Chinchilla Reproduction - Anatomy & Physiology

MALE

Scrotum and Testes

• Only a very slight scrotal region is visible externally (no true scrotum).
• Thin-walled scrotal diverticula extend cranially on either side of the base of the penis.
• Each diverticulum is occupied by the tail of the epididymis.
• On either side of the anus are two postanal sacs.
  • Caudal epididymis can lie in the postanal sacs.
• Testes and head of the epididymis is in the region of the inguinal ring.
• Large fat body extends cranially into the abdominal cavity from the cranial pole of each testis.

Accessory Sex Glands

Vesicular Glands

• Very long and tubular.

Prostate Gland

• Paired large ventral lobes and paired small dorsal lobes.

Bulbourethral Glands

• Dorsolateral to ischiocavernosus muscles.
  • Ischiocavernosus muscles are enormous, swelling on either side of the rectum and meeting over its top.

Penis

• Penis points caudally when relaxed and cranially when erect.
• 1.5cm in length
• Sigmoid flexure
• Os penis in the distal portion.
  • The small supporting bone is known as the baculum.

Copulation

• Spermatogenesis occurs at about 2-3 months.
• Copulatory maturity is not until about 8 months.
• Breeds all year round.
• Copulatory plug at mating.

FEMALE

Reproductive Tract

• Ovaries are just caudolateral to the kidneys.
• Bicornuate duplex uterus.
• Uterine lumena do not fuse.
  • The two uterine horns continue into seperate cervices
  • Open separately into a single vagina.
• Membrane covers vaginal opening except at oestrus and during parturition.

Puberty and Sexual Maturity

• Puberty at ~8 months
  • Puberty can be same year as birth, but if the chinchilla is born late in the year it will not reach puberty until the next breading season.

Oestrous Cyclicity

• In the Northern Hemisphere the breeding season is November-May.
• Seasonally polyoestrus with a mean cycle of ~40 days.
• Post-partum oestrus.
  • Often two litters per year, three are possible.
• Breeding life is ~10 years.

Gestation and Offspring

Gestation

• Long gestation period: 111 days.

Litter

• Litter size 1-6
• Precocious offspring
  • Weaning age is 6 weeks.

Mammary Gland

• Three pairs
  • One inguinal pair
  • Two lateral thoracic
• Teats protrude sideways, allowing the young to sit beside the dam and suckle.