Comparative Morphology, Anatomy, and Function of the Stem and Root of the Flowering Plants

In flowering plants, male meiosis occurs in the microsporocyte to produce four microspores, each of which develops into a pollen grain. Here we describe four mutant alleles of TETRASPORE (TES), a gene essential for microsporocyte cytokinesis in Arabidopsis thaliana. Following failure of male meiotic cytokinesis in tes mutants, all four microspore nuclei remain within the same cytoplasm, with some completing their developmental programmes to form functional pollen nuclei. Both of the mitotic divisions seen in normal pollen development take place in tes mutants, including the asymmetric division required for the differentiation of gametes; some tes grains perform multiple asymmetric divisions in the same cytoplasm. tes pollen shows a variety of abnormalities subsequent to the cytokinetic defect, including fusion of nuclei, formation of ectopic internal walls, and disruptions to external wall patterning. In addition, ovules fertilized by tes pollen often abort, possibly because of excess paternal genomes in the endosperm. Thus tes mutants not only reveal a gene specific to male meiosis, but aid investigation of a wide range of processes in pollen development and function.

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Review: Sperm: Comparative morphology and function related to altered reproductive strategies and fertility in mammals

The Professional Animal Scientist ◽

10.15232/pas.2018-01748 ◽

2018 ◽

Vol 34 (6) ◽

pp. 558-565

Author(s):

Shannon Kate Thompson ◽

Naseer A. Kutchy ◽

Samantha Kwok ◽

Zulfi N.A. Rosyada ◽

Ikhide G. Imumorin ◽

...

Keyword(s):

Reproductive Strategies ◽

Comparative Morphology ◽

And Function

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Pollen presenters in the flowering plants-form and function

Botanical Journal of the Linnean Society ◽

10.1111/j.1095-8339.1994.tb01777.x ◽

1994 ◽

Vol 115 (3) ◽

pp. 165-195 ◽

Cited By ~ 7

Author(s):

P. G. LADD

Keyword(s):

Flowering Plants ◽

Form And Function ◽

And Function

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Bivalve Morphology and Function

Notes for a Short Course: Studies in Geology ◽

10.1017/s0271164800001111 ◽

1985 ◽

Vol 13 ◽

pp. 88-101 ◽

Cited By ~ 6

Author(s):

Adolf Seilacher

Keyword(s):

Fossil Record ◽

Soft Part ◽

Biotic Interactions ◽

Comparative Morphology ◽

Internal Constraints ◽

Developmental Constraints ◽

Constructional Morphology ◽

Evolutionary Pathways ◽

And Function ◽

New Framework

This part of our course builds on the assumption that evolutionary change, although being stochastic in principle, is channeled by external and internal constraints to such a degree that it becomes quasi-predictable – or at least understandable. On this basis it makes sense to use the old methods of comparative morphology in the new framework of constructional morphology (Seilacher, 1970) in order to recognize patterns and to interpret them as trends and evolutionary pathways. For such an approach, bivalves are particularly suited:1. they deviate little from a common design (for instance they never lost their shell).2. their preservable hard parts adequately reflect the developmental biography of each individual.3. their shell form expresses the compromise between developmental constraints and functional paradigm with little interference from soft part anatomy, physiology and biotic interactions.4. they are diversified enough to provide many examples of parallel adaptations for model testing, particularly if we include the fossil record.

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The life-cycle ofProsorhynchus crucibulum(Rudolphi, 1819) Odhner, 1905, and a comparison of its cercaria with that ofProsorhynchus squamatusOdhner, 1905

Parasitology ◽

10.1017/s0031182000044504 ◽

1973 ◽

Vol 66 (1) ◽

pp. 133-164 ◽

Cited By ~ 40

Author(s):

R. A. Matthews

Keyword(s):

Egg Production ◽

Comparative Morphology ◽

Scophthalmus Maximus ◽

Connective Tissues ◽

Second Intermediate Host ◽

And Function ◽

First Time ◽

Advanced Development ◽

Conger Conger ◽

Host Tissues

The adult ofP. crucibulumis redescribed to form a basis for comparison with the cercaria and metacercaria. Particular emphasis is given to the structure and function of the rhynchus, digestive system and reproductive system. Some features, notably prepharyngeal glands and spematophores, have not previously been recorded in this species.The sporocyst and cercaria which were found inMytilus edulisare described for the first time. Out of 6907 mussels examined from Borth Rocks, Cardigan Bay, 0·26% were infected withP. crucibulumand 0·06 % withP. squamatus. The cercaria of the latter is redescribed on a comparative basis with that ofP. crucibulum, to avoid confusion. The two cercariae are clearly distinguished by three features – flame-cell formula, shape of the excretory vesicle, and structure of the tail stem (this being bilobed inP. crucibulumand trilobed inP. squamatus). The significance of the two types of tail in securing attachment to the second intermediate host is discussed.Metacercariae ofP. crucibulumwere obtained experimentally in ‘O’ group specimens ofScophthalmus maximus. Three other species of fish, namelyLimanda limanda, Onus mustelusandGobius minutuswere also successfully infected. The metacercariae did not develop in the following fish:S. rhombus, Pleuronectes platessa, Cottus bubalisandBlennius pholis. Possible mechanisms which might account for host specificity within Pleuronectidae andScophthalmusare suggested.The development of the metacercaria in the connective tissues and musculature ofS. maximuswas followed over a period of 10 months. Within 1 month of infection the hyaline cyst of parasitic origin breaks down, enabling the parasite to feed directly on the host tissues. This feature is thought to account for the advanced development of the metacercaria, which 1 month after infection could clearly be identified with the adult on the basis of comparative morphology, and at 2 months resembles the adult in every respect except the development of the vitellaria. Egg production only occurs within the intestine ofConger conger, the definitive host.

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Myelinated Nerve Fixation Techniques: Problems and Comparative Morphology

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100158364 ◽

1990 ◽

Vol 48 (3) ◽

pp. 164-165

Author(s):

James E. Van Over ◽

Theresa A. Fassel ◽

Christopher C. Hauser ◽

Hani S. Matloub

Keyword(s):

Femoral Nerve ◽

Comparative Morphology ◽

Nerve Function ◽

Sprague Dawley ◽

Myelinated Nerve ◽

Sprague Dawley Rats ◽

Cacodylate Buffer ◽

Fixation Techniques ◽

And Function ◽

Peripheral Nerve Trauma

The morphology of peripheral nerve trauma is necessary to understand the resulting alterations in nerve function. Specific traumas, such as Vibration Syndrome, directly effect nerve function. Earily changes in myelinated axons closely resemble artifact damage due to preperations for electron microscopy. If the correlation between structure and function in traumatic conditions is to be studied, it is imperative to establish a fixation technique that yields consistently good results. It is also important to characterize fixation artifacts and correlate these changes to traumatic damages.Several techniques were compared in an attempt to illustrate the quality of morphology obtained from each fixation. Femoral nerve was microsurgically harvested from Sprague Dawley rats. The nerve was then cut into 1 mm segments and fixed by a variety of methods. The basic fixation was for 2.5 hr in 2.5% glutaraldehyde (GA), followed by 3 10-minute washes in 0.1 M cacodylate buffer pH 7.2, and 2.5 hr post-fixation in 1.0% OSO4 with an additional three washes in buffer.

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Reproductive Multitasking: The Female Gametophyte

Annual Review of Plant Biology ◽

10.1146/annurev-arplant-081519-035943 ◽

2020 ◽

Vol 71 (1) ◽

pp. 517-546 ◽

Cited By ~ 1

Author(s):

Friederike Hater ◽

Thomas Nakel ◽

Rita Groß-Hardt

Keyword(s):

Pollen Tube ◽

Female Gametophyte ◽

Flowering Plants ◽

Molecular Control ◽

Repair Mechanisms ◽

Plant Hybridization ◽

Evolutionary Success ◽

Underlying Mechanisms ◽

And Function ◽

Functional Megaspore

Fertilization of flowering plants requires the organization of complex tasks, many of which become integrated by the female gametophyte (FG). The FG is a few-celled haploid structure that orchestrates division of labor to coordinate successful interaction with the sperm cells and their transport vehicle, the pollen tube. As reproductive outcome is directly coupled to evolutionary success, the underlying mechanisms are under robust molecular control, including integrity check and repair mechanisms. Here, we review progress on understanding the development and function of the FG, starting with the functional megaspore, which represents the haploid founder cell of the FG. We highlight recent achievements that have greatly advanced our understanding of pollen tube attraction strategies and the mechanisms that regulate plant hybridization and gamete fusion. In addition, we discuss novel insights into plant polyploidization strategies that expand current concepts on the evolution of flowering plants.

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