Avian Semen - Anatomy & Physiology

Introduction

Spermatogenesis and spermiation occur in much the same way as in mammals. For more information on these processes click here.

Sperm Maturation

• Spermatozoa undergo maturation and become fully fertile in the ductus deferens.
• Time required for sperm to pass from the testes to the distal ductus deferens is ~1-4 days.
• Seminal plasma, formed in the effent ducts and ductules of the epididymis, accompanies spermatozoa.
  • Seminal plasma composition can vary among species.

Sperm Storage

• In most birds, semen is stored in the ductus deferens.
• In Passeriformes, semen is also stored in the seminal glomulus/receptacle (enlarged terminal end of the ductus deferens).

'Transparent Fluid'

• Lymph-like fluid called 'transparent fluid' originates in the proctodeum and mixes with the semen during ejaculation.
  • Function of transparent fluid is uncertain, but it contains blood clotting agents that are deleterious to sperm.

Semen

Semen can be collected for artificial insemination, to evaluate reproductive potential, to detect disease and to distinguish species or subspecies.

• Consistency of normal semen ranges from watery to heavy cream.
  • Watery semen may indicate a high volume of 'transparent fluid'.
• Normal semen is white and milky.