Resumen de Long bone histology of the subterranean rodent Bathyergus suillus (Bathyergidae): ontogenetic pattern of cortical bone thickening
German Montoya Sanhueza, Anusuya Chinsamy
Patterns of bone development in mammals are best known from terrestrial and cursorial groups, but there is aconsiderable gap in our understanding of how specializations for life underground affect bone growth anddevelopment. Likewise, studies of bone microstructure in wild populations are still scarce, and they ofteninclude few individuals and tend to be focused on adults. For these reasons, the processes generating bonemicrostructural variation at intra- and interspecific levels are not fully understood. This study comprehensivelyexamines the bone microstructure of an extant population of Cape dune molerats, Bathyergus suillus(Bathyergidae), the largest subterranean mammal endemic to the Western Cape of South Africa. The aim ofthis study is to investigate the postnatal bone growth of B. suillus using undecalcified histological sections(n = 197) of the femur, humerus, tibia-fibula, ulna and radius, including males and females belonging todifferent ontogenetic and reproductive stages (n = 42). Qualitative histological features demonstrate a widehistodiversity with thickening of the cortex mainly resulting from endosteal and periosteal bone depositions,whilst there is scarce endosteal resorption and remodeling throughout ontogeny. This imbalanced bonemodeling allows the tissues deposited during ontogeny to remain relatively intact, thus preserving an excellentrecord of growth. The distribution of the different bone tissues observed in the cortex depends on ontogeneticstatus, anatomical features (e.g. muscle attachment structures) and location on the bone (e.g. anterior orlateral). The type of bone microstructure and modeling is discussed in relation to digging behavior,reproduction and physiology of this species. This study is the first histological assessment describing the processof cortical thickening in long bones of a fossorial mammal
