On the cytological features of fertilisation and related phenomena in Pinus silvestris , L

1898 ◽  
Vol 63 (389-400) ◽  
pp. 400-401
Keyword(s):  
Pinus Silvestris ◽  
Wall Formation ◽  
Canal Cell ◽  
Cytological Features ◽  
Ventral Canal ◽  
Complete Account

This paper gives a fairly complete account of the minute cytological details of the act of fertilisation and of the processes surrounding from the formation of the ventral canal cell up to the period of cl wall formation at the base of the egg. As the oosphere nucleus, after separation of the nucleus of the ventral canal cell, moves rapidly back towards the centre of the e it increases greatly in size, as described by Strasburger. Ts increase in size is shown to be due to the appearance in the nucleus of a peculiar metaplasmic substance, which fills up the nucleus, and owing to its attraction for stains, ultimately obscures the chromatin.

Elektronenmikroskopische Untersuchungen über die Eizellbildung und Eizellreifung des Lebermooses Sphaerocarpus donnellii Aust.

1965 ◽  
Vol 20 (8) ◽  
pp. 795-801 ◽  
Author(s):  
Lothar Diers
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Phase Contrast ◽  
Lipid Droplets ◽  
Unit Membrane ◽  
Light Phase ◽  
Lamellar System ◽  
Small Bodies ◽  
Canal Cell ◽  
Ventral Canal

The formation and maturation of the egg of the liverwort, Sphaerocarpus donnellii, was investigated by light, phase contrast and particularly by electron microscopy. The division of the central cell into the egg and the ventral canal cell, and the maturation of the egg, is completed within four days. All stages of this formation and maturation were examined under the electron microscope after fixation in KMnO4 or OsO4. — In the maturing egg there always occur the endoplasmic reticulum, well recognisable plastids with a poorly developed lamellar system, numerous mitochondria and dictyosomes, a rising number of lipid droplets, unknown small bodies limited by a unit membrane, and numerous ribosomes. During maturation the nucleus considerably enlarges and forms evaginations into the cytoplasm. Starch is increasingly deposited in the plastids. A degeneration of plastids has not been found.

Sexual reproduction of mountain hemlock (Tsuga mertensiana)

1975 ◽  
Vol 53 (17) ◽  
pp. 1811-1826 ◽  
Author(s):  
John N. Owens ◽  
Marje Molder
Keyword(s):  
Cell Walls ◽  
Pollen Tubes ◽  
Linear Tetrad ◽  
Form Complex ◽  
Male Gametes ◽  
Canal Cell ◽  
Micropylar Canal ◽  
Tsuga Mertensiana ◽  
Mother Cells ◽  
Ventral Canal

Meiosis of pollen mother cells begins in October of the year in which cones are initiated. They reach pachytene then become dormant until the next March. Meiosis is complete and the winged pollen mature by mid-June. Meiosis of the megaspore mother cell occurs in May, forming a linear tetrad of megaspores. The female gametophyte undergoes free nuclear division at pollination in mid-June. No pollination drop is present; rather, the pollen adheres to the sticky, splayed edge of the micropyle, where it germinates and pollen tubes grow toward the nucellus. The nucellus elongates into the micropylar canal, forming a nucellar beak, which makes contact with the pollen tubes. Several pollen tubes penetrate the nucellus.At the time of fertilization early in August, each ovule contains two to four aichegonia each having two to four neck cells in one tier. Pollen tubes penetrate the neck cells and two male gametes are formed. The ventral canal cell breaks down and fusion occurs in the center of the archegonium. Four free nuclei form and migrate to the base of the archegonium. cell walls form, and a 16-celled proembryo develops. Both simple and cleavage polyembryony occur. Rosette cells divide but do not form complex embryos. The embryo and seed are mature in October and the cones dry and open during October and November. Mature cones averaged 70 seeds, of which 46% were filled.Reproduction in mountain hemlock (Tsuga mertensiana (Bong.) Carr.) is similar to that in other species of Tsuga except for the presence of winged pollen. Any attempt to place the species in the genus Picea or place it as a hybrid midway between Picea and Tsuga is unfounded based on all of the more-conservative reproductive and embryological characteristics.

scholarly journals Female gametophyte development and embryogenesis in Taxus baccata L.

2014 ◽  
Vol 65 (1-2) ◽  
pp. 135-139 ◽  
Author(s):  
Vladimir B. Brukhin ◽  
Peter V. Bozhkov
Keyword(s):  
Early Embryo ◽  
Temperate Climate ◽  
Taxus Baccata ◽  
Linear Tetrad ◽  
Canal Cell ◽  
Nuclear Stage ◽  
Female Gametophyte Development ◽  
Ventral Canal ◽  
Embryonic Region ◽  
Suspensor Cells

Crassinucellate ovules are initiated in <em>Taxus</em>, directly from the shoot apex. The rudimentary pollen chamber is formed in the nucellus. A linear tetrad of megaspores with a functional chalazal megaspore is formed. A free-nuclear stage is charac-teristic at the beginning of megagametophyte development. Archegonia without ventral canal cell are solitary or in complexes. The embryo has a very long suspensor even after maturation. Two types of polyembryony have been revealed: i) embryogenic redifferentiation of suspensor cells and ii) cleavage of embryonic region in the early embryo. In the northern temperate climate of St. Petersburg one month delay in development of reproductive structures has been noted.

scholarly journals V. On the cytological features of fertilization and related phenomena in pinus silvestris L

1898 ◽  
Vol 190 ◽  
pp. 395-426 ◽  
Keyword(s):  
Pinus Silvestris ◽  
Food Material ◽  
Large Size ◽  
Cytological Features ◽  
Strong Resemblance

In spite of the attention which has of late years been devoted to the study of the | histology of fertilization in plants, no one has hitherto investigated in detail the cytological features of this process in the Abietinese. The oospheres of this group, owing to their large size and the presence of a quantity of food material, present a strong resemblance to a well-known type of animal ova. The fact that in this type of ovum the phenomena of fertilization are usually both much more striking and much more easily followed than is the case among plants, suggested that the oospheres of the Abietineae might be peculiarly favourable objects for study. It was with this idea that the work described in the present paper was begun in 1894.

Ultrastructure of mesotheliomas

1984 ◽  
Vol 42 ◽  
pp. 98-101
Author(s):  
Irving Dardick
Keyword(s):  
Electron Microscopy ◽  
Latent Period ◽  
Spindle Cell ◽  
Spindle Cell Sarcoma ◽  
Metastatic Adenocarcinoma ◽  
Cell Sarcoma ◽  
Cytological Features ◽  
Industrial Use ◽  
Degree Of Differentiation

With the extensive industrial use of asbestos in this century and the long latent period (20-50 years) between exposure and tumor presentation, the incidence of malignant mesothelioma is now increasing. Thus, surgical pathologists are more frequently faced with the dilemma of differentiating mesothelioma from metastatic adenocarcinoma and spindle-cell sarcoma involving serosal surfaces. Electron microscopy is amodality useful in clarifying this problem.In utilizing ultrastructural features in the diagnosis of mesothelioma, it is essential to appreciate that the classification of this tumor reflects a variety of morphologic forms of differing biologic behavior (Table 1). Furthermore, with the variable histology and degree of differentiation in mesotheliomas it might be expected that the ultrastructure of such tumors also reflects a range of cytological features. Such is the case.

Ethylene effects on cambial activity and cell wall formation in hypocotyls of Picea abies seedlings

1991 ◽  
Vol 82 (2) ◽  
pp. 219-224 ◽  
Author(s):  
Barbro S. M. Ingemarsson ◽  
Leif Eklund ◽  
Lennart Eliasson
Keyword(s):  
Cell Wall ◽  
Picea Abies ◽  
Cambial Activity ◽  
Cell Wall Formation ◽  
Wall Formation

Radiation Sickness after Therapeutic Administration of 806 mCi of 131I for Thyroid Cancer

1967 ◽  
Vol 06 (02) ◽  
pp. 170-183
Author(s):  
K. Šilink ◽  
J. Němec ◽  
J. Kubal ◽  
S. Röhling ◽  
S. Vohnout
Keyword(s):  
Bone Marrow ◽  
Thyroid Cancer ◽  
Radiation Injury ◽  
Clinical Course ◽  
External Irradiation ◽  
Bone Marrow Depression ◽  
Erythroid Hyperplasia ◽  
Cytological Features ◽  
Haematological Changes ◽  
Therapeutic Administration

SummaryThe clinical course and the haematologic events in a patient suffering from metastatic thyroid cancer after administration of 806 mCi of 131I are described. A serious bone marrow depression developed and was treated successfully. The haematological changes during the early and late phases of the radiation injury were studied in detail and compared with those after external irradiation. The haematological events after internal irradiation with 131I are characterised by initial neutrophilic leukocytosis, protracted lymphopenia, slowly developing anaemia reaching lowest values about 3 months after administration, erythroid hyperplasia in the bone marrow after recovery from bone marrow depression and prominent cytological features of the bone marrow, especially pronounced erythropoietic polyploidy.

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