Male Repro System - Exam 1

Development

1st 1/3 of gestation

Testis Determining Factor → testes development → serotonin cells secrete Anti-Mullerian Hormone

• testosterone → development of male duct system

• Dihydrotestosterone → development of penis, scrotum, and accessory sex glands

Testis

Male gonad → produce hormones and sperm

Outside abdominal cavity ~ maintained at 33*C for proper spermatogenesis

Scrotal Skin

Protects/supports testis

Had temperature sensitive neurons → sweat glands to keep cool for spermatogenesis

Testis Anatomy (1)

scrotal skin

Testis Anatomy (2) → Tunica Dartos (muscle)

• If cold/exercise→ contracts to bring close to body

• If hot → relaxes to move away from body for heat dissipation

• Testosterone dependent

Testis Anatomy (3)

tunica vaginilis parietal layer

Testis Anatomy (4)

tunica vaginilis visceral layer

Testis Anatomy (5) → Tunica Albuginea

• dense white connective tissue covering testis ~ same that surrounds the ovaries

Testis Anatomy (6) → Leydig Cells (interstitial compartments)

• between seminiferous tubules

• Sight of testosterone production

• Surrounded by lymphatic tissue/blood vessels

Testis Anatomy (7) → Sertoli Cells (nurse cells)

→ produce AMH

• line inside of seminiferous tubules

• Sperm cell production → provide nutrients to developing sperm

• Contains immature sperm cells at different stages of production

  • spermatogonia → primary spermatocyte → spermatogonia = spermatogenesis

Majority of Testis Weight

90% of testis weight/mass (sertoli + leydig)

Testis Anatomy (8) → Rete Tubules

• connect seminiferous tubules to efferent ducts

• transport spermatozoa + secretes fluids

• join at the center testis in Mediastinum

Testis Anatomy (9) → Mediastinum

• connective tissue core

• structural support/shape

• covers Rete Tubules

Testis Anatomy (10) → Efferent Ducts

• connects Rete Tubules to head of Epididymis

• surrounded by smooth muscle → like isthmus in female reproductive tract

Testis Anatomy (11) → Epididymis

• outside of testis

• head - dorsal (top) of testis

• body - along side of testis

• tail - ventral (bottom) of testis → storage of mature sperm cells ~ 5-10 ejaculations

Epididymis Functions

1. passage was for sperm cells to Vas Deferens

2. sperm cell maturation

3. fluid absorption

4. storage within tail

Testis Anatomy (12) → Spermatic Cord

• connection between testis + internal portion of male rep to tract following testicular descent

• Passes though inguinal ring found in abdominal wall

  • testicular descent

    • bulls, rams, board: last ½ of fetal life

    • Stallions: birth/shortly after

Cryptorchidism

unilateral: 1 testis in abdominal cavity, 1 in scrotum

bilateral: 2 testis remain in abdominal cavity (sterile)

“ridgeling” → cryptorchid stallion

Abnormal Function of Inguinal Ring

scrotal hernia: viscera enter the scrotum (mainly in swine)

Anatomy of Spermatic Chord (1) → Vas Deferens

• connects tail of epididymis to urethra

• capable of peristaltic contractions

• limited sperm storage

• Vasectomy: removal of portion of VD

  • Created teaser male for livestock species

Anatomy of Spermatic Chord (2) → Cremaster Muscle

• support/protect testis

• spermatogenesis

• testosterone dependent

• temperature sensitive → relax in high temp, contract in cold temp

Anatomy of Spermatic Chord (3) → Pampiniform Plexus

• veins + arteries

• supplies blood for testis

  • Cools venous blood

  • Warms arterial blood

• Need for spermatogenesis

What does the Spermatic Cord do?

it controls thermoregulation of the testis

Thermoregulation of the Testis (1)

1. thermosensitive neurons: scrotum skin, sweat glands, respiratory center

2. tunica dartos muscle: contracts/relaxes

3. cremaster muscle: contracts/relaxes

4. pampiniform plexus: arterial blood cooled by venous blood

temperature/spermatogenesis affected by… 1. hight temp 2. febrile disease 3. transporting the animal 4. showing the animal

Accessory Sex Glands

• after vas deferent → top of penis

• secretions contribute to 95-98% of ejaculate volume → sperm cells take 2-5% of volume

• provide:

  • suspending medium for sperm transport

  • nutrients (fructose)

  • buffers

• larger in boars/stallions

Accessory Sex Gland (1)

ampulla: where 2 vas deferens join at the base of the penis ~ serves no real purpose

Accessory Sex Gland (2)

seminal vesicles: fructose in ejaculate → 40-80% of ejaculate volume

Accessory Sex Gland (3)

prostate: 15-30% ejaculate volume → citric acid (energy source), ions

Accessory Sex Gland (4)

bulbourethral gland/cowper’s gland: 15-25% ejaculate volume→ alkaline materials + buffers to neutralize pH of urethra (so sperm don’t die)

Penis Types: Fibroelastic

bull, ram, boar

• rigid when non erect

• supported by sigmoid flexure (SF) + retractor penis muscle (RPM)

• during erection SF straightens and RPM relaxes

Penis Types: Vascular

stallions, primates

• no sigmoid flexure → erection achieved by engorgement of penis with blood

  • can have retractor penis muscle

Penis Types: Baculum +Bulbus Glandis

dogs, bears, raccoons

• erection achieved by engorgement of penis with blood

• penile bone (baculum)