Cell structure in pine stem segment

Well after yesterday's Blip what did you expect as it is tiny Tuesday !! :-)
Back lit at 35X magnification. Thanks to Pinkhairedlady for hosting.
The whole house is warm tonight finally :-) Gas engineer came today and sure enough it was the pump , so new pump installed and the house is warm, it has taken a while for the system to heat all around the house as it squeezes out the air.