Gerbil Reproduction - Anatomy & Physiology
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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.