We investigated the cell behaviors that drive morphogenesis of the Drosophila follicular epithelium during expansion and elongation of early‐stage egg chambers. We found that cell division is not required for elongation of the early follicular epithelium, but drives the tissue toward optimal geometric packing. We examined the orientation of cell divisions with respect to the planar tissue axis and found a bias toward the primary direction of tissue expansion. However, interphase cell shapes demonstrate the opposite bias. Hertwig's rule, which holds that cell elongation determines division orientation, is therefore broken in this tissue. This observation cannot be explained by the anisotropic activity of the conserved Pins/Mud spindle‐orienting machinery, which controls division orientation in the apical–basal axis and planar division orientation in other epithelial tissues. Rather, cortical tension at the apical surface translates into planar division orientation in a manner dependent on Canoe/Afadin, which links actomyosin to adherens junctions. These findings demonstrate that division orientation in different axes—apical–basal and planar—is controlled by distinct, independent mechanisms in a proliferating epithelium.

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The function of an epithelial tissue is intertwined with its architecture. Epithelial tissues are often described as pseudo-two-dimensional, but this view may be partly attributed to experimental bias: many model epithelia, including cultured cell lines, are easiest to image from the “top-down.” We measured the three-dimensional architecture of epithelial cells in culture and found that it varies dramatically across cultured regions, presenting a challenge for reproducibility and cross-study comparisons. We therefore developed a novel tool (Automated Layer Analysis, “ALAn”) to characterize architecture in an unbiased manner. Using ALAn, we find that cultured epithelial cells can organize into four distinct architectures and that architecture correlates with cell density. Cells exhibit distinct biological properties in each architecture. Organization in the apical-basal axis is determined early in monolayer development by substrate availability, while disorganization in the apical-basal axis arises from an inability to form substrate connections. Our work highlights the need to carefully control for 3D architecture when using cell culture as a model system for epithelial cell biology and introduces a novel tool, built on a set of rules that can be widely applied to epithelial cell culture. [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text]

A one‐dimensional non‐iterative direct method was employed for normalized crystal truncation rod analysis. The non‐iterative approach, utilizing the Kramers–Kronig relation, avoids the ambiguities due to an improper initial model or incomplete convergence in the conventional iterative methods. The validity and limitations of the present method are demonstrated through both numerical simulations and experiments with Pt(111) in a 0.1 M CsF aqueous solution. The present method is compared with conventional iterative phase‐retrieval methods.

The joint AAPT and APS PHYS21 report emphasizes preparing students for diverse career paths, including the need for more opportunities to learn innovation and entrepreneurship in physics. To support these changes, research is needed on students' interest and perceptions of innovation and entrepreneurship, and suggestions for integration into the undergraduate physics experience. We conducted semi-structured focus groups with 20 physics majors around several concepts related to innovation and entrepreneurship: technology, creativity, design, business, communication, and leadership. Emergent and thematic coding was used to analyze students' responses. Students have a complex view of innovation and entrepreneurship in physics perceiving creativity as closely related to physics, especially in undergraduate research, while business and leadership skills were distinct from physics and closer to engineering. These findings have implications for understanding students' perceptions of physics as a disciplinary community and field of study, and can assist departments seeking to better support students' careers.