The Reproductive System The Pelvis and Perineum l

The Reproductive System

The Pelvis and Perineum l Pelvic wall is formed by a. Pelvic girdle b. Sacrum c. Os coxae (ilium, ischium, and pubis)

l The three os coxae bones (innominate bones) come together to form the ACETABULUM (hip socket). l The PELVIC BRIM is a line that separates the FALSE PELVIS (superior to the brim) and the TRUE PELVIS (inferior to the brim).

l The pelvic inlet is also formed by the PROMONTORY of the sacrum and a line drawn to the pubic symphysis. l The PELVIC OUTLET is formed by a line from the inferior edge of the pubic symphysis to the tip of the coccyx and the plane extends laterally to the two ISCHIAL TUBEROSITIES.

l The pelvic inlet in females is wider than deep. l The male pelvic inlet is heart shaped. l The outlet of the female is round while on the male it is deeper than it is wide. l In the female, the wide outlet leads to a wide PUBIC ARCH.

Gender Differences in the Pelvis MALE CHARACTERISTIC FEMALE Less forward Tilt Far forward Heavier thickness Lighter Large, closer together Acetabulum Small, farther apart Acute, 50 -60 degrees Pubic arch Round, 80 -90 degrees Narrow, longer sacrum Wider, shorter Narrow, heart shaped Pelvic inlet (brim) Wider, oval Narrow Pelvic outlet wider

l There is no barrier that separates the abdominal and pelvic cavities. Therefore, intestines can drop into the pelvis and the bladder and uterus (females) can ascend into the abdomen. l In males: RECTOVESICULAR POUCH l In females: RECTOUTERINE POUCH

l These pouches are sacs within the posterior portions of the pelvic cavities. Debris can accumulate in these cavities and be a source of infection. l The peritoneal fluids circulate within these pouches. l The bladder and uterus are outside the peritoneum (retroperitoneal)

The PELVIC DIAPHRAGM -muscular barrier across the pelvic outlet. -prevents pelvic contents from falling out. -LEVATOR ANI muscle (anterior)-raises the anus -COCCYGEUS muscle is posterior and smaller

The EXTERNAL SPHINCTER ANI is voluntary l The INTERNAL SPHINCTER ANI is involuntary and part of the rectum. l There is an opening in the levator ani (urogential diaphragm) for the UROGENITAL TRIANGLE and ARCH. This is where the urogenital organs pass. l

Reproduction l l A species goal is to reproduce. 2 types: 1. ASEXUAL (without sex) a. 1 partner b. Parent and children are identical 2. SEXUAL a. 2 cells combine (fertilization) b. Children are similar but not identical to parents.

l Sex cells (sperm and egg) are made by MEIOSIS. This form of cellular reproduction reduces the number of chromosomes by half. 23 chromosomes per egg 23 chromosomes per sperm 46 chromosomes per zygote (fertilized egg)

Humans are SEXUALLY DIMORPHIC. There are two distinct forms. The primary sex organs are the TESTES (male) and OVARIES (female). They produce sex cells called gametes. They are also MIXED GLANDS. In females, all meiosis is complete before birth-therefore, all the eggs that will be present are there at birth. They are dormant. In males, meiosis begins at puberty. Therefore, spermatozoa will be produced throughout the males life from puberty to death.

l The gonads (testes and ovaries) produce hormones. They are endocrine glands. 1. Testosterone in males 2. Estrogen and Progesterone in females

l Sexual Accessory Organs help get the gametes to where they have to go: Males: tubules, penis Females: vagina, uterus, cervix, oviducts

Secondary Sex Characteristics l l Due to hormones. Have nothing to do with reproduction. They include: 1. Facial and body hair 2. Voice changes 3. Mammary glands capable of milk production 4. Increased musculature 5. Shoulders, range of motion increase 6. Increase in adipose tissue (fat) in female hip and buttocks 7. Aggression increases 8. Sex drive increases

THE MALE l Urine and semen both travel through the same tube (urethra) l There is a cord from the inguinal ligament to the scrotum. This the SPERMATIC CORD which contains blood vessels, nerves, and vas deferens.

l The URETERS from the kidneys lead to the caudal end of the bladder. The URETHRA passes caudally from the bladder. l A short distance down the urethra you will find the PROSTATE GLAND. Inferior to this gland is the ROOT of the penis.

SPERMATIC FASCIA is the covering for the spermatic cord. The spermatic cord ends in a sac that contains the testes. l The testes are oval shaped. Which contain the SEMINIFEROUS TUBULES. l Remember, the testes begin in the abdominal cavity and descend into the scrotum. l As they descend, the inguinal ligament evaginates and the spermatic fascia is formed form the aponeuroses of the inguinal ligament. l

The peritoneum lining the fascial sac is the TUNICA VAGINALIS. l Within the spermatic cord are muscle fibers from the internal oblique muscle. This forms the CREMASTER MUSCLE. When it contracts, this muscle lifts the testicle. This is important in maintaining an adequate temperature for sperm production. l

l The scrotum is the outer skin and muscle covering the testicles. The muscle within the scrotum is the DARTOS MUSCLE. l This muscle is responsible for wrinkling the skin of the scrotum also helping in keeping a stable, cooler temperature.

l The EPIDIDYMIS is attached to the testis. It has a head, body, and tail which empties into the vas deferens. l The testicle is covered by a “visceral” layer called the TUNICA ALBUGINEA.

l Internally, the testis has a network of SEMINIFEROUS TUBULES which combine to form a layer of ducts called the RETE TESTIS. The VAS EFFERENS are another layer that leads to the epididymis. l Sperm is stored in the epididymis

Whole Fetal Testis The human (5 1/2 month fetal) testis is covered by a dense fibrous tunica albuginea which contain developing blood vessels.

1 – seminiferous tubules 2 – sperm 3 – spermatid 4 – spermatocyte 2 5 – spermatocyte 1

Sperm finishes its development in the epididymis-gains a tail and its shape is streamlined. l The head of the sperm contain enzymes that dissolve the COROLLA of the ovum. l The vas deferens connects to the SEMINAL VESSICLES via the SEMINAL DUCT. After this the vas deferens is called the EJACULATORY DUCT. l

Sperm Identify the head, mid-piece, and tail. Notice the light staining acrosome at the tip of the head

Penis This cross section of the penis shows the erectile tissues of both the corpus spongiosum (lower right) and one of the corpora cavernosa (upper left).

The urethra pass through the prostate gland has many fenestrations. The prostate dumps materials into the semen through these holes. The ejaculatory duct empties into the PROSTATIC URETHRA. l The prostatic urethra is connected to the BULBOURETHRAL GLANDS or COWPER”S GLAND. Here lubricants are added to the semen. After this gland, the semen enters the PENILE URETHRA from which it leaves the body. l The root of the penis is anchored to the body. The root has a bulb in the enter and two wings (crura) on either side. l

l The penis itself is made of three cylinders of spongy tissue. 1. 2 corpus cavernosum 2. 1 corpus spongisoum The spongiosum contains the penile urethra. The spongy tissue in all three cylinders contain spaces which become engorged with blood during sexual arousal – erection.

l These three cylinders compose the BODY of the penis. l The body ends in the GLANS. l Erection is an PARASYMPATHETIC response. l Ejaculation is a SYMPATHETIC response.

For Your Information…. . l There are collagen fibers that run on the outside surface of the erectile tissue. This collagen lies at right angles to the circular fibers in the shaft. This design is to prevent the erect penis from buckling or kinking during intercourse.

Identify the Following: Penis bladder Testicle rectum Epididymis sacrum Vas deferens prostate gland Ureter bulbourethral gland Urethra seminal vessicle Corpus spongiosum Corpus cavernosum Glans Scrotum Pubic symphysis seminal duct crus of penis

THE FEMALE In the female cat, cut through the pubic symphysis. You will see a VESTIBULE. The urethra empties into the vagina through the UROGENITAL SINUS. l In humans, the urethra empties into the vestibule with the vagina. l At the end of the vagina, you will see the opening into the uterus. This is the CERVIX. l

Vaginal mucosa Endocervical opening uterus

The UTERUS is a pear-shaped, muscular organ. This is where a fertilized egg implants for development. The inferior end of the uterus is called the INTERNAL OS, which communicates with the cervix. The EXTERNAL OS is the vaginal communication. l Superior to the uterus are the openings for the OVIDUCTS. These tubes connect the uterus to the OVARIES. l The end of the oviduct forms a funnel, or INFUNDIBULUM. There is a space between the ovary and infundibulum. l

The cervix protrudes into the vaginal cavity. Here it is called the FORNIX. It has an anterior, posterior, and lateral section. l The peritoneal cavity of the female is open as the vagina ultimately leads to the infundibulum. The peritoneal cavity of males is closed. There is no entrance into the abdomen from any male pelvic organ. l

l The GREATER VESTIBULAR GLANDS (Bartholin’s Glands) are along the lateral margin of the bulb of the vestibule. They secrete a mucus substance for lubrication during sexual intercourse.

Identify the Following: Pubic symphysis Sacrum Clitoris Labia Linea alba Uterus Rectum Anus Vagina Ovary Oviduct Infundibulum

l After sperm is deposited into the vagina, they must swim toward the cervix. After entering the cervix, sperm must then find their way to one of the oviduct. Fertilization usually occurs in the distal 1/3 of the oviduct. The ZYGOTE (result of fertilization) then travels back to the uterus for implantation.

l It takes 5 days for the zygote to reach the uterus. By the time it reaches its place of implantation, it is multicellular. l At 6 weeks, you cannot distinguish between a male and female zygote. l DIFFERENTIATION-cells change to form specific structures.

cleavage morula fertilization fundus ovum blastocyst Ovarian ligament ovary body implantation fimbria follicle fornix cervix Cervical opening vagina Ovulation occuring

Ovary with corpus luteum

Here is the size of the uterus in the third trimester. Note how it displaces the bowel superiorly and fills the lower abdomen. (This unfortunate woman died accidentally, and the baby died too).

l If the fetus is a male, the gonads will descend along the GUBERNACULUM, through the INGUINAL CANAL and the WOLFFIAN DUCT. The MULLERIAN DUCT in a male becomes associated with the kidney. If it is a female, the MULLERIAN DUCT becomes the female tube system. The gubernaculum becomes the round ligments of the ovary and uterus (female)

So, what happens to the embryonic structures? MALE FEMALE A small cord anchoring the testis to the tunica vaginalis Path of descent for embryonic testis Gubernaculum Round ligament of uterus and ovary Associated with kidney and forms part of urinary tract Mullerian Duct Female tube system Tube system Wollfian Duct Associates with kidney and becomes part of the urinary system

l There are small cilia attached to the infundibulum and within the oviduct. l These cilia push the egg (ovum) along the length of the tube. The OVUM is the largest cell in the body.

The peritoneum that extends to the ovary is called the MESOVARIAN LIGAMENT. l The mesentery to the uterus is the BROAD LIGAMENT. l The ROUND LIGAMENT of the ovary and the ROUND LIGAMENT of the uterus both pass through the broad ligament. l The two round ligaments are remnants of the GUBERNACULUM, an anchor for the ovaryuterus and uterus-inguinal ligament. l

l The following structures are HOMOLOGS (structures that have same origin but different functions in the two sexes) Testes : ovaries Oviduct : male urinary tract Vas deferens : female urinary tract

The Perineum Location: from the pelvic diaphragm to the skin. l In reality: everything from the external genitals to the anus. This includes skin, arteries, fat, veins, capillaries, nerves, and lymphatics. l It is divided into two triangles: a. Anterior urogenital triangle b. Posterior anal triangle l

l If we were make a coronal section we would see: The urogenital diaphragm - supports the urogenital structures Superior to the UGD is the DEEP PERINEUM. Inferior to the UGD is the SUPERFICIAL PERINEUM.

l If we expose the inferior surface of the anterior urogenital triangle, we cannot see the levator ani because it is covered by the UGD. l The bulb of the penis is anchored to the UGD by the BULBOSPONGIOSUS MUSCLE.

l The crura (wings) of the penis are anchored to the ischium by the ISCHIOCAVERNOSUS MUSCLE. l These muscles help to expel semen during ejaculation. l In the female, the perineum is diamond shaped (as in the male)

The PERINEAL BODY extends and attaches to the anal opening. l An EPISIOTOMY is an incision into the perineal body to prevent tearing during childbirth. An incision is much easier healed than a tear. l In the female, the bulb and crura (bulbocavernosus and ischiocavernosus) come together to form the body of the CLITORIS. l The penis and clitoris are homologs. l