(sĕl)
[Pronunciation]
[L. cella, a chamber]

A mass of protoplasm containing a nucleus or nuclear material; the structural unit of all animals and plants.
Cells and cell products form all the body tissues; their structures are correlated with the functions of the organs of which these tissues are a part. Cells arise only from pre-existing cells, through cell division. Growth and development result from the increase in numbers of cells and their differentiation into different types of tissues. Specialized germ cells, the spermatozoa and ova, contain the genes to be passed to offspring.

STRUCTURE
A typical cell has a nucleus surrounded by cytoplasm. The nucleus is bounded by a double-layered nuclear membrane and contains the chromosomes, which are made of DNA and protein. One or more nucleoli, made of protein, RNA, and DNA, may be present; these are sites of ribosome formation. The cell membrane is made of phospholipids, protein, and cholesterol; it forms the outer boundary of the cell and selectively allows substances to enter or leave the cell. Within the cell are cell organelles, including ribosomes, proteasomes, endoplasmic reticulum, mitochondria, Golgi apparatus, centrioles, and lysosomes; each has a specific function.

Figure: GENERALIZED HUMAN CELL AND ORGANELLES





CELL DIVISION
Meiosis is the type of cell division in which two successive divisions produce four cells that contain half the number of chromosomes present in somatic cells. In mitosis, the other type of cell division, each of the two daughter cells contains the same number of chromosomes as the parent cell.
See: meiosis; mitosis

Subentries:
accessory cell
acidophil cell
acinar cell
adipose cell
adventitial cell
air cell
alpha cell
alveolar cell, type I
alveolar cell, type II
amacrine cell
ameloblast cell
anterior horn cell
antigen-presenting cell
argentaffin cell
atypical glandular cells
atypical glandular cells of undetermined significance
B cell
band cell
basal cell
basket cell
basophil cell
beta cell
Betz cell
bipolar cell
blast cell
blood cell
bone cell
burr cell
cancer cell
capsule cell
castration cell
CD 34+ cell
cementoblast cell
cementocyte cell
centroacinar cell
chalice cell
chief cell
chromaffin cell
cleavage cell
clue cell
columnar cell
cone cell
cuboid cell
cytotoxic T cell
daughter cell
delta cell
dendritic cell
endothelial cell
ependymal cell
epithelial cell
ethmoidal cell
fat cell
flame cell
foam cell
ganglion cell
germ cell
giant cell
glia cell
goblet cell
Golgi cell
granule cell
gustatory cell
hair cell
HeLa cell
helper T cell
holly leaf cell
horizontal cell
Hürthle cell
hybridoma cell
hyperchromatic cell
interstitial cell
intestinal absorptive cell
islet cell
juvenile cell
juxtaglomerular cell
killer cell
killer T cell
Kupffer cell
labile cell
lactotrope cell
L.E. cell
Leydig's cell
littoral cell
lutein cell
lymphokine-activated killer cell
mast cell
mastoid cell
memory cell
microglia cell
mossy cell
mother cell
mucous cell
myeloma cell
myoepithelial cell
natural killer cell
nerve cell
neuroglia cell
Niemann-Pick cell
nonstem cell
null cell
odontoblast cell
olfactory cell
oxyntic cell
parent cell
phalangeal cell
pigment cell
plasma cell
prickle cell
progenitor cell
primordial cell
Purkinje cell
pus cell
pyramidal cell
red cell
Renshaw cell
reticular cell
reticuloendothelial cell
Rieder cell
rod cell
rosette cell
Rouget cell
satellite cell
segmented cell
sensory cell
septal cell
serous cell
Sertoli cell
sickle cell
signet-ring cell
somatic cell
spider cell
squamous cell
stellate cell
stellate reticuloendothelial cell
stem cell
stem cell rescue
Sternberg-Reed cell
stipple cell
suppressor T cell
sympathicotrophic cell
sympathochromaffin cell
T cell
target cell
tart cell
taste cell
tear-drop cell
totipotent cell
Touton giant cell
Türk's irritation cell
Tzanck cell
undifferentiated cell
visual cell
wandering cell
white cell