Snake and Lizard Reproduction - Anatomy & Physiology

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Lizards (Squamata)

Male

Testes

• Located cranial to the kidneys.
• Attached to the dorsal wall by a mesochorium.
• In some species, the kidney has a posterior sexual segment that becomes swollen during the breeding season and contributes to seminal fluid.
• Right testis lies cranial to the left.
  • Intimately connected to the vena cava by short blood vessels.
• Left testis lies close to the adrenal gland.
  • Has its own testicular blood vessels.

Phallus

• Paired hemipenes
• Stored in the base of the tail.
  • Visualised externally by bulges at the ventral proximal tail.
• Only one hemipene is used during copulation.
  • Erected by vascular engorgement and muscular action.
  • Everted to protrude through the cloaca.
• Sperm passes from the ductus deferens into the male urodeum.
• Sperm is then carried in a groove down the hemipene to be deposited in the female cloaca.

Female

Ovary

• Paired
• Consists of a cluster of oocytes lined by a thin mesovarium.
• Right ovary is close to the vena cava.
  • Attached to vena cava by tiny blood vessels.
• Left ovary lies close to the left adrenal gland.
  • Has its own ovarian blood supply.

Oviduct

• Paired
• Pleated
• Wide infundibulum

Oviparity

This is the usual state for lizards, including all Geckos and Iguanas.

• Eggs are retained within the mother until birth.
• Normal clutch size is 3-5.
• Eggs covered by a leathery shell
• Can appear shrunken when laid.

Viviparity

About 1/5 of lizards are viviparous including the common European Lizard.

• Foetus retained within the oviduct.
• Primative placental type of circulation.

Breeding Season

Temperate Species

• Gonads reach maximum size on emergence from hibernation.
• Gonads are smallest during the summer months.