On the Meaning of the Various Forms of the Male Gametes in the Pines and Allied Conifers.

Cutting, E. M.

doi:10.1111/j.1469-8137.1908.tb06084.x

Cited by 2 publications

(1 citation statement)

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“…About a week before fertilization, mitosis occurs in the spermatogenous cell while it is still high up in the nucellus. Again accounts differ as to whether the eventually unequal male gametes constitute two nuclei of a binucleate sperm cell (Goroschankin, 1880, 1883; Ferguson, 1904;Cutting, 1908;Sethi, 1928;Mathews, 1932;Haupt, 1941 ; McWilliam & Mergen, 1958; Konar & Ramchandi, 1958; Konar, 1960), or two sperm cells (Strasburger, 1879, 1892; Dixon, 1894; Hirase, 1918). Coulter (1897) speaks of 'male cells' but shows only nuclei in his illustrations (cf.…”

Section: (A) Pinaceaementioning

confidence: 99%

Structure of the Male Gametophyte in Gymnosperms

Sterling

1963

Biological Reviews

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Summary Analysis of the morphological nature of the gymnospermous male gametophyte has been based on evidence from fossil gymnosperms, on a comparative survey of living vascular plants, and on ontogeny within the various families of the gymnosperms. Although fossil coniferous and taxad pollen is unknown, the fossil pollen of other gymnosperms is rather uniform in the presence of a layer of parietal cells (presumably an antheridial jacket) which surrounds a central, probably spermatogenous region. The same organization occurs in endosporal gametophytes of lower Tracheophyta of the present day. Reduction in the number of vegetative prothallial cells appears to have occurred early in gymnosperm evolution, so that the male gametophyte may be regarded essentially as a reduced antheridium. Between the fossil gymnosperms and the present forms there has occurred a reduction of the antheridial jacket and the corresponding production of a pollen tube. For various reasons, the balance of probability is in favour of a homology between the antheridial jacket of Palaeozoic gymnosperms and the tube cell of modern gymnosperms. In the lower tracheophytes and in Cordaimthus and the Recent gymnosperms, a polar organization of the endosporal male gametophyte is characteristic. On several grounds, it is shown that in this structure the presence of an antheridial stalk is precluded, and that therefore the use of the term ‘stalk cell’ is greatly in error. The cell which is often called ‘stalk cell’ is potentially–sometimes actually–spermatogenous and is sister to the virile spermatogenous cell. It is frequently sterile, however, and is therefore recognized here as the ‘sterile cell’. In the evolution of the Coniferales and the Taxales (as well as in the lower Tracheophyta) disappearance of the prothallial cells from the male gametophyte is a characteristic trend. Prothallial cells are lacking in the Taxodiaceae, Cupressaceae, Cephalotaxaceae and Taxaceae. (However, in two families, Araucariaceae and Podocarpaceae, there has developed a secondary proliferation of the prothallial cells). Recognition of the same trend in the Chlamydospermophyta and consideration of details of ontogeny indicate that prothallial cells must be absent from the gametophytes of Welevitschia and Gnetum. In these, the embryonal cell functions as an antheridial initial and produces a tube and a generative cell. The generative cell then divides into spermatogenous and sterile cells. Later, two male gametes result from division of the spermatogenous cell. Based on the morphological analyses indicated above, a terminology has been proposed which attempts to recognize morphological identities but does accept non‐committal terms of common usage, as long as they do not violate the morphological concepts. A representative synonymy is given, and some examples of the use of the suggested terminology are shown. Details of the ontogeny of the male gametophyte in the conifer and taxad families have been reviewed. Although many genera are still completely unknown, it appears c...

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Section: (A) Pinaceaementioning

confidence: 99%