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PubMed1991

Embryonic development after intra-follicular transfer of horse oocytes.

A technique was developed in which immature horse oocytes, obtained from slaughterhouse specimens, were transferred to the pre-ovulatory follicle of a mare in vivo, with resulting oocyte maturation, ovulation, fertilization and embryo development. Oocytes were collected from all follicles greater than 3 mm, and were classified as immature, maturing, expanded or denuded. The transfers were performed in the standing, tranquilized mare. The ovary containing the pre-ovulatory follicle was grasped per rectum. A trochar and cannula were placed through the abdominal wall in the flank area, ipsilateral to the grasped ovary. For the transfer, the operator introduced a needle through the cannula to puncture the outer wall of the follicle, while adjusting the position of the ovary per rectum. The mares were inseminated the day after transfer. Twenty oocyte transfers were performed. In 1 mare, 15 immature oocytes were transferred to the pre-ovulatory follicle and 12 oocytes with expanded cumuli were recovered from the follicle 24 h later. In 3 of the remaining 19 mares, the follicle filled with blood after the transfer and ovulation did not occur. Sixteen mares ovulated after oocyte transfer. One mare was killed 3 days following ovulation; flush of the removed oviduct yielded 1 embryo, 2 recently ovulated oocytes and 3 degenerating oocytes. A uterine flush for embryo recovery was performed in each of the other 15 ovulating mares, 7-11 days after ovulation. Embryos were recovered in 7 of the 15 flushes, and embryos in excess of the number of ovulations were recovered from 4 mares (2, 3, 4 and 7 embryos).

Animals↗
PubMed2003

Effects of polyvinyl alcohol administered in the diet to rats on fertility, early embryonic development, growth and development.

PVA was administered in the diet to male and female Sprague-Dawley rats (26/sex/group) at doses of 0, 2000, 3500 and 5000 mg/kg/day for two generations. The study design assessed gonadal function, estrous cycle, mating behavior, conception, gestation, parturition, lactation, weaning, and growth and development of F(1) and F(2) offspring. Parental rats were treated for 70 days prior to mating, throughout mating, gestation and lactation until sacrifice. Clinical observations, body weights and feed consumption were recorded routinely. Dietary concentrations were adjusted for each sex on a weekly basis except during gestation and lactation, to provide the intended mg/kg/day PVA levels. Pups were weighed routinely and weaned at 21 days of age prior to selection for the next generation. Unformed stool was noted predominately at the 3500 and 5000 mg/kg/day levels in P(0) and F(1) parental animals. This finding was attributed to the high levels of PVA being fed and subsequently excreted in the stool. Slight decreases in the mean body weights of P(0) males were noted at 2000 and 5000 mg/kg/day. Feed consumption was elevated at the 3500 and 5000 mg/kg/day doses in both generations but not during either lactation period. These increases generally were observed in a dose-related manner (g/kg/day), as a result of the large amount of PVA being consumed to maintain the caloric intake necessary for normal growth. There were no effects of PVA on P(0), F(1) male or female reproductive performance or pup survival, growth, organ weights, and macroscopic or microscopic observations at doses of 2000, 3500 and 5000 mg/kg/day. Therefore the no-observed-effect level (NOAEL) is 5000 mg/kg/day for both parental and offspring in this reproductive study.

Administration, Oral↗
PubMed2001

Induced ovulation, mating success and embryonic development in the stripe-faced dunnart, Sminthopsis macroura.

Induced ovulation resulting in normal embryos is rare in marsupials. In this study natural and induced ovulations were compared in mature Sminthopsis macroura (n = 122). Comparison of maturation of preovulatory oocytes by ovarian histology and examination of oocytes removed from developing follicles in 12 ovaries of 23 animals receiving 0.058 iu equine serum gonadotrophin (eSG) g(-1) with ovaries of 12 animals undergoing natural cycles showed that oocyte maturation was significantly more irregular when it was induced (P < 0.001). Postovulatory stages were examined by estimating the number of eggs ovulated from ovarian histology, and by counting oviduct and uterine contents recovered after ovulation. S. macroura receiving 0.087 iu eSG g(-1) (n = 34), administered as one (n = 17) or two (n = 17) injections, were significantly (P < 0.05) more likely to ovulate (74%), mate (80%) and have conceptuses (66%) than were animals receiving 0.058 iu eSG g(-1) (12, 53 and 0%, respectively) (n = 17), and the values were similar to those in animals (n = 36) undergoing natural cycles (100, 81 and 56%, respectively). Induced ovulation using 0.087 iu eSG g(-1) yielded significantly (P < 0.05) more oocytes per ovary (20.8 +/- 8.5; combined data) than did ovulation in animals undergoing natural cycles (13.7 +/- 3.2) (ANOVA, t test). The responses of animals induced in different phases of the oestrous cycle with 0.087 iu eSG g(-1) were not significantly different (ANOVA) with respect to the number of corpora lutea per ovary, conceptuses per animal or days to ovulation after injection. However, the proportion of females that responded after receiving 0.058 iu eSG g(-1) in the luteal phase was significantly different from that in animals treated with the same dose in the intermediate phase (P < 0.01) and in non-cyclic females treated with 0.058 iu eSG g(-1) (P < 0.02). The main benefits of the treatment were that normal embryos resulted and that 70-78% of non-cyclic animals could be induced to ovulate.

Anestrus↗
PubMed1985

Fucose-containing glycolipids are stage- and region-specific antigens in developing embryonic brain of rodents.

A monoclonal antibody (against 7A antigen), raised against a homogenate of embryonic rat forebrain, marks the distribution of region- and developmental stage-specific cell-surface antigens in the mammalian central nervous system. In the mouse, immunocytochemical staining revealed that 7A antigen is expressed almost exclusively in germinal layers of the cerebral cortex beginning as early as day 11 of gestation and becomes undetectable by birth. The typical staining is seen at embryonic days 13-15, in which only the ventricular and the subventricular zones of the cerebral cortex are intensely labeled, whereas most other areas of the brain are unlabeled. Tissue culture studies indicate that the 7A antigen is localized at the plasma membrane. Molecular species possessing the antigen are identified as neutral glycolipids that contain the X-determinant trisaccharide: (formula; see text) This glycoconjugate is expressed in embryonic brains of many mammalian species (mouse, rat, rabbit, calf, and human) and may be a cell-surface component important in normal development of the central nervous system.

Animals↗
PubMed1993

Two molecules related to the VEGF receptor are expressed in early endothelial cells during avian embryonic development.

We present the partial cloning and the expression patterns of two putative growth factor receptor molecules named Quek1 and Quek2 (for quail endothelial kinase) in chick and quail embryos from gastrulation to embryonic day 9 (E9). Quek1 and Quek2 show high homology to three interrelated murine and human genes, flk-1, KDR and flt. Flt was recently shown to be the receptor for the endothelial cell mitogen vascular endothelial growth factor (VEGF). In situ hybridization of Quek1 and Quek2 to sections of avian embryos showed that they are both expressed essentially by endothelial cells, that we identified with a monoclonal antibody (Mab) QH1 specific for endothelial and white blood cells of the quail. Quek1 is expressed in the mesoderm from the onset of gastrulation, whereas Quek2 message is first detected on QH1-expressing endothelial cells. The expression pattern of Quek1 suggests that it could identify the putative precursor of both endothelial and hematopoietic lineages, the hemangioblast. Quek1 and Quek2 are not expressed in all endothelial cells throughout life. At E9, after the initial phase of vasculogenesis, these genes are switched off in various compartments of the vascular network.

Animals↗
PubMed1991

Embryonic development of choline acetyltransferase in thoracic spinal motor neurons: somatic and autonomic neurons may be derived from a common cellular group.

This investigation focused on the relationship between neurotransmitter phenotype expression and rat motor neuron development, as studied with choline acetyltransferase (ChAT) immunocytochemical techniques. The development of two subclasses of motor neurons, somatic and autonomic efferents, was examined in the upper thoracic spinal cord. ChAT was first detected in a few neurons on embryonic day 12 1/2 (E12 1/2), and in numerous cells located in a single, ventrolaterally located column in the intermediate zone on E13. By E14, this group of ChAT-positive neurons was more intensely immunoreactive, and their axons could be traced to appropriate targets in developing somatic muscle and paravertebral sympathetic ganglia. During the E15-16 period, somatic and autonomic motor neurons separated into two distinct subgroups, with the latter cells being observed to translocate dorsally. By E17, these autonomic motor neurons reached their final positions in the midportion of the intermediate zone. The autonomic motor neurons were observed to extend transverse dendritic bundles across the spinal cord between E15-16, but evidence of the longitudinal bundles of sympathetic preganglionic dendrites was not observed until after birth. A recent study of cholinergic thoracic motor neurons found that both somatic and autonomic cells were generated synchronously during the E11-12 period (Barber et al., Soc Neurosci Abstr 15:588, 1989). In combination with the present results, these data indicate that no more than 1 1/2 days are necessary after motor neuron genesis before a few cells begin to express detectable levels of ChAT, and that no more than 2 days are required before large numbers express this marker of the cholinergic phenotype. Further comparisons of the present findings with those of previous investigations of the development of both somatic and autonomic motor neurons (Dennis et al., Dev Biol 81:266, 1981; Rubin, J Neurosci 5:685, 697, 1985) indicate that these cells contain ChAT at the time their axons are growing toward their respective peripheral targets 1 day before the time when physiological evidence of function is manifest. Furthermore, the present results suggest that both subclasses of motor neurons initially migrate together from the ventricular zone into a single motor column within the ventral intermediate zone, and that the autonomic neurons subsequently translocate dorsally. Thus, autonomic motor neurons appear to be an exception to the generalization that postmitotic neurons migrate directly from the germinal zone to their final positions within the central nervous system.

Animals↗
PubMed2002

Interactions between sterol biosynthesis genes in embryonic development of Arabidopsis.

The sterol biosynthesis pathway of Arabidopsis produces a large set of structurally related phytosterols including sitosterol and campesterol, the latter being the precursor of the brassinosteroids (BRs). While BRs are implicated as phytohormones in post-embryonic growth, the functions of other types of steroid molecules are not clear. Characterization of the fackel (fk) mutants provided the first hint that sterols play a role in plant embryogenesis. FK encodes a sterol C-14 reductase that acts upstream of all known enzymatic steps corresponding to BR biosynthesis mutants. Here we report that genetic screens for fk-like seedling and embryonic phenotypes have identified two additional genes coding for sterol biosynthesis enzymes: CEPHALOPOD (CPH), a C-24 sterol methyl transferase, and HYDRA1 (HYD1), a sterol C-8,7 isomerase. We describe genetic interactions between cph, hyd1 and fk, and studies with 15-azasterol, an inhibitor of sterol C-14 reductase. Our experiments reveal that FK and HYD1 act sequentially, whereas CPH acts independently of these genes to produce essential sterols. Similar experiments indicate that the BR biosynthesis gene DWF1 acts independently of FK, whereas BR receptor gene BRI1 acts downstream of FK to promote post-embryonic growth. We found embryonic patterning defects in cph mutants and describe a GC-MS analysis of cph tissues which suggests that steroid molecules in addition to BRs play critical roles during plant embryogenesis. Taken together, our results imply that the sterol biosynthesis pathway is not a simple linear pathway but a complex network of enzymes that produce essential steroid molecules for plant growth and development.

Amino Acid Sequence↗
PubMed1994

Timetable of in vivo embryonic development in the grey short-tailed opossum (Monodelphis domestica).

The timing of development was examined in 496 embryos from female Monodelphis domestica collected at known time intervals after video recorded mating. Ovulation occurred approximately 20 hr (day 1) after mating, and fertilization was observed by 24 hr. Transport through the oviducts was rapid, and pronuclear stage embryos were recovered from the uterus as early as 24 hr after mating. Second cleavage had occurred by 55 hr after mating. Three-celled embryos were among those collected on day 3 after mating, indicating that asynchronous cleavage of blastomeres can occur from the two-cell stage. The four-cell stage persisted for approximately 24 hr, and embryos that had undergone third cleavage were first recovered 74 hr after mating. Embryos that had undergone fourth to fifth cleavage were found 96-100 hr (4 days) after mating and complete unilaminar blastocysts by 5.5 days after mating. Primary endoderm formed from an already distinct embryonic area of the unilaminar blastocyst early on day 7 after mating. Formation of the bilaminar blastocyst was completed rapidly, on day 7 after mating. The primitive streak appeared on day 10 after mating, and organogenesis rapidly ensued on a timetable similar to that reported for Didelphis virginiana (McCrady, 1938). Close contact with the maternal circulation was established on day 11 and by day 12 maternal and embryonic tissues could not be separated without damage. The length of the gestation period from fertilization to birth was approximately 13.5 days. These observations provide the basis for further embryological cellular and molecular studies of this species as a laboratory model for marsupial development.

Animals↗
PubMed2005

GATA6 is essential for embryonic development of the liver but dispensable for early heart formation.

Several lines of evidence suggest that GATA6 has an integral role in controlling development of the mammalian liver. Unfortunately, this proposal has been impossible to address directly because mouse embryos lacking GATA6 die during gastrulation. Here we show that the early embryonic deficiency associated with GATA6-knockout mice can be overcome by providing GATA6-null embryos with a wild-type extraembryonic endoderm with the use of tetraploid embryo complementation. Analysis of rescued Gata6-/- embryos revealed that, although hepatic specification occurs normally, the specified cells fail to differentiate and the liver bud does not expand. Although GATA6 is expressed in multiple tissues that impact development of the liver, including the heart, septum transversum mesenchyme, and vasculature, all are relatively unaffected by loss of GATA6, which is consistent with a cell-autonomous requirement for GATA6 during hepatogenesis. We also demonstrate that a closely related GATA factor, GATA4, is expressed transiently in the prehepatic endoderm during hepatic specification and then lost during expansion of the hepatic primordium. Our data support the proposal that GATA4 and GATA6 are functionally redundant during hepatic specification but that GATA6 alone is available for liver bud growth and commitment of the endoderm to a hepatic cell fate.

Animals↗
PubMed2006

Promoter of the heat shock testis-specific Hsp70.2/Hst70 gene is active in nervous system during embryonic development of mice.

The Hsp70.2/Hst70 gene is a unique member of the 70 kDa heat shock proteins multigene family whose activity is regulated developmentally; in adult mice and rats its expression is restricted mostly to meiotic and postmeiotic male germ cells. In aim to analyze activity of the Hsp70.2/Hst70 promoter in developing embryos we have constructed transgenic mice expressing EGFP reporter gene under control of the rat Hst70 promoter. The appearance of EGFP fluorescence coincides with series of major developmental events, such as extra-embryonic membranes formation, axial rotation, formation of neural tube and the primordium of central nervous system, formation of differentiated somites, extensive remodeling of the heart, development of fingers and toes, and sensory organs formation. Activity of the Hst70 promoter localizes mostly inside nervous system indicating the role of Hsp70.2/Hst70 gene in development of this system.

Animals↗
PubMed1982

Changes in acetylcholinesterase molecular forms during the embryonic development of Torpedo marmorata.

Multiple molecular forms of acetylcholinesterase from electric organ and electric lobe of Torpedo marmorata were examined at various developmental stages by sucrose density sedimentation. Four major forms were characterized by their apparent sedimentation coefficients of 6 S, 11 S, 13 S, and 17 S. Embryonic lobe possessed at early stages predominantly the 11 S form. With maturation the 17 S form became the most abundant. The early embryonic stages of the electric organ were characterized by predominating amounts of 6 S and 11 S forms. With differentiation of the postsynaptic membrane of the developing electrocytes, 13 S and 17 S forms replaced the slower-sedimenting forms. Concomitant with the formation of synaptic contacts, a transient increase in the 13 S form was followed by a dramatic accumulation of rapid-sedimenting 17 S form. The establishment of fully functional synapses was accompanied by an increase in the amount of the hydrophobic 6 S form. At birth, equal amounts of 6 S and 17 S form were found, with the other forms present in only trace amounts. The observed characteristic changes correlated with morphological and physiological events, indicating a close functional relationship between the accumulation of the 17 S form and synapse formation and the accumulation of the 6 S form and onset of function.

Acetylcholinesterase↗
PubMed1995

Expression of multidrug resistance (mdr) gene(s) in primary lymphoid organs of chicken immune system during embryonic development.

The presence of a multidrug resistance (MDR) related protein, P-170, in normal and pathological lymphoid cells has been described. The present report evaluates the expression of the mdr 1 gene by using the reverse Polymerase Chain Reaction (PCR) on cells obtained from the thymus and bursa of chicken embryos starting from day 12 until hatching. Results show that the thymic cells are positive from day 12 to the end of the observation period. In contrast, mdr mRNA was detected in the bursa from day 14 to day 17 of embryonic life. Possible relationships between the expression of mdr and the development of T and B lymphocytes are discussed.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1987

Changes in the glycosylation pattern during embryonic development of mouse kidney as revealed with lectin conjugates.

Distribution of lectin-binding sites in adult and developing mouse kidney was studied with fluorochrome- and peroxidase-coupled lectins. Effects of fixation methods on lectin-binding patterns were also compared. Un-induced mesenchymal cells and ureter bud of the early metanephros reacted with Concanavalin A, Lens culinaris, Ricinus communis I, and wheat germ agglutinins, whereas binding sites for both soybean and peanut (PNA) agglutinins were seen only in ureter bud tissue. On induction, PNA positivity rapidly appeared in the induced, condensed areas of the metanephrogenic mesenchyme. Early glomeruli expressed heterogeneously terminal galactosyl and N-acetylgalactosaminyl moieties in the podocytes. Later, these sites disappeared and were apparently covered by sialic acids. Endothelia also displayed a comparable sialylation of terminal saccharide moieties during maturation. Binding sites for many of the above lectins were also found in the developing proximal and distal tubules. Terminal fucosyl residues, characteristic of mature proximal tubules, appeared during day 13 of development. Dolichos biflorus agglutinin reactivity, typically seen in the collecting ducts, appeared by day 13. Griffonia simplicifolia-I-B4 isolectin reactivity was exclusively localized to endothelial in adult kidney cortex, but in embryonic kidneys reactivity with collecting duct and podocytes was also seen. These results suggest that the compartmentalized expression of cell glycoconjugates in adult mouse kidney is acquired in a sequential manner during development. Such sequential appearance of the mature glycosylation pattern probably reflects functional maturation of the nephron.

Animals↗
PubMed2005

The pathway to femaleness: current knowledge on embryonic development of the ovary.

Increasing evidence indicates that organogenesis of the ovary is not a passive process arising by default in the absence of the testis pathway. A coordinated interaction is actually in force between somatic cells and female germ cells in embryonic ovaries, thus creating a unique microenvironment that facilitates the formation of follicles. Identification of the functional roles of several novel regulatory elements such as Figalpha, Foxl2, follistatin, and Wnt4 reveals the complexity of early ovarian organization. Challenges await us to establish the molecular connections of these molecules as well as to discover new candidates in the pathway of early ovarian development.

Animals↗
PubMed2002

Fibrinogen stabilizes placental-maternal attachment during embryonic development in the mouse.

In humans, maternal fibrinogen (Fg) is required to support pregnancies by maintaining hemostatic balance and stabilizing uteroplacental attachment at the fibrinoid layer found at the fetal-maternal junction. To examine relationships between low Fg levels and early fetal loss, a genetic model of afibrinogenemia was developed. Pregnant mice homozygous for a deletion of the Fg-gamma chain, which results in a total Fg deficiency state (FG(-/-)), aborted the fetuses at the equivalent gestational stage seen in humans. Results obtained from timed matings of FG(-/-) mice showed that vaginal bleeding was initiated as early as embryonic day (E)6 to 7, a critical stage for maternal-fetal vascular development. The condition of afibrinogenemia retarded embryo-placental development, and consistently led to abortion and maternal death at E9.75. Lack of Fg did not alter the extent or distribution pattern of other putative factors of embryo-placental attachment, including laminin, fibronectin, and Factor XIII, indicating that the presence of fibrin(ogen) is required to confer sufficient stability at the placental-decidual interface. The results of these studies demonstrate that maternal Fg plays a critical role in maintenance of pregnancy in mice, both by supporting proper development of fetal-maternal vascular communication and stabilization of embryo implantation.

Abortion, Spontaneous↗
PubMed1984

Effects of elevated temperatures on the embryonic development and corpus luteum activity in the Japanese long-fingered bat, Miniopterus schreibersii fuliginosus.

Gravid female Japanese long-fingered bats were kept in captivity without hibernation at elevated temperatures (23-25 degrees C) in winter. The embryonic growth rate was accelerated and consequently parturition was advanced by a period equivalent to that of exclusion from hibernation as compared with that in the wild population. The corpus luteum became active, as indicated by an increase in the 'light' lutein cells in an experimental bat pregnant with a 15-mm embryo, but was less active (more 'dark' cells) in 2 hibernating control bats with an implanting blastocyst.

Animals↗
PubMed2001

Optical approaches to embryonic development of neural functions in the brainstem.

The ontogenetic approach to physiological events is a useful strategy for understanding the functional organization/architecture of the vertebrate brainstem. However, conventional electrophysiological techniques are difficult or impossible to employ in the early embryonic central nervous system. Optical techniques using voltage-sensitive dyes have made it possible to monitor neural activities from multiple regions of living systems, and have proven to be a useful tool for analyzing the embryogenetic expression of brainstem neural function. This review describes recent progress in optical studies made on embryonic chick and rat brainstems. Several technical issues concerning optical recording from the embryonic brainstem preparations are discussed, and characteristics of the optical signals evoked by cranial nerve stimulation or occurring spontaneously are described. Special attention is paid to the chronological analyses of embryogenetic expression of brainstem function and to the spatial patterning of the functional organization/architecture of the brainstem nuclei. In addition, optical analyses of glutamate, GABA, and glycine receptor functions during embryogenesis are described in detail for the chick nucleus tractus solitarius. This review also discusses intrinsic optical signals associated with neuronal depolarization. Some emphases are also placed on the physiological properties of embryonic brainstem neurons, which may be of interest from the viewpoint of developmental neurobiology.

Animals↗