Twenty or thirty years ago, no one would have expected babies born extremely prematurely—between 23 and 25 weeks’ gestation, considered the edge of viability—to survive long enough for their performance as elementary schoolers to be an issue.
But times change. Treatments like surfactants and prenatal steroids, along with improvements in ventilators and nutrition, have often enabled extremely premature children to survive.
The question is now one of long-term development. How will a child born at the edge of viability do—physically, cognitively, intellectually—in the long run? What impairments might he or she face, and how severe will they be?
The typical approach to answering those questions is to carry out a series of physical and cognitive assessments when the child is around 18 to 22 months old. But, as Mandy Brown Belfort, MD, MPH—one of Boston Children’s Hospital’s neonatologists—notes, assessments at that age may not tell you much about how the child will do later on.
They’re small, they’re transparent, and they breed at an amazing rate. They may hold the key to understanding the genetics of many human diseases. And they may help scientists discover new drugs – quicker and cheaper. Oh, and they’re fish.
The zebrafish (Danio rerio to the taxonomists) is a striped tropical fish, no longer than your pinky finger, that looks like it would be more at home in someone’s aquarium than in a laboratory. But for several reasons, zebrafish are powerful organisms for stem cell, developmental, and genetic research:
Despite our distance from zebrafish on the evolutionary tree, they’re surprisingly similar to us from a genetic standpoint.
Because of their small size, they can be housed at high densities.
Compared to other model organisms like mice, they’re relatively inexpensive to care for.
An adult female zebrafish can lay 300 eggs each week. By comparison, a mouse might have a single 12-pup litter each month.
Their skin is permeable, so they can absorb drugs directly from the water of their tank.
Zebrafish embryos are transparent, offering a window into their bodies; some lines, like Casper, remain transparent through adulthood. …