FIGURE F3.1.1 • Karyotypes obtained with the FISH technique. a. Karyotype of a normal male. The white box inset shows the XX chromosome pair of a normal female. The red box inset reveals an abnormality in chromosomes 14 and 8. (Courtesy of the Applied Imaging International Ltd., Newcastle upon Tyne, UK.) b. A metaphase spread from a patient with Prader-Willi/Angelman syndrome. The yellow box inset shows the enlarged pair of chromosome 15. (Courtesy of Dr. Robert B. Jenkins.) 1 6 7 8 8 9 10 11 12 13 19 20 21 22 X XX Y 14 14 15 16 17 18 2 3 4 5 15 baba appear Feulgen-negative with Feulgen-positive nucleolus-associated chromatin that often rims the nucleolus.
The nuclear envelope, formed by two membranes with a perinuclear cisternal space between them, separates the nucleoplasm from the cytoplasm.
The nuclear envelope provides a selectively permeable membranous barrier between the nuclear compartment and the cytoplasm, and it encloses the chromatin. The nuclear envelope is assembled from two (outer and inner) nuclear membranes with a perinuclear cisternal space between them. The peri nuclear clear cisternal space is continuous with the cisternal space of the rER (Fig. 3.5). The two membranes of the envelope are perforated at intervals by nuclear pores that mediate the active transport of proteins, ribonucleoproteins, and RNAs between the nucleus and cytoplasm. The membranes of the nuclear envelope differ in structure and functions:  The outer nuclear membrane closely resembles the membrane of the endoplasmic reticulum and in fact is continuous with rER membrane (see Fig 3.5). Polyribosomes are often attached to ribosomal docking proteins present on the cytoplasmic side of the outer nuclear membrane.
 The inner nuclear membrane is supported by a rigid network of intermediate protein filaments attached to its inner surface called the nuclear (fbrous) lamina. In addition, the inner nuclear membrane contains specific lamin receptors and several lamina-associated proteins that bind to chromosomes and secure the attachment of the nuclear lamina.
The nuclear lamina is formed by intermediate filaments and lies adjacent to the inner nuclear membrane.
The nuclear lamina, a thin, electron-dense intermediate filament networklike layer, resides underneath the nuclear
FOLDER 3.2 Clinical Correlation: Regulation of Cell Cycle and Cancer Treatment