Gerbil Reproduction - Anatomy & Physiology

()Map REPRODUCTIVE SYSTEM (Map) SMALL DOMESTIC MAMMALS

Male

Anogenital distance in the adult is ~10mm (twice that of the female).

Penis

• Os penis lies within the tissue of the penis.

Testes

• Two testes in an external scrotum.
• Testes descend at 30-40 days.
• Active spermiogenesis and mating apparent from 10 weeks of age.
• In the young animal, scrotum is obvious and dark in colour.

Reproductive Behaviour

• Abdominal sebacious gland is large and apparent at ~4 weeks.
  • Rubbed along the ground to mark territorial boundaries.
• Form monogamous pairs/Harems
  • Fighting among males is common

Mammary Gland

• Teats are absent.

Female

Reproductive Tract

• Bicornuate uterus
• Two channels of the cervix separated almost to the single entrance into the vagina.

Puberty and Sexual Maturity

• Sexual maturity is at ~9-12 weeks.

Oestrous Cyclicity

• Polyoestrous
• Oestrous cycle length: 4-6 days
• Post-parturient oestrus
• Spontaneous ovulator.

Breeding Characteristics

• Monogamous (in contrast to rats and mice).
• Mating usually occurs in the evening.
• Copulation plug is small and lies deep in the vagina, so cannot easily be detected.

Gestation and Offspring

Gestation

• Gestation period is 22-26 days.
• May produce a litter every 30-40 days and can produce a total of 10 litters.
• Maximum breeding age is 20 months, but usually the time between the first and last litter is ~1 year.
• Pseudopregnancy may occur.

Litter

• Mean litter size is 4-5.
• Altricial offspring.
  • Hairless, blind and virtually helpless.
  • Ears open at 5 days.
  • Eyes open at 16-17 days.
  • Cannibalisation/abandonment is rare.

Mammary Gland

• 4 pairs of teats.