Male Reproductive System Anatomy Flashcards
What is urology?
The study of surgical and medical diseases of the male and female urinary tract system and the male reproductive organs
What is andrology?
Medical study of the male reproductive system
What is endocrinology?
Study of biology and medicine dealing with the endocrine system, its diseases, and its secretions
What is the male gamete called?
spermatozoon (singular)
spermatozoa (plural)
What is the reproductive system closely related to and why?
The urinary system. They develop their tubules and ducts so that they are interdependent on each other
What is the common passages way of the urinary system and the reproductive tract in males?
Urethra
What are the four main parts of the male reproductive system?
Two testes/testicles, scrotum, accessory organs (which include ducts and glands), and the penis
What produces spermatozoa/sperm?
Testes
What produces testosterone?
Testes
What is testosterone?
Male sex hormone
What is the function of the scrotum?
Provides a favorable environment for production and maturation of spermatozoa
What is a benefit of sperm cells that egg cells don’t have?
They’re a type of cell that is easy to be produced, so they can be produced quickly in mass quantities
What plays a role in ease of sperm cell production?
Temperature
What is the ultimate goal of the spermatozoa?
Reaching the ovum of the female in a condition that allows fertilization of the ovum
What structures help the spermatozoa reach the ovum?
Epididymis, ductus deferens, urethra, penis, and accessory sex glands (ampullary glands, vesicular glands, prostate, and bulbourethral glands)
What is the sigmoid flexure?
A bend in the penis that allows the penis to fold when the retractor penis muscle contracts and straighten during erection
What animal has a corkscrew penis?
Pig/boar
Where does spermatogenesis occur?
The testes
What varies between species about the testes?
Shape, size, and location
What does the spermatic cord contain?
blood vessels, nerves, lymphatics, and ductus deferens
What does the spermatic cord do?
Suspends each individual testis in the scrotum
What are the spermatic cord and testicle invested/covered by?
The peritoneum, which is a serosal sac (contains serous fluid) also called the vaginal tunic/sheath
What does the investment (covering) of the spermatic cord imply?
Fetal testis developed in the abdomen and reached the scrotal position by migrating through the serosa-lined abdominal cavity, and carried its serosal coverings with it
Each testis consists of a coiled mass of what surrounded by what?
Seminiferous tubules surrounded by a heavy fibrous capsule called the tunica albuginea
What do the seminiferous tubules consist of?
Mutliple cell types
What does the tunica albuginea do?
Divides the testis into different lobules
What do the septa/trabeculae do?
Pass inward from the tunica albuginea and divide the testis into lobules
What does dividing the testis do?
Provides framework and support for the seminiferous tubules and the interstitial tissue that produces testosterone
What is the initial site of spermatogenesis?
The seminiferous tubules
Where doe the seminiferous tubules send sperm?
Into a network of tubules called the rete testis
What does the rete testis drain into?
Efferent ductules
What do the efferent ductules come together to form?
Epididymal duct
What does the connective tissue between the seminiferous tubules contain?
Interstitial/Leydig cells
What do interstitial cells do?
Secrete testosterone when stimulated by the gonadotropin lutenizing hormone (LH)
What type of cells are found within the seminiferous tubules?
Sustentacular/Sertoli
What do the Sertoli cells do in regard to spermatozoa?
Envelop developing spermatozoa and their precursors, which begins the differentiation into sperm cells
They also nourish the developing sperm cells
What do the Sertoli cells do in regard to hormones?
Mediate the effects of the gonadotropin follicle-stimulating hormone (FSH) and testosterone on developing germ (sperm) cells
What direction does sperm cell creation move within the seminiferous tubules?
From the outside in
How does sperm cell structure compare to egg cell structure?
Sperm cells are much smaller and simpler in structure than egg cells are
What is the primary location for maturation of sperm?
The epididymis
What does maturation of sperm involve?
Adding components that give them a higher likelihood of being mobile to the extent they can reach an egg
What makes up the epididymis?
Long, convoluted epipdidymal duct that connects efferent ductules of the testis with the ductus deferens
What does the epididymis appear like?
A firm, arcing appendage on one side of the testis
How long is the period of maturation for spermatozoa?
10-15 days
What are the three divisions of the epididymis?
Head, body, tail
What part of the epididymis do the efferent ductules empty into?
Head
What part of the testis does the body of the epididymis lie on?
Long axis
How and where is the tail of the epididymis connected?
Connected by ligaments to the testis and the vaginal tunic
What does the duct of the epididymis tail continue as?
Ductus deferens
What does the ductus deferens do?
Convey sperm from the testis to the proximal portion of the urethra
What is the ductus deferens?
A muscular tube that undergoes peristalsis to propel the spermatozoa from the epididymis to the urethra
What does the ductus deferens pass through when leaving the epididymis tail?
Inguinal canal
What does the ductus deferens do within the spermatic cord?
Separates the neurovascular parts of the cord from the sperm transfer parts
What is the scrotum?
A cutaneous sac that conforms in size and shape to the testes
What are characteristics of the scrotal skin?
Thin, pliable, relatively hairless (except in sheep)
What is responsible for suspending the scrotum?
Inguinal canal
What is the tunica dartos and where is it found?
A layer of fibroelastic tissue mixed with smooth muscle fibers that is found immediately under the scrotal skin
What happens to the tunica dartos and the scrotum in cold weather?
The muscle fibers of the tunica dartos contract and hold the testes against the abdominal wall, which helps keep them warm
What is the scrotal septum and what does it do?
A fibrous sheet extending from the tunica dartos that divides the scrotum into two compartments, one for each testis
What is deep to the tunica dartos?
Several layers of fascia, which are not easily separated
What is the cremaster muscle, where is it found, and what does it do?
A slip of muscle superficial to the spermatic cord that helps draw the testicle closer to the body wall when temperatures are low or as a reflex to protect it
What is the inguinal canal?
A passage from the abdominal cavity to the exterior of the body
Where do gonads develop in the male and female?
In the lumbar region (well within the abdominal cavity) and immediately caudal to the kidney
After development, what is the difference between the male and female gonads?
Ovaries remain in the abdominal cavity near their origin, but the testes descend a considerable distance from their origin
What is significant about the environment of the scrotum?
A slightly lower temperature than normal body temperature, which is favorable to spermatogenesis
When is descent of the testes normally complete?
Birth or shortly after
What helps the testes descend?
The fibrous gubernaculum guides the testes down. The gubernaculum is a cordlike structure that extends from the testis through the inguinal canal to the skin in the region that will become the scrotum
What is it called when a testis doesn’t descend and what is an animal with this condition called?
The testis is called a cryptorchid testis and the animal is called a cryptorchid
How common are cryptorchid pigs?
1/200-300
What happens to a cryptorchid in terms of spermatogenesis?
A cryptorchid with both testes in the abdomen likely will be sterile since spermatogenesis needs a cooler temperature than the body, which is found in the scrotum
What happens to a cryptorchid in terms of hormones?
The higher temperature of cryptorchid testes does not interfere with testosterone production, so the animal will behave like a normal animal
What is castration?
Removal of the testes in a male
Can also be applied to ovariectomy, which is the removal of the ovaries in the female
What is vasectomy?
Transection, usually with ligation (closing off) or removal of a section, of the ductus deferens
How does a vasectomy affect function of the testes?
Prevents delivery of spermatozoa but has no effect on production of hormones
What is the main function of the male accessory sex glands?
Produce the bulk of the ejaculate/semen, which is the medium of transport for sperm
What does semen do in relation to sperm?
It provides conditions for nutrition of the sperm and works as a buffer against the acidity of the female genital tract
What are the four accessory male sex glands?
1.) Ampulla of the ductus deferens
2.) Vesicular glands
3.) Prostate gland
4.) Bulbourethral gland
Which accessory sex glands are paired?
Ampulla of the ductus deferens, vesicular glands, and the bulbourethral gland
How do the male accessory sex gland compare across species?
Vary in shape and size, but relative location is similar
What are the ampullae?
Glandular enlargements associated with terminal parts of the ductus deferens
What animals are the ampullae well developed in and what animals are they not?
They are well developed in the stallion, bull, and ram, but are relatively absent in the boar
What do the glands of the ampullae do?
Empty into the ductus deferens and contribute to the volume of semen
What is another name for the vesicular glands?
Seminal vesicles
What do the vesicular glands/seminal vesicles do?
Merge with ipsilateral ductus deferens to create a short ejaculatory duct, which empties into the pelvic urethra
What does the prostate gland do?
Produces an alkaline solution that gives semen its odor
What happens to the multiple ducts of the prostate gland?
They open in two parallel rows, one on each side of the lumen of the urethra
What is testosterone and other hormones’ functions in relation to the accessory sex glands?
Necessary for supporting growth and differentiation of the accessory sex glands during puberty and for their maintenance during sperm production
What is another name for the bulbourethral glands?
Cowper’s glands
Where are the bulbourethral glands located?
Paired glands on each side of the urethra cranial to the ischial arch and caudal to the other accessory glands
In what species are the bulbourethreal glands especially large?
Boar
What are the three areas of the penis?
Glans, body, and cura/roots
What is the glans of the penis?
The free extremity at the end
What is the body of the penis?
The main portion
What are the cura/roots of the penis?
The part of the penis that attach it to the ischial arch of the pelvis
What is the corpora cavernosa?
Erectile tissue that exists in paired columns that make up the bulk of the penile body’s internal structure
What does the corpus cavernosum consist of?
It is filled with blood sinusoids (irregularly shaped blood vessels)
What is the corpus cavernosum divided into and what is it divided by?
Trabeculae by sheets of connective tissue
What are the sheets of connective tissue that divide the corpus cavernosum derived from?
The tunica albuginea, which is a heavy fibroelastic capsule that surrounds the penis
What species have a fibroelastic penis?
Ruminants and swine
What makes up the bulk of the fibroelastic penis?
Connective tissue that forms the trabeculae makes up the bulk of the penis
Because of the density of the connective tissue in the fibroelastic penis, what is a characteristic of it when not erect?
It is still firm
What does the sigmoid shape of bulls, boars, and rams’ penises allow?
When erect, the retractor penis muscles relax (usually hold the penis at a bend) and the penis can straighten at the sigmoid flexure
What happens to the fibroelastic penis when preparing for intromission/insertion?
Increases in length
Diameter stays the same
What species have a musculocavernous penis?
Stallion
What is characteristic of the musculocavernous penis?
Blood sinusoids (irregular blood vessels) predominate over connective tissue
What does an erection result in in a musculocavernous penis?
Transformation of the penis from a flaccid consistency to a rigid shape, with an increase in girth as the sinusoids fill with blood
What are the crura?
Proximal parts of the corpora cavernosa
What is contained between the corpora cavernosa?
Penile urethrea
What part of the penis shows significant variation between species?
Glans
What is the urethral process?
A free portion of the urethra that projects beyond the glans in horses and sheep
What is the shape of the bull and ram’s glans?
Helmet-shaped
What is the shape of the bull’s external urethral opening?
Twisted groove
What is the shape of the boar’s penis?
Twisting cranial extremity with a small glans
When does erection occur?
When more blood enters the penis by way of the arterial supply than leaves by the veins
What does increased blood volume during erection do to the penis?
Enlarges it (in all directions in a stallion) and makes it turgid
What type of penis requires significantly less blood to become erect?
Fibroelastic penis
What is the main effect of erection in a fibroelastic penis?
Lengthening of the penis by straightening the sigmoid flexure (think of a bent garden hose straightening when water pressure increases)
Why are different species’ penises shaped differently?
To correspond to the structure of the female cervix
What is the prepuce?
An invaginated fold of skin surrounding the free extremity of the penis
How does the prepuce vary among individuals?
It differs among species, but sometimes even within species
What makes up the outer and inner surfaces of the prepuce?
Outer surface is fairly typical skin
Inner layer is a mucous membrane that has a preputial layer lining the prepuce and a penile layer covering the surface of the free extremity of the penis
What is the prepuce of the horse shaped like?
A double fold that has two concentric layers surrounding the retracted penis
What is the prepuce of the pig shaped like?
Has a diverticulum (extending pouch/sac) dorsal to the preputial orifice
What happens to the prepuce of a pig?
It accumulates urine, secretions, and dead cells, which causes a significant odor
