A hypotonic solution is a liquid mixture where there is a lower concentration of particles or solutes compared to another liquid or solution. Full definition
I think a very important experiment reported in 1970 by Robert Macey at U.C. Berkeley, showed that red cells which are osmotically very active, shrink in hypertonic solutions, swell in hypotonic solutions, in milliseconds. (scientificamerican.com)
When the baby is born water can not pass into his lungs because hypertonic solutions are denser and prevent hypotonic solutions from merging or coming into their presence. (attachfromscratch.com)
Hypotonic solution - treated cells were fixed in methanol: acetic acid (3:1 in volume) for 30 minutes at room temperature, dropped onto pre-cleaned slides and stained with DAPI. (journals.plos.org)