THE MALE REPRODUCTIVE SYSTEM
Exercise 30 A&P 233THE REPRODUCTIVE SYSTEM
Male and female reproductive systems develop from similar embryonic tissue. First few weeks of development, male and female embryos are indistinguishable. Adult reproductive systems share some functional similarities.DESCENT OF THE TESTES
Ovoid structures about 5 cm long and 3 cm wide. Located within the scrotal sac (scrotum) During fetal development they are near the kidneys and slowly move inferiorly in the abdominal cavity. During the 7th month they descend through the inguinal canals* SCROTUM
Sac of skin and superficial fascia that hangs outside the abdominopelvic cavity at the root of the penisContains paired testicles separated by a midline septumIts external positioning keeps the testes 3C lower than core body temperatureWALL OF THE SCROTUM
In the dermis, there is a thin layer of smooth muscle known as the dartos muscle. Contractions of this muscle causes wrinkling of the skin. The cremaster muscle is a thicker layer of skeletal muscle that lowers and raises the testes based on temperature.INSIDE THE SCROTUM
Each testes is enclosed by the tunica vaginalis, a continuation of the peritoneum that lines the abdominopelvic cavity. A fibrous capsule covers each testis called the tunica albuginea.
TESTICLE
* The tunica albuginea gives rise to septa (partitions) that divide the testis into lobules (about 250) Each lobule contains 3 or 4 highly coiled seminiferous tubules These converge to become rete testis which transport sperm to the epididymis*
* SPERMATIC CORD
Contains the structures running from the testicles to the pelvic cavity. Passes through the inguinal canal Contents: Vas Deferens Nerves Blood Vessels* ACCESSORY GLANDS: SEMINAL VESICLES
Lie on the posterior wall of the bladder and secrete 60% of the volume of semen Seminal fluid: Fructose: provides energy for the sperm. Fibrinogen: helps turn semen into a bolus that can be readily propelled into the vagina. Prostaglandins: decrease cervical mucus viscosity and stimulate reverse peristalsis of the uterus. Join the ductus deferens to form the ejaculatory duct* POSTERIOR BLADDER
* POSTERIOR BLADDER* ACCESSORY GLANDS: PROSTATE GLAND
Doughnut-shaped gland that encircles part of the urethra inferior to the bladder Plays a role in the activation of sperm Enters the prostatic urethra during ejaculation Prostatic secretions include: Citrate: is a food source (TCA cycle) Proteolytic enzymes: acts to "decoagulate" the semen that was coagulated by seminal vesicle secretions, which helps the sperm begin their journey once inside the vagina* BULBOURETHRAL GLANDS (COWPER’S GLANDS) Pea-sized glands inferior to the prostate Produce alkaline mucus prior to ejaculation that neutralizes traces of acidic urine in the urethra
*
*
* SEMINIFEROUS TUBULES
* EPIDIDYMISEpididymis: Storage and maturation area for sperm Its head joins the efferent ductules and caps the superior aspect of the testis The duct of the epididymis has stereocilia that: Absorb testicular fluid Pass nutrients to the sperm Nonmotile sperm enter, pass through its tubes and become motile (propelled by peristalsis) Upon ejaculation the epididymis contracts, expelling sperm into the ductus deferens
* SPERMIOGENESIS: SPERMATIDS TO SPERM
* SPERM
Sperm have three major regions Head :contains DNA and has a helmet-like acrosome containing hydrolytic enzymes that allow the sperm to penetrate and enter the egg Midpiece: contains mitochondria spiraled around the tail filaments Tail :a typical flagellum produced by a centriole