physiology of reproduction (male reproductive system)

The manufacturing complex of the male (in testis)

1) high speed manufacturing ~ needs to be cool, many sperm

2) finishing shops ~ fluid absorption

- epididymis head: infinity shape movement

- epididymis body: forward/backward movement

3) warehouse and shipping ~ storage, smooth muscle contractions

- epididymis tail: storage

4) final alterations and packaging ~ metabolic substrates (fructose and citric acid), protective surface coating, transport for sperm (lots of fluid)

- vas deferens

5) delivery system ~ erection, protrusion, emission, ejaculation

male reproductive system

Testis Determining Factor (TDF) -> Testes develop -> sertoli cells secrete anti-müllerian hormone (AMH) -> AMH causes leydig cells to differentiate between ... 1) testosterone -> development of male duct system and 2) Dihydrotestosterone -> development of penis, scrotum and accessory sex glands

Testis

1. produce hormones

2. produce sperm

- rests outside of the abdominal cavity

spermatogenesis

sperm cell development from immature to most mature

33C for that to happen

scrotal skin

- protects and supports the testis

- contains temperature sensitive neurons

- contains sweat glands

- necessary for spermatogenesis

tunica dartos muscle

muscle layer lining scrotal skin, necessary for spermatogenesis

- relax during high temperatures, increase SA and heat dissipation

- contract during cold temperatures, decrease SA and heat dissipation

- pulls testis closer to body for protection

- testosterone dependent

- temperature sensitive

vaginal cavity, in the male, is between the tunica _____ muscle and the tunica _____

dartos ; albuginea

tunica albuginea of testis

dense white tissue covering the testis

Lobule of testis contains ...

seminiferous tubules which have sertoli cells ; whole thing is surrounded by tunica albuginea

- (interstitial compartments) contain leydig cells

leydig cells

located between seminiferous tubules

- produce testosterone

- surrounded by blood vessels and lymphatic tissue

sertoli cells

line inside seminiferous tubules

- serve as site of sperm cell production

- approx 90% testis weight

Rete tubules

connects seminiferous tubules to the efferent ducts

- transport spermatozoa/secreted fluids

- join together at the center of testis in the mediastinum

Mediastinum

connective tissue, core of testis

- provides structural support/gives testis oblong shape

- covers rete tubules

efferent ducts

connect rete tubules to head of epididymis

- lined with columnar cells

- surrounded by smooth muscle

epididymis

located outside of body

- head; dorsal to testis

- body; side the testis

- tail; ventral to tetis

epididymis functions

1. passageway for sperm cells

2. sperm cell maturation (spherical to flattened head)

3. absorption of fluids increases sperm cell concentration

- nurse cells: sertoli cells ~ secrete fluids

4. storage of sperm cells ~100 billion sperm cells

- primarily in the tail

- good concentration until about 9 ejaculations

Spermatic cord

provides support to the tesis

- maintains connection between testis and internal portions of male repro tract following testicular descent

- passed thru inguinal ring

- bulls, rams, boars last half of fetal life

- stallions shortly after birth

cryptorchidism

testis do not drop

1. Unilateral = 1 testis remains in abdominal cavity and 1 descends into scrotum

2. Bilateral = 2 testis remains in abdominal cavity (sterile = infertile)

scrotal hernia

abnormal function of inguinal ring

- viscera enter the scrotum

- mainly swine

"inguinal hernia - opened too much, digestive tract came down

3 portions of spermatic cord

1. vas deferens

2. cremaster muscle

3. pampiniform plexus

vas deferens

connect tail epididymis to urethra

- capable of contractions and sperm storage after vasectomy

- vasectomy = removal of vas deferens

- epididymectomy = removal of portion of the epididymis

cremaster muscle

raises and lowers testicles

- support and protection of tetis

- necessary for spermatogenesis

- testosterone dependent

- temperature sensitive

- relax during high temperatures to move testis away from body

- contract during cold temperatures to bring testis closer to body

pampiniform plexus

veins and arteries supplies blood to testis

- countercurrent heat exchange

- necessary for spermatogenesis

- cool venous blood (33C) and warm arterial blood (39C)

- testicular temp is ~5/6C lower than body

thermoregulation of testis

1. thermosensitive neurons (located - scrotal skin)

- scrotal skin

- regulate sweat glands

- regulate respiratory center

2. tunica dartos muscle (located - lines scrotal skin)

- contracts or relaxes

3. cremaster muscle (located - spermatic cord)

- contract or relaxes

4. pampiniform plexus (located - spermatic cord) ?????

- warm arterial blood is cooled by venous blood

high temperatures and high humidity can ...

prevent mechanisms used for spermatogenesis.

To help one should;

- provide fresh clean water

- provide shade

- avoid working breeding males

Heat stress decreases ...

sperm production which can not be restored until 8 weeks after

Factors Disrupting Spermatogenesis

1. high ambient temperatures

2. febrile diseases for 3-5 days

3. transportation of the animal

4. showing of the animal

what structure does the spermatic cord run through as it enters the body cavity?

inguinal ring

which tissue layer is the cremaster muscle attached too?

tunica vaginalis parietal layer

what are the functions of vas deferens?

1. connect tail of epididymis to urethra

2. sperm cell storage

3. takes sperms up

4. transports sperm from tail of epididymis to base of penis

tissue layers of the testis outer to innermost

1. scrotal skin

2. tunica dartos muscle

3. tunica vaginalis parietal

4. tunica vaginalis visceral

5. tunica albuginea

what are the Accessory sex glands

1. Ampulla

2. Seminal Vesicles (vesicular glands)

3. prostate

4. bulbourethral gland (cowpers gland)

Accessory sex gland functions

*located after vas deferens

- 95-98% ejaculate volume

- sperm takes up 2-5% volume

- provides

1. sperm transportation

2. provides nutrients ~ fructose, from seminal vesicle; secrets citric acid from prostate gland

3. buffers ~ thru urethra

4. species variation in size and function

Ampulla

~ in stallion ~

- where two vas deferens join to pelvic urethra

- does not secrete/as active as other glands

Seminal Vesicle (vesicular gland)

~ in stallion ~

- provides 40-80% ejaculate volume

- main fructose (energy) provider in ejaculate

Prostate

~ in stallion ~

- provides 15-30% ejaculate volume

- citric acid as energy source

- and other ions (from prostate)

- correct osmolarity

Bulbourethral glands (cowpers gland)

~ in stallion ~

- provides 15-25% ejacultae volume

- produces alkaline and buffers to neutralize pH of urethra

- clear part of ejaculate

- cleans and sends cells through

Emission

mixture of sperm cells and other accessory sex glands

Stallions produce ___ mL of ejaculate

100

Boars produce ___ mL of ejaculate

100-400

- large vesicles and no ampulla

sigmoid flexure

- S shape in urethra

- extension of penis outside of body

Fibroelastic penis type

- bull, ram, boar

- rigid in non-erect state

- small amount of blood enters penis and slightly enlarges at erection

- supported by sigmoid flexure (straightens) and retractor penis muscle (relaxes)

(during erection)

Retractor penis type

- releases nitric oxide to dilate blood vessels

- produces cyclic guanosine

- monophosphate makes vessels bigger

Vascular penis type

- stallions, primates, elephants

- no sigmoid flexure

- erection achieved by engorgement of penis with blood

Baculum and Bulbus Glandis penis type

- dogs

- erection achieved by engorgement of penis with blood

-Penile bone (i.e. baculum)