This was one of the organ-growing baths whose contained fluid was what Pia would be investigating for the month. She leaned over and peered into the container at a miniature translucent object suspended in the liquid by a kind of spiderweb that she was later to find out was made of the same material as real spiderwebs. As for the object itself, she could see it was connected by filament-thin lines to a central clamp where the lines were gathered. A thicker cable fed out of the bath and down into the body of the cart, where there was a boxy device with multiple readouts monitoring the conditions in the bath. An attached magnifying device on a movable arm was also connected to the cart. Pia maneuvered it into position so she could see the contained object better. Although it was not too much larger than a pine nut, its appearance was unmistakably that of a kidney, albeit a very tiny kidney. Most of the lines contained red fluid along one larger one that was clear. The red ones were presumably functioning as veins and arteries. The clear one was acting as the ureter to take away the urine the miniature organ was producing. To one side of the container was a jet, like one attached to a pool circulator, only in miniature. It was pulsating at a very rapid rate. Gentle eddies of liquid coursed around the container, causing the organ’s surface to pulsate slightly.

“We find that we must keep the fluid in the baths in constant motion despite the organs being perfused internally. But it has to be carefully modulated. Occasionally the rigid bath sets up a wash that can disturb the organ.” Yamamoto had stepped over to join the students. He noticed Pia straighten, looking down the length of the room.

“It’s quite something, isn’t it?” he said, speaking directly to her. “Of course, I see it every day, so I’ve come to take it all for granted.”

“How are the organs started?” Pia asked.

“They are started in tissue culture dishes designed to mimic the mouse uterine environment in terms of temperature and with pulsation waves close to the normal mouse heart rate of around five hundred and fifty beats a minute. As I said earlier, the whole process, first in the tissue culture dishes and then in these organ baths, is a ballet of gene expression with a careful adherence to sequence and timing. It starts with an aliquot of induced pluripotent stem cells held in close proximity by spiderweb-like restraints. Remember, to form a whole organ we have to involve all three germ layers: ectoderm, mesoderm, and endoderm. Once the organ has reached a size that can be manipulated, it is moved into these baths to develop to its full extent.”

“Are there other organs in here besides kidneys?” Will asked.

“Heavens yes,” Yamamoto said. “We’ve got all the usual transplantable organs such as livers, pancreases, lungs, and hearts so far. The kidney program is the most advanced, since it was kidneys we started with. To prove we are on track with what we have been doing, we have already transplanted some organs back into the individual mice from which the fibroblasts were taken with complete and utter success. And let me share another leap forward that we are in the process of making. We’ve found that carrying out organogenesis with multiple organs works even better than growing them singularly, meaning we have preparations in which the developing organs are helping each other, like the heart pumping the perfusing fluid and the kidneys removing waste.”