microvilli z plane сгуpts 4 days Figure Q22-1 Fluorescent cells in crypts in mouse intestines at various times after activation of expression of fluorescent proteins (Problem 22-6). The images are taken in the xz plane, which cuts through multiple crypts, as indicated in the schematic drawing. Roughly 50 crypts are visible in each section. Dotted white circles identify some individual crypts. Scale bars are 100 um. (Adapted from H.J. Snippert et al., Col 143:134-144, 2010. With permission from Elsevier.) 4 weeks 30 weeks
At any given time, intestinal crypts of mice com-
prise about 15 stem cells and 10 Paneth cells. After cell
division, which occurs about once a day, the daughter
cells remain stem cells only if they maintain contact with a
Paneth cell. This constant competition for Paneth-cell con-
tact raises the possibility that crypts might become mono-
clonal over time; that is, the crypt cells at one point in time
might derive from only 1 of the 15 stem cells that existed
at some earlier time. To test this possibility, you use the
so-called confetti marker that upon activation expresses
any one of three fluorescent proteins in the stem cells of
the crypt. You then examine crypts at various times to
determine whether they contain cells with multiple colors
or only one color (Figure Q22–1). Do the crypts become
monoclonal over time or not? How can you tell?
Trending now
This is a popular solution!
Step by step
Solved in 2 steps
