Table 2.

Advantages and Disadvantages of Zebrafish Embryos or Juveniles in Xenotransplantation Studies of Brain Tumors.

Embryos		Juvenile Fish
Advantages	Disadvantages	Advantages	Disadvantages
Transparency enables high-resolution microscopic observations	Experiments last only a few days	Longer-term experiments are possible	Reduced transparency limits the resolution of microscopic observations
No need for immunosuppression	Can accommodate only a few hundred mammalian cells	Can accommodate more mammalian cells	Xenotransplantation requires immunosuppression
No need for feeding	Organ systems are still developing	Most organ systems are mature	Require feeding
	Blood-brain barrier is developing	Blood-brain barrier is functional