Figure 3 : Microanatomy and histology of the medullary bone-like tissue and the more compacted secondary tissues in multiple sections of 2007.111.1(20).

From: Medullary bone-like tissue in the mandibular symphyses of a pterosaur suggests non-reproductive significance

Figure 3

Note that medullary bone-like tissue is in different phases of development: areas of intact bone are seen in (a) and (b); resorption just started in (c) and (d); advanced resorption only leaves a ring of the tissue in the cavity in (f). In (c) the interwoven compact secondary tissue with large SO-lacunae is sandwiched between two recesses showing medullary bone-like tissue deposition, and is separated from them by distinct resorption lines. In (e) and (f), the highly porous, unorganized secondary bone is sandwiched between the endosteal lamellae of a central cavity and the primary cortex. Image in (d) was taken under single plane polarizers; the rest of the images under crossed plane polarizers aided by lambda wave plate. Abbreviations: Dol, dynamic osteocyte lacunae; El, endosteal lamellae; Es, eroded endosteal surface; Hl, Howship lacunae; Icsb, interwoven compact secondary bone; Ipsb, interwoven porous secondary bone; Lc, lamellar compaction; Mbr, remnant of medullary bone-like tissue; rc, resorption channels and cavities; Sol, static osteocyte lacunae; Vc, vascular canal; Wbs, woven bone struts. Other abbreviations as in Fig. 2.