Good day/evening for everyone!

I have a technical questions, about microscopy of roller bottles, and a more broad problem: how to control adhesion-dependent cells in large roller bottles?

1) My institute received a CO2-incubator with an installed roller, and a pack of roller bottles to start. However the bottles are large in diameter, 12-cm diameter. There are no microscopes to accomodate such height (in my institution).

Would anyone who worked out this problem tell me, what you do to control cell density of cultures growing in such large bottles? Do your lab have a microscope capable of accomodating vessels of 12-cm height? Can you share model (of the microscope), supplier?

2) And more general question: are there ways exist to control the adhesion cells growth without microscopy?

My lab has intense use of adhesion-dependent cells, such as HEK293, I want to utilize with the benefit my new CO2-incubator/roller toy.

Many thanks in advance to all who can help.