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A gametangium (pl.: gametangia) is a sex organ or cell in which gametes are produced that is found in many multicellular protists, algae, fungi, and the gametophytes of plants. In contrast to gametogenesis in animals , a gametangium is a haploid structure and formation of gametes does not involve meiosis .
Female gametophytes of the liverwort Marchantia polymorpha. Gametophores are prominent structures in seedless plants on which the reproductive organs are borne. [citation needed] [1] The word gametophore (more accurately gametangiophore) is composed of the greek ‘gamete-,’ referring (loosely) to gametangia [citation needed] and ‘-phore’ (Greek Φορά, "to be carried"). [2]
A gametophyte (/ ɡ ə ˈ m iː t ə f aɪ t /) is one of the two alternating multicellular phases in the life cycles of plants and algae. It is a haploid multicellular organism that develops from a haploid spore that has one set of chromosomes. The gametophyte is the sexual phase in the life cycle of plants and algae.
In plants, male reproductive structures include stamens in flowering plants, which produce pollen. [3] Female reproductive structures, such as pistils in flowering plants, produce ovules and receive pollen for fertilization. [4] Mosses, ferns, and some similar plants have gametangia for reproductive organs, which are part of the gametophyte. [5]
The female gametangia are called archegoniophores, they have a taller stem and an umbrella-like structure at the top, approximately 1 cm (0.39 in) wide, from which the common name is derived. They also reproduce asexually via gemma cups which form on the surface of the thallus, they are approx. 4 mm (0.16 in) wide and 3 mm (0.12 in) high. [ 2 ]
Gametogenesis is a biological process by which diploid or haploid precursor cells undergo cell division and differentiation to form mature haploid gametes.Depending on the biological life cycle of the organism, gametogenesis occurs by meiotic division of diploid gametocytes into various gametes, or by mitosis.
[1] [2] Both monoicous (/ m ɒ ˈ n oʊ ə k ə s /) [3] and dioicous gametophytes produce gametes in gametangia by mitosis rather than meiosis, so that sperm and eggs are genetically identical with their parent gametophyte. It has been suggested that monoicy may have benefits in dry habitats where the ability to produce sporophytes is limited ...
Dioicy (/ d aɪ ˈ oʊ ə s i /) is a sexual system in non-vascular plants where archegonia (female organs) and antheridia (male organs) are produced on separate plants in the gametophyte phase. [1] It is one of the two main sexual systems in bryophytes , the other being monoicy .