Primary Sporogenous Cell Research Articles

Embryology of Iris sanguinea Donn ex Horn. and its systematic relationship

Iris sangumea Dorm ex Horn. is a perennial cold-tolerant herbs of the Iris genus of Iridaceae, which has a well-formed, bright color and adaptability. Through understanding the flower bud differentiation, Sporogenesis, gametogenesis, fertilization and embryogenesis of I. sangumea, we developed flowering regulation and control breeding. I. sangumea flower bud differentiation was observed in April for 21 days; in this stage, the early differentiation process was slow, temperature was more than 5 °C, if the temperature is shorter than this, most flower bud will have no differentiation, and turn to vegetative growth; later differentiation is faster and required temperature is from 5 to 8 °C and gradually rose to 10‒12 °C. The temperature in April plays the definitely role in the number of bud differentiation. Three stamina contain tetrasporangiate anthers and a glandular tapetum. The anther wall is composed of four cell layers inclduding the epidermis, the endothecium, one middle layer and the secretory tapetum. The type of anther wall development the dicotyledonous type. After pollen maturation, the anther wall forms a double-layer containing only epidermis and endothecium. Simultaneous cytokinesis is of the continuous type during meiosis of microspore mother cell results in a zygomorphous or tetragonal tetrad. Mature pollen grains are two-celled. I. sangumea’s stylar canal is hollow, open type style, and the gynoecium has three carpels. The ovaries have axial placentas. The ovule is anatropous, bitegmic and crassinucellate. The primary sporogenous cell differentiates directly as the megaspore. The megaspore tetrads are linear, T-shaped or juxtaposed. Generally, the first of the tetrad megaspores at the chalaza becomes functional while the other three degenerate. A mature embryo sac with seven cells and eight nuclei embryo sac is of the polygonum type. For dichogamy, the male gametophyte matures about 2 days earlier than the female gametophyte. The pollen tube entered into the embryo sac for 22–24 h after pollination. The dormancy stage of fertilized ovules is 5‒6 days, and the fusion of sperm and egg nucleus is of the premitotic type. The primary endosperm cell has shorter dormancy of 4‒6 days, and endosperm formation is of the nuclear type.

Ontogenetic characterization of sporangium and spore of Huperzia serrata: an anti-aging disease fern

Background Huperzia serrata is a medicinal plant used in Traditional Chinese Medicine, which has been used to prevent against aging diseases. It is mainly propagated by spores and grows extremely slowly. Due to severe harvest, it is a highly endangered species. In this report, we characterize ontogenesis of sporangia and spores that are associated with propagation. A wild population of H. serrata plants is localized in western Hunan province, China and protected by Chinese Government to study its development (e.g. sporangia and spores) and ecology. Both field and microscopic observations were conducted for a few of years.ResultsThe development of sporangia from their initiation to maturation took nearly 1 year. Microscopic observations showed that the sporangial walls were developed from epidermal cells via initiation, cell division, and maturation. The structure of the mature sporangial wall is composed of one layer of epidermis, two middle layers of cells, and one layer of tapetum. Therefore, the sporangium is the eusporangium type. Spore development is characterized into six stages, initiation from epidermal cell and formation of sporogenous cells, primary sporogenous cell, secondary sporogenous cell, spore mother cell, tetrad, and maturation.ConclusionThe sporangial development of H. serrata belongs to the eusporangium type. The development takes approximately 1 year period from the initiation to the maturation. These data are useful for improving propagation of this medicinal plant in the future.

Embryology of Iris mandshurica Maxim. (Iridaceae) and its systematic relationships

Sporogenesis, gametogenesis, fertilization and embryogenesis of Iris mandshurica Maxim. were observed using the normal paraffin method. The results are as follows: the development of the anther wall following the dicotyledonous type consisting of four layers, the epidermis, the endothecium, one middle layer and the secretory tapetum. Fibrous thickenings develop in the endothecium when the anther is shed. Simultaneous cytokinesis during microsporogenesis results in a tetrahedral tetrad of microspores. Mature pollen grains are two-celled. The ovary is inferior and trilocular with axial placenta. The ovule is anatropous, bitegminous and crassinucellate. The archesporial cell below the nucellar epidermis undergoes periclinal division producing the primary parietal cell and the primary sporogenous cell. The primary parietal cell participates in the nucellar formation; the primary sporogenous cell differentiates directly as the megasporocyte. Successive cytokinesis in the megasporocyte usually produces the linear tetrad, and the chalazal megaspore of the tetrad develops into a Polygonum-type embryo sac. The fertilization mode is porogamy. The pollen tube enters into the embryo sac and discharges two sperm 16–20 h after pollination. The fertilization is the postmitotic type of syngamy. The first division of the zygote is transversal. Endosperm formation is of the nuclear type. The systematic significance of the embryological characters of I. mandshurica is discussed.

Mrnas and a cloned histone gene are differentially expressed during anther and pollen development in rice (Oryza sativa L.)

Spatial and temporal changes in the distribution of mRNA sequences during anther and pollen development in rice (Oryza sativa) were investigated by in situ hybridization with [3H]polyuridylic acid ([3H]poly(U)) and a cloned rice histone gene probe. Annealing of sections with [3H]poly(U) showed that poly(A)-containing RNA (poly(A)+RNA) was uniformly distributed in the cells of the anther primordium. During the formation of the archesporial initial, the primary parietal cell, the primary sporogenous cell and tapetum, there was no differential accumulation of poly(A)+RNA in their progenitor cells. Preparatory to meiosis, there was a sharp decrease in poly(A)+RNA concentration in the epidermis and middle layer of the anther wall, although the label persisted in the endothecium, tapetum and microsporocytes. Poly(A)+RNA concentration decreased in these cell types during meiosis and attained very low levels in the disintegrating tapetum and the persistent endothecium of the post-meiotic anther. Pollen development was characterized by the absence of [3H]poly(U) binding sites in the uninucleate microspores and by their presence in the vegetative and generative cells of the bicellular pollen grain. In anther sections hybridized with [3H]histone probe, gene expression was only detected in the endothecium of the premeiotic anther and in the bicellular pollen grains.

Ovule development in Brassica campestris: a light microscope study

A light microscope study was made of ovule development in Brassica catnpestris L. cv. Candle (canola, rapeseed), from the initiation of the ovule to the mature megagametophyte. The ovule is bitegmic and campylotropous and exhibits the Polygonum-type of megagametophyte development. The inner integument is dermal in origin from a series of wedge-shaped initials. The outer integument is derived from both dermal and subdermal initials that originate proximal to the inner integument. The megasporocyte arises from an archesporial or primary sporogenous cell. The products of meiosis are a triad or tetrad of megaspores. Expansion of the megagametophyte is micropylar and coincides with the formation of a large central vacuole. The mature binucleate central cell is devoid of the large central vacuole characteristic of the coenocytic and early cellular stages of megagametophyte development. The cell walls of the mature egg apparatus and antipodals are periodic acid – Schiff positive. The antipodals, unlike the cells of the egg apparatus, do not increase in size following their formation.

EMBRYOLOGICAL STUDIES IN THE FAMILY SAXIFRAGACEAE (S.L.). I. DEVELOPMENT OF THE OVULE AND EMBRYO SAC IN SAXIFRAGA FORTUNEI VAR. PARTITA (MAKINO) NAKAI

The development of the ovule, megaspore and megagametophyte in Saxifraga fortunei var. partita (Makino) Nakai was observed. The ovule is anatropous, bitegmic, and crassinucellate. Both integuments originate from the epidermis. The archesporium is considered to be multicellular. The primary sporogenous cell functions as the megaspore mother cell which forms a T‐shaped tetrad. The chalazal member of the megaspore tetrad is functional and develops into a Polygonum‐type embryo sac. In the pyriform synergids the filiform apparatus is observed, but any hook or indentations could not be recognized. The antipodal cells are detectable until the Helobial endosperm undergoes several nuclear divisions. Secondary multiplication of the nuclei or the cells of the antipodals could not be observed.

A COMPARATIVE STUDY OF OVULE AND MEGAGAMETOPHYTE DEVELOPMENT IN FIELD‐GROWN AND GREENHOUSE‐GROWN PLANTS OF GLYCINE MAX AND PHASEOLUS AUREUS (PAPILIONACEAE)

A study of ovule and megagametophyte development in field‐ and greenhouse‐grown plants of Glycine max (L.) Merrill and Phaseolus aureus Roxb. reveals several consistent features for both species. These features include: a multiple archesporium, enlargement of a primary sporogenous cell directly into a megasporocyte, production of unequal dyad cells, a functional chalazal megaspore, Polygonum‐type development, and a hypostase. A filiform apparatus was not observed in either species. Several marked differences in development also occur. Phaseolus usually produces one sporogenous cell per ovule; Glycine produces 2–3 sporogenous cells per ovule. Meiosis II is synchronous in Phaseolus but nonsynchronous in Glycine. Linear tetrads are produced in Phaseolus, whereas linear and T‐shaped tetrads are found in Glycine. Starch grains accumulate in the mature megagametophyte of Glycine but are absent at that stage in Phaseolus. The usefulness of the modified clearing fluid, benzyl benzoate‐4½, for the study of ovule and megagametophyte development in Glycine max and Phaseolus aureus is here demonstrated. In addition, the study indicates for both species that megagametophyte development in plants grown under field conditions is markedly similar to development in plants grown in the more uniform conditions of the greenhouse. Accordingly, these findings suggest generally that embryological data collected from plants grown under greenhouse conditions will reflect those from plants found in nature.

A Comparative Study of Ovule and Megagametophyte Development in Field-Grown and Greenhouse-Grown Plants of Glycine Max and Phaseolus aureus (Papilionaceae)

A study of ovule and megagametophyte development in field- and greenhouse-grown plants of Glycine max (L.) Merrill and Phaseolus aureus Roxb. reveals several consistent features for both species. These features include: a multiple archesporium, enlargement of a primary sporogenous cell directly into a megasporocyte, production of unequal dyad cells, a functional chalazal megaspore, Polygonum-type development, and a hypostase. A filiform apparatus was not observed in either species. Several marked differences in development also occur. Phaseolus usually produces one sporogenous cell per ovule; Glycine produces 2–3 sporogenous cells per ovule. Meiosis II is synchronous in Phaseolus but nonsynchronous in Glycine. Linear tetrads are produced in Phaseolus, whereas linear and T-shaped tetrads are found in Glycine. Starch grains accumulate in the mature megagametophyte of Glycine but are absent at that stage in Phaseolus. The usefulness of the modified clearing fluid, benzyl benzoate-4½, for the study of ovule and megagametophyte development in Glycine max and Phaseolus aureus is here demonstrated. In addition, the study indicates for both species that megagametophyte development in plants grown under field conditions is markedly similar to development in plants grown in the more uniform conditions of the greenhouse. Accordingly, these findings suggest generally that embryological data collected from plants grown under greenhouse conditions will reflect those from plants found in nature.

COMPARATIVE MEGASPOROGENESIS IN PAPILIONACEAE

Megasporogenesis in 16 species of Papilionaceae has been investigated. Archesporial development in Papilionaceae is usually hypodermal, but subhypodermal origin has been observed. The archesporial cell develops directly into the megasporocyte, or divides to produce a parietal cell and a primary sporogenous cell. The parietal cell is always oriented toward the micropylar end of the developing ovule. It may or may not divide to contribute to the nucellar mass as the primary sporogenous cell enlarges to form the megasporocyte. A single megasporocyte is produced in most species investigated. Of those species that form more than one megasporocyte, few develop more than one tetrad of megaspores, and in no case is more than one megagametophyte produced. Meiosis occurs in the megasporocyte to form a tetrad of megaspores. Several variations in tetrad patterns are explored here. Monosporic development is the prevalent condition in Papilionaceae; however, bisporic development does occur.

Comparative Megasporogenesis in Caesalpiniaceae

This investigation concerns four species: Cercis canadensis L., Cassia abbreviata Oliv. var. granitica, Cassia nictitans L., and Gleditsia triacanthos L. In Cercis canadensis the archesporium is subhypodermal and may consist of one or two cells. A single hypodermal archesporial cell develops in the other three species. The hypodermal archesporial cell in the Cassia species and in G. triacanthos divides periclinally to form a parietal cell and a primary sporogenous cell. Derivatives of the parietal cell contribute to the nucellar mass as the sporogenous cell enlarges to form the megasporocyte. In Cercis canadensis the megasporocyte is formed by direct enlargement of the archesporial cell. Meiosis occurs in all species to form a tetrad of megaspores. Frequently the micropylar dyad member in Cassia nictitans fails to undergo the second meiotic division. While only the chalazal megaspore functions in megagametogenesis, there is a tendency for the third megaspore to persist in all species. On one occasion two linear tetrads were observed in an ovule of G. triacanthos.

Developmental Morphology of the Megasporangium and Embryogeny in Ipomoea reptans Poir. and Related Species

In Ipomoea reptans Poir. the development of the megasporangium involves the appearance of a parietal tissue intervening between the nucellar protoderm and the primary sporogenous cell, the latter functioning directly as the megaspore mother cell. Following meiosis, the chalazal megaspore develops into a female gametophyte containing three cells in the egg apparatus, a single antipodal cell, and two polar nuclei. The development of the megasporangium is thus monosporic, its later stages being a deviation from the typical Polygonum type. The ensuing embryogeny is a variation of the Solanad type. The present paper gives a comprehensive review of literature presented by previous investigators who worked on other species in the Convolvulaceae. It is conclusively found that the development of the parietal tissue, the female gametophyte, and the embryo varies considerably among members of this family. Inconsistencies occur even among the different species of the same genus. The developmental patterns of these structures, therefore, are of little use in determining the phylogenetic relationships of plants in the Convolvulaceae.

The development of the ovule and megagametophyte in Rhexia mariana

The ovules of Rhexia mariana are bitegmic and anatropous or rarely atropous. Periclinal divisions in the nucellar epidermis at the micropylar end produces a nucellar cap. A terminal pore in the nucellus is formed by the suppression of anticlinal divisions in the epidermis and subsequent separation of the cells during nucellar enlargement. A single hypodermal archesporium divides, producing a primary parietal cell and primary sporogenous cell. The primary parietal cell establishes a prominent parietal tissue as the primary sporogenous cell differentiates into the megasporocyte. Two prominent nucleoli that consistently appear in the archesporium persist in the primary sporogenous cell and the megasporocyte. Meiosis produces a tetrad of megaspores in either linear or approximately T-shaped arrangement. Cells of the nucellus adjacent to the sporogenous cell, megasporocyte, and tetrad rarely give rise to megagametophytes aposporically. The chalazal megaspore functions in megagametogenesis. Shortly after the first nuclear division, vacuoles migrate and coalesce between the nuclei. Two more nuclear divisions establish the four- and eight-nucleate megagametophytes. The chalazal nuclei are situated laterally and are noticeably smaller than the micropylar nuclei in both four- and eight-nucleate stages. The two polar nuclei remain in close contact, usually near the egg apparatus, but sometimes near the center of the megagametophyte. The three antipodal nuclei are ephemeral with degeneration completed by the time the egg apparatus is established. Orientation of the egg apparatus places the synergids on the side of the megagametophyte adjacent to the funiculus and the egg cell on the opposite side. The similarities and differences in ovule and megagametophyte development between Rhexia mariana and the tropical representatives of Melastomataceae previously investigated are discussed.

Development of the Ovule and Megagametophyte in Wisteria sinensis

Eight campylotropous ovules initiate development from primordia on the placental ridge in the ovary of Wisteria sinensis Sweet. Integumentary primordia arise from the nucellar mass, and the ovules arch toward the stylar region of the ovary. Usually a hypodermal archesporial cell gives rise to a primary sporogenous cell which enlarges to form the megasporocyte. Subsequent meiotic divisions show that monosporic or bisporic megagametogenesis can occur. Three antipodals organize in the chalazal region but rapidly disintegrate. The synergids form in the micropylar egion of the embryo sac and undergo dissolution before fertilization, leaving the egg cell and fused polar nuclei present at fertilization. The ovule at maturity has a micropylar canal which consists of an exostome, a mesostome, and an endostome.

Studies on Morphology and Affinity of the Parkeriaceae. II. Sporogenesis, Development of the Gametophyte, and Cytology of Ceratopteris thalictroides

1. The development and structure of sporangium and gametophyte in Ceratopteris thalictroides (L.) Ad. Brongn. have been described, as well as observations on morphology of the somatic chromosomes and meiotic behavior. 2. Sporangial development agrees with that in the higher ferns. The sporangial initial divides obliquely; the outer initial produces four capsular segments in cyclic order, and then the inner cell gives rise to four tapetal initials in the same sequence. The primary sporogenous cell undergoes successive divisions to produce eight spore mother ceils, while the tapetal initials give rise to eighty tapetal cells in two layers, the inner layer containing sixty-four, the outer sixteen cells. 3. Development of the gametophyte is regular and normal and that of the antheridium and archegonium follows the sequence usual in leptosporangiate ferns except that the formation of the primary cover cell of the archegonium is belated. The gametophyte is devoid of an apical cell and hairs, is normally thin an...

MEGASPOROGENESIS AND DEVELOPMENT OF MEGAGAMETOPHYTE IN ULMUS

MEGASPOROGENESIS AND DEVELOPMENT OF MEGAGAMETOPHYTE IN ULMUS

Morphological and Cytological Studies on Carica papaya

1. In Carica papaya the primary sporogenous cell appears within the young ovule as the integuments are beginning to differentiate. One or two layers of parietal tissue are present. 2. The megaspore mother cell is formed simultaneous with the development of the two integuments. 3. Through two meiotic divisions the megaspore mother cell produces an axial row of four megaspores, the chalazal one of which develops into a normal seven-celled, eight-nucleate megagametophyte; the other three megaspores disintegrate. The haploid number of chromosomes is nine. 4. The mature megagametophyte is minute compared with the massive integuments and nucellus. The egg cell enlarges as the megagametophyte grows, and a filiform apparatus develops late in the differentiation of the synergids. The antipodal cells disintegrate almost immediately after their formation. 5. Under greenhouse conditions pollen tubes enter the ovules about 10 days after pollination. Fertilization occurs approximately 13-15 days after pollination. Zygotes persist for about 5-8 days before they divide. Divisions occur irregularly in the young embryos. There is a definite lag in the embryo development of this species, while endosperm development is very rapid, as is differentiation of the seed coat. 6. The large massive pollen tube persists within the embryo sac up to at least 64 days after pollination. The fact that it is closely pressed against the many-celled embryo may suggest a nutritive relationship between it and the young developing embryo. 7. At approximately 79 days after pollination the endosperm shows a transition from the free-nuclear state to a cellular condition, beginning at the micropylar end of the sac. Mature endosperm contains an abundance of oil and aleurone grains, but starch is absent. 8. The seed coat is derived chiefly from the outer integument of the ovule, which grows considerably to form the firm compact endotesta and a transparent gelatinous sarcotesta. 9. The vascular bundle in a more mature ovule extends from the funiculus along the outer integument into the inner integument at the chalazal end of the ovule, where it branches widely to form an umbrella-like structure. 10. Modified elongated nucellar cells at the chalazal end of the ovule, located relatively close to the endosperm and also to the vascular tissue, may play an essential role in some nutritive relationship existing between the entering food supply and the endosperm. 11. Only a very small percentage of the ovules in a given pistil produce embryos, even though endosperm and pollen tubes are present. However, an ovule may grow and develop to a certain extent after pollination, even though fertilization does not occur.

Morphological Study of Agave lechuguilla

1. Origin of the floral organs of Agave lechuguilla is acropetal, sepals appearing first and carpels last. 2. The flower is epigynous. Its vascular anatomy is simple, being a direct divergence of vascular bundles into the separate organs. All vascular bundles ending in either sepal or petal structures are derived from bundles differentiated early in connection with these floral parts. 3. The ovule is anatropous and has two integuments. Placentation is axial. 4. Megasporogenesis starts with differentiation of a single hypodermal archesporial cell and ends with formation of a tetrad of megaspores arranged usually in linear fashion. Two variations in megaspore arrangement were noted. 5. Periclinal division of the archesporial cell gives rise to a primary parietal cell and to a single primary sporogenous cell which enlarges and becomes the megaspore mother cell. Development of the megagametophyte follows the so-called normal type. 6. A single parietal layer is present in the ovule, disintegrating when the megagametophyte enlarges. 7. The vascular tissue of the ovule does not stop at the base of the chalaza but tracheids penetrate the nucellus to the megagametophyte. 8. Anther development follows the common method. The archesporium consists of a group of cells. Periclinal divisions give rise to the primary parietal and primary sporogenous cells. Continued periclinal and anticlinal divisions of the primary parietal cells form the wall tissue. The sporogenous cells enlarge and function as microspore mother cells. There are two successive divisions of the microspore mother cells, resulting in four microspores. 9. The tapetum is derived from the innermost layer of the parietal tissue. 10. The mature anther shows well-defined endothecia three or four cells in thickness and disintegration of the stomium.

Cytological Investigations of Pisum sativum

1. Each theca of the anther of Pisum sativum contains many microspore mother cells. 2. Cell plates are formed on the cytoplasmic strands midway between the nuclei of the tetrad. 3. The microspore cell divides to form a two-celled pollen grain. 4. The tube nucleus disintegrates before germination of the pollen grain. 5. The generative cell divides within the pollen tube to form two male gamete cells. 6. Each ovule usually contains one primary sporogenous cell; two or three cells have been observed in some instances. 7. An apical hypodermal archesporial cell divides to form a primary sporogenous cell and a primary parietal cell. 8. The primary sporogenous cells function as megaspore mother cells. 9. Usually four megaspores are formed as a result of the meiotic divisions. 10. The chalazal megaspore develops into an eight-nucleate, seven-celled megagametophyte; the other megaspores disintegrate. 11. One megagametophyte is usually found in an ovule; occasionally two are present. 12. The mature ovule is half an...

Macrosporogenesis and Embryology of Melilotus

1. In Melilotus a single apical hypodermal cell is differentiated in the young ovule as an archesporial cell. This cell divides to form a primary parietal and a primary sporogenous cell. 2. The primary sporogenous cell functions as the macrospore mother cell in M. officinalis and in the Redfield Yellow variety of sweet clover. A number of sporogenous cells (1-3) are usually formed in M. alba, but only one of them undergoes further development. 3. In consequence of two divisions, the macrospore mother cell produces a row of four macrospores, the chalazal one of which develops into a 7-celled embryo sac of the usual type; the other three macrospores disintegrate. 4. The micropylar end of the nucellus breaks down and the embryo sac elongates greatly, the basal portion becoming deeply imbedded in the nucellus and the apical portion extending so as to lie in direct contact with the inner integument. 5. The polar nuclei fuse and the fusion nucleus comes to lie just basal to the egg apparatus. 6. The antipodal cells disintegrate just prior to fertilization. 7. The apices of the synergids elongate and a distinct filiform apparatus is produced. 8. The pollen tube enters the embryo sac between the synergids and the egg, and the synergids are rarely broken down in consequence of fertilization but persist for some time thereafter. 9. Fertilization occurs under greenhouse conditions between 18 and 21 hours after pollination. 10. The zygote, by transverse divisions, forms a filament of three or four cells. The terminal cell of this filament forms the embryo. The basal cells by further divisions form a multicellular suspensor. 11. The primary endosperm nucleus divides before the zygote, and there are usually four or more free nuclei in the embryo sac at the time of division of the zygote. 12. Cell division in the endosperm begins in the region of the suspensor at about the time the embryo has reached the 16-celled stage. 13. The endosperm is entirely absorbed by the time the embryo is mature. 14. Remnants of the suspensor are still present after the absorption of the endosperm. 15. The haploid number of chromosomes is 8. Melilotus alba and Redfield Yellow each have one pair of satellite chromosomes.

Physiological Importance of Calcium in Legume Inoculation

1. The origin of the large solitary sporangium is marginal. 2. The sporangium wall and tapetum arise from segments cut from a dolabrate apical cell. 3. The primary sporogenous cell by three successive divisions gives rise to sixteen spore mother cells. 4. Subsequent to the formation of the spore mother cells and the tapetal plasmodium there is rapid increase in the sporogenous mass. 5. A striking feature is the formation of multinucleate spore mother cells, which is not uncommon. 6. Two features render additional support to the relationship of Schizaeaceae to Marsileaceae proposed by Campbell and supported by Bower: (a) The spore output of S. rupestris has advanced to 64 per sporangium as compared with the prevailing number of 128 in most species. This reduction in spore output has reached the upper limit of Pilularia (64-32). (b) Multinucleate spore mother cells resulting from a failure of wall formation following nuclear division is a step toward the heterosporous condition of the Marsileaceae.