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Typical rupture of spermatium \ trichogyne seal. ( A ) First spermatial nucleus emerging (arrow ; T l 0) ; ( B ) nucleus (arrow) near end of trichogyne (4 h 40 d approx.) ; ( C ) explosive release of pressure at edge of seal (4 h 43 d ) ; ( D ) continuing emission of cytoplasm, further collapse of trichogyne cytoplasm 8 s after ( C ). Scale bar represents 10 μ m. 

Typical rupture of spermatium \ trichogyne seal. ( A ) First spermatial nucleus emerging (arrow ; T l 0) ; ( B ) nucleus (arrow) near end of trichogyne (4 h 40 d approx.) ; ( C ) explosive release of pressure at edge of seal (4 h 43 d ) ; ( D ) continuing emission of cytoplasm, further collapse of trichogyne cytoplasm 8 s after ( C ). Scale bar represents 10 μ m. 

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In the red alga Bostrychia moritziana, release of spermatia is triggered by slight osmotic shock; they emerge under pressure apparently generated by swelling of the mucilaginous sheath. Spermatia adhere tenaciously to trichogynes of the carpogonium. Adhesion triggers spermatial mitosis, which is complete in about 30–45 min; there is no cytokinesis...

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... our preparations, attachment between the cells was a weak point in the events of fertilization. Many cells ruptured because of inadequate sealing at the contact site and some video sequences clearly show abrupt release of pressure and cytoplasm through the edge of the seal, causing immediate death of both cells (Fig. 7A-D). We cannot tell whether this fragility is normal or induced by the trauma of observation. Rupture could occur before plasmogamy or after (Fig. 7A-D), while nuclei were moving along the trichogyne. Multiple plasmogamies were common, resulting from the unnaturally high number of spermatia each trichogyne had been exposed to. When ...
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... because of inadequate sealing at the contact site and some video sequences clearly show abrupt release of pressure and cytoplasm through the edge of the seal, causing immediate death of both cells (Fig. 7A-D). We cannot tell whether this fragility is normal or induced by the trauma of observation. Rupture could occur before plasmogamy or after (Fig. 7A-D), while nuclei were moving along the trichogyne. Multiple plasmogamies were common, resulting from the unnaturally high number of spermatia each trichogyne had been exposed to. When multiple spermatia had attached to a trichogyne, the chance of rupture increased with the increased oppor- tunities for inadequate ...
Context 3
... cases, even the first nucleus appeared to have halted movement before entering the carpogonium, but fertilization might have been previously achieved by an unobserved nucleus from one of the several attached spermatia. Our results generally suggest the existence of a cytoplasmic block preventing polyspermy. It is also possible that rupture (as in Fig. 7) is an active means of preventing ...

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... In the youngest stage observed, the hypogynous cell appeared to have fused with the multinucleate supporting cell and to have borne a trichogyne laterally and directed towards the thallus surface (Fig. 23).Figure 24 shows a stage in which a haploid nucleus is present towards the tip of the trichogyne. This may be one of the two nuclei thought to enter the trichogyne after sperm attachment (Pickett-Heaps & West, 1998). The second nucleus had evidently effected fertilization by fusing with the nucleus of the carpogonium and had been deposited into the upper end of the fusion cell formed by fusion of the hypogynous cell with the supporting cell. ...
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