資料來源 : pyDict
分割,割斷,細胞分裂
資料來源 : Webster's Revised Unabridged Dictionary (1913)
Segmentation \Seg`men*ta"tion\, n.
The act or process of dividing into segments; specifically
(Biol.), a self-division into segments as a result of growth;
cell cleavage; cell multiplication; endogenous cell
formation.
{Segmentation cavity} (Biol.), the cavity formed by the
arrangement of the cells in segmentation or cleavage of
the ovum; the cavity of the blastosphere. In the gastrula
stage, the segmentation cavity in which the mesoblast is
formed lies between the entoblast and ectoblast. See
Illust. of {Invagination}.
{Segmentation nucleus} (Biol.), the body formed by fusion of
the male and female pronucleus in an impregnated ovum. See
the Note under {Pronucleus}.
{Segmentation of the ovum}, or {Egg cleavage} (Biol.), the
process by which the embryos of all the higher plants and
animals are derived from the germ cell. In the simplest
case, that of small ova destitute of food yolk, the ovum
or egg divides into two similar halves or segments
(blastomeres), each of these again divides into two, and
so on, thus giving rise to a mass of cells (mulberry mass,
or morula), all equal and similar, from the growth and
development of which the future animal is to be formed.
This constitutes regular segmentation. Quite frequently,
however, the equality and regularity of cleavage is
interfered with by the presence of food yolk, from which
results unequal segmentation. See {Holoblastic},
{Meroblastic}, {Alecithal}, {Centrolecithal},
{Ectolecithal}, and {Ovum}.
{Segmentation sphere} (Biol.), the blastosphere, or morula.
See {Morula}.
資料來源 : WordNet®
segmentation
n 1: (embryology) the repeated division of a fertilised ovum
[syn: {cleavage}]
2: the act of dividing or partitioning; separation by the
creation of a boundary that divides or keeps apart [syn: {division},
{partition}, {partitioning}, {sectionalization}, {sectionalisation}]
資料來源 : Free On-Line Dictionary of Computing
segmentation
(Or "segmentation and reassembly", SAR) Breaking
an arbitrary size {packet} into smaller pieces at the
transmitter. This may be necessary because of restrictions in
the communications channel or to reduce {latency}. The pieces
are joined back together in the right order at the receiver
("reassembly"). Segmentation may be performed by a {router}
when routing a packet to a network with a smaller maximum
packet size.
The term "segmentation" is used in {ATM}, in {TCP/IP}, it is
called "fragmentation" an is performed at the {IP} layer
before the "fragments" are passed to the {transport layer}.
See for example {ATM forum} {UNI} 4.0 specification.
[Better reasons?]
(1999-06-14)