Untitled Quiz

Introduction to Avian & Reptile Reproductive Anatomy & Physiology

• Aims and objectives for the study include:
  • Understanding the gross reproductive anatomy and physiology of male and female birds and reptiles,
  • Appreciation of environmental and nutritional factors that stimulate reproduction
  • Comprehension of temperature-dependent sex determination in chelonians and lizards
  • Knowledge of oviparous (egg-laying) and viviparous (live birth) reproductive strategies.

Bird Reproductive Anatomy (Male)

• DNA sexing of monomorphic species is possible
• Male reproductive anatomy includes:
  • Testis (paired organs)
  • Vas deferens
  • Cloaca

Bird Reproductive Anatomy (Female)

• DNA sexing of monomorphic species is possible
• Including:
  • Ovary (typically left only)
  • Infundibulum
  • Magnum
  • Isthmus
  • Uterus
  • Shell gland
  • Vagina
  • Cloaca

Seasonal Reproductive Cycle in Birds

• Most psittacines (parrots) breed during spring and summer
• Factors influencing breeding season include photoperiod, presence of a mate, and proper nutrition.
• Appropriate temperature, humidity, and nesting area are essential

Egg Production

• Calcium storage for shell production is critical, involving mobilization of calcium using parathyroid hormone
• Ovulation is crucial in the reproductive process
• Ovulation (2-4 eggs/clutch) happens through LH surge, estrogen increase, and fertilization takes place internally within the infundibulum.
• Progesterone inhibits the further ovulation, and triggers incubation behaviors, where brood patches (featherless areas) and crop milk (prolactin) are important aspects of egg incubation.

Reptile Reproductive Anatomy (Female Lizards)

• Paired ovaries located in the mid-dorsal coelom
• Oviducts are thin walled

Reptile Reproductive Anatomy (Male Lizards)

• Paired testes located in the mid-dorsal coelom
• Renal sexual segment for seasonal proliferation
• Paired hemipenes

Lizard Sex Identification

• Features are used for identifying gender in lizards
  • Head conformation
  • Presence of pores (femoral and anal)
  • Hemipenal bulges

Sex Identification of Snakes (Female)

• Paired, elongated ovaries (vary in size from 56-85% SVL, 20% BL)
• Thinly-walled oviducts

Sex Identification of Snakes (Male)

• Paired testes (near adrenals and kidneys)
• Renal sexual segments (seasonal proliferation of distal convoluted tubules)
• Paired hemipenes

Tail Length in Snake Sex Identification

• Males generally have longer tails compared to females

Hemipenal Probing in Snake Sex Identification

• Males probe a distance of 6-14 subcaudal scales—significantly farther than females.

Female Chelonians

• The ovaries (paired) are near the kidneys, in a small state initially
• Oviducts are more muscular, and responsive to oxytocin

Male Chelonians

• Paired testes are located in the mid-dorsal coelom near the kidneys.
• They have single phallus

Chelonian Sex Identification

• Shell differences
• Tail lengths
• Some aquatic males display longer nails

Courtship & Intromission

• Male-induced trauma
• Cloacal alignment
• Internal fertilization.

Oviparous Egg Production

• All chelonians are oviparous
• Many lizards and snakes are also oviparous
• Features that influence egg incubation include:
  • Temperature (26 to 33°C)
  • Humidity (90 to 100%).

Temperature-Dependent Sex Determination

• Most chelonians have sex determined by incubation temperature
• An increase in temperature leads to females
• Some lizards have sex determined by temperature, but this may vary.

(Ovo)viviparous

• Some lizards and snakes exhibit (ovo)viviparous characteristics, meaning they incubate unshelled eggs internally
• This requires close monitoring of female husbandry conditions and appropriate temperature and nesting area.