Male And Female Reproductive Systems (Anatomy)

Question 1

Describe the components and function of the male reproductive system and its associated accessory organs

Answer 1

• The male reproductive system serves to produce sperm and introduce them into the female body.

Testes

• Suspended within the scrotum.
• Surrounded by a dense connective tissue called the tunica albuginea.
• Connective tissue septa extend from the tunica albuginea into the parenchyma and dividing each testis into lobules.
• Each testis contains approximately 800 tightly coiled seminiferous tubules.
• The testes are responsible for producing sperm and testosterone.

Epididymis

• Posterior aspect of the testis.
• Highly coiled with a head, body, and tail.
• Lined with pseudostratified columnar columnar epithelium with stereocilia.
• Smooth muscle around the outside so that it can contract and propel sperm.
• Stores sperm and recycles immature sperm.

Ductus deferens/ vas deferens

• The duct of the epididymis straightens out at the tail, turns 180 degrees, and becomes the ductus deferens.
• It ascends into the abdominopelvic cavity via the spermatic cord, through the inguinal canal.
• The wall of the duct is composed of thick smooth muscle and is lined with columnar epithelium with stereocilia.
• The ductus deferens can store sperm for several months.
• After passing between the bladder and ureter, the duct turns downward behind the bladder and widens into a terminal ampulla.
• The ductus deferens ends by uniting with the duct of the seminal vesicle.

Seminal vesicles - 60% of semen volume

• Tubular gland
• Joins with the ductus deferens to form the ejaculatory duct.
• Secrete glycoproteins which provide energy for sperm.

Prostate gland - 30% of semen volume

• Small muscular organ which encircles the prostatic urethra.
• Produces a weakly acidic, thin, milky fluid which protects sperm as they pass through the prostate.

Bulbourethral glands (Cowper’s Glands) - 5% of semen volume

• Empties into the penile urethra.
• Secretes thick alkaline mucus which protects the sperm against the acidic urethra.

Penis

• The shaft consists mainly of three cylindrical bodies called erectile tissues.
• An erectile body called the corpus spongiosum passes along the ventral side of the penis and encloses the penile urethra. It expands at the distal end to fill the entire glans.
• Proximal to the glans, the dorsal side of the penis has a corpus cavernosum on each side. Each is ensheathed in a fibrous tunica albuginea and they are separated from each other by a median septum. When filled they make the penis become erect.

Question 2

Describe the main histological features of the sites of sperm production within the testis (seminiferous tubules) and relate these to the fact that they are lined by Sertoli cells and developing germ cells (spermatogonia, spermatocytes, spermatids)

Answer 2

Seminiferous tubules
- Each tubule is about 80cm long.
- Site of spermatogenesis.
- Contain germ cells (outermost to innermost):
Spermatogonia (stem cells)
Primary spermatocytes (diploid)
Secondary spermatocytes (haploid)
Spermatids (haploid)
Spermatozoa (haploid)
- Lined by Sertoli cells which:
Maintain the blood-testis barrier
Support spermatogenesis
Support spemiogenesis

Question 3

Describe a typical spermatozoon

Answer 3

• Lacks many organelles.
• Lacks an energy reserve and therefore absorbs nutrients from surrounding fluid.
• Functionally immatures (has to undergo capacitation to be functionally mature.
• Incapable of coordinated locomotion.
• The head contains the nucleus and the acrosome which contains enzymes to help penetrate the ovum.
• The midpiece contains mitochondria for energy.
• The flagellum allows for movement.

Question 4

Describe the components and function of the female reproductive system and its associated accessory organs

Answer 4

Ovary

• Outer layer of dense connective tissue called the tunica albuginea.
• The germinal epithelium is classified as a simple cuboidal epithelium.
• The interior of the ovary is divided into a central medulla and an outer cortex.
• The medulla is a core of fibrous connective tissue and large arteries and veins. The cortex is the site of ovarian follicles each of which consists of one developing ovum surrounded by numerous follicular cells.

Fallopian tube

• Canals about 10cm long leading from each ovary to the uterus.
• At the distal end it flares into a structure called the infundibulum with feathery projections called fimbriae. The middle and longest part is called the ampulla. Near the uterus it forms a narrower isthmus.
• Enfolded in the mesosalpinx, which the superior margin of the broad ligament.
• Surrounded by concentric layers of smooth muscle, and has a highly folded mucosa with a ciliated columnar epithelium.
• The cilia beat the egg towards the uterus with the help of muscular contractions.

Uterus

• Its function is to harbour the foetus, nourish it, and expel it at the end of its development.
• Under normal conditions it tilts forward over the urinary bladder.
• The uterine wall consists of three layers: the perimetrium (simple squamous epithelium); the myometrium (middle thickest layer); and the endometrium.

Question 5

Describe the histological features of the ovary with particular regard to the development of the oocyte.

Answer 5

Primordial follicle

• Consists of a primary oocyte surrounded by a simple squamous layer of follicular cells.
• Follicle-stimulating hormone triggers the start of the ovarian cycle.

Primary follicle

• Consists of a primary oocyte, several layers of follicular cells, and the zona pellucida (glycoprotein gel).
• The follicular cells increase in size and produce hormones for the developing oocyte.

Secondary follicle

• Distinguished by multiple layers of follicular cells which are now called granulosa cells.
• The follicle is now enclosed by the tough theca folliculi. This has a rich supply of blood vessels which deliver nutrients, hormones, and cholesterol to the oocyte.
• Before ovulation, the granulosa cells begin secreting follicular fluid which pools in the follicle wall. As these pools enlarge, they merge and become a single fluid-filled cavity called the antrum.
• On one side of the antrum is a mound of granulosa cells called the cumulus oophorous which covers the primary oocyte and secures it to the follicle wall.
• The innermost layer of cells of the cumulus oophorous, surrounding the oocyte, forms the corona radiata.

Tertiary (Graafian) follicle

• The primary oocyte has now become a secondary oocyte.
• It captures and sequesters follicle-stimulating hormone.
• It stretches the ovarian wall, creating a permanent bulge on the surface of the ovary.
• In the last day of ovulation, the oocyte and cumulus oophorous break away from the follicle wall and float freely in the antrum, ready for ovulation.

Question 6

Briefly describe histological features of other reproductive organs such as the epididymis, fallopian tubes, and uterus

Answer 6

Epididymis
- Posterior aspect of the testis.
Epididymis
- Highly coiled with a head, body, and tail.
- Lined with pseudostratified columnar epithelium with stereocilia.
- Surrounded by smooth muscle on the outside.
- It stores sperm and recycles immature sperm.

Fallopian tubes

• Highly folded mucosa with a ciliated columnar epithelium.
• Surrounded by concentric layers of smooth muscle which when contracted enhance the movement of the cilia.
• The cilia increase the surface area and create currents when they beat which propels the egg and sperm for fertilisation.

Uterus

• Has three layers of smooth muscle called the perimetrium, myometrium, and endometrium.
• The perimetrium is the outermost layer. It is a thin serosa of simple squamous epithelium and loose connective tissue.
• The myometrium is the middle and thickest layer. Composed mainly of bundles of smooth muscle. The myometrium produces the contractions that help expel the foetus.
• The endometrium has a simple columnar epithelium, compound tubular glands, and a lamina propria populated by leukocytes. The superficial half is called the stratum functionalis and is shed in each menstrual period. The deeper layer is called the stratum basalis which stays behind and regenerates a new functional layer in the next cycle.