Dense core vesicles during photoreceptor development

Summary The presence of dense core vesicles in the terminal expansions of photoreceptors in development is decribed in the chick embryo retina, from the 16th to the 18th day of incubation.Acknowledgment. J.M.G.-G. was supported by a grant from the Comision Asesora de Investigacion Cientifica y Tecnica, Madrid, Spain.     

Sexual differences in the development of plasma thyroxine levels in the embryo and young chick]

Plasma thyroxine (T4) levels were separately ascertained in male and female embryo and young chicken from the 12th day of incubation till the 4th day after hatching by the thyroxine binding globulin technique. In both sexes, plasma T4 reach a peak the 20th day of incubation, but values are significantly higher in females. A sharp decrease occurred thereafter, plasma T4 tending toward adult values the 4th day after hatching.     

Development and use of shell-less quail chorio-allantoic-membrane cultures to study developing skeletal tissues; a qualitative study

Summary A technique is described for in vitro culture of the quail embryo from the 1st to the 18th day of development. The embryos are cultured in Teflon hammocks, suspended in glass supports and kept in a humidified atmosphere at 36.5°C. The quail CAM is used as support and cell source for developing non-quail cartilage and bone. The quail cells can be identified histologically and easily recognized by Feulgen-staining which is demonstrated in the presence of quail chondro- or osteoclasts in a mouse long bone rudiment cultured on the CAM.     

Development and use of shell-less quail chorio-allantoic-membrane cultures to study developing skeletal tissues; a qualitative study

A technique is described for in vitro culture of the quail embryo from the 1st to the 18th day of development. The embryos are cultured in Teflon hammocks, suspended in glass supports and kept in a humidified atmosphere at 36.5 degrees C. The quail CAM is used as support and cell source for developing non-quail cartilage and bone. The quail cells can be identified histologically and easily recognized by Feulgen-staining which is demonstrated in the presence of quail chondro- or osteoclasts in a mouse long bone rudiment cultured on the CAM.     

Serotoninergic innervation of the paraventricular organ in chick embryo and chick; histofluorescence and autoradiography study optic and electron microscopy]

Fluorescence microscopy (Falck and Hillarp technique) of 11th day old chick embryo shows aminergic neurons and processes in the paraventricular organ area. Administration of tritiated amines permits us to observe uptake and storage of serotonin only as early as the 10th day; this suggests a very early hypothalamic serotoninergic nervous system differentiation.     

Demonstration of a basal lamina in cocultures of thyroid cells and embryonal swine skin cells]

Porcine thyroid and embryo skin cells were isolated and cultured. Cultures from each kind of cells, as well as cocultures were fixed twice a week for electron microscopy. On day 8th a basal lamina like material appears only in the cocultures, along the basal plasmalemma of the reassociated thyroid cells. This amorphous material increases up to day 17th.     

Befunde aus der Frühentwicklung des Rattenkeimes als Beitrag zur Rhythmik der Entwicklung

Summary On the fourth day of development of the rat embryo all of the stages are found from the two-cell stage to the blastocele stage even among embryos from the same litter. On the seventh day, they all show egg-cylinder stages without exception. The time interval between cleavages from the second to the sixth day of development is not constant and, in fact, varies over a wide range, even among embryos from the same litter.     

Agmatine iminohydrolase activity during development and germination of groundnut seeds

Summary During the development of groundnut seeds agmatine iminohydrolase activity increased in the cotyledons but remained constant in the embryo. In seeds stored for 1 year, decreased activity of the enzyme was found in both cotyledons and embryo. During germination, the enzyme activity increased in the cotyledons, but in the embryo it increased up to day 3 and then decreased to the initial level.Acknowledgments. This work was supported by grants from the University Grants Commission under the DSA programme. We thank Dr S.K. Srivastava for his helpful suggestions and giving us access to his facilities.     

Effects of retinoic acid on embryonic development of mice in culture

The effects of all-trans-retinoic acid (RA) (tretinoin) on the craniofacial development of mouse embryos were examined using whole embryo culture. In day 8 embryos cultured for 48 h, embryonic growth was inhibited concentration-dependently by all-trans-RA treatment. Most of the treated embryos exhibited hypoplasia of the primary palatal processes and a reduction in the development of the first visceral arches. In day 10 embryos cultured for 48 h, although embryonic growth was not inhibited at any concentrations of all-trans-RA, median cleft lip (93%), hypoplasia of the primary palatal processes (37%) and limb reduction deformities (48%) occurred commonly. Furthermore, RA treatment greatly reduced the size of the secondary palatal processes. The incorporation of 3H-thymidine in the treated maxillary processes was decreased to 65% of the control value at 1.0 x 10(-7) M all-trans-RA. These findings indicate that all-trans-RA is teratogenic in mouse whole embryo culture.     

Effects of retinoic acid on embryonic development of mice in culture

Summary The effects of all-trans-retinoic acid (RA) (tretinoin) on the craniofacial development of mouse embryos were examined using whole embryo culture. In day 8 embryos cultured for 48 h, embryonic growth was inhibited concentration-dependently by all-trans-RA treatment. Most of the treated embryos exhibited hypoplasia of the primary palatal processes and a reduction in the development of the first viscreral arches. In day 10 embryos cultured for 48 h, although embryonic growth was not inhibited at any concentrations of all-trans-RA, median cleft lip (93%), hypoplasia of the primary palatal processes (37%) and limb reduction deformities (48%) occurred commonly. Furthermore, RA treatment greatly reduced the size of the secondary palatal processes. The incorporation of³H-thymidine in the treated maxillary processes was decreased to 65% of the control value at 1.0×10^–7 M alltrans-RA. These findings indicate that all-trans-RA is teratogenic in mouse whole embryo culture.     

Sur les effets du 5-fluoruracile injecté à l'embryon de Poulet à des stades avancés de l'incubation

Summary 5-FU, injected into the chick embryo on the 5th and the 8th day of incubation, has an immediate lethal effect and a later lethal effect which are very attenuated. On the other hand, when injected in very high doses, the substance has a uniform teratogenic action and causes malformations which attain specifically the members, the brain, and the beak.

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Ces recherches ont été faites grâce à un subside du Fonds National Suisse de la recherche scientifique et de la Fondation E. Barell.     

Development of melatonin rhythm in the pineal gland and eyes of chick embryo

A melatonin rhythm was observed in the pineals of 18-day-old chick embryos incubated under a light-dark regime of 186 h. A low pineal melatonin content was found during the light phase of the day. Concentrations started to increase 2 h after dark onset and reached maximum levels after 4 h of darkness. The amplitude of the pineal melatonin rhythm increased considerably after 2 days and night-time concentrations in 20-day-old embryos were more than 5 times higher than in 18-day-old ones. Significant day/night differences in melatonin production were found both in pineals and eyes. Exposure of eggs to 1 h of light during the dark period decreased the high melatonin concentrations in the eyes but not in the pineals of the 20-day-old chick embryo. The results suggest that in this precocial bird at least part of the circadian system may already operate during embryonic life.     

High altitude influence on the level and turn-over time of cardiac norepinephrine in rats

Summary In rats exposed to an altitude, of 2,900 meters the level of endogenous cardiac norepinephrine decreases after the 5th day of exposure. The turner-over time of the amine proceeds in 3 steps which are probablyrelated to periods of stress and adaptation: initial increase, important decrease from the 5th day and return to a normal value from the 12 th day.     

Intact teratogenic immunoglobulins may reach the rat embryo

It is known that heterologous antiserum against rat kidney homogenate may induce congenital malformations when injected into pregnant rats during the period of organogenesis. Teratogenic rabbit antibodies against a purified rat renal tubular glycoprotein were isolated, labelled with 125I and injected into pregnant rats on the 10th day of gestation. Extracts of visceral yolk-sacs (VYS) and embryos were obtained 16 h later and chromatographed separately on a Sephacryl S-300 gel filtration column. The resultant chromatograms showed several radioactive peaks, one of which coincided with the eluate of intact rabbit immunoglobulins G (IgG). We interpret the result as an indication that some undigested intact teratogenic IgG were present in VYS and the embryo.     

A close look at the mammalian blastocyst: epiblast and primitive endoderm formation

During early development, the mammalian embryo undergoes a series of profound changes that lead to the formation of two extraembryonic tissues—the trophectoderm and the primitive endoderm. These tissues encapsulate the pluripotent epiblast at the time of implantation. The current model proposes that the formation of these lineages results from two consecutive binary cell fate decisions. The first controls the formation of the trophectoderm and the inner cell mass, and the second controls the formation of the primitive endoderm and the epiblast within the inner cell mass. While early mammalian embryos develop with extensive plasticity, the embryonic pattern prior to implantation is remarkably reproducible. Here, we review the molecular mechanisms driving the cell fate decision between primitive endoderm and epiblast in the mouse embryo and integrate data from recent studies into the current model of the molecular network regulating the segregation between these lineages and their subsequent differentiation.     

Distribution of monoamine oxidase in hippocampal region of the rat

The distribution and development of type A and type B monoamine oxidase (MAO) activities in the hippocampal region of the rat was investigated with biochemical microdetermination. Type A MAO is absolutely dominant and unevenly distributed in the hippocampus. The development of type A MAO in the hippocampus seems to be delayed and reachs adult levels by the 30th day after birth.     

Distribution of monoamine oxidase in hippocampal region of the rat

Summary The distribution and development of type A and type B monoamine oxidase (MAO) activities in the hippocampal region of the rat was investigated with biochemical microdetermination. Type A MAO is absolutely dominant and unevenly distributed in the hippocampus. The development of type A MAO in the hippocampus seems to be delayed and reachs adult levels by the 30th day after birth.     

A simple method for counting nuclei in the preimplantation mouse embryo

An easy and rapid method of counting the number of cells in the preimplantation mouse embryo is described. The procedure increases the speed with which large numbers of embryos can be processed using a simple squash technique. Cell numbers are determined by exposing the embryos to the fluorescent DNA-binding dye, Hoechst 33258, removing the zona pellucida and simply squashing the embryo and counting the number of fluorescent nuclei. An increase in fluorescent intensity and maintenance of nuclear conformation of the squashed preparations are greatly improved by the use of the non-ionic detergent Triton X-100. Viability of dye-treated fertilized one-cell and blastocyst stage embryos is maintained at least up to day 13 of pregnancy following transfer of the embryos to the uteri of pseudopregnant recipients. Additional uses for this staining technique are discussed.     

Estrogenic inhibition of testicular growth by R2858 in preweanling rats

Daily injections of physiologic doses of R2858 into preweanling rats from the 10th to the 19th day of age resulted in reduced testicular growth compared to controls. Body weights and other organ weights were unaffected. Leydig cells were smaller and less numerous, and showed distinct changes in ultrastructural morphology. Results of this study suggest that alpha-fetoprotein permits normal testicular development during postnatal life.     

Sul meccanismo di azione delle sostanze che modificano lo sviluppo embrionale

Summary The lithium chloride and the substances, which are capable of producing a similar effect on the embryo development, increase the viscosity of proteins from the Amphibian embryo. The sodium thiocyanate, the sodium iodide and the pyocyanine lower it. The proteins fractions which can appear in elongated particles are those which feel the action of the thiocyanate and of the pyocyanine.