LIGHT MICROSCOPE AND ULTRASTRUCTURAL STUDIES OF THE MALE GAMETOPHYTE IN GINKGO BILOBA: THE SPERMATOGENOUS CELL

1975 ◽  
Vol 62 (9) ◽  
pp. 974-981 ◽  
Author(s):  
Ernest M. Gifford ◽  
Joseph Lin
Keyword(s):  
Ginkgo Biloba ◽  
Light Microscope ◽  
Male Gametophyte ◽  
Ultrastructural Studies ◽  
Spermatogenous Cell

The development of the male gametophyte and spermatogenesis in Taxus baccata L

1986 ◽  
Vol 228 (1250) ◽  
pp. 85-96 ◽  
Keyword(s):  
Pollen Tube ◽  
De Novo ◽  
Male Gametophyte ◽  
Generative Cell ◽  
Equal Size ◽  
Taxus Baccata ◽  
Transverse Wall ◽  
Proximal Pole ◽  
Spermatogenous Cell ◽  
Tube Cell

The development of the male gametophyte of Taxus baccata has been studied over a period of 20 weeks, from germination of the microspore in February to spermatogenesis in July. A few days after germination the microspore nucleus divides and a transverse wall forms at the equator cutting off the small generative cell and a large tube cell. The latter immediately begins to expand to form the pollen tube. The first division thus establishes the polarity of the gametophyte and the generative cell is regarded as proximal. The transverse wall is ephemeral, and within six weeks it has disappeared. The nucleus of the generative cell divides while still at the proximal pole. The two daughter nuclei are unequal in size, but they remain associated and together move distally. The larger nucleus eventually becomes the nucleus of the spermatogenous cell, and the smaller the sterile nucleus. The spermatogenous cell acquires a distinctive cytoplasm and becomes surrounded by a wall which arises de novo . The nucleus of the spermatogenous cell enlarges, but always remains towards one side of the cell so that at mitosis the spindle is contained within one hemisphere. After division the wall of the spermatogenous cell is ruptured and the two sperms are released as naked nuclei of equal size. The cytoplasm of the spermatogenous cell degenerates as it enters the tube, but remains recognizable until fertilization.

Insemination of the archegonium and fertilization in Taxus baccata L

1988 ◽  
Vol 89 (4) ◽  
pp. 551-560
Author(s):  
ROGER I. PENNELL ◽  
PETER R. BELL
Keyword(s):  
Pollen Tube ◽  
Male Gametophyte ◽  
Sperm Nucleus ◽  
Taxus Baccata ◽  
Close Apposition ◽  
Cell Cytoplasm ◽  
Spermatogenous Cell ◽  
Tube Lumen ◽  
Sperm Nuclei ◽  
Progressive Enlargement

A study of fertilization in Taxus baccata in the electron microscope has revealed novel features. Insemination of the archegonium is facilitated by local perforation of the wall of the young pollen tube. Digestion of the wall begins before the pollen tube pierces the megaspore membrane but is not completed until its tip makes contact with the neck cells of the archegonium. As soon as a pore is formed a single sperm nucleus and some cytoplasm of the male gametophyte enter the archegonium. Which of the paired sperm nuclei move from the pollen tube into the archegonium appears to be a matter of chance. Close apposition of sperm nucleus and egg nucleus is followed by the formation of numerous points of contact between the two. The membranes fuse at these points and pores are rapidly formed. The progressive enlargement of these pores ultimately eliminates any partitions and yields the zygotic nucleus. There is a possibility that, as in some other gymnosperms, the plastids and mitochondria of the zygote come in part from the male gametophyte, but whether from the remains of the spermatogenous cell cytoplasm or from the. pollen tube lumen is not clear.

scholarly journals Ultrastructural studies on the sporogenous tissue and anther wall of Leucojum aestivum (amaryllidaceae) in different developmental stages

2012 ◽  
Vol 84 (4) ◽  
pp. 951-960 ◽  
Author(s):  
Nuran Ekici ◽  
Feruzan Dane
Keyword(s):  
Developmental Stages ◽  
Male Gametophyte ◽  
Anther Wall ◽  
Pollen Mother Cells ◽  
Ultrastructural Studies ◽  
Leucojum Aestivum ◽  
Sporogenous Tissue ◽  
Mother Cells ◽  
Polar Distribution ◽  
Early Phases

In this study, ultrastructures of anther wall and sporogenous tissue of Leucojum aestivum were investigated during different developmental stages. Cytomictic channels were seen between pollen mother cells during prophase I. Polar distribution was described in the organelle content of pollen mother cells and microspores in early phases of microsporogenesis and also in pollen mitosis. Active secretion was observed in tapetal cells. Previous reports about developmental stages of male gametophyte were compared with the results of this study.

scholarly journals Translocation of the generative cell towards the centre of the pollen grain due to changes in the vacuolar system in Ranunculus repens L.

2015 ◽  
Vol 42 (2) ◽  
pp. 295-300 ◽  
Author(s):  
Maria Charzyńska
Keyword(s):  
Light Microscope ◽  
Male Gametophyte ◽  
Generative Cell ◽  
Pollen Grain ◽  
Vegetative Cells ◽  
Vacuolar System

On the basis of observations performed under the light microscope on the development of the male gametophyte of <i>Ranunculus repens</i> L., the hypothesis is advanced that the translocation of the generative cell from a position adjacent to the wall towards the centre of the pollen grain, associated with change in the shape of this cell, is the result of vacuolization of the generative and vegetative cells and the interaction of these two vacuole systems.

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