146 
Monitoring Stem Cell Research 
Autosome: Any chromosome other than a sex chromosome, that is, 
any chromosome other than an X or a Y. (SMD) 
Bacteria: Any of numerous unicellular microorganisms, existing ei- 
ther as free living organisms or as parasites, and having a broad 
range of biochemical, often pathogenic properties. 
Blastocyst: (a) Name used for an organism at the blastocyst stage of 
development. (CR) (b) A preimplantation embryo of about 150 to 200 
cells. The blastocyst consists of a sphere made up of an outer layer of 
cells (the trophectoderm), a fluid-filled cavity (the blastocoel), and a 
cluster of cells on the interior (the inner cell mass). (NIH) 
Blastocyst stage: An early stage in the development of embryos, 
when (in mammals) the embryo is a spherical body comprising an 
inner cell mass that will become the fetus surrounded by an outer 
ring of cells that will become part of the placenta. (CR) 
Bone marrow: The soft, fatty, vascular tissue that fills most bone 
cavities and is the source of red blood cells and many white blood 
cells. 
Cardiomyoctes: Heart muscle cells. 
Cartilage: A type of connective tissue that is firm but resilient. It is 
found in joints and also as supportive structure, for example in the 
ears. 
Cell culture: Growth of cells in vitro on an artificial medium for ex- 
perimental research. (NIH) 
Cerebrospinal fluid: A blood serum-like fluid that bathes parts of the 
brain and the interior cavity of the spinal cord. 
Chromosomes: Structures inside the nucleus of a cell, made up of 
long pieces of DNA coated with specialized cell proteins, that are 
duplicated at each mitotic cell division. Chromosomes thus transmit 
the genes of the organism from one generation to the next. (CR) 
Clone: A line of cells that is genetically identical to the originating 
cell; in this case, a stem cell. (NIH) 
Cord blood: Blood in the umbilical cord and placenta. 
PRE-PUBLICATION VERSION 
