https://onlinelibrary.wiley.com/doi/10.1002/9781119312994.apr0625
These patterns arise due to exine's assembly into various nano- and microstructures, and due to the absence of exine deposition at certain areas of the pollen surface. The areas that have reduced exine deposition, or lack it completely, are known as pollen apertures, and their patterns are also species specific and highly variable.

https://molgen.osu.edu/sites/default/files/apr0625-Review-final-compressed.pdf
Exine and Aperture Patterns on the Pollen Surface (a) (c) (d) (e) (b) (g) (h) (i) (f) Figure 1 Exines assume beautiful and often dramatically different patterns on pollen surfaces across plant taxa. Confocal images of pollen from species belonging to several plant families. Pollen grains are stained with the fluorescent dye auramine O that

https://www.semanticscholar.org/paper/Exine-and-Aperture-Patterns-on-the-Pollen-Surface:-Wang-Dobritsa/b2a445e3a70520f12c106c0caa70c0fd35ed6fa2
The current state of knowledge about the exine and aperture patterns, their perceived roles in plant reproduction, and the cellular and molecular mechanisms that guide their formation are reviewed. Pollen grains, the male gametophytes of seed plants, surround themselves with a complex pollen wall for protection from various environmental stresses. The deposition and assembly of exine, the

https://www.researchgate.net/publication/328675573_Exine_and_Aperture_Patterns_on_the_Pollen_Surface_Their_Formation_and_Roles_in_Plant_Reproduction
microscopic patterns formed by cell walls of diatoms and skeletons of radiolarians (Anderson, 1983; Sumper, 2002; Gordon et al., 2009). Individuals of the same species usually produce. pollen with

https://www.pnas.org/doi/full/10.1073/pnas.2011084117
The shell of a pollen grain encapsulates the male plant genetic material it carries. It consists of two biopolymeric layers: intine, a soft cellulosic interior layer, and exine, a hard exterior layer composed of sporopollenin and impermeable to water (2, 5, 7).The two layers are not homogeneous throughout the shell, and regions which significantly differ structurally and morphologically from

https://www.pnas.org/doi/pdf/10.1073/pnas.2011084117
When pollen grains become exposed to the environment, they rapidly desiccate. To protect themselves until rehydration, the grains undergo characteristic infolding with the help of special structures in the grain wall—apertures—where the otherwise thick exine shell is absent or reduced in thickness. Recent theoret-

https://www.nature.com/articles/s41477-021-00951-9
Pollen grains of flowering plants are surrounded by a robust wall, called exine. In most species, exine is deposited on the pollen surface non-uniformly, with certain regions of the surface

https://royalsocietypublishing.org/doi/10.1098/rsif.2018.0533
The modulus was determined with atomic force microscopy by using direct nanomechanical mapping of the pollen shell surface. The moduli were atypically high for non-crystalline organic biomaterials, with average values of 16 ± 2.5 GPa (ragweed), 9.5 ± 2.3 GPa (pecan) and 16 ± 4.0 GPa (Kentucky bluegrass). The amorphous pollen exine has a

https://pubmed.ncbi.nlm.nih.gov/31521218/
Certain surface areas receive fewer exine deposits and develop into regions whose structure and morphology differ significantly from the rest of pollen wall. These regions are known as pollen apertures. Across species, pollen apertures can vary in their numbers, positions, and morphology, generating highly diverse patterns.

https://link.springer.com/chapter/10.1007/978-3-7091-9079-1_2
Abstract. The "fundamental" structure, the groundwork of the exine, is a three-dimensional network recoverable from exines of pteridophyte spores and the pollen of gymnosperms and angiosperms following many different degrading methods. It can also be derived from fossil exines and untreated exines during early stages of microspore

https://www.pnas.org/doi/full/10.1073/pnas.0911223107
Harmomegathy is the characteristic folding of pollen grains to accommodate the decrease in cellular volume due to water loss.The partial desiccation of the pollen grain following its release from the anther results in the grain falling into a dormant state that ensures the cellular material survives until the pollen grain reaches the stigma of a flower.

https://www.sciencedirect.com/science/article/pii/S0168945219308210
To protect male reproductive cells and facilitate pollination, developing pollen grains surround themselves with a complex cell wall. The outer pollen wall, called exine, commonly consists of two layers, the outer sexine and the inner nexine [36].In most seed plant species, exine is deposited on the pollen surface non-uniformly, with certain surface areas developing into pollen apertures.

https://nph.onlinelibrary.wiley.com/doi/10.1111/j.1469-8137.2007.02060.x
They proposed that 'exine pattern is generated by the ... (1988) demonstrated that the large spines, so characteristic of mature pollen grains, are lacking in microspores ... We now have some persuasive models of how self-assembly might generate the vast array of complex nano-scale features encountered in pollen grains. The exciting

https://link.springer.com/chapter/10.1007/978-3-642-41787-0_6
The pollen wall comprises the outer exine and the inner intine layers. It plays important roles in protecting pollen from various environmental stresses including microbial attack and in cell-cell recognition during pollination. The exine is further divided into a sexine and a nexine layer. The material for the exine is provided directly by the

https://www.nature.com/articles/s41598-021-87619-8
In monocot species the exine usually has ... while applying strong bases affected the main features of the exine structure ... E. et al. Foldable structures and the natural design of pollen grains.

https://www.sciencedirect.com/science/article/pii/S0092867419300479
The geometric diversity of pollen grain surface patterns has intrigued scientists for decades. The developmental processes of these cell walls are nearly identical between taxa, and self-assembly may be a mechanism for pattern formation (Hemsley and Gabarayeva, 2007, Gabarayeva and Grigorjeva, 2016); however, no unifying physical theory has emerged to explain the mechanism underlying the

https://www.cambridge.org/core/books/molecular-and-cellular-aspects-of-plant-reproduction/pollen-exine-the-sporopollenin-enigma-and-the-physics-of-pattern/6611A571AD6E295DDAEE50917F2B4FDB
Pollen exine - the sporopollenin enigma and the physics of pattern ... plants inherent in the usually brief life-cycle of the male spore has driven the assembly of various adaptive features that endow its protective capsule with remarkable properties. ... for example, the pollen wall of many species has become modified to carry specific self

https://www.biologydiscussion.com/palynology/morphological-characteristics-of-pollen-grains/64545
Bilateral isopolar grains have three planes of symmetry, one horizontal and two vertical. In some bean- shaped or boat-shaped spore/pollen there is only one vertical plane of symmetry with an opening towards the end of the grain. Characteristic # 4. Shape: The shape of the pollen grains varies from species to species.

https://www.sciencedirect.com/science/article/pii/S0176161721000274
1. Introduction. Pollen development is a complex process that mainly includes the division and differentiation of anther primordial cells, the meiosis of microsporocytes, the formation of the pollen wall, and the release of pollen grains (Wilson and Zhang, 2009; Hesse et al., 2016).Among these steps, the formation of the pollen wall is an important event in the process of pollen development.

http://www.botany.unibe.ch/paleo/pollen_e/surface.htm
THE SURFACE OF MICROSPORES. Within the pollen-morphological main groups or classes the differences in the structure und sculpturing of the exine of pollen grains are important characteristics for identification. The inner structure of the exine can be either tectate or intectate. The sculpturing of the pollen grain is the ornamentation of the exine surface which can be psilate, foveolate

https://link.springer.com/content/pdf/10.1007/978-3-319-06511-3_4.pdf
Although the morphology of pollen grains varies among different species, the pollen wall structure is mainly consisted of layers such as intine, exine, and pollen coat, from the inside to the outside. Exine generally contains nexine, bacula, and tectum (Fig. 1c-f) (Zhang et al. 2011). Arabidopsis exine has a thin nexine layer, a

https://cales.arizona.edu/spls/content/pattern-formation-pollen-surface-case-aperatures
Across species, pollen apertures often differ in shape, number, and positions, but within a species aperture patterns are usually the same. This suggests that, in a given species, developing pollen can consistently mark some of its surface regions as different from the rest of the surface, so that only certain areas will develop into apertures.

https://www.nature.com/articles/220389a0
Abstract. THE chief purpose of Mepham and Lane in their recent article 1 seems to be to establish that the exine of the pollen grain is formed by secretion from within the microspore and owes