Comparative Morphology of Skeletal Development in and : Divergent Stiffening Patterns Due to Different Matrix Calcification Processes.

Before calcification begins, the early embryonic and fetal skeletal development of both mammalian and the chondrichthyan fish consists exclusively of cartilage. This cartilage is formed and shaped through processes involving tissue segmentation and the frequency, distribution, and orientation of chondrocyte mitoses. In the subsequent developmental phase, mineral deposition in the cartilage matrix conditions the development further.

Skeletal calcification patterns of batoid, teleost, and mammalian models: Calcified cartilage versus bone matrix.

This study compares the skeletal calcification pattern of batoid Raja asterias with the endochondral ossification model of mammalians Homo sapiens and teleost Xiphias gladius. Skeletal mineralization serves to stiffen the mobile elements for locomotion. Histology, histochemistry, heat deproteination, scanning electron microscopy (SEM)/EDAX analysis, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and Fourier transform infrared spectrometry (FTIR) have been applied in the study.

Fin systems comparative anatomy in model Batoidea Raja asterias and Torpedo marmorata: Insights and relatioships between musculo-skeletal layout, locomotion and morphology.

The macroscopic and microscopic morphology of the appendicular skeleton was studied in the two species Raja asterias (order Rajiformes) and Torpedo marmorata (Order Torpediniformes), comparing the organization and structural layout of pectoral, pelvic, and tail fin systems. The shape, surface area and portance of the T. marmorata pectoral fin system (hydrodynamic lift) were conditioned by the presence of the two electric organs in the disk central part, which reduced the pectoral fin surface area, suggesting a lower efficiency of the "flapping effectors" than those of R.

The combined cartilage growth - calcification patterns in the wing-fins of Rajidae (Chondrichthyes): A divergent model from endochondral ossification of tetrapods.

The relationship between cartilage growth - mineralization patterns were studied in adult Rajidae with X-ray morphology/morphometry, undecalcified resin-embedded, heat-deproteinated histology and scanning electron microscopy. Morphometry of the wing-fins, nine central rays of the youngest and oldest specimens documented a significant decrement of radials mean length between inner, middle and outer zones, but without a regular progression along the ray. This suggests that single radial length growth is regulated in such a way to align inter-radial joints parallel to the wing metapterygia curvature.