Credit: Lab of Wellington V. Cardoso, MD, PhD/Columbia University Medical Center
Vitamin A deficiency during fetal development can lead to excessive growth of smooth muscle surrounding the airways, making the lungs overly reactive to stimulation from the environment later in life and thus at risk to develop asthma. In these cross-sectional images of the lungs of embryonic mice, the dark stains represent smooth muscle. The left image is from a mouse whose mother was fed sufficient vitamin A, while the right image is from a mouse whose mother was fed insufficient vitamin A.