostate or seminal vesicles
Infection / inflammation
Damage to their nerves or blood supplies
Some hormonal disorders
Tumors
Some drugs used in treating tumors or infections
Aging
Blockage of vas deferens, ejaculatory duct, or urethra
Usually caused by infection / inflammation
Scarring from trauma
Birth defects
Disorders of erection
Inability to get or keep erection, or erection too soft
(erectile dysfunction or impotence):
Stress / psychological issues
Damage to nerves or blood vessels supplying penis
Damage to erectile bodies
Various drugs used to treat hypertension, high cholesterol, heart disease,
kidney disease, liver disease, and others
Smoking, alcohol
Steroid abuse
Poor nutrition
Disorders of erection
Inability to get or keep erection, or erection too soft
(erectile dysfunction or impotence):
Stress / psychological issues
Damage to nerves or blood vessels supplying penis
Damage to erectile bodies
Various drugs used to treat hypertension, high cholesterol, heart disease,
kidney disease, liver disease, and others
Smoking, alcohol
Steroid abuse
Poor nutrition
Abnormally persistent erections (Priapism)
Damage to nerves or blood vessels
Trauma to erectile bodies preventing blood from flowing out
Disorders of ejaculation
Premature ejaculation (before or very early in intercourse)
Psychological stress
Overstimulation
Insufficient volume of semen
Usually secondary to disorders of prostate or seminal vesicles
Orgasm without ejaculation:
Blockage of ejaculatory duct and/or urethra
Prostate and seminal vesicles unable to form semen
Treatment for male infertility typically involves:
Decreasing physiological and psychological stress
Lowering temperature of testes to increase sperm production
Limiting intercourse to increase number of sperm / ejaculation
Stopping tobacco, alcohol, or drug use
Correcting nutritional issues
Antibiotic treatment of infections
Surgical correction of varicocele
or blockages
Hormone supplementation
Erectile dysfunction drugs
Similar problems seen in women:
Disorders of ovulation:
No oocytes produced or oocytes produced at irregular intervals
Defects in ovaries
Damaged blood supply to ovaries
Pituitary fails to stimulate oogenesis
Stress
Obesity
Strenuous exercise
Excessive weight loss
Some drugs used in treating
tumors or infections
Estrogen and/or progesterone
Aging
Disorders of female reproductive tract:
Blockage of Fallopian tube
Usually caused by infection / inflammation
Scarring from trauma or ectopic pregnancies
Birth defects
Fallopian tube unable to transport sperm and/or preembryo
Usually secondary to insufficient estrogen and/or progesterone from ovaries
Poor nutrition
(Disorders of female reproductive tract)
Uterus will not support implantation and embryo
Infection or inflammation
Insufficient estrogen and/or progesterone from ovaries
Tumors
Endometriosis
Usually associated with hormonal disorders
Cervical scarring
Usually caused by infection
Vaginal constriction or inadequate lubrication
Failure of arousal
Insuffient estrogen and/or progesterone
x
Treatment for female infertility typically involves:
Decreasing physiological and psychological stress
Stopping tobacco, alcohol, or drug use
Correcting nutritional issues
Antibiotic treatment of infections
Surgical correction of endometriosis
or blockages
Hormone supplementation
Treatment for infertility:
In many cases where other treatments
do not work, a couple will use in-vitro
fertilization and embryo transfer.
May involve sperm and eggs of both parents,
or
May involve donated sperm or eggs.