A gametangium (: gametangia) is a sex organ or cell in which are produced that is found in many multicellular , algae, Fungus, and the of . In contrast to gametogenesis in , a gametangium is a haploid structure and formation of gametes does not involve meiosis.
Types of gametangia
Depending on the type of gamete produced in a gametangium, several types can be distinguished.
Female
Female gametangia are most commonly called
Archegonium.
They produce
and are the sites for
fertilization. Archegonia are common in algae and primitive plants as well as
. In
, they are replaced by the
embryo sac inside the
ovule.
Male
The male gametangia are most commonly called
Antheridium.
They produce
Sperm that they release for fertilization. Antheridia producing non-motile sperm (spermatia) are called
spermatangia. Some antheridia do not release their sperm. For example, the
oomycete antheridium is a
syncytium with many sperm
Cell nucleus and fertilization occurs via fertilization tubes growing from the antheridium and making contact with the egg cells. Antheridia are common in the gametophytes in "lower" plants such as
,
,
and
ginkgo. In "higher" plants such as
and flowering plants, they are replaced by
.
Isogamous
In
isogamy, the gametes look alike and cannot be classified into "male" or "female." For example, in
, two gametangia (single
multinucleate cells at the end of
) form good contact with each other and fuse into a
zygosporangium. Inside the zygosporangium, the nuclei from each of the original two gametangia pair up.
See also
-
Zoosporangium, a gametangium that produces motile isogamous gametes, called
