Fuente: WIPO "tomato" The disclosure relates to photocleavable crosslinkers that are suitable for preparing photodegradable hydrogels and to methods for volumetric imaging of biological specimens by photochemical sectioning and imaging of photodegradable hydrogels. A photocleavable crosslinker according to the disclosure can include one or more water-soluble hydrocarbon linkers, two or more reactive functional groups such as ethylenically unsaturated groups, and one or more photocleavable groups. A crosslinked hydrogel can be formed between the photocleavable crosslinker and other hydrogel monomers. The crosslinked hydrogel can be used as a matrix immobilize a biological or other sample material in a hydrogel composite. The hydrogel composite and the sample material therein can be volumetric imaged by sequentially and repeatedly optically imaging an image layer of the hydrogel composite and then photochemically sectioning a depolymerization layer of the hydrogel composite.