Structural changes in the pollinated and unpollinated avocado stigma and style

1979 ◽  
Vol 38 (1) ◽  
pp. 49-60
Author(s):  
M. Sedgley
Keyword(s):  
Structural Changes ◽  
Tube Wall ◽  
Light And Electron Microscopy ◽  
Pollen Tubes ◽  
Persea Americana ◽  
Initial Contact ◽  
Transmitting Tissue ◽  
Intercellular Substance ◽  
Pollen Tube Wall ◽  
Stigma Secretion

Structural changes in the pollinated and unpollinated avocado (Persea americana Mill) stigma and style up to 42 h after first opening of the flower were investigated using light and electron microscopy. The pollen tubes grew in the stigma secretion and intercellular substance and initial contact occurred between the plasma membrane of the male and the cuticle and stigma secretion of the female. The pollen tube wall started to develop 15 min after pollination and increased in thickness up to 24 h after pollination. By 18 h after first opening of the flower, starch had disappeared and cell wall thickenings were present in both the pollinated and unpollinated stigma and style. The wall thickenings developed more slowly in the unpollinated than in the pollinated tissue. They contained lipid and were bounded by callose. Degeneration of the cytoplasm of some of the papilla and transmitting tissue cells occurred only following the passage of the pollen tubes and may be of importance in tube nutrition. There was no degeneration in the unpollinated stigma and style and the cytoplasm did not start to lose clarity until 42 h after first opening of the flower.

Structure of the Stigma and Style of the Avocado

1978 ◽  
Vol 26 (5) ◽  
pp. 663 ◽  
Author(s):  
M Sedgley ◽  
MS Buttrose
Keyword(s):  
Electron Microscopy ◽  
Smooth Endoplasmic Reticulum ◽  
Freeze Fracture ◽  
Persea Americana ◽  
Transmitting Tissue ◽  
Intercellular Substance ◽  
Thin Sections ◽  
Transmission Electron ◽  
Tissue Cells ◽  
Stigma Secretion

The structure of the stigma and style of the avocado (Persea americana Mill.) was investigated by light microscopy, scanning electron microscopy and transmission electron microscopy of thin sections and freeze-fracture replicas. The stigmalstyle was asymmetrical and a groove, lined with transmitting tissue, extended the whole length of the structure. Stigma papillae fringed this groove for about a third of its length. There was no clear distinction between stigma papillae and stylar transmitting tissue cells but there was a gradation of structure down the axis. The papilla cells were long with large and small vacuoles; the transmitting tissue cells had small vacuoles only. The stigma secretion and intercellular substance of the transmitting tissue contained carbohydrate and lipid. Clusters of plastids with little internal structure and electron-dense stroma were abundant in the cells of the stigma and transmitting tissue along with extensive smooth endoplasmic reticulum. Both single vesicles and multivesicular bodies were observed fusing with the plasmalemma which was abnormally rough in freeze-fracture profiles. It is suggested that the cells of the stigma and transmitting tissue have a largely secretory function and may be approaching or have reached senescence when the flower opens.

Growth of barley pollen tubes in vivo. I. Ultrastructural aspects of early tube growth in the stigmatic hair

1979 ◽  
Vol 57 (4) ◽  
pp. 386-396 ◽  
Author(s):  
David D. Cass ◽  
Daniel J. Peteya
Keyword(s):  
Electron Microscopy ◽  
Pollen Tube ◽  
Hair Cell ◽  
Tube Wall ◽  
Periodic Acid ◽  
Pollen Tubes ◽  
Tube Growth ◽  
Reserve Carbohydrate ◽  
Pollen Tube Wall ◽  
Hair Surface

Barley styles were examined with transmission electron microscopy (TEM) and scanning electron microscopy (SEM) before and after pollination. Pollen tube penetration of a stigmatic hair may follow initial missing of the hair and (or) a period of growth on the hair surface. Changes in hair cell walls occur at penetration sites. Absence of demonstrable reserve carbohydrate in hair cells and styles and its abundance in pollen tubes suggest that early tube growth is largely dependent on endogenous substrates relative to its carbohydrate requirement. The pollen tube wall has an inner, somewhat reticular region and an outer, multilayered fibrillar region. Membrane-bound pollen tube vesicles containing reticular material fuse with the pollen tube membrane, contributing to development of the pollen tube wall. Vesicles and tube wall are stained by Ruthenium Red; this staining is compared with results of periodic acid–silver proteinate treatment. Two types of tube growth anomalies are reported. In the first, a tube may grow out of a hair and discharge its cytoplasm onto the hair surface through an aperture. Discharged, naked tube cytoplasm often remains appressed to hair surfaces. In the second, a tube may grow into a hair cell and discharge its contents therein through an apparently similar aperture. Vegetative nuclei appear unaltered during early pollen tube growth, but there are minor structural alterations in sperms and vegetative cell cytoplasm.

Germination and growth of sponge gourd (Luffa cylindrica) pollen tubes and FTIR analysis of the pollen tube wall

2009 ◽  
Vol 122 (4) ◽  
pp. 638-644 ◽  
Author(s):  
Bo Jiang ◽  
Zonggen Shen ◽  
Jinbo Shen ◽  
Da Yu ◽  
Xianyong Sheng ◽  
...  
Keyword(s):  
Pollen Tube ◽  
Tube Wall ◽  
Pollen Tubes ◽  
Ftir Analysis ◽  
Luffa Cylindrica ◽  
Sponge Gourd ◽  
Pollen Tube Wall ◽  
Germination And Growth

An Ultrastructural and Radio-Autographic Study of the Evolution of the Interphase Nucleus in Plant Meristematic Cells (Allium Porrum)

1974 ◽  
Vol 14 (2) ◽  
pp. 263-287
Author(s):  
J. G. LAFONTAINE ◽  
A. LORD
Keyword(s):  
Interphase Nucleus ◽  
Structural Changes ◽  
Tritiated Thymidine ◽  
Light And Electron Microscopy ◽  
Allium Porrum ◽  
Meristematic Cells ◽  
Fibrillar Material ◽  
Nuclear Structures ◽  
S Period ◽  
Dense Chromatin

Radioautography under both light and electron microscopy was exploited to investigate the structural changes of the chromatin reticulum which characterizes the interphase nucleus of a number of plants. Allium porrum meristematic plant cells were used for this purpose. In this species, the telophase chromosomes uncoil into dense strands which, during the G1 period, gradually give rise to a coarse reticulum. There then follows an extensive unravelling of portions of these strands, and high-resolution radioautography reveals that labelling with tritiated thymidine predominantly occurs over zones of the nucleus consisting of diffuse fine fibrillar material. As the S-period progresses, a chromatin reticulum reappears throughout the nuclear cavity, the tortuous strands being approximately 0.25 µm in diameter. Most of the radioautographic grains still remain over the light nucleoplasmic areas but a number of these are now located on the outermost portion of the dense chromatin profiles. By the end of the S-period, the chromatin strands are slightly thicker (ca. 0.3 µm) and form a looser reticulum. Labelling has decreased noticeably in nuclei of that period, the radioautographic grains being grouped into clusters resting over more or less spherical regions of the chromatin reticulum. Judging from their localization at the surface of the nucleolus or close to the nuclear envelope, these structures correspond to chromocentres. The additional interesting finding that such nuclear structures appear much less compactly organized strongly suggests that chromocentres undergo important conformational modifications during duplication of their DNA.

Cerebral autosomo-dominant arteriopathy with subcortical infarctions and leukoencephalopathy

2021 ◽  
Vol 26 (5) ◽  
pp. 30-38
Author(s):  
E. A. Savchuk ◽  
E. P. Golubinskaya ◽  
T. N. Shcherbinina ◽  
G. Yu. Voronin ◽  
E. O. Savchuk ◽  
...  
Keyword(s):  
Clinical Case ◽  
Structural Changes ◽  
Light And Electron Microscopy ◽  
Joint Work ◽  
Genetic Studies ◽  
Small Vessels ◽  
Clinical Case Study ◽  
The Family ◽  
Probable Diagnosis

The article presents an analysis of the literature and a clinical case of a rare disease from the group of diseases of small vessels — cerebral autosomal dominant arteriopathy with subcortical infarction and leukoencephalopathy (CADASIL).It is based on the deposition of osmiophilic granulation material in vessels of small and medium caliber. A mutation in the NOTCH3 gene on chromosome 19p13 leads to significant structural changes in the walls of small arteries due to impaired differentiation and maturation of smooth muscle cells.CADASIL is characterized by four key symptoms: migraines, recurrent ischemic strokes, mental disorders, and cognitive decline. The clinical case study is presented from the standpoint of a multidisciplinary patient-oriented approach of joint work of neurologists and morphologists. On the basis of clinical and laboratory criteria, a probable diagnosis was made. To confirm it, a muscle biopsy was performed (a musculocutaneous flap from the inner surface of the thighs and forearms), in order to conduct light and electron microscopy. The details of the results of the morphological study, which made it possible to verify the patient’s diagnosis, are presented. Differential diagnostic judgments are presented and recommendations for genetic studies in the family, prognosis and treatment of the patient are given.

Anatomy of the Unpollinated and Pollinated Watermelon Stigma

1982 ◽  
Vol 54 (1) ◽  
pp. 341-355
Author(s):  
M. SEDGLEY
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Light And Electron Microscopy ◽  
Freeze Fracture ◽  
Pollen Grain ◽  
Acidic Polysaccharides ◽  
Before And After ◽  
Em Autoradiography ◽  
Pollen Grain Wall ◽  
Stigma Secretion

The structure of the watermelon stigma before and after pollination was studied using light and electron microscopy, freeze-fracture and autoradiography. The wall thickenings of the papilla transfer cells contained callose and their presence prior to pollination was confirmed using EM-autoradiography, freeze-fracture and fixation. No further callose thickenings were produced following pollination. Pollination resulted in a rapid increase in aqueous stigma secretion and localized disruption of the cuticle, which appeared to remain on the surface of the secretion. Autolysis of the papilla cells, which had commenced prior to pollination, was accelerated and appeared to take place via cup-shaped vacuoles developed from distended endoplasmic reticulum. The reaction was localized to the papilla cells adjacent to the pollen tube only. Both pollen-grain wall and stigma secretion contained proteins, carbohydrates, acidic polysaccharides, lipids and phenolics.

The growth of the pollen tube wall in Oenothera organensis

1975 ◽  
Vol 18 (3) ◽  
pp. 519-532
Author(s):  
H.G. Dickinson ◽  
J. Lawson
Keyword(s):  
Pollen Tube ◽  
Tube Wall ◽  
Wall Material ◽  
Fibrillar Material ◽  
Stage Of Development ◽  
Large Numbers ◽  
Membrane Bound ◽  
Pollen Tube Wall ◽  
Different Sources ◽  
Dictyosome Vesicles

The growth of the pollen tube wall of Oenothera is effected by the expulsion of fibrillar material from the cytoplasm into the developing wall. This material may also be seen in the cytoplasm, contained in membrane-bound vesicles. It is not clear how the content of the vesicles is discharged, but it appears not to involve the participation of microtubules. The source of the cytoplasmic fibrillar bodies depends upon the stage of development of the pollen tube. The earilest growth is derived from the inclusion into the wall of vesicles containing pre-formed materials present in the grain on pollination. During the next stage of growth the wall is derived from the content of double-membraned inclusions also present in the pollen. The content of the former vesicles is not so similar to the wall as the latter, but intermediates between the 2 types of vesicle may be seen in the cytoplasm, indicating that the former are formed from the latter. Most of the tube wall is derived from the products of dictyosomes in the pollen grain or tube. These dicytosomes are few in number and they must be exceedingly active. This, and the observation that dictyosome vesicles are frequently associated with banked complexes of mitochondria, indicates that some steps in the metabolism of the vesicular content, perhaps phosphorylation, take place distant from the dicytosomes. These different sources of fibrillar material presumably permit the rapid starting of tube growth, without any attendant metabolism. However, it would be impossible to include enough pre-formed wall material in the grain to enable the full growth of the tube, so once started, it seems that the tube then relies on the elaboration of simple reserves for the contruction of its wall. These reserves are likely to be held in the pollen, and may be the large numbers of starch grains characteristic of the pollen cytoplasm.

Functional medial thickening and folding of the internal elastic lamina in coronary spasm

2011 ◽  
Vol 300 (2) ◽  
pp. H423-H430 ◽  
Author(s):  
Yasumi Uchida ◽  
Yasuto Uchida ◽  
Akimasa Matsuyama ◽  
Atsushi Koga ◽  
Yuko Maezawa ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Structural Changes ◽  
Light And Electron Microscopy ◽  
Coronary Spasm ◽  
Cellular Level ◽  
Internal Elastic Lamina ◽  
Circular Smooth Muscle ◽  
The Media ◽  
Medial Thickening ◽  
Elastic Lamina

Although there are a number of studies on vasospastic angina, the structural changes at the cellular level that occur in the coronary arterial wall during spasm are not well known. Coronary spasm was induced by brushing the coronary adventitia in nine anesthetized beagles, and structural changes in the spastic coronary segments were examined by light and electron microscopy, making comparisons with the adjacent nonspastic segments. The % diameter stenosis of the spastic segments as measured angiographically was 79.4 ± 12% (mean ± SD). Light microscopic changes in the spastic and nonspastic segments were as follows: medial thickness 1,512 vs. 392 μm ( P < 0.0001) and % diameter and % area stenoses of spastic segment 81.0% and 96.5%, respectively, indicating that spasm was induced by medial thickening. Circular smooth muscle cells (SMCs) in the media were arranged in parallel with the internal (IEL) and external (EEL) elastic lamina in nonspastic segments but radially rearranged in spastic segments. SMCs were classified by their patterns of connection to IEL into six types by electron microscopy. Of these, three contracted and pulled the IEL toward the EEL, causing folding of the IEL and waving of EEL resulting in thickening of the media and narrowing of the lumen. We conclude that coronary spasm was elicited by radial rearrangement of the medial SMCs due to their own contraction and resultant medial thickening and folding of IEL, creating a piston effect to narrow the lumen, i.e., spasm.

scholarly journals A floral transmitting tissue-specific glycoprotein attracts pollen tubes and stimulates their growth

Cell ◽  
1995 ◽  
Vol 82 (3) ◽  
pp. 383-393 ◽  
Author(s):  
Alice Y Cheung ◽  
Hong Wang ◽  
Hen-ming Wu
Keyword(s):  
Pollen Tubes ◽  
Transmitting Tissue ◽  
Tissue Specific

scholarly journals Morphometric evaluation of features of remodeling of chondrocites of joint surfaces of temporomandibular joint of experimental animals in hyperglycemia

2021 ◽  
Vol 11 (6) ◽  
pp. 137-142
Author(s):  
Mykhailo Hnatiuk ◽  
Lesia Rubas
Keyword(s):  
Temporomandibular Joint ◽  
Structural Changes ◽  
Articular Surface ◽  
White Male ◽  
Relative Volume ◽  
Male Rats ◽  
Intercellular Substance ◽  
Temporal Fossa ◽  
Articular Surfaces ◽  
Joint Surfaces

Aim: to study morphometrically the peculiarities of remodeling of chondrocytes of the articular surfaces of the temporomandibular joint in hyperglycemia.Materials and methods: Quantitative morphological methods were used to study diameters of chondrocytes and their nuclei, nuclear-cytoplasmic relationship in these cells, relative volume of damaged chondrocytes, intercellular-chondrocytic relationship in mature chondrocytes of the articular surfaces of the temporomandibular joint of 45 laboratory mature white male rats with simulated diabetes.Results: A comprehensive analysis of the morphometric parameters presented in the article showed that they did not differ in the articular surfaces of the temporal fossa and mandibular head of the intact temporomandibular joint. The expressed structural changes of chondrocytes were revealed at a monthly and a two-month diabetic arthropathy of this joint.Conclusions: Proceeded studies and obtained results suggest that prolonged hyperglycemia leads to diabetic arthropathy of the TMJ, which is characterized by atrophy of chondrocytes, violation of nuclear-cytoplasmic relationships, an increase in the relative volume of damaged chondrocytes and volume of intercellular substance. The detected changes in quantitative morphological parameters depended on the duration of hyperglycemia and dominated in the cartilaginous tissue of the articular surface of the mandibular head.

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