جستجوی مقالات مرتبط با کلیدواژه « میکروسپور » در نشریات گروه « زیست شناسی »

Ajowan, belonging to Apiaceae, is one of the most medicinal plants in Iran and is naturally distributed in Ethiopia, Egypt, and India. Despite the homogeneity of flower characteristics in the family, nevertheless, a high diversity of flower morphology can be seen in this genus. Given the pharmacological importance of Ajowan, the developmental stages of its male and female organs were examined.

Flower buds in different developmental stages were harvested, fixed in FAA, and maintained in 70% Ethanol. After performing various steps, including clarification and embedding in paraffin, microtomy sections were made. The Hematoxylin-eosin was used to stain the slices.

Based on the results, the initiation pattern of floral organ development is acropetal, in which the sepals initiate first, followed by petals, and finally, stamens. Initiation of gynoecium occurs with delay to the stamen. Isostemonous stamens, secretory tapetum layer, tetrahedral microspore tetrad, spindle shape microspores, mature pollen with two-celled and three germinal furrows. Asynchrony of microspore development was observed in the anthers of the same plant flowers and the pollen sacs of the same anther. Also, the development of male and female gametophytes was not synchronized in the same flower. Inferior ovary, anatropous ovules, the linear type of megaspore tetrad, polygonum type of functional megaspore formation and embryo sac development are other characteristics of this plant.

In botanical and taxonomical science embryological studies are specially important. In this research, developmental stages of pollen grains and ovules were studied in Salvia verticillata L of Lamiaceae family.The flower and buds in different developmental stages were removed, fixed in FAA, stored in70% ethanol, embedded in paraffin and sliced with a microtome. Staining was done with Hematoxilin and Eosin. The prepared slides from different developmental stages were studied carefully using a light microscope. On the basis of this research results, ovule was anatropous, bitegumic and tenuinucellate. The development of the embryo sac followed the mono-sporic, polygonum type. After the meiosis, megaspore tetrads had linear arrangement. First, embryo sac was very small, so that its nuclei were compressed linearly but in maturation progress, embryo sac sustained longitude growth considerably. The anther was bisporangia. In S. verticillata, the tapetum was plasmodial and secretory with tetra- nucleate and bi-nucleate cells. In species microspore tetrads were observed with tetrahedral and tetragonal arrangement.

Haussknechtia elymaitica Boiss. belongs to Apiaceae family.Considering the importance of recognizing the developmental stages in the development of biology knowledge Haussknechtia elymaitica Which is a rare and endemic species of Iran, was selected for this research. The samples of vegetative and reproductive organs at different stages of development were gathered and investigated by cell-histology methods. The investigation of the anatomical structure of vegetative organs showed that the secretory cavity are arranged between the parenchymal tissues of the leaf. Section of flower buds revealed that anthers had 4 pollen sacs, the division of pollen mother cell was of the simultaneous type, microspore tetrads were of tetragonal type and the tapetum layer was secretory. The ovary was found to be two chambered and two-carpeled; the ovule to be anatropous and to have one membrane. In embryogenic investigationit was found that the embryos were globular, cordate, cotyledonary and torpedo-shaped and the transition between globular embryos to cordate embryos was found. The vegetative organs were observed to have the general structure of dicotyledons. The development patterns of ovule and embryo sac follow the Polygonum type. Tetrahedral, Tetragonal and Liner microspore tetrads were observed. All stages of embryogenesis were covered in this study.

In botanical science developmental and embryological studies are especially important. In this research, developmental stages of pollen grains and ovules were studied in an Origanum genuse, Origanum vulgare. The flower and buds in different developmental stages were removed, fixed in F.A.A, stored in 70% ethanol, embedded in paraffin and sliced with a microtome. Staining was done with Hematoxilin and Eosin. The prepared slided from different developmental stages were studied carefully using a light microscope. The results showed that ovaries were hypogyny type and have four loccules with axile type of placentation. In every locules one ovule, and in embryo sac globular, heart shape, torpedo and cotyledonary embryo were observed. In the anther wall four layers were observed: epiderm, middle layer, mechanical layer and tapetum (from outer to inner layer). In the early stage of pollen development, tapetum was secretory layer then in the late pollen developmental stages becom plasmodium. Tetrads were tetrahedral type. Mature Pollen grains in equatorial view were elongated, elliptic to rectangular-obtuse, and in polar view they were spheroidal, hexahedron-obtuse or hexahedron. The pollen grains were 6-pericolpate that stretches along the equatorial face and narrowing at the poles. The ornamentation of exine surface was reticulate-faveolate. The P/E ratio (Polar axis/Equatorial axis) was 1.13.

Mangifera indica is an evergreen tree belongs to the Anacardiaceae family، in Iran it is found in the Hormozgan and Baluchistan provinces. Till now، no research has been carried out regarding the structural characteristic and development of this species; therefore in the present study structure of vegetative organs and developmental characteristics of reproductive stages was investigated. The vegetative organs were cut and fixed in glycerin and ethanol. The young flowers and buds were sampled at different developmental stages. Samples were fixed in FAA and sliced using a microtome. Staining was carried out with Eosin and Haematoxylin. The primary and secondary structures of root، shoot، petiole، leaf، inflorescence axil and shoot apical meristem showed similarity to dicotyledons. Generative organs contained androecium with 5 stamens which one was reproductive while others were sterile. The anther had 2 parts and 4 pollen sacs. The tapetum layer was secretary type and pollens were three porated. The gynocecium had a carpel with one cameotropous ovule and one tegument. The placentation was of a basal type. The secretary tissues were seen in vegetative organs of the plant. Base on the anatomical findings، we observed a characteristics similarity between this plants and other Angiosperms. With respect to the results of the developmental stages of reproductive organs new information for recognition of this plant was obtained.

In botanical and taxonomical science embryological studies are specially important. In this research, developmental stages of pollen grains and ovules were studied in Centaurea iberica. The flower and buds in different developmental stages were removed, fixed in FAA, stored in 70% ethanol, embedded in paraffin and sliced with a microtome. Staining was done with Hematoxilin and Eosin. The prepared slides from different developmental stages were studied carefully using a light microscope. On the basis of this research results, ovule was anatropous, bitegumic and tenuinucellate. The development of the embryo sac followed the mono-sporic, polygonum type. After the meiosis, megaspore tetrads had linear arrangement. First, embryo sac was very small, so that its nuclei were compressed linearly but in maturation progress, embryo sac sustained longitude growth considerably. The anther was tetra-sporangiate. InC. iberica, the tapetum was plasmodial with bi-nucleate cells. In species microspore tetrads were observed with tetrahedral, tetragonal and linear arrangement. Pollen grains were two-celled and tricolpate.