I SH in amphibian oocytes (upper panel) and mouse mitotic chromosomes (lower panel). Upper panel: Autoradiograph of nuclei from a Xenopus ovary after ISH with ³H-labeled rRNA showing the progressive increase in amplified rDNA as the nucleus enlarges. Reproduced from Fig. 2 in Gall (2016). Lower panel: Autoradiograph of an interphase nucleus and mitotic chromosomes of the mouse after ISH. The probe is ³H-labeled RNA that was transcribed in vitro from CsCl gradient-isolated mouse satellite DNA. Reproduced from Fig. 3 in Gall (2016).