DG: using this measurement we can calculate growth rates
In some experiments, using Tg(hsp70:HA-mCherryTM), we can also measure shedding rates.

Basic questions about outer segment renewal remain:
• What is the growth molecular machinery that adds new material at the base of outer segment
• How do photoreceptors ‘know’ how much material to add daily?
• Is growth mostly constitutive or is it tightly regulated?
• What is the shedding molecular machinery that daily sheds chunks of distal outer segments?
• Is there an outer segment length set-point? If so, what molecules determine the set-point?
• Are the processes of growth and shedding coordinately regulated?
• Does deregulation of the renewal process contribute to retinal disease?