3.1 Histological analysis of bones and viscera
3.1.1 Bone preservationnext section
In spite of demineralisation and various damaged areas, histology performed on Zweeloo Woman’s bone fragments showed that important cellular structures such as Haversian canals and the lamellate structure have survived (fig. 3) (Pyatt et al. 1991).
There is no evidence of generalised destruction caused by mineral dissolution. Such alteration is characterised by the general loss of identifiable features such as bone lamellae, osteocytes and canaliculi (Hollund et al. 2011).
The high degree of preservation of the bone’s microstructure may indicate that the Zweeloo body was recovered from a slightly acidic peat bog with better bone tissue preserving qualities than highly acidic highland peat bogs (Petska et al. 2010). The acidic conditions of high-lying bogs often result in well-preserved bodies with excellent soft tissue preservation combined with totally decalcified bones (Bennike 2003, 39).
3.1.2 Viscera preservation
Our understanding of the long-term survival of viscera (i.e. lungs, heart, liver, blood vessels, kidneys and reproductive system) in bog bodies has increased in recent years.
The liver and kidney, the two organs in which the greater part of the volume consists of epithelial cells, are commonly reduced in size, deformed by the pressure of the peat bog layers or unrecognisable, whereas the lungs and intestinal wall (but not its lining epithelium) are usually the best preserved and most recognisable viscera (Aufderheide 2003, 175-176).
In our specific case we were able to confirm the results of the initial macroscopic identification. The paraffin sections of the kidney provided a perfect survey of the kidney tissue, including major characteristic regions such as the cortex and the renal pelvis (fig. 4A). Tubule-like structures were identified in the renal corpuscle (fig. 4B).
The liver material appeared to be less well preserved than the kidney sample. Nevertheless, liver parenchyma with polygonal-shaped hepatocytes and connective tissue could still be clearly distinguished in the paraffin sections (fig. 5A).
A relatively large number of eggs of the lancet liver fluke Dicrocoelium dendriticum was observed in the liver paraffin sections (B). Parasitological findings showing a case of true dicrocoeliasis in a bog body are reported elsewhere (Searcey et al. forthcoming).