Male and Female Reproductive Systems. Male Reproductive Anatomy Scrotum – The loose skin and superficial fascia that hangs from the root of the penis.

Male and Female Reproductive Systems

Male Reproductive Anatomy

• Scrotum – The loose skin and superficial fascia that hangs from the root of the penis. It is separated in half by a ridge called a raphe. Each portion or sac contains a single testis. The cremaster muscle holds the testes in place . Relaxation or contraction moves the testes in relation to the body. The testes need to remain 2-3 degrees Celsius cooler than the body for sperm formation to occur (Panpiniform plexus)


• Testes – The testes are paired oval glands in the scrotum. The descend into the scrotum through the inguinal canal during the seventh month of fetal development. Each testical contain 200-300 lobules separated by the tunica albuginea. Each lobule has 2-3 seminiferous tubules that produce the sperm. This process is known as spermatogenesis



• Remember the Sertoli cells of the testes are responsible for producing the sperm, whereas the Leydig cells are responsible for producing testosterone which is responsible for libido (sexual drive)


• Epididymis – functionally the epididymis is the site of sperm maturation, the process by which sperm acquire motility and are able to fertilize an oocyte. This process takes about 14 days. The ductus epididymis store sperm for short periods of time and helps to propel it during sexual arousal by peristaltic action of the smooth muscle into the vas deferens (ductus deferens)


• Vas Deferens – the vas deferens is continuous with the epididymis. The vas deferens stores sperm for up to several months. The vas deferens conducts the sperm into the urethra. Sperm that is not ejaculated is eventually reabsorbed. The vas deferens is what is cut during a vasectomy


• Spermatic Cord – The spermatic cord is an accessory organ contains the testicular artery and vein that carries testosterone in circulation


• Ejaculatory Duct – The ejaculatory duct is formed by the union of the seminal vesicle and the vas deferens. The ejaculatory duct passes through the prostate it secretes sperm and seminal secretions just before the release of sperm into the urethra


• Urethra – The urethra is the shared terminal end for sperm and urine. The urethra is about 8 inches long and passes through the center of the penis. It ends at the external urethral orifice

Male Reproductive Anatomy – Accessory Sex Glands

• The accessory sex glands secrete most of the liquid portion of the semen that protects the sperm and facilitates their movement. The accessory sex glands include the seminal vesicles, the prostate and the bulbourethral gland


• Seminal Vesicles – The seminal vesicles or seminal glands secrete an alkaline viscous fluid that contains fructose. The alkaline fluid neutralizes the acidic environment of the urethra (helps kill bacteria) and the female reproductive tract. The fructose is used for ATP production by the sperm. It helps to contribute to sperm motility and constitutes 60% of the semen volume


• Prostate – The prostate is about the size of a golf ball. The prostate secretes a milky, slightly acidic fluid that contains citric acid (used by sperm for ATP production via the Krebs cycle), proteolytic enzymes, involved in fertilization and seminalplasm an antibiotic to kill naturally occurring bacteria in the female reproductive tract. Prostate secretions make up 25% of the ejaculate (prostate specific antigen – PSA)


• Bulbourethral gland (Cowper’s gland) – are pea sized paired organs that secrete alkaline fluids and mucus that lubricates the end of the penis and decreases the number of sperm damaged during ejaculation

Semen

• The semen is a mixture of liquids that consists of secretions from the seminiferous tubules, seminal vesicles, prostate and bulbourethral glands. The volume of semen is between 2.5 – 5 ml with 50-150 million sperm/ml. Semen is clear. The secretions of the prostate gland give it its milky appearance

Arousal and Ejaculation

• Remember that arousal is controlled by the parasympathetic nervous system, wheras ejaculation is controlled by the sympathetic nervous system. A convenient mnemonic devise is Point and Shoot (parasympathetic and sympathetic)


• Penis – The penis contains the urethra and is the passageway for semen and the excretion of urine. The body of the penis is composed of three cylinders the two larger corpora cavernosa and the middle smaller corpus spongiosum. This tissue contains the erectile tissue that fills with blood during erection and helps to keep the urethra open until after ejaculation


• Penis – At the distal end of the penis is the slightly enlarged glans penis which contains the slit like opening of the urethra. In non-circumcised males this is covered by the foreskin. The suspensory ligament holds the penis to the body


• Ejaculation – The powerful release of semen due to peristaltic action is a sympathetic reflex coordinated by the nerves of the lumbar spine. During ejaculation the sphincter of the bladder closes to prevent simultaneous urination. After ejaculation arteries supplying the erectile tissue constrict reducing blood flow and making the sinus smaller, the veins drain away the blood and the penis becomes flaccid

Fertilization – it takes about three days for the rapidly dividing zygote to exit the fallopiantube and reach the uterus where it settles down and begins the process of placentation

At this point of development the structures that eventually form the face and neck are becoming evident. The heart and blood vessels continue to develop. And the lungs, stomach, and liver start to develop. A home pregnancy test is now positive.

4 Weeks

Fetal Development at 8 Weeks

The baby is now a little over half an inch in size. Eyelids and ears are forming, and the tip of the nose is visible. The arms and legs are well formed. The fingers and toes grow longer and more distinct.


The fetus measures about 2 inches and starts to make its own movements. You may start to feel the top of your uterus above the pubic bone. Your doctor may hear the baby's heartbeat with special instruments. The sex organs of the baby should start to become clear.


The fetus now measures about 4.3 to 4.6 inches and weighs about 3.5 ounces. The top of your uterus should be felt about 3 inches below your belly button. The baby's eyes can blink and the heart and blood vessels are fully formed. The baby's fingers and toes should have fingerprints.


The baby weighs about 10 ounces and is a little over 6 inches long. Your uterus should be at the level of your belly button. The baby can suck a thumb, yawn, stretch, and make faces. Soon -- if you haven't already -- you'll feel your baby move, which is called "quickening."

Time for an Ultrasound

An ultrasound is generally performed for all pregnant women at 20 weeks of gestation. During this ultrasound, the doctor will confirm that the placenta is healthy and attached normally and that your baby is growing properly in the uterus. The baby's heartbeat and movement of its body, arms, and legs can also be seen on the ultrasound. The gender of the baby can usually be determined at 20 weeks.


The fetus weighs about 1.4 pounds now. It responds to sounds by moving or increasing its pulse. You may notice jerking motions if it hiccups. With the inner ear fully developed, it may be able to sense being upside down in the womb.


The fetus weighs about 2 pounds 6 ounces. It changes position frequently at this point in pregnancy. There's a good chance of survival if your baby is born


Often moving, the fetus weighs almost 4 pounds. The baby's skin has fewer wrinkles as a layer of fat starts to form under the skin. It will gain up to half its birth weight between now and delivery.


Babies differ in size, depending on many factors (such as gender, the number of babies being carried, and size of the parents), so your baby's overall rate of growth is as important as the actual size. On average, it's about 18.5 inches and weighs close to 6 pounds. The brain has been developing rapidly. Lungs are nearly fully developed. The head is usually positioned down into the pelvis by now. A pregnancy is considered "at term" once 37 weeks has been completed!

Birth!

A mother's due date marks the end of her 40th week. A pregnancy begins with implantation and the delivery date can be calculated using the first day of the last period. Based on this, pregnancy can last between 38 and 42 weeks with a full-term delivery occurring around 40 weeks.