This animal was injected with colchicine and was sacrificed four hours later. This drug blocks mitoses in metaphase which accumulate in the epithelium in the lower half of the glands (arrows).

This field illustrates the site of intensive proliferation and renewal of epithelial cells.

Note the absence of metaphase plates in the upper part of the crypts (*).

Stain: H–­­E
Magnification: ×650