The room is extremely warm. A table is against the far wall of the space, illuminated by a giant red heat lamp strung up above it. On the table are lined up eight tubular vats—they look like modified Erlenmeyer flasks, but at their top is inserted a ridged plastic engine. The beveled edges very gently stir the fluid, which glows pinkish under the red lights. At the bottom of each vat sits a cerebral organoid. They are pale colorless lumps. But not uniform in structure. Some have bumps and ridges others don’t have, while one has a deep central groove. Another has a large cataract-white rounded protuberance. They look truly mysterious, alien, and in their whiteness, their colorlessness, they impress upon the observers their protean nature.

“In the bioreactors,” Todd continues, “it can grow in 3D so it starts to differentiate into a recognizable cerebral phenotype. Neurons, ganglia, glia, and so on. All in a manner similar to the cortex. There’s even the cortical layers.”

Mike approaches one of the vats, poking a finger at an organoid—“What’s this liquid?”

“That’s the Matrigel. The stirring creates currents so the organoid gets this continuous nutrient bath.”

“Oh my god, they’re so big!” Carmen exclaims, examining the lump nearest to her, as large as a baby’s fist. “The last paper had them at, what, ten millimeters? The diameter must be three, maybe even four inches! How did you solve the problem of blood supply?”

Todd blushes at Carmen’s words—“Actually it was a rather ingenious idea we had. We provide a structure for them to grow around, like a—”

“A tree?” Carmen asks, glancing at Kierk, struck by a sense of déjà vu. The flash of the great tree Yggdrasil at night. But while Todd is still nodding, she exclaims—“Oh! You mean like a garden trellis for a growing plant!”

“That’s, that’s exactly—”

“But that doesn’t solve the blood supply problem,” Carmen continues, “unless . . . wait, unless it was a tree that was both porous and hollow! That way the Matrigel circulates to the inner cell mass that normally gets starved because there’s no vascular system!” She looks over to Todd for confirmation, who is flabbergasted.

“Yeah, exactly . . . an artificial vascular system of our making. It really does look like a tree, but small and fine. Like you said, porous and hollow, so the Matrigel can reach the inner cell mass. The organoid grows around it. It took us . . . a really long time to figure out . . .” He’s still ogling Carmen.

“Applications?” Alex asks, standing back from the table, unnerved.

“Oh, everything! If you’re suffering from a neurological disorder, we can make a few of these from a skin biopsy. We can test drugs on them before we try them on you. Check toxicity levels. Or identify the etiology of the disease. This is the future of personalized medicine.”

“So whose is whose?” asks Jessica.