taxonID	type	description	language	source
03812165E429D017FC9324C9048AFEC8.taxon	description	Although the canaliculi appear short in longitudinal section (Fig. 3 D), the cross-sections of most limb bones reveal the presence of complex canalicular networks in the vicinity of the osteocyte bodies (Fig. 3 E – H). The aspect of these networks is somewhat reminiscent of the so-called aspidinocytes, which are thin and elongated unmineralized spaces observed in aspidin, a type of acellular bone. The origin and function of these structures have been subject of debates. (Hancox, 1972; see also the critical discussion of this concept in Francillon-Vieillot et al., 1990 b). The canaliculi have a primarily radial orientation, but tend to converge towards the lumen of vascular canals, when present (Fig. 3 E). It is rare to observe a direct contact between these canalicular extensions and the peri-somatic part of osteocyte lacunae. Their presence in the layer of lamellar endosteal bone (centripetally deposited) surrounding the medullary cavity (Fig. 3 F), testifies that these structures are not anchoring fibres (e. g. Sharpey’s fibres), with which they could have a superficial resemblance. There is little doubt that they indeed represent a complex network of canaliculi, but with ramifications mainly developing at some distance from osteocyte bodies. This situation could indeed explain why it is difficult to clearly show that they originate from the osteocyte lacunae. Vascular canals are mostly represented by primary osteons, whose lumen varies from 10 to 40 µm in diameter, depending on the level of the section, and the individual or species considered (Figs 3 H, 4 – 6). Simple vascular canals are also observable, although they are less frequent and always associated, when present, to primary osteons. In many individuals of diverse taxa, the cortical layers (of periosteal origin) show a pronounced deflection under the vascular canals (Fig. 4 B). This feature is evidence of the primarily periosteal origin of intra-cortical vascularization. Besides the primary osteons, some secondary osteons occur in the peri-medullary region of Nanorana vicina and Pipa pipa (Fig. 4 A). Vascular canals have a preferential longitudinal orientation; however, oblique or even radial canals can be observed in association with longitudinal ones (Figs 3 H, 4 A, B, 5, 6). The distribution of the vascular canals, regardless of their nature, can be random (Fig. 4 C), but this condition is rare; they rather tend to be organized either in radial rows (Figs 4 D, 5 B, 6 A – D), or in circumferential layers (Fig. 4 F), or in a combination of both. In Rhinella marina, the primary osteons are arranged in concentric layers and tend to have a circumferential orientation (Fig. 4 F); this locally gives the bone an apparent laminar organization (but the latter does not correspond, of course, to a fibro-lamellar complex). STATISTICAL ANALYSES	en	Canoville, Aurore, Laurin, Michel, De Buffrénil, Vivian (2018): Quantitative data on bone vascular supply in lissamphibians: comparative and phylogenetic aspects. Zoological Journal of the Linnean Society 182 (1): 107-128, DOI: 10.1093/zoolinnean/zlx016, URL: http://academic.oup.com/zoolinnean/article/182/1/107/3873883
