Fabiano Campos Lima

Ontogeny of the Shell Bones of Embryos of Podocnemis unifilis (Troschel, 1848) (Testudines, Podocnemididae)

The aim of the present study was to investigate the sequence of shell bone formation in the embryos of the Pleurodira, Podocnemis unifilis. Their bones and cartilage were collected and cleared before staining. The shell was also examined by obtaining a series of histological slices. All the bony elements of the plastron have independent ossification centers, which subsequently join together and retain two fontanelles until the period of hatching. This turtle has a mesoplastra, which is characteristic of the Podocnemididae. The carapace begins to form concurrently with the ossification of the ribs at the beginning of stage 20. All the plates, except the suprapygal, initiate ossification during the embryonic period. The main purpose of the histological investigation was to highlight the relationship between the formation of the carapace and ribs with that of the neural plates. The costal and neural plates were found not to independent ossification centers, but to be closely related to components of the endoskeleton, originating as expansions of the perichondral collar of the ribs and the neural arches, respectively. Considering the ribs as an endoskeletal element of the carapace, the carapace and plastron begin ossification at the same stage in P. unifilis. This pattern reveals similarities with other Pleurodira, as well as evident variations, such as the presence of the seven neural bones and the presence of only one ossification center in the nuchal plate. Anat Rec, 2011.

Ontogeny of the Plastron of the Giant Amazon River Turtle, Podocnemis expanse (Schweigger, 1812) (Testudines, Podocnemididae)

Podocnemis expanse, known popularly as the giant Amazon river turtle, is widely exploited. This makes specimens available for various studies, and we used this opportunity to investigate aspects of the development of the plastron. We examined several stages of pre- and post- hatching development in embryos and hatchlings collected starting from day 18 of natural incubation. Embryos and hatchlings were cleared and double stained for cartilage and bone. The epiplastron, endoplastron, hyoplastron, hypoplastron, xiphiplastron, and mesoplastron bones form the complete plastron of this turtle. In stage 16, bone centers become visible in most of the bones of the plastron. Alizarin Red stain retention indicated that the sequence of bone ossification is as follows: first the hyoplastron and the hypoplastron, then the endoplastron followed by the xiphiplastron, and lastly the mesoplastron. The epiplastron bone shows an ossification center only in stage 20. All these elements have independent ossification centers and join together only later. The plastron closes completely seven months after hatching.

A Staging Table of Post-Ovipositional Development for the South American Collared LizardTropidurus torquatus(Squamata: Tropiduridae): IN OVO STAGING TABLE OFTROPIDURUS TORQUATUS

The mouse, chicken, African clawed frog, and zebrafish are considered ¨model organisms¨ due to their extensive embryological and genetic characterization. However, they are far from representative of known diversity, impairing phylogenetic analyses of developmental patterns. Since squamates have historically received limited attention in developmental studies, we here describe the developmental sequence for Tropidurus torquatus, and provide the first post‐ovipositional developmental series for the lizard family Tropiduridae. Fifteen developmental stages are described based on morphological traits such as the eye and accessory visual structures, pharyngeal arches, fusion of facial primordia, limb development, pigmentation, and scales. Organogenesis is already in progression at oviposition (Stage 28), with embryos continuing to develop at the incubation temperature of 30°Cu2009±u20091°C, and hatching after 75u2009±u20095 days, at Stage 42. Comparisons with other lizards show a conserved embryonic sequence, however developmental timing differences were found in features such as the pharyngeal arches, endolymphatic sacs, pigmentation and scales. The development of the phallic and cranial lip of the cloaca anlages are compared with that of other lizards. The order of T. torquatus fore‐ and hindlimb formation differs from that most commonly observed in lizards. The abundance and close association of this species with urban environments, as well as the ease of capturing and managing females, makes T. torquatus an attractive source of developmental data for future experimental and ontogenetic studies. Anat Rec, 300:277–290, 2017.

Chondrogenesis of the limbs and mesopodial ossification of Podocnemis expansa Schweigger, 1812 (Testudines: Podocnemidae).

We address the chondrogenic formation of the limbs and the mesopodial ossification pattern of the Pleurodira Podocnemis expansa, to resolve the homology of these elements as well as the pattern of connection of the autopodial elements and the origin of the digital arch. Embryos and juveniles of P. expansa were cleared and stained for cartilage and bone. The fore‐ and hind‐limbs were also studied histologically. We describe the development of the stylopodium and zeugopodium originating from a Y‐shaped cartilaginous condensation, and the differentiation of the primary axis and the digital arch in the initial stages of limb development. The most pronounced changes were observed in the chondrogenic pattern and ossification of the mesopodium, although development of the digits is similar and we found no ontogenetic reduction such as that described for other Testudines. In this study, as in previous research involving several groups of reptilian sauropsids, we found an inconsistent pattern between the chondrogenic formation and mesopodial ossification of the limbs, indicating that these developmental events are dissociated. In summary, the chondrogenic and ossification sequences of these elements do not follow the same pattern. In addition, the differences found between P. expansa and other species to which it was compared clearly indicate that these events follow more than one pattern in Testudines. J. Morphol., 2011.

Ontogeny of the Appendicular Skeleton in Melanosuchus niger (Crocodylia: Alligatoridae)

The objective of the present study was to analyze chondrogenesis and the ossification pattern of the limbs of Melanosuchus niger in order to contribute with possible discussions on homology and the fusion pattern of autopodial elements and phylogeny. In the Reserva Extrativista do Lago Cuniã, Rondônia, Brazil, six nests were marked and two eggs removed from each nest at 24-hour intervals until hatching. Embryos were cleared using KOH; bone tissue was stained with alizarin red S and cartilage with Alcian blue. Routine staining with HE was also performed. In the pectoral girdle, the scapula showed ossification centers before the coracoid process. In the pelvic girdle, the ilium and the ischium were condensed as a single cartilage, although ossification took place through two separate centers, forming distinct elements in the adult. The pubis developed from an independent cartilaginous center with free end, which reflects its function in breathing. In the initial stages, the stylopodium and the zeugopodium developed from the condensation of a Y-shaped cartilage in the limbs, and differentiation of the primary axis and digital arch were observed. The greatest changes were observed in the mesopodia. In their evolution, Crocodylia underwent a vast reduction in the number of autopodial elements as a consequence of fusions and ossification of some elements. This study shows that the chondrogenesis and ossification sequences are dissociated. Moreover, the differences between M. niger and other species show clear variation in the patterns for these events in Alligatoridae.

Anatomical and Topographical Description of the Digestive System of Caiman crocodilus (Linnaeus 1758), Melanosuchus niger (Spix 1825) and Paleosuchus palpebrosus (Cuvier 1807)

Mediante comparaciones anatomicas y topograficas describimos el sistema digestivo de C. crocodillus, M. nigeri y P. palpebrosus. Se utilizaron dos sistemas digestivos de C. crocodillus, uno de M. nigeri y uno de P. palpebrosus, fijados en formalina al 10% y pertenecientes al laboratorio de ensenanza e investigacion de fauna silvestre (LAPAS) de la Universidade Federal de Uberlândia. En primera instancia se realizo la descripcion del sistema digestivo de las mencionadas especies, seguido de comparaciones topograficas. Luego, fueron tomados registros fotograficos con camara DSC H20 SONY. Adicional a esto, nos apoyamos con radiografias del tracto gastrointestinal y fotografias del sistema digestivo de C. crocodillus antes de ser fijados en formalina. Los resultados demuestraron que el sistema digestivo de estas tres especies de caimanes esta constituido por una boca grande, faringe corta, esofago alargado y rectilineo, estomago dilatado con relacion a las otras partes del tracto digestivo, pancreas alojado entre las dos primeras curvaturas duodenales ventrales, intestino delgado plegado, intestino grueso con un diametro mayor en relacion a los segmentos anteriores y una cloaca donde tambien terminan los sistemas urinarios y reproductor. La descripcion anatomica y topografica del sistema digestivo de C. crocodillus, M. niger y P. palpebrosus puede ser extrapolada para otros cocodrilos por la semejanza comportamental interespecies e intraespecificas.

Ontogeny of the Postcranial Axial Skeleton of Melanosuchus niger (Crocodylia, Alligatoridae)

This study proposes the description of the development of the postcranial axial skeleton, including vertebrae, gastralium, ribs, sternum, and interclavicle, in Melanosuchus niger. Six nests were marked and two eggs removed from each nest at 24‐hr intervals until hatching. For posthatching evaluation, 30 hatchlings were kept in captivity and one exemplar was euthanized at three‐day intervals. Samples were diaphanized using potassium hydroxide (KOH), alizarin red S, and Alcian blue. A routinely generally used method was applied for histological evaluation. It was difficult to define in which vertebrae the development of cartilaginous centers began, but it was possible to observe that this condensation advanced in the craniocaudal direction. The condensation started in the vertebral arches and was visibly stronger in the cervical and dorsal regions, advancing to the lumbar, sacral and, last, to the caudal region. The atlas showed a highly different morphology compared with the other cervical vertebrae, with a short intercenter, two neural arches, and a proatlas. The ossification process began in the body of cervical vertebrae III to VIII and alizarin retention decreased in the last vertebrae, indicating a craniocaudal direction in bone development, similar to cartilage formation. In the histological sections of gastralium and interclavicles of M. niger at several development stages, it was possible to observe that these elements showed intramembranous development. Anat Rec, 301:607–623, 2018.

Osteologia do neurocrânio de Iguana iguana (Squamata : Iguanidae)

O crânio representa o segmento com conspicuas adaptacoes que, nos lagartos, podem ser conservativas ou impulsionadas por pressoes seletivas. Objetivando subsidiar o conhecimento morfologico dos repteis, fornecemos uma descricao detalhada dos ossos que formam o neurocrânio de Iguana iguana iguana com base na analise de tres esqueletos secos de especimes adultos. O crânio da referia especie possui caracteristicas basais entre os lagartos sem o fechamento das aberturas cranianas e formato geral triangular. As estruturas osseas que formam a base craniana apresentam muitas fusoes, principalmente no assoalho. Na face caudal o exoccipital e o opistotico estao fundidos e formam o otoccipital, que contribui para a formacao dos tercos laterais do condilo occipital. A parte central do condilo e formada pelo supraoccipital. Fusoes e estruturas esqueleticas presentes em Iguana sao similares aos demais lagartos. Nao foram descritas autapomorfias no neurocrânio para esta especie.

Skeletogenesis of the pelvic girdle and pelvic members in embryos of Caiman yacare (Crocodylia: Alligatoridae)

Caiman yacare embryos were collected and subjected to the bone cleared and Alizarin staining to analyze the ontogenic patterns of the skeletal ossification of the pelvic girdle and members. Ossification of C. yacare pelvis begins at 36 days of incubation. The femur, tibia and fibula present simultaneous stain retention at 30 days. It has four tarsal bones, the calcaneus, the talus, distal III and distal IV. Their ossification starts with the calcaneus from the 40th day of incubation, followed by the talus. At 54 days, the distal tarsal IV is conspicuous, as is the outline of the distal III. Each foot has five metatarsi (MT) and 13 phalanges (phalangeal formula 2:3:4:4). Ossification of the metatarsi begins at 36 days and follows the sequence MTI=MTII=MTIII=MTIV>MTV. The first phalanges begin the ossification process on the 36th day and continue up to the last day of incubation. The sequence of ossification of the proximal phalanges is PPI=PPII=PPIII>PPIV, while that of the medial phalanges is MPII> MPpIII>MDpIII>MPpIV>MDpIV and that of the distal phalanges is DPI>DPII>DPIII>DPIV, and the ontogenic pattern of the bones of the pelvic girdle and members of C. yacare differs from that of other reptiles, albeit with a few similarities. n n Key words: Alizarin, morphology, ossification, pantanal caiman, reptiles.