archegonium การใช้

• As the zygote divides and grows, it does so inside the archegonium.
• In land plants, the zygote is formed within a chamber called the archegonium.
• Since the sperm must swim to the archegonium, fertilisation cannot occur without water.
• The horn-shaped sporophyte grows from an archegonium embedded deep in the gametophyte.
• The gametophytes produce male ( antheridium ), and female ( archegonium ) gametes.
• A lateral branch from the main plant axis bears the female shoot archegonium at its meristem.
• Once the embryo has expanded beyond the enclosing archegonium, it is no longer termed an embryo.
• Fertilisation takes place when the nucleus of one of the sperm cells enters the egg cell in the megagametophyte s archegonium.
• In seedless plants, the archegonium is usually flask-shaped, with a long hollow neck through which the sperm cell enters.
• Sexual reproduction involves the production of ascospores, commencing with the fusion of an archegonium and an antheridium, with sharing of nuclei.
• Each archegonium has a slender hollow tube, the " neck ", down which the sperm swim to reach the egg cell.
• When the sporophyte has developed all three regions, the seta elongates, pushing its way out of the archegonium and rupturing it.
• In these plants, the embryo begins its existence attached to the inside of the archegonium on a parental gametophyte from which the egg cell was generated.
• These sporelings develop via an embryo stage from a fertilized egg inside an archegonium and depend on the gametophyte for their early stages of growth before becoming independent sporophytes.
• The female organs are known as archegonia ( " sing . " archegonium ) and are protected by a group of modified leaves known as the perichaetum ( plural, perichaeta ).
• Firstly, their gametophytes produce sperm and eggs in multicellular structures ( called'archegonia'), and fertilization of the ovum takes place within the archegonium rather than in the external environment.
• Secondly, and most importantly, the initial stage of development of the fertilized egg ( the zygote ) into a diploid multicellular sporophyte, take place within the archegonium where it is both protected and provided with nutrition.
• The inner wall of the archegonium lies in close contact with the " foot " of the developing embryo; this " foot " consists of a bulbous mass of cells at the base of the embryo which may receive nutrition from its parent gametophyte.
• It is a short-lived and inconspicuous heart-shaped structure typically 2 5 millimeters wide, with a number of rhizoids ( root-like hairs ) growing underneath, and the sex organs : archegonium ( female ) and antheridium ( male ).
• Two sperm nuclei from a pollen grain ( the microgametophyte ), rather than a single sperm, enter the archegonium of the megagametophyte; one fuses with the egg nucleus to form the zygote, the other fuses with two other nuclei of the gametophyte to form'endosperm', which nourishes the developing embryo.