Fruit Development of Pistacia vera (Anacardiaceae) in Relation to Embryo Abortion and Abnormalities at Maturity

1996 ◽  
Vol 44 (1) ◽  
pp. 35 ◽  
Author(s):  
YD Shuraki ◽  
M Sedgley
Keyword(s):  
Pollen Tube ◽  
Fruit Development ◽  
Embryo Sac ◽  
Vascular Bundles ◽  
Pistacia Vera ◽  
Bright Field ◽  
Embryo Abortion ◽  
Common Cause ◽  
Bright Field Microscopy ◽  
Pollen Tube Penetration

This study investigated fruit development of the Pistacia vera L. cultivars Kerman and Sirora using bright field microscopy. Normal fruit development was compared with that of seedless (blank) and small seeded (semi-blank) fruits to identify the stages at which degeneration occurred. In normal fruits, pericarp growth took place up to week 4 after pollination and preceded embryo, endosperm and funicle proliferation between weeks 4 and 16. Endocarp (shell) and exocarp (hull) development occurred between weeks 8 and 16. Blank and semi-blank fruits were identified by slower growth and lack of exocarp colouration. Blank fruits resulted from one of five patterns of ovule degeneration caused by funicle degeneration, embryo sac absence, embryo sac degeneration, lack of pollen tube penetration of the embryo sac, or failure of endosperm cellularisation. Funicle degeneration was the most common cause of blanking and was observed either at the site of pollen tube penetration or at the chalazal end of both pollinated and unpollinated ovules. Degeneration of funicular tissue extended towards the vascular bundles. Small seeded or semi-blank fruit resulted from degeneration of the cotyledons during the latter stage of embryo development.

Embryology of Eucalyptus Spathulata and E. platypus (Myrtaceae) Following Selfing, Crossing and Reciprocal Interspecific Pollination

1996 ◽  
Vol 44 (6) ◽  
pp. 661 ◽  
Author(s):  
M Sedgley ◽  
L Granger
Keyword(s):  
Pollen Tube ◽  
Embryo Development ◽  
Bright Field ◽  
Cross Pollination ◽  
Self Pollination ◽  
Bright Field Microscopy ◽  
Low Levels ◽  
Pollen Tube Penetration ◽  
Ovule Penetration

Embryology of Eucalyptus spathulata Hook. and E. platypus Hook. (subgenus Symphyomyrtus, section Bisectaria) was investigated by bright field microscopy to determine the cause of ovule failure at 2 months following selfing, crossing and reciprocal interspecific pollination. Eucalyptus spathulata retained more capsules and produced more seeds following cross- than self-pollination, whereas there was no difference between selfing and crossing for E. platypus. Both species produced seeds following interspecific pollination, but germination was low. Highest ovule penetration by a pollen tube, and ovule growth at 2 months, was observed following crossing of E. spathulata and following interspecific pollination of E. platypus. Most self-pollinated ovules of both species were degenerating and were either unfertilised or had undivided zygotes and free nuclear endosperm. Muticellular pro-embryos were more common in cross-pollinated and interspecific pollinated ovules than following selfing. It was concluded that ovule degeneration of E. spathulata and E. platypus following selfing resulted from low levels of pollen tube penetration and fertilisation, and that in those ovules which were fertilised, the zygote generally failed to divide. Degeneration following cross-pollination of E. spathulata also resulted from failure of the zygote to divide, and in E. platypus additional reasons were low levels of pollen tube penetration and fertilisation, and lack of cellularisation of the endosperm. Ovule degeneration of both species following interspecific pollination included failure of the zygote to divide, but in E. spathulata it also resulted from slower embryo development and reduced cellularisation of the endosperm.

Cytoskeletal organisation and modification during pollen tube arrival, gamete delivery and fertilisation in Plumbago zeylanica

Zygote ◽  
1993 ◽  
Vol 1 (2) ◽  
pp. 143-154 ◽  
Author(s):  
Bing-Quan Huang ◽  
Elisabeth S. Pierson ◽  
Scott D. Russell ◽  
Antonio Tiezzi ◽  
Mauro Cresti
Keyword(s):  
Pollen Tube ◽  
Embryo Sac ◽  
Central Cell ◽  
Egg Cell ◽  
Target Cells ◽  
Sperm Cells ◽  
Plumbago Zeylanica ◽  
Rhodamine Phalloidin ◽  
Male Gametes ◽  
Pollen Tube Penetration

The cytoskeletal organisation of the isolated embryo sac and egg cells of Plumbago zeylanica was examined before, during and after pollen tube penetration into the embryo sac to determine the potential involvement of microtubules and actin filaments in fertilisation. Material was singly and triply stained using Hoechst 33258 to localise DNA, fluorescein isothiocyanate (FITC)-labelled anti- α-tubulin to detect microtubules and rhodamine-phalloidin to visualise F-actin. Microtubules in the unfertilised egg cell are longitudinally aligned in the micropylar and mid-lateral areas, aggregating into bundles near the filiform apparatus. In the perinuclear cytoplasm of the egg cell, microtubules become more or less randomly aligned. F-actin bundles form a longitudinally aligned mesh in the chalazal cytoplasm of the egg cell. In the central cell, microtubules and F-actin are distributed along transvacuolar strands and are also evident in the perinuclear region and at the periphery of the cell. During pollen tube penetration, sparse microtubule bundles near the pathway of the pollen tube may form an apparent microtubular ‘conduit’ surrounding the male gametes at the delivery site. Actin aggregates become organised near the pathway of the pollen tube and at the delivery site of the sperm cells. Subsequently, actin aggregates form a ‘corona’ structure in the intercellular region between the egg and central cell where gametic fusion occurs. The corona may have a role in maintaining the close proximity of the egg and central cell and helping the two sperm cells move and bind to their target cells. The cytoskeleton may also be involved in causing the two nuclei of the egg and central cell to approach one another at the site of gametic fusion and transporting the two sperm nuclei into alignment with their respective female nucleus. The cytoskeleton is reorganised during early embryogenesis.

scholarly journals Histologic Examination of a Sea Pig (Scotoplanes sp.) Using Bright Field Light Microscopy

2021 ◽  
Vol 9 (8) ◽  
pp. 848
Author(s):  
Elise E. B. LaDouceur ◽  
Linda A. Kuhnz ◽  
Christina Biggs ◽  
Alicia Bitondo ◽  
Megan Olhasso ◽  
...  
Keyword(s):  
Deep Sea ◽  
Body Wall ◽  
Monterey Bay ◽  
Bright Field ◽  
Male And Female ◽  
Rete Mirabile ◽  
Lateral Body ◽  
Bright Field Microscopy ◽  
Microscopic Findings ◽  
Tube Feet

Sea pigs (Scotoplanes spp.) are deep-sea dwelling sea cucumbers of the phylum Echinodermata, class Holothuroidea, and order Elasipodida. Few reports are available on the microscopic anatomy of these deep-sea animals. This study describes the histologic findings of two, wild, male and female Scotoplanes sp. collected from Monterey Bay, California. Microscopic findings were similar to other holothuroids, with a few notable exceptions. Sea pigs were bilaterally symmetrical with six pairs of greatly enlarged tube feet arising from the lateral body wall and oriented ventrally for walking. Neither a rete mirabile nor respiratory tree was identified, and the large tube feet may function in respiration. Dorsal papillae protrude from the bivium and are histologically similar to tube feet with a large, muscular water vascular canal in the center. There were 10 buccal tentacles, the epidermis of which was highly folded. Only a single gonad was present in each animal; both male and female had histologic evidence of active gametogenesis. In the male, a presumed protozoal cyst was identified in the aboral intestinal mucosa, and was histologically similar to previous reports of coccidians. This work provides control histology for future investigations of sea pigs and related animals using bright field microscopy.

scholarly journals Paving the Way for Fertilization: The Role of the Transmitting Tract

2021 ◽  
Vol 22 (5) ◽  
pp. 2603
Author(s):  
Ana Marta Pereira ◽  
Diana Moreira ◽  
Sílvia Coimbra ◽  
Simona Masiero
Keyword(s):  
Pollen Tube ◽  
Pollen Tube Growth ◽  
Current Knowledge ◽  
Embryo Sac ◽  
Tube Growth ◽  
Signaling Cascades ◽  
Secretory Cells ◽  
Transmitting Tract ◽  
Specialized Tissue

Angiosperm reproduction relies on the precise growth of the pollen tube through different pistil tissues carrying two sperm cells into the ovules’ embryo sac, where they fuse with the egg and the central cell to accomplish double fertilization and ultimately initiate seed development. A network of intrinsic and tightly regulated communication and signaling cascades, which mediate continuous interactions between the pollen tube and the sporophytic and gametophytic female tissues, ensures the fast and meticulous growth of pollen tubes along the pistil, until it reaches the ovule embryo sac. Most of the pollen tube growth occurs in a specialized tissue—the transmitting tract—connecting the stigma, the style, and the ovary. This tissue is composed of highly secretory cells responsible for producing an extensive extracellular matrix. This multifaceted matrix is proposed to support and provide nutrition and adhesion for pollen tube growth and guidance. Insights pertaining to the mechanisms that underlie these processes remain sparse due to the difficulty of accessing and manipulating the female sporophytic tissues enclosed in the pistil. Here, we summarize the current knowledge on this key step of reproduction in flowering plants with special emphasis on the female transmitting tract tissue.

Overgrowth of Pollen Tubes in Embryo Sacs of Rhododendron Following Interspecific Pollinations

1986 ◽  
Vol 34 (4) ◽  
pp. 413 ◽  
Author(s):  
EG Williams ◽  
V Kaul ◽  
JL Rouse ◽  
BF Palser
Keyword(s):  
Pollen Tube ◽  
Embryo Sac ◽  
Pollen Tubes ◽  
Egg Cell ◽  
Interspecific Crosses ◽  
Main Body

Frequent overgrowths of pollen tubes within the embryo sac are characteristic of a number of interspecific crosses in the genus Rhododendron (Ericaceae). The combined techniques of sectioning, squashing and whole-ovule clearing have confirmed that in ovules showing this phenomenon the pollen tube fails to terminate growth and release sperms on entry into a synergid; instead it continues to grow beyond the synergid and egg cell, often filling the main body of the embryo sac with a coiled and distorted mass. Such ovules fail to develop further. The occurrence and possible causes of this error syndrome are discussed.

Reproductive incompatibility barriers in crosses between Vaccinium corymbosum and V. elliottii

1985 ◽  
Vol 63 (11) ◽  
pp. 1987-1996 ◽  
Author(s):  
C. E. Munoz ◽  
P. M. Lyrene
Keyword(s):  
United States ◽  
Cell Division ◽  
Pollen Tube ◽  
Resting State ◽  
Southeastern United States ◽  
Female Parent ◽  
Vaccinium Corymbosum ◽  
Highbush Blueberry ◽  
Embryo Abortion ◽  
Reproductive Incompatibility

A study was made of barriers to hybridization between tetraploid V. corymbosum L., the cultivated highbush blueberry, and V. elliottii Chapm., a wild diploid blueberry which may be useful in breeding cultivars adapted to the southeastern United States. Both prefertilization and postfertilization barriers were detected. Prefertilization barriers were mainly observed when V. elliottii was the male parent and were manifested as an arrest of pollen tube growth at the base of the style. In cases where fertilization did take place, regardless of which species was used as the female, a strong postfertilization barrier usually prevented development of hybrid zygotes. Zygotes remained in a resting state after fertilization and usually aborted before dividing. Meanwhile, the endosperm underwent four to six cycles of cell division before it started to degenerate. A causal relationship between embryo abortion and endosperm malfunction was not clearly established. Endosperm malfunction and embryo abortion were delayed when V. corymbosum was the female parent.

Bright-Field Microscopy Techniques

2017 ◽  
pp. 307-344
Author(s):  
Onkar D. Dhingra ◽  
James B. Sinclair
Keyword(s):  
Bright Field ◽  
Bright Field Microscopy ◽  
Microscopy Techniques

scholarly journals Probing roto-translational diffusion of small anisotropic colloidal particles with a bright-field microscope

2021 ◽  
Vol 44 (4) ◽  
Author(s):  
Fabio Giavazzi ◽  
Antara Pal ◽  
Roberto Cerbino
Keyword(s):  
Particle Size ◽  
Rotational Motion ◽  
Colloidal Particles ◽  
Aqueous Suspension ◽  
Translational Motion ◽  
Translational Diffusion ◽  
Experimental Demonstration ◽  
Bright Field ◽  
Microscopic Scale ◽  
Bright Field Microscopy

Abstract Soft and biological materials are often composed of elementary constituents exhibiting an incessant roto-translational motion at the microscopic scale. Tracking this motion with a bright-field microscope becomes increasingly challenging when the particle size becomes smaller than the microscope resolution, a case which is frequently encountered. Here we demonstrate squared-gradient differential dynamic microscopy (SG-DDM) as a tool to successfully use bright-field microscopy to extract the roto-translational dynamics of small anisotropic colloidal particles, whose rotational motion cannot be tracked accurately in direct space. We provide analytical justification and experimental demonstration of the method by successful application to an aqueous suspension of peanut-shaped particles. Graphic abstract

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