Selective gray matter staining of human brain slices: optimized use of cadaver materials

Morphology and morphometry of the spinal cord and meninges in Egyptian Baladi goat (Capra hircus): Stereomicroscopy of blue-stained gray matter

The study objective is to obtain normal morphology and morphometric data from Baladi goat spinal cord segments. Using Tompsett's technique for staining gray matter with a blue stain allowed us to calculate the quantity or area of gray and white matter and thus the total area of each segment. The spinal cord of the goat started at the extent of the middle-third of the occipital condyles, and the tapered end of the spinal cord terminated at the center of the first sacral vertebra. The total length of the spinal cord was 73.3 ± 2.5 cm on average. C3 was the longest spinal segment, measuring 3.95 cm. The gray matter area had a high value at the cervical and lumbar enlargements, with C8 having the highest value of gray matter cross sectional area at 12 mm2 and C7 having the highest value of white matter cross sectional area at 42 mm2 . The area of white matter of the cervical region was higher than that of the other spinal regions. At C7, the total cross section area reached its maximum of 53 mm2 . The cervical enlargement included segments from C6 to T1, while the lumbar enlargement included L5 to S1. The dura mater is connected cranially to the dens of the axis and caudally to the fourth and fifth lumbar vertebrae. The epidural space height between lumbar vertebrae was 2 mm in all lumbar spaces and 3 mm in the lumbosacral space. The normal morphology and morphometric data of the goat spinal cord segments may be useful in pathological conditions of the spinal cord and during epidural anaesthesia technique.

Macroscopic brain gray matter staining: historical protocol overview and neuroanatomy learning applications in second-year medical students

Macroscopic staining in anatomical samples of the central nervous system is a technique that has been used for decades to achieve better differentiation of multiple gray matter structures, such as the cortex, basal ganglia, and cerebellar nuclei. Staining methods are based on using the different components of the brain, mainly the lipids present in the white matter. These techniques have been progressively forgotten while computer renderings are increasing; however, as a primary exposure to surgical anatomy, stained brain specimens are considered a helpful tool. We aim to summarize different staining techniques, their principles, and their current applications for neuroanatomy learning purposes. In total, four gray matter staining protocol descriptions (Mulligan's, Roberts's, Alston's, and Prussian Blue) were performed, as well as Likert scale surveys of second-year medical students about their perceptions of the stained sections. The results showed that the different macroscopic stains for brain tissue are based on lipid and reactant interactions, intending to increase the white matter (WM) and gray matter (GM) contrast. The search also showed that most staining protocols would take 2 days to develop. Efficient preservation options include submerging the sections in formaldehyde solutions, formaldehyde-free solutions, ethanol, or applying plastination techniques. Based on the student's perspective, the stained slices seem to be a valuable alternative to facilitate the study and identification of the basal ganglia and their relationships with the white matter (from 51.2 to 72% based on the Likert scale) compared with the non-stained sections. In conclusion, macroscopic staining of brain tissue continues to be a valuable tool for comprehensively studying the brain. Further research is needed to determine the efficacy of stained specimens as teaching tools.

Fixation and staining methods for macroscopical investigation of the brain

The proper preservation of human brain tissue is an indispensable requirement for post-mortem investigations. Neuroanatomical teaching, neuropathological examination, neurosurgical training, basic and clinical neuroscientific research are some of the possible downstream applications of brain specimens and, although much apart from one another, proper tissue fixation and preservation is a common denominator to all of them. In this review, the most relevant procedures to fixate brain tissue are described. In situ and immersion fixation approaches have been so far the most widespread ways to deliver the fixatives inside the skull. Although most of them rely on the use of formalin, alternative fixative solutions containing lower amounts of this compound mixed with other preservative agents, have been attempted. The combination of fixation and freezing paved the way for fiber dissection, particularly relevant for the neurosurgical practice and clinical neuroscience. Moreover, special techniques have been developed in neuropathology to tackle extraordinary problems, such as the examination of highly infective specimens, as in the case of the Creutzfeldt-Jakob encephalopathy, or fetal brains. Fixation is a fundamental prerequisite for further staining of brain specimens. Although several staining techniques have been developed for the microscopical investigation of the central nervous system, numerous approaches are also available for staining macroscopic brain specimens. They are mostly relevant for neuroanatomical and neuropathological teaching and can be divided in white and gray matter staining techniques. Altogether, brain fixation and staining techniques are rooted in the origins of neuroscience and continue to arouse interest in both preclinical and clinical neuroscientists also nowadays.

Phenoxyethanol-Based Embalming for Anatomy Teaching: An 18 Years' Experience with Crosado Embalming at the University of Otago in New Zealand

Embalming fixatives such as formaldehyde and phenol have been associated with occupational health hazards. While anatomists aim at replacing these chemicals, this seems presently unfeasible in particular for formaldehyde. Furthermore, fixation protocols usually require well-equipped facilities with highly experienced staff to achieve good fixation results in spite of only a minimal use of formaldehyde. Combining these aspects, a technique robust enough to be carried out by morticians is presented, resulting in durable tissues with minimal formaldehyde use. An embalming protocol involving phenoxyethanol was established, using concentrations of 7 and 1.5 Vol% of phenoxyethanol in the fixative and the conservation fluid, respectively. Visual, haptic, histological, and biomechanical properties and their perceived potential to positively influence student learning outcomes were compared to standard embalming techniques. The phenoxyethanol technique provides esthetic, durable, and odorless tissues. Bleaching is less pronounced compared to ethanol- or formaldehyde-based protocols. The tissues remain pliable following the phenoxyethanol-based embalming and can be used for biomechanical experiments to some extent. Phenoxyethanol-fixed tissues are well suited for undergraduate teaching with perceived positive learning outcomes and partly for postgraduate training. Phenoxyethanol tissues provide the option to obtain well-preserved histology samples, similar to those derived from formaldehyde. The provided protocol helps replace the use of phenol and formaldehyde for conservation purposes and minimizes the use of formaldehyde for the initial injection fixation. Phenoxyethanol-based embalming forms an effective alternative to standard embalming techniques for human cadavers. It is simple to use, allowing fixation procedures to be carried out in less sophisticated facilities with non-anatomy staff.