XVI International Botanical Congess

The Aloe vera L. ( sabila ) karyotype was studied in order to determine the localization of the nucleolus organizing regions (NORs) and to observe the chromosome core in metaphase chromosomes using the silver staining technique and light microscopy. Terminal NORs were observed on the short arms of smallest chromosomes ( pairs 6 and 7 ) as well as on chromosomes 1 and 4 in the same position. Dark bands were found in most chromosomes, especially in pair 4. It is suggested that these bands could be nucleoli derived from a heterochromatic region which has been named N-heterochromatin. The chromosome core was observed like a central black line throughout the length of the chromatid.