RESUMEN

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.

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RESUMEN

No presente estudo avaliou-se a origem, a distribuição e a ramificação do nervo radial de 30 gatos adultos, 15 machos e 15 fêmeas, sem raça definida, mediante dissecação mesoscópica, após a fixação dos espécimes em solução aquosa de formaldeído a 10%. O referido nervo mostrou-se polifasciculado desde a origem até sua ramificação em ramos superficial e profundo. Sua origem ocorreu a partir dos ramos ventrais do sexto (26,7%), sétimo (100%) e oitavo (100%) nervos espinhais cervicais e do ramo ventral do primeiro (100%) nervo espinhal torácico. Na região do braço, onervo radial cedeu ramos musculares em todos os animais (100%) para os músculos tensor da fáscia do antebraço, cabeça longa do tríceps braquial, cabeça acessória do tríceps braquial, cabeça medial do tríceps braquial, cabeça lateral do tríceps braquial e ancôneo, emitindo de 14 a 25 ramos nervosos nesta região. O ramo ventral do sexto nervo espinhal cervical apresentou diferença significativa (p menor ou igual a 0,05) em relação ao sexo dos animais, ocorrendo quase que exclusivamente nas fêmeas, além dos fascículos nervosos, que diferiram significativamente de acordo com a região estudada.

The present study evaluated the origin, distribution and ramification of the radial nerves were studied in 30 adult domestic cats. The sample included 15 females and 15 males of unknown breed. The specimens were fixed in 10% formaldehyde solution. The radial nerve showed many fascicles from the origin also your ramification insuperficial and deep branches. Radial nerves were observed to originate, in 16 cases (26.7%), from the ventral branch of the sixth cervical spinal nerve; in 60 cases (100%), from the ventral branch of the seventh cervical spinal nerve; in 60 cases (100%), from the ventral branch of the eight cervical nerve and in 60 cases (100%), from the ventral branch of the first thoracic nerve. The radial nerves branched out, in all of the animals studied (100.0%), to the tensor fasciae antebrachii,long, accessory, medial and lateral heads of the triceps branchii and anconeus muscles. The radial nerve emits of 14 to 25 nervous branches in this region. However, the branch of the sixth cervical spinal nerve and the nervous fascicles reveal significant differences (p smaller or equal 0.05), respectively, in or with relation to sex of the animals and the studied region.

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