Mitochondria to Bitter Melon: Understanding the 3D Ultrastructure of the Cell Via 2D Thin Section Reconstruction and the History of Mitochondrial Visualization.

The origin of histology-the study of microscopic anatomy-is intimately connected with the development of the light microscope and improvements in lens design and manufacture.However, knowledge of the ultrastructure of the cell was hampered by the very nature of light microscopy, which, due to the physical properties of the visible electromagnetic spectrum, could never provide the magnification and resolution for study of the granules seen in cells, which we now know as the organelles. When the electron microscope was developed in the 1930s, a beam of electrons replaced light as the source of illumination, and the inner details of the cell could be observed directly. With thin sections obtained by transmission electron microscopy, cell biologists could embark on the task of reconstructing 3D microstructure via the painstaking stacking of the individual slices.The three-dimensional visualization of the mitochondrion was particularly challenging, as its convoluted structure could be interpreted in several ways based on differences observed by George Palade at the Rockefeller Institute for Medical Research (NYC), and Fritiof Sjöstrand at the Karolinska Institutet (Stockholm). Palade's interpretation was eventually accepted as correct due to its alignment with the findings of biochemists investigating the cascade of molecular interactions known as the Krebs cycle, responsible for the production of cellular energy in the form of adenosine triphosphate (ATP). However, it can also be argued that Palade's visualization via a physical model of the mitochondrion, which he built with sheets of wax, photographed, and published in 1953, better enabled colleagues to comprehend its unique inner structures known as cristae.To teach undergraduate science students about this pivotal moment in cell biology and add to their understanding of the reconstruction process, a pedagogical exercise was created in which students are provided with outline drawings of various organic objects cut in random planes of section. Working individually at first, and then in groups, they are tasked with collaborating to devise an accurate description of the shape and texture of the object. After their observations are presented to the class, they are shown a photo of the object prior to its sectioning to determine if their observations were correct.

From Scope to Screen: The Evolution of Histology Education.

Histology, the branch of anatomy also known as microscopic anatomy, is the study of the structure and function of the body's tissues. To gain an understanding of the tissues of the body is to learn the foundational underpinnings of anatomy and achieve a deeper, more intimate insight into how the body is constructed, functions, and undergoes pathological change. Histology, therefore, is an integral element of basic science education within today's medical curricula. Its development as a discipline is inextricably linked to the evolution of the technology that allows us to visualize it. This chapter takes us on the journey through the past, present, and future of histology and its education; from technologies grounded in ancient understanding and control of the properties of light, to the ingenuity of crafting glass lenses that led to the construction of the first microscopes; traversing the second revolution in histology through the development of modern histological techniques and methods of digital and virtual microscopy, which allows learners to visualize histology anywhere, at any time; to the future of histology that allows flexible self-directed learning through social media, live-streaming, and virtual reality as a result of the powerful smart technologies we all carry around in our pockets. But, is our continuous pursuit of technological advancement projecting us towards a dystopian world where machines with artificial intelligence learn how to read histological slides and diagnose the diseases in the very humans that built them?

Formalin use in anatomical and histological science in the 19th and 20th centuries.

The introduction of formalin, a formaldehyde solution, as a disinfectant and fixative was an essential improvement in anatomical and histological science. This paper is an outline of the historical use of formalin based on primary source texts and historical studies. We describe how the discovery of acetaldehyde in the 18th century led to the development of formalin as the most common ingredient in embalming fluids in the 20th century and is still used today. Particularly important contributions to this process were made by Justus von Liebig, Alexander Butlerow and August Wilhelm Hofmann in the development of anatomical and histological preparation techniques, and by Ferdinand Blum, Ferdinand Julius Cohn, Frederick C. Kenyon and Victor Wehr in the practical uses of formaldehyde solutions in preservation and fixation of soft tissues. However, formalin is not without its drawbacks and as its toxicity became more understood, method to mitigate its effects were demanded. Eventually safer preparation techniques were developed, including Hagens' plastination and Thiel Embalming Method. These techniques may someday largely replace high-concentration formalin solutions but they both still require at least small quantities of formaldehyde to preserve tissues for study.

Innsbruck's histological institute in the third Reich: Specimens from NS-victims.

As elsewhere, the cadavers of Nazi victims were used at the 'Alpenunversität Innsbruck' for the education of medical students. They were also used by members of the Institute of Anatomy and the Institute of Histology for scientific research and publications. In 2018, over 300 drawers were discovered in a laboratory anteroom of the Innsbruck Histological Institute containing around 15,000 histological slides. After a closer examination, 237 slides were found to have human tissues from victims of the 3rd Reich possibly. These 237 slides were produced between May 1938 and March 1944. All 237 slides were digitized, the labels carefully analysed, and some of the victims were identified. Several specimens come from the tissues of three Nazi victims who were executed in Munich-Stadelheim and whose bodies were brought to the Innsbruck Anatomical Institute. From there, the organs were passed on to the Histological Institute Innsbruck. Inscriptions on other slides such as "Cl[ara]. 40", "hing[erichtet]. Clara" or "Hinger[ichtet]. Cl[ara]." prove that the specimens were most likely sent to the Institute by the histologist Max Clara. At this time, Clara was Director of the Leipzig Anatomical Institute and still had close ties to the Innsbruck Institute, where he had been trained. Based on several sources, some Nazi victims could be identified by name; biographical traces complement this identification. Under what political and sociological conditions future generations will look at the crimes of the Nazi dictatorship is not yet foreseeable. As anatomists and scientists, we must be cautious about removing evidence from this terrible time. Therefore, we will bury all slides where relatives wish to do so or where it is clear that Rabbi Polak's "Vienna Protocol" must be applied. However, the remaining slides will be kept safe for eventual further investigation.