Ultrastructure of Oogenesis in Dryopteris crassirhizoma Nakai

Wen-mei, Bao; He, Qun; Wang, Quanxi; Guo-wei, Tian; Cao, Ji

doi:10.1111/j.1744-7909.2005.00040.x

Cited by 9 publications

(9 citation statements)

References 19 publications

(28 reference statements)

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“…Moreover, a similar structure has also appeared in a fertilized egg of the fern C. richardii , but it was not described as a mating structure (Lopez‐Smith and Renzaglia 2008). Hitherto, such a pore has not been reported in the mature egg of ferns so far investigated (Bell and Mühlethaler 1962a,b; Cave and Bell 1974; Myles 1978; Bell 1980, 1986; Fasciati et al 1994b; Bao et al 2003, 2005; Lopez‐Smith and Renzaglia 2008). The present investigation describes the pore for the first time.…”

Section: Discussionmentioning

confidence: 93%

Ultrastructure of the Mature Egg and Fertilization in the Fern Ceratopteris thalictroides

Cao

Wang

2009

JIPB

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The ultrastructure of the mature egg and fertilization in the fern Ceratopteris thalictroides (L.) Brongn. were observed by transmission electron microscopy. The results revealed that the mature egg possesses an obvious egg membrane at the periphery of the egg. Furthermore, a fertilization pore was identified in the upper egg membrane of the mature egg. The structure of the pore is described for the first time. The fertilization experiment indicated that spermatozoids crowd into the cavity above the egg through the neck canal of the archegonium; however, only one of these can penetrate into the egg through the fertilization pore. Immediately on penetration of the spermatozoid, the egg begins to shrink. The volume of the fertilized egg decreases to almost one-half that of the unfertilized egg. As a result, the protoplasm of the fertilized egg becomes dense and opaque, which may lead to a situation where the organelles of both the egg and the fertilizing spermatozoid become indistinguishable. Simultaneously, abundant vesicles containing concentric membranes or opaque materials appear near the fertilization pore in the cytoplasm of the fertilized egg. These vesicles are considered to act as a barrier that prevents polyspermy. The present study provides a new insight into the ultrastructure of the mature egg and the cytological mechanism of fertilization in ferns.

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Section: Discussionmentioning

confidence: 93%

Ultrastructure of the Mature Egg and Fertilization in the Fern Ceratopteris thalictroides

Cao

Wang

2009

JIPB

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“…As in other ferns, such as Pteridium (Bell and Duckett 1976), Athyrium (Fasciati et al 1994), Osmunda (Bao et al 2003), and Dryopteris (Bao et al 2005), a layer of extra egg membrane is formed around the mature egg of C. thalictroides . The extra egg membrane is considered to be formed by the deposition of sheets of ER on the inner surface of the plasmalemma (Cao et al 2008).…”

Section: Discussionmentioning

confidence: 94%

“…Oogenesis in the ferns, including Pteridium aquilinum (Bell and Mühlethler 1962a, b; Bell and Duckett 1976), Histiopteris incisa (Bell 1980), Osmunda cinnamomea var. asiatica (Bao et al 2003), and Dryopteris crassirhizoma (Bao et al 2005), has been investigated. These investigations revealed that the egg of homosporous ferns is surrounded by a conspicuous extra egg membrane.…”

Section: Introductionmentioning

confidence: 99%

“…This same structure has been regarded as a venter coat, covering the top of the egg, in the ferns Athyrium filix‐femina (Fasciati et al 1994) and Ceratopteris richardii (Lopez‐Smith and Renzaglia 2008). The extra egg membrane was considered to be formed by materials derived from the egg (Cave and Bell 1974; Bell and Duckett 1976; Bell 1986; Bao et al 2003, 2005). We previously revealed that the extra egg membrane of Ceratopteris thalictroides is formed by sheets of ER (Cao et al 2008).…”

Section: Introductionmentioning

confidence: 99%

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Formation of the Fertilization Pore during Oogenesis of the Fern Ceratopteris thalictroides

Cao

Wang

Wen-mei

2010

JIPB

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The development of the fertilization pore during oogenesis of the fern Ceratopteris thalictroides was followed using transmission electron microscopy. The newly formed egg is appressed closely to the adjacent cells. There are well-developed plasmodesmata between the egg and the ventral canal cell, but none between the egg and the jacket cells of the archegonium. During maturation, a separation cavity is formed around the egg. However, a pore region persistently connects the egg and the ventral canal cell. The extra egg membrane is formed by deposition of sheets of endoplasmic reticulum (ER), but no ER is deposited on the inner surface of the pore region. Thus, a fertilization pore, covered by a layer of plasmalemma, is formed. The ventral canal cell undoubtedly participates the formation of the fertilization pore, probably by absorbing the sheets of ER beneath the pore region. The functional significance of the ventral canal cell in formation of the fertilization pore is discussed. The features of the mature egg include that abundant concentric membranes and osmiophilic vesicles occur in the cytoplasm of the mature egg. The initial, round nucleus of the egg eventually becomes cup-shaped. This investigation gives some new insights about the cells participating oogenesis in ferns.Cao JG, Wang QX, Bao WM (2010) Formation of the fertilization pore during oogenesis of the fern Ceratopteris thalictroides.

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“…In advanced ferns, this egg envelope, located at the upper surface of the egg, is particularly thick (Bell and Mühlethaler 1962b;Fasciati et al 1994;Bao et al 2005;Cao et al 2008Cao et al , 2009Cao et al , 2010a. In Ceratopteris and Adiantum, the egg envelope appears to be composed of multiple membranes or reticulate structures (Cao et al 2008(Cao et al , 2010b.…”

Section: The Egg Envelope and Separation Cavitymentioning

confidence: 94%

Cytological features of oogenesis and their evolutionary significance in the fern Osmunda japonica

2011

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The development of the egg and canal cells in the fern Osmunda japonica Thunb. was studied during oogenesis by transmission electron microscopy. The mature egg possesses no fertilization pore and no typical egg envelope. In addition, an extra wall formed around the canal cells during oogenesis and apparently blocked protoplasmic connections between the egg and the canal cells. The periodic acid Schiff (PAS) reaction revealed that the extra wall was most likely composed of polysaccharides. Maturation of the egg was accompanied by the formation of a separation cavity above the egg and by some changes in the morphology of the nucleus and cytoplasmic organelles. The chromatin of the nucleus becomes condensed and the upper surface of the nucleus becomes closely associated with the plasmalemma. Amyloplasts in the egg cytoplasm were numerous and conspicuous, with most in close proximity to the nucleus. Finally, the cytoplasm on one side of the egg became vesiculated and the overlying plasmalemma was easily disrupted. These cytological features of the egg and the canal cells during oogenesis in O. japonica are markedly different from those of the leptosporangiate ferns and suggest a significant evolutionary divergence in reproductive cellular features between Osmundaceae and leptosporangiate ferns.

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Ultrastructure of Oogenesis in Dryopteris crassirhizoma Nakai

Cited by 9 publications

References 19 publications

Ultrastructure of the Mature Egg and Fertilization in the Fern Ceratopteris thalictroides

Ultrastructure of the Mature Egg and Fertilization in the Fern Ceratopteris thalictroides

Formation of the Fertilization Pore during Oogenesis of the Fern Ceratopteris thalictroides

Cytological features of oogenesis and their evolutionary significance in the fern Osmunda japonica

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