Reproductive System
Directions
- Print this PDF worksheet for a hardcopy guide as you work through this lesson.
- Within the lesson click the red linked headings to bring up the desired starting point within the cadaver for your work.
- Use the provided images on the worksheet to annotate and identify specific anatomical structures.
Welcome back for one last journey down anatomy lane! This trip takes us through our final system but obviously we have two clearly gender differentiated systems. As chivalry dictates, ladies first.
The female reproductive system is designed to produce a monthly secondary oocyte AND to support the developing embryo and fetus through the gestation period. We'll begin our examination at the superior end of this system and generally work our way through.
- Suspensory Ligament - The suspensory ligament anchors the ovary to the superior pelvic wall.
- Broad Ligament - Locate the several parts of the broad ligament which anchor the ovary to the uterus as well as the uterus to the pelvic wall.
- Ligament of the Ovary - This ligament also connects the ovary to the uterus.
These ligaments hold the ovaries in place within the pelvic cavity. Dissect them away to clearly reveal the following:
- Ovaries - The ovaries produce secondary oocytes that develop into ova if fertilization occurs. They also are primary endocrine glands producing progesterone and estrogens, the female sex hormones.
- Uterine Tubes - Also called fallopian tubes or oviducts, these tubes are about 10 cm (4 inches) long and provide a route for sperm to reach an ovum and transport secondary oocytes, or fertilized ova, from the ovaries to the uterus.
- Fimbria - Examine the inferior end of the left uterine tube (the right uterine tube has fimbria too, but it is not as visible from this perspective as it is on the left side of your specimen). Note that it ends in an apparent fringe, the fimbria, which is actually a set (or collection) of small finger-like projections. These projections "sweep" up a released secondary oocyte from the ovary moving it into the uterine tube.
- Uterus - The uterus serves as the passageway for an unfertilized outbound secondary oocyte, inbound sperm, and as implantation and development site for a fertilized ovum. The uterus is the source of menstrual flow if fertilization does not occur. Not specified in your specimen, the cervix is the narrow inferior portion of the uterus that opens to the vagina.
- Round Ligaments - These are bands of fibrous connective tissue that connect from the uterus just inferior to the uterine tube junction to a point on the labia majora (part of the external anatomy).
- Vagina - At about 10 cm long, this canal is the receptacle for the penis during intercourse and the outlet for both menstrual flow and childbirth. It is situated between the urinary bladder and the rectum and attaches directly to the uterus.
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Vulva - The vulva is the collective term for the female external genitalia, which includes:
- Clitoris - This small cylindrical mass of erectile tissue is homologous to the glans penis in males. As with males, the clitoris is capable of enlargement upon tactile stimulation and has a role in female sexual excitement.
- Labia Majora (Majus = singular) - Homologous to the male scrotum, this pair of external longitudinal folds are covered by pubic hair and contain an abundance of adipose tissue, sebaceous oil glands, and apocrine sudoriferous (sweat) glands.
- Labia Minora (Minus = singular) - Medial to the labia majora are these two smaller skin folds. They are devoid of pubic hair and fat and have few sudoriferous glands. They do, however, contain many sebaceous glands. The labia minora are homologous to the male spongy urethra.
On we go to the other half of reproduction. The male reproductive system has evolved for production and delivery of sperm as well as joint functions with the urinary system.
Let's begin by dissecting away the external & internal spermatic and cremasteric fascia. Next, rotate your specimen for a lateral perspective and identify:
- Testis (Left) - First, notice some asymmetry in our specimen in that he only has a left testis as the right testis was surgically removed. The testes are the sites of both sperm formation and testosterone production.
- Epididymis - The epididymis is primarily composed of a tightly coiled tubule, the ductus epididymis which receives immature spermatids from the testis. Sperm maturation occurs here by acquiring a flagellum for motility and the ability for ovum fertilization. Maturation of the sperm occurs over a 14 day period. The epididymis is also involved in propelling sperm into the ductus (vas) deferens during sexual arousal via peristaltic movements along its length. If stretched out, the ductus epididymis would be about 20 feet long! The epididymis can store viable sperm for several months!
- Ductus Deferens - At the inferior end of the epididymis (the tail) the ductus epididymis becomes less convoluted and its diameter increases. At this point it ascends and is known as the ductus, or vas, deferens. The ductus deferens transports sperm to the urethra during sexual arousal, again by peristaltic contraction of its muscular walls. The ductus is capable of sperm storage, too, for up to several months.
- Spermatic Cord - This is a supporting structure that, as you can see, ascends out of the scrotum and contains the ductus deferens as well as the testicular artery and veins. Dissect away the spermatic cord to fully reveal the ductus deferens.
- Seminal Vesicles - The paired seminal vesicles provide about 60% of semen fluid volume. Included in these fluids is fructose which is used by sperm for ATP production. This fluid is also alkaline which helps neutralize the acidic environment in the male urethra and female reproductive tract that would otherwise inactivate and kill sperm.
- Prostate - Initially, locate this gland from the lateral perspective then, rotate your specimen back to the anterior perspective and you should be able to locate this space along either side of the urethra. The prostate secretes a milky and slightly acidic fluid that contains citric acid for ATP production, proteolytic enzymes that break down the clotting proteins from the seminal vesicles, and seminalplasmin which is an antibiotic that helps decrease the number of naturally occurring bacteria in semen and the lower female reproductive tract. Prostatic secretions make up about 25% of semen volume.
- Bulbourethral Glands (Cowper's Glands) - These small paired glands are not visible within your specimen. They are only about the size of a pea and are located inferior to the prostate on either side of the urethra. During sexual arousal, the bulbourethral glands secrete an alkaline fluid into the urethra that further protects sperm passing through the acidic passageway. These glands also secrete mucus which reduces friction and potential damage to ejaculated sperm.
- Ejaculatory Ducts - First, rotate your specimen to the lateral perspective and dissect away the prostate. This reveals the ejaculatory duct through which sperm and seminal vesicle secretions pass just before the release of semen from the urethra to the exterior.
- Urethra - As indicated in your urinary study, the urethra is the shared terminal duct of both the male urinary and reproductive systems.
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Penis Structure - The penis body is composed of three cylindrical tissue masses which are erectile tissues composed of numerous blood sinuses, namely the:
- Corpora Cavernosa
- Corpus Spongiosum
- Glans Penis
- Root of the Penis - The proximal portion of the penis attached to the body.
- Bulb of the Penis - The expanded portion of the corpus spongiosum base.
That's it, folks!
Self-test Labeling Exercises