Functional lecithin:cholesterol acyltransferase deficiency and high density lipoprotein deficiency in transgenic mice overexpressing human apolipoprotein A-II.

The concentration of high density lipoproteins (HDL) is inversely related to the risk of atherosclerosis. The two major protein components of HDL are apolipoprotein (apo) A-I and apoA-II. To study the role of apoA-II in lipoprotein metabolism and atherosclerosis, we have developed three lines of C57BL/6 transgenic mice expressing human apoA-II (lines 25.

Prenatal development of the rat sinuatrial node.

In order to study the origin and mode of differentiation of the cells which make up the sinuatrial node, samples of the sinuatrial junction of rat embryos of different ages were studied by transmission electron microscopy. From a seemingly morphologically homogeneous cell population at 11 days, an ultrastructural differentiation occurs from day 12. So, one could see: a) irregular-shaped cells with dark nucleus and medium-sized contractile apparatus which we have identified as ordinary ("working") atrial myocardiocytes and, b) pale cells with a clear spheroidal nucleus and cytoplasm containing few organelles and fine myofibrils which we have classified as nodal cells.

Presence or absence of glycogen-beta particles in sinoatrial node cells.

The sinoatrial node is formed by specialized cells, the main ultrastructural differences of which, as compared with ordinary atrial myocardium, are a pale cytoplasm and sparse myofibrils. Moreover, nodal cells have been described to contain large amounts of glycogen particles in their pale cytosol; these glycogen inclusions are often used as the main criterion for identifying nodal cells. Nevertheless, the presence of glycogen cytosolic inclusions has been discussed by several authors.