During cardiac c-looping, the heart transforms from a straight tube into a c-shaped tube, presenting the first evidence of left-right asymmetry in the embryo. C-looping consists of two primary deformation components: ventral bending and dextral rotation. This study examines the role of actin polymerization in bending of the heart tube. Exposure of stage 9-11 chick embryos to low concentrations of the actin polymerization inhibitors cytochalasin D (5 nM-2.0 microM) and latrunculin A (LA; 25 nM-2.0 microM) suppressed looping in a stage- and concentration-dependent manner in both whole embryos and isolated hearts. Local exposure of either the dorsal or ventral sides of isolated hearts to LA also inhibited looping, but less than global exposure, indicating that both sides contribute to the bending mechanism. Taken together, these data suggest that ongoing actin polymerization is required for the bending component of cardiac c-looping, and we speculate that polymerization-driven myocardial cell shape changes cause this deformation.

Looping is a vital event during early cardiac morphogenesis, as the initially straight heart tube bends and twists into a curved tube, laying out the basic pattern of the future four-chambered heart. Despite intensive study for almost a century, the biophysical mechanisms that drive this process are not well understood. To explore a recently proposed hypothesis for looping, we constructed a finite element model for the embryonic chick heart during the first phase of looping, called c-looping. The model includes the main structures of the early heart (heart tube, omphalomesenteric veins, and dorsal mesocardium), and the analysis features realistic three-dimensional geometry, nonlinear passive and active material properties, and anisotropic growth. As per our earlier hypothesis for c-looping, actin-based morpho-genetic processes (active cell shape change, cytoskeletal contraction, and cell migration) are simulated in specific regions of the model. The model correctly predicts the initial gross morphological shape changes of the heart, as well as distributions of morphogenetic stresses and strains measured in embryonic chick hearts. The model was tested further in studies that perturbed normal cardiac morphogenesis. The model, taken together with the new experimental data, supports our hypothesis for the mechanisms that drive early looping.

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The inclusion of human body dissection in anatomical science curricula has been described as a critical educational experience for the mastery of anatomical structures and concepts. To ensure that body donors are ethically acquired and suitable for anatomy education, Anatomical Donation Programs (ADPs) are tasked with the responsibility of acquiring body donors for basic and clinical science curricula. Considering the personal and institutional impact of SARS‐CoV‐2, a national survey was conducted to examine the current effect of the pandemic on ADP protocols, body donation, and the sustainability of ADPs in the United States (U.S.). Eighty‐nine U.S. ADPs were identified and contacted for optional participation in a survey to assess the impact of the SARS‐CoV‐2 pandemic on their programs. Survey data were collected and managed using REDCap electronic data capture tools. Thirty‐six ADPs (40.5% response rate) from the nine U.S. Divisions are represented in the survey results. Data were collected on ADP descriptions and demographics, SARS‐CoV‐2 impact on ADPs and protocols, and body donation and ADP sustainability. Almost all ADPs reported that the pandemic has affected their ADP operations in some way; however, the sustainability for the majority of ADPs appears likely and donor availability remains stable due to a proportional decrease in body donations and body donor requests. As the long‐term impact on ADPs has yet to be determined, the authors plan to reevaluate the lasting impact of the SARS‐CoV‐2 pandemic on body donation, ADP sustainability, and anatomical science education throughout the year 2021.

Cardiac looping is a vital morphogenetic process that transforms the initially straight heart tube into a curved tube normally directed toward the right side of the embryo. We examined the role of biomechanical forces during the initial stages of looping, when the heart bends and rotates into a c-shaped tube (c-looping). C-looping consists of two primary deformation components: ventral bending and dextral (rightward) rotation (torsion). Embryonic chick hearts were subjected to mechanical and chemical perturbations, and the experiments were simulated using a computational model. The results suggest that bending is driven primarily by actin polymerization within the heart tube, while rotation is driven by external loads due to the splanchnopleure and omphalomesenteric veins. The results of this study may help investigators searching for the link between gene expression and the mechanical processes that drive looping.