Analysis of entire transparent rodent bodies after clearing could provide holistic biological information in health and disease, but reliable imaging and quantification of fluorescent protein signals deep inside the tissues remained a challenge. Here, we developed vDISCO, a pressure driven, nanobody based whole-body immunolabeling technology to enhance the signal of fluorescent proteins by up to two orders of magnitude. This allowed us to image and quantify subcellular details through bones, skin and highly autofluorescent tissues of intact transparent mice. For the first time, we visualized whole-body neuronal projections in adult mice. We assessed CNS trauma effects in the whole-body and found degeneration of peripheral nerve terminals in the torso. Furthermore, vDISCO revealed short vascular connections between skull marrow and brain meninges, which were filled with immune cells upon stroke. Thus, our new approach enables unbiased comprehensive studies of the interactions between the nervous system and the rest of the body.

Highlights d CHAPS forms smaller micelles allowing full permeabilization of aged human organs d SHANEL enables centimeters deep molecular labeling and clearing of whole human organs d SHANEL renders intact adult human brain and kidney transparent d Deep learning and light-sheet microscopy with SHANEL allows human organ mapping

Thiel-fixed specimens have outstandingly lifelike visual and haptic properties. However, the original Thiel method is expensive and requires an elaborate setup. It is therefore of principal interest to modify the Thiel method in order to make it available to a broader user group. A modified Thiel embalming method will be described in detail and compared to ethanol-glycerin fixation with the help of illustrative examples. The visual properties, haptic properties, the usability for performing histological investigations, costs and potential health aspects will be considered. Tissues fixed with the modified Thiel technique gave results similar to the original method, providing more realistic visual and haptic properties than ethanol-glycerin embalming. However, Thiel fixation is significantly more expensive and requires more precautions to minimize potential health hazards than ethanol-glycerin-fixed tissues. In contrast to ethanol-glycerin-fixed specimens, the Thiel-fixed specimens are not suitable for histological investigations. Both modes of fixation are inappropriate for biomechanical testing. Modified Thiel embalming simplifies the availability of body donors with lifelike properties and has cost-saving advantages to the original technique. Thiel-embalmed body donors are ideally suited for clinical workshops but have restrictions for student dissection courses in facilities with limited storage space, air circulation or technical staff. Vice versa, ethanol-glycerin-fixed body donors are well suited for student dissection courses in such an environment but are limited in their use for clinical workshops. Modified Thiel embalming therefore ideally complements ethanol-glycerin fixation in order to provide customized solutions for clinical workshops and student dissection courses in a wide range of applications.

Anatomical fixation and conservation are required to prevent specimens from undergoing autolysis and decomposition. While fixation is the primary arrest of the structures responsible for autolysis and decomposition, conservation preserves the state of fixation. Although commonly used, formaldehyde has been classified as carcinogenic to humans. For this reason, an adequate substitute was developed. Ethanol-glycerin fixation and thymol conservation are described and compared with formaldehyde and phenol in this technical report. The setup, tissue qualities, financial aspects, and health concerns of this method are discussed. Ethanol-glycerin fixation and thymol conservation provide outstanding haptic and optic tissue qualities. Typical formaldehyde and phenol effects, such as skin, airway, and eye irritation, as well as carcinogenic effects, can be circumvented by using ethanol-glycerin and thymol instead. Ethanol-glycerin fixation is more expensive than formaldehyde and requires an explosion-proof facility. However, the absence of health effects and its convincing tissue qualities balance these higher costs. Therefore, ethanol-glycerin fixation and thymol conservation provide a potential alternative and complement established fixation techniques. The use of carcinogenic formaldehyde and toxic phenol can be effectively restricted through the use of the described method.

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Recent advantages in the anatomical understanding of the face have turned the focus toward the subcutaneous and deep facial fat compartments. During facial aging, these fat-filled compartments undergo substantial changes along with other structures in the face. Soft tissue filler and fat grafting are valid methods to fight the signs of facial aging, but little is known about their precise effect on the facial fat. This narrative review summarizes the current knowledge about the facial fat compartments in terms of anatomical location, histologic appearance, immune-histochemical characteristics, cellular interactions, and therapeutic options. Three different types of facial adipose tissue can be identified, which are located either superficially (dermal white adipose tissue) or deep (subcutaneous white adipose tissue): fibrous (perioral locations), structural (major parts of the midface), and deposit (buccal fat pad and deep temporal fat pad). These various fat types differ in the size of the adipocytes and the collagenous composition of their extracellular matrix and thus in their mechanical properties. Minimal invasive (e.g., soft tissue fillers or fat grafting) and surgical interventions aiming to restore the youthful face have to account for the different fat properties in various facial areas. However, little is known about the macro- and microscopic characteristics of the facial fat tissue in different compartments and future studies are needed to reveal new insights to better understand the process of aging and how to fight its signs best.

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