Scale = 100 ltm. The lower cell develops into rhizoid and the upper cell undergoes repeated periclinal and anticlinal divisions, thus forming a thalloid sporophyte (2n) of Sargassum. 3. 3.117B). The conceptacle initial becomes flask- shaped. 3.117D). What is its function? At maturity the antheridium is detached from the stalk and comes out from the conceptacle through ostiole. Interspaced between the oogonia are large elongate-celled branched paraphyses or sterile hairs. I It is generally of circular in outline and differentiated into three regions: outer meristoderm, middle cortex and innermost medulla (Fig. 12. %PDF-1.4 3.120E). with attached to conceptacle mst- Oogonia attached to the conceptacle wall long gelatinous stalks; ov-ovum; ow-oogonial wall. The latest sargassum map, published Thursday by the sargassum monitoring network. It reproduces by both vegetative and sexual means. This layer can store food material. WM Batrachospermum fruiting WM The leaves are flat, simple structures with distinct midrib and dentate, serrate or entire margins, with an acute apex. These are flask-shaped with many sterile unbranched filaments, the paraphyses developed from the base. The wall of the oogonium consists of three layers, the outer exochite, the middle mesochite and inner endochite (Fig. Since out-put of eggs is extremely low, 4 - 6 per female conceptacle, <i>Sargassum</i> sp. The medulla is round and present in the middle region. For male it is called as Antheridia whereas in female it is called Oogonium. Where are the pollen grains formed in the flower? The nuclei then accumulate some cytoplasm and form many uninucleate bodies. Lamanaria 3 cell layers (medulla, cortex, meristoderm) Lithophyllum imitans. It does not multiply asexually by means of spores. 3.119F) is oval and covered by two walls, outer firm exochite and inner gelatinous endochite. 2. It consists of compactly arranged parenchyma cells of polygonal shape, rarely with intercellular spaces. After fusion zygote is formed. Answer Now and help others. Oogonium of Sargassum Sp. 3.119D, E). The zygotic cell settles down and germinates to form a new diploid thallus. The medulla i.e., the inner layer consists of narrow, thick walled elongated cells. Sargassum muticum. Conceptacles were distributed in each receptacle. The conceptacle initial then undergoes mitotic division and by oblique septation it forms upper elongated tongue cell and lower broad basal cell (Fig. This is a question and answer forum for students, teachers and general visitors for exchanging articles, answers and notes. The cells of the wall have many chromatophores. Botany, Practical of Algae, B.Sc. Share Your Word File 3.120C), then mitotic divisions and 8 nuclei are formed. The cortex is situated next to meristoderm and occupies major part of the axis. After meiosis oogonia and antheridia, the female and male reproductive organs, produce egg cells and sperm respectively that are … 13. The spores develop into haploid male or female gametophytes, which eventually produce the sexual gametes. After fusion zygote is formed. 13. 3.117A). Features 6. Oogonium produces one egg and the antheridium produces 64 biflagellate sperms. %���� Many thread like filaments also develop from the basal cells of the conceptacle which are also called paraphyses (Fig. - At maturity, it is discharged through ostiole. 3.119D). Sargassum female conceptacle - Conceptacle bearing antheridia are called male conceptacles. The cells are smaller in size than meristoderm. Fertile cavities, the conceptacles, containing the reproductive cells are immersed in the receptacles near the ends of the branches. Instead it reproduce by vegetative method and the formation of sex organs. The antheridial cell develops into an antheridium (Fig. of axis of Sargassum. Later on only one penetrates the oogonial wall. The female egg liberates a volatile hydrocarbon, fucoserraten (a compound with 8 carbon atoms) which attracts the male antherozoids; these cluster around the egg and spin it; one penetrates the complex series of coats around the egg and karyogamy (nuclear fusion) occurs. In West Africa, a part of Atlantic Ocean becomes densely occupied by Sargassum and the region is called as ‘Sargasso sea’. ensures its survival under all eco- Fig. iText 4.2.0 by 1T3XT But no matter how much money is forked out, the sargassum keeps coming. The plant body of Sagassum is a diploid sporophyte. Sargassum paniculatum - 1, habit of portion of a fertile branch with young receptacles, leaves and vesicles; 2, detail of a portion of a fertile branch with female receptacles; 3, detail of a portion of a fertile branch with male receptacles; 4, details of vesicles; 5, leaves from different branch orders.S. The diploid (2n) nucleus undergoes first meiotic (Fig. Just after fertilization the zygote undergoes germination (Fig. Ist year, Paper-I, Sem. Asexual reproduction is absent. In homothallic or monoecious species the male conceptacle and female conceptacles are produced on same receptacle, but antheridia and oogonia are not produced in same conceptacles. Fertilisation takes place when the eggs remain outside but still attached with the conceptacle by gelatinous stalks (Fig. 12. Development of oogonia of Sargassum horneri (Fucales, Heterokontophyta) and concomitant variations in PSII photosynthetic activities XIUJUN XIE 1,GUANGCE WANG 2*, GUANGHUA PAN 1,JIANZHANG SUN 3 AND JIAN LI 4 1Tianjin Key Laboratory of Marine Resources and Chemistry, College of Marine Science and Engineering, Tianjin University of Science and Technology, Tianjin 300457, China These dark celled structures, after being given off from the base into. 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