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Abstract Macrophages hold vital roles in immune defense, wound healing, and tissue homeostasis, and have the exquisite ability to sense and respond to dynamically changing cues in their microenvironment. Much of our understanding of their behavior has been derived from studies performed using in vitro culture systems, in which the cell environment can be precisely controlled. Recent advances in miniaturized culture platforms also offer the ability to recapitulate some features of the in vivo environment and analyze cellular responses at the single‐cell level. Since macrophages are sensitive to their surrounding environments, the specific conditions in both macro‐ and micro‐scale cultures likely contribute to observed responses. In this study, we investigate how the presence of neighboring cells influence macrophage activation following proinflammatory stimulation in both bulk and micro‐scale culture. We found that in bulk cultures, higher seeding density negatively regulated the average TNF‐α secretion from individual macrophages in response to inflammatory agonists, and this effect was partially caused by the reduced cell‐to‐media volume ratio. In contrast, studies conducted using microwells to isolate single cells and groups of cells revealed that increasing numbers of cells positively influences their inflammatory activation, suggesting that the absolute cell numbers in the system may be important. In addition, a single inflammatory cell enhanced the inflammatory state of a small group of cells. Overall, this work helps to better understand how variations of macroscopic and microscopic culture environments influence studies in macrophage biology and provides insight into how the presence of neighboring cells and the soluble environment influences macrophage activation. 

Nasal turbinals, scrolled thin bones of the nasal cavity, increase surface area for conditioning inspired air or for olfaction in mammals. To assess function in Eptesicus fuscus (Big Brown Bat), we quantify surface area of respiratory and olfactory turbinals from birth to adult size, using data from microCT scans before and after iodine staining. Surface area of each turbinal is significantly correlated with postnatal age and cranial length. The surface area of the maxilloturbinal and first ethmoturbinal (ET I) grows faster, relative to skull size, than surface area of caudal ethmoturbinals or the frontoturbinal. Histological examination of selected specimens reveals ET I grows disproportionately more presumptive respiratory mucosa than olfactory mucosa, supporting the hypothesis that ET I has a dual function. Lastly, we find that distribution of olfactory mucosa in the caudal nasal cavity diminishes with age. Our findings suggest a reduction in olfactory function in E. fuscus, perhaps due to a diminished role in food acquisition by this aerial insectivore.