Plate I. Basic patterns of BI 78D3 initiation in bryophyte spores. All illustrations are oriented with the sporocyte wall uppermost. Magnification is based on the single bar in 1. 1–3. Wall pattern is determined by distinct precursors (P) associated with cytoplasmic stalks in the 2n sporocyte wall (SW) in certain liverworts. PM, plasma membrane. 1. TEM of capitulate precursors in Haplomitrium. Bar = 0.2 μm. 2. Aniline blue stain showing callosic nature of reticulate exine precursors in the deeply lobed sporocyte of Pallavicinia. Bar = 6.1 μm. 3. TEM of exine precursors of Pallavicinia showing the elongate cytoplasmic stalks capped by exine precursors. Bar = 0.33 μm. 4. Andreaea. The spore wall is deposited by the young spore within the sporocyte wall (SW) as globules of initial exine (E) adjacent to the plasma membrane (PM). Bar = 0.09 μm. 5. Sphagnum. The first layer of exine in the young spore is a continuous multilamellate layer (MLL) that develops in the sporocyte wall (SW). The plasma membrane (PM) is underlain by microtubules (MT). Bar = 0.12 μm. 6. Takakia. Segments of tripartite lamellae (TPL) develop outside the plasma membrane in the sporocyte wall (SW) that surrounds the young spore. Bar = 0.1 μm. 7. In bryopsid mosses, a single continuous layer of tripartite lamella (TPL) establishes the foundation layer in the spore wall. SW, sporocyte wall. Bar = 0.1 μm. 8. Leiosporoceros. Following meiosis, a distinct multilamellate layer (MLL) is deposited outside the plasma membrane in the sporocyte wall (SW). Bar = 0.12 μm.Figure optionsDownload full-size imageDownload as PowerPoint slide
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