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PubMed1991

Glycoconjugates in the otolithic organ of the developing chick embryo.

The presence of glycoconjugates in the otolithic organ of developing chick embryos was investigated histochemically using lectins. On the 6-day-old chick embryo, intense labelling with lectins was observed in the sensory epithelium, on the surface of the epithelium and on the immature otoconia. The otoconia were intensely labelled with lectins at every stage of the chick embryos, while the labelling with lectins in the sensory epithelium became weaker with the maturing of the otoconia. In TEM observation, the secretory granules of the supporting cells of the sensory epithelium were labelled with lectin. The reaction of lectin was more intense in the electronic dense zone of the otoconium than in the electronic lucent zone at every stage of the chick embryos. These findings indicate that the precursors of the otoconia are secreted by the supporting cells of the sensory epithelium and that glycoconjugates play an important role in otoconial formation.

Animals↗
PubMedDate not supplied

Changes of creatine concentration during development of chick embryo.

Changes of creatine concentration during development of chick embryo. Acta physiol. pol., 1985, 36 (3): 208-215. Investigations were carried out on embryos of Star Cross chicken after 6, 8, 10, 12, 14, 16, 18 and 20 days of incubation. It was found that the concentration of total creatine increased from 0.18 to 0.67 mg/g of embryo weight. The increase of creatine concentration at the time of development of the embryo was proportional to the increase in nitrogen concentration, and the share of creatine nitrogen in the pool of total nitrogen was about 1% throughout the whole period of embryonal development and during the first two days after hatching. The amount of creatine in fresh egg and in the yolk sac of the newly hatched chicken was about 1.5 mg. It was estimated that chick embryos during their development synthesized, on the average, 18 mg (6 mMol) of creatine. The course of changes in creatine concentration in the developing chick embryo is very similar to the course of changes in the rate of heat production.

Aging↗
PubMed1984

[The problem of testosterone secretion by the chick embryo testis: new research].

The aim of this study was to determine whether the chick embryo testis was able to convert dehydroepiandrosterone and androstenedione into testosterone. Testes from 17-19 day old chick embryos were cultured in vitro in the presence of tritiated dehydroepiandrosterone or androstenedione of high specific activity, and the radioactive testosterone formed was isolated by thin-layer chromatography and identified by recrystallization to constant specific activity. Parallel experiments with mouse embryo testes showed that these methods were valid. However, since specific activity with chick embryo testes was very low and could not be brought to constancy, testosterone could not be identified with these testes. It is concluded that the 17-19 day old chick embryo testis cannot form testosterone from either dehydroepiandrosterone or androstenedione. This conclusion is in keeping with the absence of a physiological role for testosterone in the male chick embryo.

Androstenedione↗
PubMed1996

Schwann cell apoptosis during normal development and after axonal degeneration induced by neurotoxins in the chick embryo.

In the present work, we show that chick embryo Schwann cells die by apoptosis both during normal development and after axonal degeneration induced by neurotoxin treatment. Schwann cell apoptosis during development takes place during a period roughly coincidental with normally occurring motoneuron death. Administration of NMDA to chick embryos on embryonic day 7 induces extensive excitotoxic motoneuronal damage in the spinal cord without any apparent effects on neurons in the dorsal root ganglia (DRG). The death of Schwann cells in ventral nerve roots after NMDA treatment causes degenerative changes that display ultrastructural features of apoptosis and exhibit in situ detectable DNA fragmentation. By contrast, NMDA treatment does not increase the death of Schwann cells in dorsal nerve roots. In situ detection of DNA fragmentation in combination with the avian Schwann cell marker 1E8 antibody demonstrates that dying cells in ventral nerve roots are in the Schwann cell lineage. Administration of cycloheximide does not prevent the toxic effects of NMDA on motoneurons, but dramatically reduces the number of pyknotic Schwann cells and DNA fragmentation profiles in the ventral nerve roots. In ovo administration of various tissue extracts (muscle, brain, and spinal cord) from the chick embryo or of the motoneuron conditioned medium fails to prevent Schwann cell apoptosis in NMDA-treated embryos. Intramuscular administration of the snake toxin beta-bungarotoxin produces a massive death of both lateral motor column motoneurons and DRG neurons, resulting in a substantial increase in the number of pyknotic Schwann cells in both ventral and dorsal nerve roots. It is concluded that during development, axonal-derived trophic signals are involved in the regulation of Schwann cell survival in peripheral nerves.

Animals↗
PubMed1981

Influence of temperature of incubation on chicken embryo tracheal organ cultures and chick embryos infected with strains of avian infectious bronchitis virus.

The ciliostatic and embryo lethal effect of four strains of avian infectious bronchitis virus (IBV) were observed at two different incubation temperatures. In organ cultures, nephrosis-producing IBV strains (GN-2 and M-41) were slightly more ciliostatic and respiratory strains (Beaudette and Kita-1/Tokushima) less ciliostatic at 40.5 degrees C than at 37 degrees C. Mortality of chicken embryos infected with the GN-2, M-41 and Kita-1/Tokushima strains was greater at 40.5 degrees C than at 37 degrees C, while the reverse was true of the Beaudette strain which caused no embryo mortality at 40.5 degrees C. The Beaudette strain of IBV was the only one which could not be recovered from the kidneys of young chickens four days after infection. These results indicate that the different IBV strains may show variation in virulence at different temperatures in ovo and in organ cultures and this may be a reflection of the virulence and tropism for chickens.

Animals↗
PubMed1998

Induction of primitive streak and Hensen's node by the posterior marginal zone in the early chick embryo.

In the preprimitive streak chick embryo, the search for a region capable of inducing the organizer, equivalent to the Nieuwkoop Center of the amphibian embryo, has focused on Koller's sickle, the hypoblast and the posterior marginal zone. However, no clear evidence for induction of an organizer without contribution from the inducing tissue has been provided for any of these structures. We have used DiI/DiO labeling to establish the fate of midline cells in and around Koller's sickle in the normal embryo. In the epiblast, the boundary between cells that contribute to the streak and those that do not lies at the posterior edge of Koller's sickle, except at stage X when it lies slightly more posteriorly in the epiblast. Hypoblast and endoblast (a second lower layer formed under the streak) have distinct origins in the lower layer, and goosecoid expression distinguishes between them. We then used anterior halves of chick prestreak embryos as recipients for grafts of quail posterior marginal zone; quail cells can be identified subsequently with a quail-specific antibody. Anterior halves alone usually formed a streak, most often from the posterior edge. Quail posterior marginal zones without Koller's sickle were grafted to the anterior side of anterior halves. These grafts were able to increase significantly the frequency of streaks arising from the anterior pole of stage X-XI anterior halves without contributing to the streak or node. Stage XII anterior halves no longer responded. A goosecoid-expressing hypoblast did not form under the induced streak, indicating that it is not required for streak formation. We conclude that the marginal zone posterior to Koller's sickle can induce a streak and node, without contributing cells to the induced streak.

Animals↗
PubMed1993

Development to the blastocyst stage of pig embryos cultured in the amniotic fluid of developing chick embryos.

Early-stage pig embryos were collected from superovulated donor gilts (60-72 hr post hCG injection) and co-cultured in modified Brinster medium for ovum culture (mBMOC-2) + porcine oviduct epithelial cells (POEC) or in the amniotic fluid of a developing chick embryo (CEAm). The development rate to the compacted morulae or blastocyst stage was significantly higher (P < 0.01) in embryos co-cultured in CEAm (60.0%) than those co-cultured in mBMOC-2 + POEC (18.0%). The results indicate that CEAm could be used for production of compacted morulae or blastocysts from early-stage pig embryos. This culture system could also be valuable in situations where a CO2 controlled incubator is not available.

Amniotic Fluid↗
PubMed2006

Vagal neural crest contribution to the chick embryo cloaca.

Intrinsic innervation of the developing chick cloaca is provided by the enteric nervous system, a network of neurons and glia that lies within its walls. The enteric nervous system originates from neural crest cells that migrate from the vagal and sacral regions of the neural tube during the early stages of development. Abnormal cloacal development can cause a number of anorectal anomalies including persistent cloaca. Our study aimed to investigate the contribution of vagal neural crest cells to the total population of enteric neurons and glia within the chick embryo cloaca, using quail-chick chimeras. Chicken embryos were incubated until the 10-12 somite stage (ss). The vagal neural tube, corresponding to somites 1-7, was then microsurgically ablated in ovo and isochronic and isotopic quail grafts were performed. The eggs were then reincubated until embryos were harvested at E12. Whole embryos were fixed in Bouin's fluid, embedded in paraffin wax and sectioned. Immunohistochemistry was carried out using the HNK-1 antibody to label all neural crest cells, and the quail-specific antibody, QCPN, to label quail cells. QCPN-immunoreactive cells were seen to make up a large proportion of enteric neurons and glia within the walls of the embryonic cloaca. HNK-1 labelled all neural crest cells in the myenteric and submucosal plexuses as well as the sacral crest-derived nerve of Remak, while QCPN-positive cells were evident in both plexuses but mostly in the submucosal plexus, where they appeared to make up the majority of neurons. Results show that the chick embryo cloaca is primarily innervated by vagal neural crest cells. Further studies to investigate the contribution of sacral neural crest cells to the same region will give further insight into the development of the enteric nervous system within the embryonic cloaca.

Animals↗
PubMedDate not supplied

The hen's fertile egg screening test (HEST): a comparison between the acute toxicity for chick embryos and rodents of 20 drugs.

The possibilities of using developing chick embryos for evaluating drug activities and toxicities were studied by determining LD50 values for 20 drugs with 14 different pharmacological activities. Fifteen-day old chick embryos received drugs through the air cell and deaths were measured at 48 hr after the treatments. The LD50 values were determined and compared to the i.v., i.p., s.c. and p.o. values from mice listed in the Registry of Toxic Effects of Chemical Substance. The systemic toxicity of 15-day-old chick embryos to drugs were similar to those of mice with the following exceptions. The chick embryos seemed to be more sensitive than mice to antineoplastic or antibiotic agents such as actinomycin D and doxorubicin, whereas, LD50 values of cholinergic and cholinergic blocking drugs by this method were 10 to 20 fold of LD50 (i.v.) of mice. These observations are important for applying the hen's fertile screening test (HEST) to the determination of drug activities other than that of embryo toxicity or teratogenic activity.

Animals↗
PubMed1991

Regional development of alpha-methyl-D-glucoside transport in the small intestine of chick embryos and newly-hatched chicks.

A regional study of the intestinal hexose transport shows the role played by duodenum, jejunum and ileum during the chick perinatal development. From at least two days before hatching the three regions of small intestine accumulate alpha-Méthyl-D-Glucose (alpha-MG) by mediated transport mechanisms, and phloridzin inhibit about 90% of the uptakes. This ability reaches the maximal level at 1 day after hatch in the three regions. Before hatching the jejunum shows higher transport levels than the observed values in the duodenum and ileum, but the three regions show similar values at 1 day after hatch. In the following days, the alpha-MG transport ability is strongly reduced in the duodenum, slightly reduced in the jejunum and maintained in the ileum until at least 7 day-old chicks.

Animals↗
PubMed1991

Chick embryo muscarinic and purinergic receptors activate cytosolic Ca2+ via phosphatidylinositol metabolism.

In dissociated cells from chick embryos or from chick limb buds, acetylcholine (ACh) induced an increase in cellular levels of inositol 1,4,5-trisphosphate (Ins-P3) and of inositol 1,3,4,5-tetrakisphosphate (Ins-P4). The concentration of Ins-P3 was enhanced transiently, whereas the level of Ins-P4 remained elevated for at least 20 min after addition of ACh. In most cases the increase in Ins-P4 levels was more pronounced than that of Ins-P3 levels. The inhibition of the ACh-induced inositol-phosphate response by atropine (half-maximal inhibition at 10 nM) indicates the involvement of muscarinic receptors, which in chick embryo cells induce a transient rise and a following persistent elevation of cytosolic Ca2+ activity (G. Oettling et al. (1989) J. Dev. Physiol. 12, 85-94). Adenosine 5'-triphosphate (ATP) elicited a similar transient rise in cytosolic Ca2+ activity, however, without a subsequent plateau. ATP also caused an increase in inositol-oligophosphate levels. Thus, both muscarinic and purinergic receptors in chick embryo cells are coupled to phospholipase C. The enzymatically formed Ins-P3 mediates the release of Ca2+ from internal stores. The Ca2+ signal could be involved in embryonic cell migration during morphogenesis.

Acetylcholine↗
PubMed1992

Laminin in the endolymphatic sac and vestibular endorgans of developing chick embryos.

The expression of laminin was analyzed in the vestibular endorgans of chick embryos using immunohistochemical methods. The basement membrane of the otocyst in the 5-day-old chick embryo was positive for laminin. In the 9-day-old chick embryo, the basement membrane of the macula of the saccule and utricle was positive, but the crista ampullaris showed a very weak positive reaction. The basement membrane of the endolymphatic sac in the 11-day-old chick embryo was strongly positive. These results suggest that laminin may be an essential substance with regard to the pathology of the vestibular endorgans. Moreover, the uneven distribution of laminin suggests that the basement membrane plays a role whose importance is yet to be determined in the physiology of the inner ear.

Animals↗
PubMed1957

The role of a natural antibody in the rejection of mouse tumor cells by the chick embryo.

Cells of the Krebs ascites tumor of mice grow well in the body of the chick embryo until about the 17th day of incubation, when degeneration of the tumor can be seen in tissue sections and viable tumor cells begin to disappear from the internal organs of the embryo. This death of tumor cells follows the appearance in the chick embryo of serum gamma globulins. Among these are antibodies which can agglutinate the tumor cells in vitro, and destroy their viability. These antibodies occur in the blood without the introduction of any foreign antigen. Their possible origin is discussed. Small numbers of mouse tumor cells growing in the chick embryo are completely eliminated shortly after the time when antibodies ordinarily become detectable. When the number of cells present is larger, viable cells persist longer, and at still higher cell numbers, the embryo or chick is unable to eliminate the tumor, and is itself killed by it. Gamma globulins of older birds injected into young chick embryos bearing growing tumor clear the embryonic organs of viable tumor cells.

Animals↗
PubMed1985

The presence of peroxisomal carnitine palmitoyltransferase in chick embryo liver.

Hepatic peroxisomes and mitochondria from 20-day-old chick embryo were separated by sucrose density gradient centrifugation and the characteristics of carnitine acyltransferases in these organelles were studied. The carnitine acyltransferase activities in peroxisomes were increased markedly by the treatment of chick embryo with clofibrate, while those in mitochondria did not change. In the liver of clofibrate-treated chick embryo, approximately 50% of total liver carnitine palmitoyltransferase (CPT) activity was present in the peroxisomal fraction. Peroxisomal CPT activity was easily solubilized, in contrast with mitochondrial CPT. The solubilized protein solutions from isolated peroxisomes and mitochondria were separately chromatographed on a column of Blue Sepharose CL-6B after the gel filtration on Sephadex G-25. Peroxisomal CPT was completely bound to a Blue Sepharose CL-6B column and was eluted below 0.25 M KCl, whereas mitochondrial CPT was not retained on the column. The substrate specificity profile of peroxisomal CPT with long-chain acyl-CoAs (C8 to C18) was similar to that of mitochondrial CPT, and the apparent Km value of peroxisomal CPT for palmitoyl-CoA was 5.2 microM, being similar to that of mitochondrial CPT. It is concluded that carnitine long-chain acyltransferase, which is different from mitochondrial CPT and is induced by clofibrate treatment, is present in peroxisomes of chick embryo liver.

Acyltransferases↗