Ediacaran pithy macroalga Lanceaphyton n. gen. from South China

With differentiated tissues and organs, a high-level eukaryotic macroalga Lanceaphyton xiaojiangensis n. gen. n. sp. lived on the middle–late Ediacaran (ca. 560–551 Ma) seafloor in South China. Its body had a pith (perhaps mechanical tissue) and outer tissue (perhaps epidermis and/or cortex). The lance-like macroalga consists of an unbranching thallus that grew over the sediment surface for sunlight and a holdfast grown into sediments to keep the thallus fixed on the seafloor. The pithy stipe (lower thallus) might have served to support the upper pithless thallus for photosynthesis. The holdfast is composed of a tapering pithy rhizome growing down into the sediments, with many filamentous pithless rhizoids dispersedly growing within the sediments. With the differentiated tissues and organs, especially the pith accounting for about half of the width of the rhizome and stipe, Lanceaphyton n. gen. was a high-level eukaryotic macroalga, similar to phaeophytes in morphological features, but further research is needed on its microstructural details. The pithy macroalga shows that the macroalgal pith had emerged in the Ediacaran. UUID: http://zoobank.org/bc924c5c-84e4-4170-9ca1-caee0d56c6d5.

EP.TU.659Comparison of Gallbladder Tissue Tensile Strength between Thiel Embalmed Cadavers and Living Patients

Aim Formalin-embalmed cadavers have traditionally been used as an integral part of anatomy teaching and surgical training. Cadaveric tissue can, however, be compromised by distorted appearance, shrinkage, rigidity and unnatural colouration. The Thiel embalming process produces more ‘life-like’ specimens and it could be postulated that these may be more suitable for surgical training. This study aimed to provide quantifiable and repeatable measurements for the mechanical tissue properties of Thiel embalmed cadavers. Methods Four gallbladders were removed from Thiel Embalmed cadavers and eleven from living patients during laparoscopic cholecystectomies. The specimens were prepared into a uniform ‘hour-glass’ shape. The cadaveric specimens were loaded onto the Instron tensometer and the patient specimens were loaded onto a portable hand-held tensometer. The samples were extended until complete tensile failure occurred allowing measurement of the tissues’ tensile strength and strain. Results Nine samples were obtained from the four Thiel embalmed gallbladders and 27 samples yielded from the 11 living patients’ gallbladders. The mean ultimate tensile strength of the Thiel samples was 2.16 ± 0.91 MPa compared with 2.24 ± 1.40 MPa in the living patient group (p = 0.85). The Thiel embalmed cadaveric samples had a lower measured mean strain than the living patient gallbladders of (123 ± 33% vs. 233 ± 91%, p < 0.01). Conclusion This study demonstrates that, while tissue strength is well preserved, there may be some differences in how the tissues feel, related to differences in elongation during handling in Thiel embalmed gallbladder tissue.

Passive myocardial mechanical properties: meaning, measurement, models

Passive mechanical tissue properties are major determinants of myocardial contraction and relaxation and, thus, shape cardiac function. Tightly regulated, dynamically adapting throughout life, and affecting a host of cellular functions, passive tissue mechanics also contribute to cardiac dysfunction. Development of treatments and early identification of diseases requires better spatio-temporal characterisation of tissue mechanical properties and their underlying mechanisms. With this understanding, key regulators may be identified, providing pathways with potential to control and limit pathological development. Methodologies and models used to assess and mimic tissue mechanical properties are diverse, and available data are in part mutually contradictory. In this review, we define important concepts useful for characterising passive mechanical tissue properties, and compare a variety of in vitro and in vivo techniques that allow one to assess tissue mechanics. We give definitions of key terms, and summarise insight into determinants of myocardial stiffness in situ. We then provide an overview of common experimental models utilised to assess the role of environmental stiffness and composition, and its effects on cardiac cell and tissue function. Finally, promising future directions are outlined.