Figure 3.

Mammary organoids grown in microcontainers exhibit contractility

(A) Filmstrips show single contractions of three organoids. Maximum dilation and contraction denoted with blue and red arrowheads, respectively.

(B) Overnight dynamics of a single organoid shows 17 contraction events. Green highlighting shows a sequence of high-frequency contractions.

(C) Dynamics of a single contraction.

(D) Poincaré plot embeds temporal dynamics for mammary organoids. Examples of heart, exponential, and normal distributions shown for comparison to organoid contractions. Density in red. n = 50 organoids.

(E and F) Contractility frequency (E) and magnitude (F) histograms for a population (n = 57) of organoids across 21 hr. Kernel density in blue, accompanying box-and-whisker plots in red.

(G) Immunostaining for smooth muscle actin, phalloidin, and cytokeratin 14.

(H) Latrunculin (2 μM) (n = 20 organoids) and jasplakinolide (2 μM) (n = 22 organoids) treatments, targeting actin, prevent contractions.

(I) ML-7 treatment, targeting smooth muscle myosin light-chain kinase, prevents contractions. n = 59 organoids. Scale bars are 50 μm. Code to construct (D), (H), and (I) is available in Data S1.