Reproduction Flashcards
What are the 2 types of castration?
Open castration - vaginal tunic is opened
Closed castration - vaginal tunic is not opened
Define cryptorchidism.
Failure of the testes to descend through the inguinal canal to the scrotum, and so is retained in the abdominal cavity.
Causes infertility, tumours, torsion and behavioural problems.
During castration, if you can only locate 1 teste, always go back int the abdominal cavity to remove both.
What is the spermatic cord comprised of?
Ductus deferens Testicular artery and vein Pampiniform plexus Testicular plexus of nerves lymph drainage Connective tissue Visceral layer of vaginal tunic
What is the function of the mesorchium?
Alongside the cremaster muscle and ductus deferens, mesorchium helps support the testes.
Describe what happens during testicular descent.
In the descent of the testis, they must pass through the inguinal canal to get down into the scrotum.
So during descent, as it is retroperitoneal, it stays outside the peritoneum.
During descent, the peritoneal cavity has pushes a finger-like process through the inguinal canal as well, which lies next to the testis and is called the vaginal process. The part of the peritoneum that surrounds the vaginal process is called the veginal tunica.
Describe the structure of the vaginal tunic.
Made up of 2 layers:
- The inside layer closely adheres to the structures it covers at each point and it is called the visceral vaginal tunic.
- The second layer is the parietal vaginal tunic.
The gap between the layers is celled the vaginal cavity and is continuous with the peritoneal cavity.
Name the 4 layers that must be cut through in a castration.
- The skin
- A smooth muscle layer called the dartos muscle
- External spermatic fascia, which is a loose connective tissue layer, which can be easily broken down in blunt dissection
- Internal spermatic fascia, which is a very strong fibrous collagenous connective tissue layer, which requires a scalpel
Compare and contrast the 2 types of castration.
If you cut through the internal spermatic fascia, it opens up the vaginal process, as the parietal vaginal tunica is adhered to closely to the internal spermatic fascia. This is an open castration. If the internal spermatic fascia is intact, this is a closed castration.
Either method of castration involves breaking down some ligaments at the bottom. These are remnants of embryological structures that help the testis descend down into the scrotum.
What is the cranial gonadal ligament?
Cranial gonadal ligament – at the start of testis descent, cranial gonadal ligament degenerates and descent begins.
Describe the caudal gonadal ligament.
Caudal gonadal ligament/gubernaculum extends down through the inguinal ring and into the scrotum. It guides descent. It remains intact and is divided into 3 parts:
- Proper ligament of the testis – runs between testis and epididymis. Remaining parts of the ligament of the tail of the epididymis and the scrotal ligament.
- Ligament of the tail of the epididymis – this ligament is much tougher than the scrotal ligament. Broken down in an open castration.
- Scrotal ligament - broken down in a closed castration.
Describe the canine penis.
- Is a musculocavernous type of penis.
- Large cavernous spaces fill up with blood during erection.
- Glans divided into pars longa glandis and bulbus glandis, involved in copulatory lock.
- Penile urethra is completely surrounded by cavernous erectile tissue called corpus spongiosum. There is a collagenous layer surrounding this called the tunica albuginea.
- Corpus cavernosa – pair of cavernous bodies dorsal to penile urethra and corpus spongiosum tissue. These ossify more distally to form the os penis, meaning the do penis is always partially erect.
- Cura attach penis to ischial arch at the root of the penis.
How does erection occur in the musculocavernous penis?
- In the flaccid penis, sympathetic nerves bring about tonic contraction of the smooth muscle in the walls of the erectile tissue and the retractor penis muscle.
- In arousal, the sympathetic tone is inhibited and the smooth muscle in the walls of cavernous spaces relaxes and allows the spaces to fill with blood.
- At the same time, the muscles in the urogenital diaphragm, the ischiocavernosus, ischiourethralis and bulbospongiosus, compress venous return, trapping blood and causing swelling, increasing length and width.
What is copulatory lock?
The ischiourethralis muscle contracts around the dorsal vein of the penis to stop venous return. There is also relaxation of the retractor penis muscle, which allows and increase in length.
However, there is another possible route of blood exit from the penis: the superficial vein of the glans. It is constricted by the vestibularis muscle, which is located in the bitch. So this muscle surrounds and compresses the vestibule in the female reproductive tract. This causes copulatory lock and complete swelling of the bulbus glandis here. Lock can last for 20 minutes.
Describe the species differences in scrotum topography.
- In the bull and ram, the scrotum is pendulous and vertical, and the orientation of the testes is almost vertical.
- In the cat and boar, the scrotum is very caudal, almost horizontal and sub anal.
- The dog and stallion are somewhere in the middle of these two.
How is teste conformation different between large and small animals and what are the species differences?
Different to small animals, the head of the epididymis is next to the pampiniform plexus and the tail is away from the pampiniform plexus in large animals.
- In general, the testes in carnivores are relatively more horizontally placed, as well as in the horse and pig. The head of the epididymis is more cranial and the tail more caudal.
- In the ruminants, because the testes are vertically placed, the head is dorsal and the tail is ventral.
How does erection occur in the fibroelastic penis?
Sigmoid flexure retains penis within prepuce and bilateral retractor penis is contracted due to decreased sympathetic tone.
Engorgement restricted to sigmoid flexure, retractor penis muscle relaxes and flexure straightening, protruding from penis.
Describe the species differences in the size and shape of musculocavernous penises.
Cats faces caudally and is covered with barbs to induce ovulation in the queen.
The horse penis is more complex, as it has an elongation of the urethra called the urethral process that sits in a depression called the urethral fossa. This has clinical significance.
Describe the species differences of the size and shape of fibroelastic penises.
- Bull has tiny glans and a raphe that twists around
- Ram has a worm-like urethral process, which has clinical implications with kidney stones, and a bump on the left side celled the tuberculum spongiosum.
- Pig’s is long and thin but corkscrews when erect, which has implications for AI.
What is the function of the male gonadal accessory glands?
There are 4 different types. Their purpose is to produce seminal fluid to facilitate motility and nutrition for the sperm. There are species variations in size, shape and presence in each animal (though all mammals have a prostate).
Describe the accessory gonadal glands of the dog.
Prostate - clinically significant if old entire males get prostatitis, an inflamed prostate due to the effects of testosterone. This is not normally malignant but will cause great discomfort and problems defecating. The prostate can be palpated rectally.
Ampullae – difficult to see as they are really thickenings of the distal parts of the ductus deferens.
Describe the accessory gonadal glands of the pig.
- Prostate
- No ampullae
- Vesicular glands – seminal vesicles close to the bladder.
- Huge bulbourethral glands
Describe the accessory gonadal glands of the ox and horse.
Have all 4 glands, but vary in shape and size.
In the ox, most of the accessory glands are situated near the neck of the bladder.
Describe the blood supply to the large animal male reproductive tract.
Internal iliac supplied the internal pudendal arteries and veins.
In horses, cranial gluteal artery and obturator artery.
Describe the innervation of the large animal male reproductive tract.
Autonomic innervation due to pelvic and hypogastric nerves.
Somatic innervation due to the genitofemoral nerve and pudendal nerve.
In basic male pelvic blood supply, what 3 sections is blood supply split into?
- Blood supply to the penis
- Blood supply to the testis
- Blood supply to the scrotum and prepuce
How does the internal iliac artery supply the male pelvis?
Bilateral and supplies internal pelvic organs, penis and perineum.
- Goes deep into the pelvic cavity. 1st branch is the umbilical artery to the bladder. 2nd branch gives off the caudal gluteal artery to the guts.
- Then becomes the internal pudendal artery. 1st branch is the urogenital artery. 2nd branch is the vaginal artery, which becomes the uterine artery and anastamoses with the ovarian artery.
- Internal pudendal artery exits via the ischiorectal fossa and becomes the penile artery.
How does the testicular artery supply the male pelvis?
It branches off the aorta and travels through the inguinal canal to reach the testis.
How does the external iliac artery supply the male pelvis?
Supplies the hindlimb and exits through the femoral canal to become the femoral artery.
- Has a branch called the deep femoral artery, which gives off the pudendoepigastric trunk.
- One of the branches of the pudendoepigastric trunk is called the external pudendal artery, which goes through the inguinal canal to supply the scrotum and prepuce in the male (mammary glands in female).
- Another branch of the pudendoepigastric trunk is the caudal deep epigastric that supplies the inside of the caudoventral wall inside the body.
Describe autonomic innervation of the male pelvis.
- Sympathetic – exits CNS via thoracolumbar region and innervate the pelvis via the hypogastric nerves (are paired).
- Parasympathetic – cranial and sacral outflows only. Vagus does not travel the whle way to the pelvis. Sacral outflow/pelvic nerves reach pelvis.
Describe somatic innervation of the male pelvis.
Exits CNS via lumbosacral plexus, which is comprised of the last 5 lumbar and first 3 sacral nerves.
• Genitofemoral nerve = L3-L4 = inguinal canal
• Femoral nerve = L4-L6 = femoral canal
• Obturator nerve = L4-L5 = obturator foramen in the os coxi
• Lumbosacral trunk = L6-S2 = greater sciatic foramen and makes up a lot of
the sciatic nerve
• Pudendal nerve = S1-S3 in dogs, S2-4 in horses and cows = ischiorectal fossa
• Caudal rectal nerve may be its own nerve or be a branch of the pudendal
What is the function of the uterine tube?
Uterine tubes catches any oocytes that are ovulated from the surface of the ovary and convey them to the uterine horn.
It provides the correct conditions for fertilisation.
Runs between the ovaries and the tip of the corresponding uterine horn.
What are the 3 sections of the uterine tube?
Infundibulum – widest part near the ovary and has finger-like projections which are called fimbriae. The direct/waft ova into the uterine tube.
Ampulla – where fertilisation occurs.
Isthmus – narrowest section
What are the 3 layers of the uterine wall?
- Mesometrium – the outer mesentery layer supports the uterus
- Myometrium – the smooth muscle layer
- Endometrium – the inner lining of the uterus
What is the function of the cervix?
Acts as the junction between the uterine body and the vagina.
What is the structure of the cervix?
Contains a high proportion of collagen and smooth muscle fibres.
Cervical canal is very narrow and is normally closed. Can be filled with a mucus plug.
Cervical canal only opens at times of mating to allow the passage of sperm and the time of parturition, when the canal expands greatly.
Depending on species, some may have change sin the appearance of the cervix depending where they are in the oestrus cycle, caused by hormonal changes. Example: mare
Describe the blood supply to the uterus.
Paired arteries:
- Ovarian artery – a direct branch of the aorta.
- Uterine artery – a branch of the vaginal artery. Vaginal artery branches into smaller branches near the uterine wall to supply it. It anastomoses with the ovarian artery.
Name the different mesenteries that support the different parts of the female reproductive tract.
- Mesovarium – supports ovaries
- Mesosalpinx – supports the uterine tube
- Mesometrium – supports the uterus
- Pelvic fascia surrounds the distal part of the reproductive tract, vagina and vestibule. They are located within the pelvic cavity and outside of the peritoneum.
Describe the peritoneal attachments that support the female reproductive tract.
- There are 2 peritoneal attachments that hold the ovaries up against the dorsal body wall and are part of the mesovarium.
- There are 2 attachments that attach uterine body to the dorsolateral body wall and are part of the mesometrium.
Name the female gonadal ligaments.
The cranial gonadal ligament/suspensory ligament is divided into 2 parts in the female:
- The proper ligament is the part between the ovary and the tip of the uterine horn
- The round ligament runs through the mesometrium, down to the inguinal canal in the bitch
What is the ovarian bursa and how are they formed?
In some species, the ovaries are completely surrounded by a bag or fold of peritoneum, a pocket formed by the mesovarium and mesosalpinx.
Formed when mesosalpinx and mesovarium overlap and form a ridge tent, the bottom of which has an opening. This forms the bursa.
