Male reproductive system

What type of organ is the male reproductive tract?

Endocrine

What are the functions of the male reproductive tract

1 - produce sperm

2 - deliver sperm

3 - produce testosterone, estrogen, dihydrotestosterone (DHT) and inhibin

What do you call hanging balls or outside of the abdominal cavity

pendular

What type of animals have a sigmoid flexure and what is it

All small ruminants have one. it is penis of certain male mammals that keeps the organ retracted inside the body until sexual arousal.

What makes the stallion testicles different

they are non pendular, the prostate is onebody, no sigmoid flexure, nonexpandable shaft.

Differences in the boar

fibroelastic penis, makes a lot of sperm, huge vesticular glands, produce a lot of seminal fluid, nonpendular, has a pouch called preputial diverticulum that makes phermonones.

Differences in the dog

one accessory gland - prostate (good model for prostate cancer), nonpendullar, glands penis has two parts

1. bulbus glandis - produces the lock during mating

2. pars longa glands

most prominent bone in the dog penis.

Differences in cats

penis is pointing back wards, no vesicular glands only prostate, glands penis has spines.

What is the functions of the testicle

1. produce sperm

2. synthesize hormones and proteins (cytokines to keep system healthy)

3. secrete fluids

What are the testicle structures

1. Testicular capsule (visceral vaginal tunic and tunica albuginea) (closest to the testicle).

2. Parenchyma - start producing sperm

3. Mediastinum

Describe the testicular capsule

Visceral vaginal tunic surrounds the testicle

Tunica albuginea is very hard and protects the testicle and it makes projections inside the testicle, keeps strucuture, helps move sperm

Describe the testicle parenchyma

They contain the seminiferous tubes where spermiogenesis is taking place. All the tubes connects and end up in one little vas deferences

Describe the interstitial compartment

leydig cells cells outside the seminiferous tubes. Leydig cells produce testosterone and estrogens in reponse to luteinizing hormone LH.

Sertoli cells on the walls of seminiferous tubes.

Spermatagonia cells - sperm cells of the testicle

Mediastinum

dense structure in the middle on an ultrasound. protects testicle from collapsing.

Spermatic cord

cord that connects the inguinal to dorsal pole of the testis. Contains everything it needs to survive like arteries, veins and lymphatic vessels. Cremaster muscle. pampiniform plexus.

Functions: provide basic physiology needs of the testicle, heat exchanger device, recirculate testosterone.

Pampiniform plexus

structure that is right on the spermatic cord closer to the testicle. finger like viens bring blood from the testicle to the body. all around the artery. heat exhnage acts like a cooler. provides consent blood pressure.

Pulse pressure elimination in the spermatic cord

there is no pulse pressure to move blood because it will cause death of sperm due to tunica no tbeing ablle to move

Cremaster muscle

Structures:

1 - striatum muscle

2 - part of the internal abdominal oblique muscle

Functions:

1. support testis, facilitates the return of blood protects testicle

2. retracts when threatended and during sexual activity

Scrotum

-two lobed sac

• four layers

1. skin

2. tunica dartos (smooth muscle)

3. scrotal fascia

4. parietal vaginal tunic

Pendular (bull, ram) and non-pendular (stallion)

Scrotum function

1. temperature regulation

2. physical protection of the testicle

List the ducts in the male reproductive system starting from the testicle

1. Seminiferous tubes (tubulus contortus and rectus)

2. rete testis

3. efferent ducts

4. epididymis

5. duct deferens

6. pelvic urethra

7. penile urethra

Seminiferous tubules structures

1. contractile peritubular cells

2. basement membrane

3. seminiferous or germinal epithelium

Seminiferous epithelium

1 - basal compartment with sertoli cells (somatic) and spermatogonia (germ cell)

2 - adluminal compartment with sertoli cells sperm at different stages of development

Sertoli cell

• analogous to granulosa cells in the ovary

• “host” for developing sperm cells

• the number of sertoli cells positively correlates with the number of sperm produced.

• receptors for FSH and testosterone

• they are connected to each other via tight junctions

In response to FSH, Sertoli cells produce

1. estrogen (attraction)

2. DHT: dihydrotestosterone (secondary sex characteristics)

3. inhibin (feedback)

Sertoli cells and blood-testis barrier

Tight junctions separating the basal compartment from the adluminal compartment of the seminiferous epithelium form the “blood-testis barrier” blocking access of immune cells and molecules such as antibodies into the adluminal compartment

Excurrent Duct system - outside testicle

1. efferent ducts - connect rete testis to the epididymis, reabsorbs rete testis fluid

2. epididymis

3. duct deferns

epididymis structure

1. head

2. body

3. tail: it is a convoluted duct (30 to 60 meters) surrounded by smooth muscle.

Epididymis functions

1. reservoir of sperm

2. transport of sperm

3. maturation of sperm

4. reabsorption of fluid (so much fluid needs to be reabsorbed)

5. protein secretion

Seminal plasma (fluid) is produced in

1. epididymis

2. ampulla

3. vesicular glands

4. prostate gland

5. bulbourethral glands

Seminal fluid function

1. transport of sperm during ejaculation

2. retention of sperm in the female reproductive tract

Ampulla

enlargement of the mucosa in the last portion of the duct deferens, it opens into the pelvic urethra

vesicular glands (seminal vesicles)

secretions delivered into the pelvic urethra: there is great variation in size between species

very active

prostate gland

located between the bladder and pelvic urethra

two parts: corpus and disseminate

The disseminated part is also called the urethral gland

the prostate is the only accessory gland in the dog

Bulbourethral glands

paired glands on either side of the pelvic urethra. they provide mucus secretion composing the pre-sperm, neutralizing the pH of the urethra

Penis structure and function

1. Base crus penis attached to the ischial arhc

2. shaft

3. glans

Function is to deliver sperm to the female

Glans penis

Homologous to the female clitoris

cat glans has spines

alpaca stiff cartilaginous process

boar corkscrew shape

Erectile tissues

Corpus cavernosum most of the penis, houses the corporal sinusoids

Corpus spongiosum surrounding the penile urethra and gland penis

Erectile tissue in the dog

Glands: bulbus glandis and pars longa glandis

Penis muscles

1. Urethralis: striated muscle around the urethra that moves seminal plasma and sperm into the penile urethra (help move sperm along and secretions of accesory glands)

2. ischiocavernosus: striated muscle, short paired muscles in the root of the penis and lateral surface (helps the penis become erect)

3. Bulbospongiosus: striated muscle from the root of the penis down to the caudal and ventral surfaces, covers the bulbourethral glands and empties secretions into the penile urethra (help move sperm along and secretions of accesory glands)

4. 4. retractor penis: smooth muscle paired along the ventral penis (contracts after)

What are the two types of penile shafts

• expandable

• non-expandable/fibroelastic

Which species have an expandable penile shaft

• dog

• human

• stallion

Expandable shafts have large corporal sinusoids.

Which species have a non-expandable/fibroelastic penile shaft?

• bull

• boar

• ram

fibroelastic shaft, sigmoid flexure (ruminants) and two retractor penis smooth muscles inserted into the coccygeal vertebrae

What is the major erectile tissue making up most of the penis?

Corpus cavernosum, which houses the corporal sinusoids

What is the corpus spongiosum?

erectile tissue that surrounds the penile urethra and glans penis

What is unique about the alpaca penis?

It has a stiff cartilaginous process.

What is unique about the boar's penis?

The glans has a corkscrew shape.

What are the seven ducts sperm pass through, in order?

Seminiferous tubes → rete testis → efferent ducts → epididymis → duct deferens → pelvic urethra → penile urethra

What are the two portions of the seminiferous tubes?

1. tubulus contortus = convoluted portion where spermatogenesis takes place

2. tubulus rectus = straight portion that connects with the rete testis

What do the efferent ducts connect? What additional function do the efferent ducts perform?

they connect the rete testis to the head of the epididymis. They reabsorb rete testis fluid.

What are the three major structures of the testicle?

A. Testicular capsule
B. Parenchyma
C. Mediastinum

What are the two parts of the testicular capsule?

1. Visceral vaginal tunic

2. Tunica albuginea

What is the visceral vaginal tunic?

A continuation of the visceral peritoneum and is a serosa.

What is the tunica albuginea?

A strong capsule made of connective tissue and smooth muscle. It sends projections into the testicle and connects with the mediastinum.

What are the two compartments of the testicular parenchyma?

1. Tubular compartment

2. Interstitial compartment

What is found in the tubular compartment of the testicle?

The seminiferous tubes, including:

• Tubulus contortus

• Tubulus rectus

Where does spermatogenesis take place?

In the convoluted portion of the seminiferous tubes called the tubulus contortus.

What is found in the interstitial compartment?

• Connective tissue

• Vessels

• Nerves

• Leydig cells

What is the mediastinum of the testicle?

Central connective tissue that protects the rete testis from collapsing.

What are the three structures of the seminiferous tubules?

1. Contractile peritubular cells

2. Basement membrane

3. Seminiferous/germinal epithelium

What are the two compartments of the seminiferous epithelium?

• Basal compartment: Sertoli cells + spermatogonia

• Adluminal compartment: Sertoli cells + sperm at different stages of development

What is the function of Sertoli cells in sperm development?

Sertoli cells act as the "host" for developing sperm cells.

Q: What is the relationship between the number of Sertoli cells and sperm production?

A: The number of Sertoli cells positively correlates with the number of sperm produced.

What forms the blood-testis barrier?

Tight junctions between Sertoli cells.

What does the blood-testis barrier do?

It separates the basal compartment from the adluminal compartment and blocks access of immune cells and large molecules such as antibodies into the adluminal compartment.

What are the two important endocrine cell types in the testicle?

• Leydig cells

• Sertoli cells

Q: Where are Leydig cells located?

A: In the interstitial compartment of the testicular parenchyma.

Q: What hormones do Leydig cells produce?

• testosterone

• estrogens

Where are Sertoli cells located?

In the seminiferous epithelium of the seminiferous tubules.

What hormones do Sertoli cells produce in response to FSH?

1. estrogen

2. DHT (dihydrotestosterone)

3. inhibin

Which cells respond to LH

Leydig cells

What happens when LH stimulates leydig cells

Leydig cells produce testosterone and estrogen

Which cells respond to FSH

Sertoli cells

What do Sertoli cells produce in response to FSH

Estrogen, DHT, inhibin

Compare the roles of LH and FSH in the testicle.

• LH → Leydig cells → testosterone + estrogens

• FSH → Sertoli cells → estrogen + DHT + inhibin

Where does the spermatic cord extend?

From the inguinal ring to the dorsal pole of the testis.

What structures are contained in the spermatic cord?

1. Artery, veins and lymphatic vessels

2. cremaster muscle

3. pampiniform plexus

What are the three major functions of the spermatic cord

1. provide basical physiological needs of the testis

2. act as a heat exchanger device

3. recirculate testosterone

What type of muscle is the cremaster muscle

Striated muscle that is part of the internal abdominal oblique muscle.

What are the functions of the cremaster muscle

support the testis, facilities return of blood, protects the testicle, retracts during threats and sexual activity

What is the basic structure of the pampiniform plexus

a finger like wrapping that surrounds the testicular artery

What happens to the pampiniform plexus veins as they leave the area

They connect with a single testicular vein that runs into the caudal vena cava

What are the three functions of the pampiniform plexus

1. decrease testicular temperature by up to 6 degree Celsius

2. provide constant blood pressure

3. recirculate testosterone back to the testicle

How does the pampiniform plexus help regulate testicular temperature?

It functions as a heat exchanger, allowing blood traveling toward the testis to be cooled.

How does the pampiniform plexus affect blood pressure entering the testicle?

It reduces blood-pressure variability and provides pressure around the median between systolic and diastolic pressure.

How much does blood-pressure variability change across the pampiniform plexus?

• Above pampiniform plexus: about 40 mmHg variability

• Below pampiniform plexus: about 10 mmHg variability

What are the four layers of the scrotum from superficial inward?

• Skin

• Tunica dartos — smooth muscle

• Scrotal fascia

• Parietal vaginal tunic

What type of muscle is the tunica dartos?

Smooth muscle

Which species have pendular scrotums according to the lecture? Which species have non-pendular scrotums according to the lecture?

Pendular - bull and ram

non-pendular - stallion boar

Does having non-pendular testicles mean testicular temperature cannot be decreased?

No. The lecture's iClicker statement that temperature cannot be decreased in animals with non-pendular testicles is false.

Where is seminal plasma/fluid produced?

• Epididymis

• Ampulla

• Vesicular glands/seminal vesicles

• Prostate gland

• Bulbourethral/Cowper's glands

Which structures that produce seminal fluid are accessory glands?

• Ampulla

• Vesicular glands

• Prostate gland

• Bulbourethral glands

What are the two functions of seminal fluid listed in the lecture?

1. Transport sperm during ejaculation

2. Retention of sperm in the female reproductive tract

Q: Is seminal fluid required for fertility when assisted reproductive techniques are used?

No. The lecture states that it is not required for fertility if assisted reproductive techniques are used.

What is the ampulla

An enlargement of the mucosa in the last portion of the duct deferens that opens into the pelvic urethra.

Where do the vesicular glands deliver their secretions?

Into the pelvic urethra.

What is important about vesicular gland size among species?

There is great variation in size between species.

Where is the prostate gland located?

Between the bladder and pelvic urethra.

What are the two parts of the prostate gland?

• Corpus

• Disseminate

The disseminated portion is also called the urethral gland.

What is unique about the dog's accessory sex glands?

The prostate is the dog's only accessory gland.