Structure of the posthepatic septum and its influence on visceral topology in the tegu lizard, Tupinambis merianae (Teiidae: Reptilia)

  title={Structure of the posthepatic septum and its influence on visceral topology in the tegu lizard, Tupinambis merianae (Teiidae: Reptilia)},
  author={Wilfried Klein and Augusto Shinya Abe and Denis V. Andrade and Steve F. Perry},
  journal={Journal of Morphology},
The posthepatic septum (PHS) divides the body cavity of Tupinambis merianae into two parts: the cranial one containing the lungs and liver and the caudal one containing the remaining viscera. The PHS is composed of layers of collagenous fibers and bundles of smooth muscle, neither of which show systematic orientation, as well as isolated blood vessels, lymphatic vessels, and nerves. Striated muscle of the abdominal wall does not invade the PHS. The contractions of the smooth muscles may… 
Evolution and Functional Differentiation of the Diaphragm Muscle of Mammals.
The DIAm pump evolved from the advantage afforded by more effective generation of both a negative Pth for ventilation of the lungs and a positive Pab for venous return of blood to the heart and expulsive behaviors such as airway clearance, defecation, micturition, and child birth.
Role of the post-hepatic septum on breathing during locomotion in Tupinambis merianae (Reptilia: Teiidae)
Tupinambis merianae increased minute ventilation by increasing both tidal volume and breathing frequency during sustained locomotion at 0.17 m s-1.5 m, suggesting that the PHS facilitates ventilation by acting as a mechanical barrier, preventing the viscera from moving cranially during physical exertion.
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The amphibian ‘diaphragm’ seems to be functionally similar to the mammalian crural diaphragms, and it is suggested that the original role of the diphragm was not respiratory but gastrointestinal.
The evolutionary origin of the mammalian diaphragm
A caseian point for the evolution of a diaphragm homologue among the earliest synapsids
The paleobiology and the respiratory apparatus of one of the oldest lineages of mammal‐like reptiles: the Caseidae is analyzed and it is deduced that a homologue of the mammalian diaphragm had already evolved about 50 Ma earlier than previously assumed.
Herniation of Duodenum into the Right Ventral Hepatic Peritoneal Cavity with Groove Formation at the Ventral Hepatic Surface in a 2-Week-Old Chicken
This is the first report of duodenum herniation into the right ventral hepatic peritoneal cavity resulting in groove formation on the ventral hepatatic surface in a 2-week-old chicken.
A new scenario of the evolutionary derivation of the mammalian diaphragm from shoulder muscles
It is hypothesized that the diaphragm was acquired in two steps: first, forelimb muscle cells were incorporated into tissues to form a primitive diaphagm in the stem synapsid grade, and second, the diphragm in cynodonts became entrapped in the region controlled by pulmonary development.
Trade-offs in the Evolution of the Respiratory Apparatus of Chordates
Compared with the kinetic bronchoalveolar mammalian lung, the avian system combines a large surface area and thin air–blood barrier of the constant volume lung with ease of inflation of the air sacs, resulting in energy-efficient gas exchange.
Comparative Evaluation of the Cadaveric and Computed Tomographic Features of the Coelomic Cavity in the Green Iguana (Iguana iguana), Black and White Tegu (Tupinambis merianae) and Bearded Dragon (Pogona vitticeps)
The results provide an atlas of the normal cross‐sectional and computed tomographic anatomy of the coelomic cavity in the green iguana, the black and white tegu and the bearded dragon, which is useful in the interpretation of any imaging modality.


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It is proposed that the post-hepatic septum may restrict passive visceral movement during breathing, thereby increasing the efficiency of respiratory effort; a modification that could benefit the fitness of active, predatory teiids.
Reptilian lungs. Functional anatomy and evolution.
  • S. Perry
  • Medicine, Biology
    Advances in anatomy, embryology, and cell biology
  • 1983
This work Morphometry of Reptilian Lungs, with Special Emphasis on the Comparison of the Unicameral Lungs of the Teju, Tupinambis nigropunctatus Spix, and the Multicameral lungs of the Savanna Monitor, Varanus exan- thematicus (Bosc), and Speculations on the Evolution of the Amniote Respiratory System.
Activity of the hypaxial muscles during walking in the lizard Iguana iguana.
  • D. Carrier
  • Biology
    The Journal of experimental biology
  • 1990
The demands of locomotion may provide a functional explanation for the basic organization of the hypaxial muscles of tetrapods and support the hypothesis that the hypAXial muscles act to stabilize the trunk during locomotion.
Interrelationship of static mechanical factors and anatomical structure in lung evolution
Comparison of breathing pattern, elastic work of breathing and ventilatory rate indicates that a low-work strategy predominates in reptiles and in birds, which are obligatory rib breathers, and the evolutionary implications of static mechanics for lung structure are discussed.
The evolution of locomotor stamina in tetrapods: circumventing a mechanical constraint
Tetrapod lineages that gave rise to modern ectotherms apparently retained the constraint, becoming either highly specialized for burst activity based on anaerobic metabolism or specialized in passive mech- anisms of defense against predators.
Circulatory impairment induced by exercise in the lizard Iguana iguana.
It is suggested that mechanical coupling of the pulmonary and cardiac pumps may have been important for the evolution of high-speed locomotor stamina in terrestrial vertebrates.
Respiratory muscle compensation for unilateral or bilateral hemidiaphragm paralysis in awake canines.
It is concluded that an integrated strategy of respiratory muscle compensation for unilateral or bilateral diaphragm paralysis occurs among chest wall, abdominal, and diaphagm segmental muscles, with relative contributions of individual muscles adjusted according to the degree of diaphragem dysfunction.
Ventilation and gas exchange in lizards during treadmill exercise.
Because minute ventilation increased more than did oxygen consumption, an increase in lung PO2 during exercise is predicted and, thus, Varanus exanthematicus appears effectively to ventilate its lungs to match the increased metabolic rate during locomotion at moderate speed.
The correlates of foraging mode in a community of brazilian lizards
Mesure de l'intensite de l'approvisionnement chez des especes sympatriques, Ameiva ameiva, Cnemidophorus lemniscatus, Kentropyx striatus et Anolis auratus