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Specialized ependyma in the posterior mesencephalon of the chicken: the fine structure of the subtrochlear organ.

A formation of specialized ependymal cells in the posterior mesencephalon of the domestic fowl, designated as the subtrochlear organ, was examined with light-, scanning- and transmission electron microscopy. This organ possessing the form of the letter "V" is located in the ventricular wall of the posterior mesencephalon. Its apex marks the median sulcus, while the arms of the V are directed rostrolaterally. Ependymal cells lining the subtrochlear organ usually project an extremely elongated process into the subependymal region and are classified into three types according to their surface features: (1) cells with a bulb-shaped protrusion that projects into the ventricle, (2) single cilium-bearing cells, and (3) cells with a tuft of cilia. The first type of cell is restricted to the median portion of the subtrochlear organ; its bulb-shaped protrusion contains numerous ribosomes. The second type of cell predominates in the arm (rostrolateral) area; in its apical cytoplasm such ciliary structures as basal body are rarely seen. The third type of cell is usually assembled into several small islands on the arm area; it has many basal bodies and other ciliary structures in the apical cytoplasm.

Animals↗

Ultrastructural reactions of spinal ganglia to tri-ortho-cresyl-phosphate: effects of neurotoxicity.

The ultrastructure of neurons in spinal ganglia of the domestic fowl poisoned with tri-ortho-cresyl-phosphate (TOCP) shows characteristic changes. The light neurons react to TOCP by a marked increase in the number of neurofilaments. These neurons also contain mitochondria in various degenerative stages. Several of the altered mitochondria show an increasing osmiophilia. Some of the darker neurons display a hypertrophy of the endoplasmic reticulum or a relative increase of neurofilaments. The mitochondria in some of these cells show early stages of degeneration. These changes appear 13 days after TOCP ingestion.

Animals↗

Steady-state sodium absorption and chloride secretion of colon and coprodeum, and plasma levels of osmoregulatory hormones in hens in relation to sodium intake.

The plasma levels of four osmoregulatory hormones and their target ion-transport systems in the lower intestines of the domestic fowl were determined in order to elucidate their interrelationship and their setpoints in relation to NaCl intake. White Plymouth Rock hens were adapted to six intake levels of NaCl (0.20 +/- 0.02-24.7 +/- 1.9 mmoles Na+.kg bw-1.day-1) for 6 weeks. The Na+ absorption and the Cl- secretion of colon and coprodeum were characterized in vitro by the effects of hexoses, amino acids, amiloride, and theophylline on the short-circuit current (SCC) and electrical potential difference (PD). The NaCl-conserving system of the adult chicken is set at low intake levels of NaCl as the 80% range (quantized by non-linear, logistic regression analyses) of the change in the plasma [ALDO], the amiloride-inhibitable Na+ absorption of coprodeum and colon (delta SCC), occurred from 0.18 to 2.3, from 0.9 to 4.3, and from 1.2 to 7.3 mmoles Na+.kg bw-1.day-1, respectively. These results demonstrate that the amiloride-inhibitable Na+ absorption of coprodeum is more closely linked to plasma [ALDO] than that of colon. The aminoacid-Na+ coabsorption of colon increased over exactly the same range of Na+ intake as the colonic amiloride-inhibitable Na+ absorption decreased, whereas the hexose-Na+ coabsorption increased at higher levels of Na+ coabsorption increased at higher levels of Na+ intake, from 2 to 11 mmoles Na+.kg bw-1.day-1. Both these Na+ absorption types had reached their maximums at 24.7 mmoles Na+.kg bw-1.day-1, whereas the plasma [AVT] and plasma [PRL], although significantly increased, apparently had not; their 80% range of change occurred from 9.9 to 99 mmoles Na+.kg bw-1.day-1, and the main changes in plasma osmolality were predicted to occur from 5.4 to 107 mmoles Na+.kg bw-1.day-1. These results suggest that these colonic and hormonal variables conserve osmotically-free water and operate at high NaCl intake. The theophylline-induced colonic Cl- secretion did not change with NaCl intake, whereas the stimulation of SCC in coprodeum decreased with increasing NaCl intake: the main change occurred between 0 and 3.2 mmoles Na+.kg bw-1.day-1. Thus, all ion-transport capacity (although the nature of the Na+ transport changes). It is suggested that hormones defending the extracellular volume and composition are regulated close to zero input and output of both NaCl and water, regardless of whether they are NaCl conserving or free-water conserving.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

Aldosterone-induced sodium transport in lower intestine. Effects of varying NaCl intake.

Short-circuit current (SCC) and electrical potential difference (PD) were measured in two epithelia of the lower gut of the domestic fowl, coprodeum and colon, mounted in vitro in the Ussing-chamber. The birds were suddenly switched from a low-NaCl to a high-NaCl diet, and 24 h aldosterone treatment (3 X 42.7 micrograms/kg i.m.) given from zero to 5 days after dietary change. The effects on SCC and PD of addition of amino acids, and later amiloride, to the bathing media were measured, because a low-NaCl-diet which releases endogenous aldosterone, inhibits amino acid stimulation (in colon) and induces amiloride inhibition of SCC and PD (in both coprodeum and colon). Birds were slaughtered 4 h after the last injection as single injections of aldosterone showed maximal change of SCC and PD, and maximal amino acid and amiloride effects, at that time. Control intramuscular injections of aldosterone showed a mono-exponential decline of the plasma concentration with a half time of 47 min. In colon the aldosterone treatment induced the low-NaCl diet pattern of the transport parameters regardless of the delay after resalination. In coprodeum SCC declined gradually with time and reached 25% of the value at low-NaCl diet when aldosterone was given 5 days after resalination. The data suggest that colon maintains a high flush of sodium through the epithelial cells regardless of whether the entry is via the amiloride-blockable sodium channel or the non-electrolyte stimulated pathway.(ABSTRACT TRUNCATED AT 250 WORDS)

Aldosterone↗

Avian colonic ion transport: effects of corticosterone and dexamethasone.

1. Corticosterone, a natural corticosteroid hormone in birds, when injected into domestic fowl (Gallus domesticus) (2000 micrograms.kg-1, 4-5 h before experiment) increases both the basal Isc (short-circuit current) and amiloride-sensitive Isc as well as the PD across the colon in vitro. Dexamethasone, a synthetic analogue (650 micrograms.kg-1, 4-5 h before experiment) also increases the basal and amiloride-sensitive Isc as well as PD in these preparations. 2. In marked contrast, longer term injection or infusion of dexamethasone (650 micrograms.kg-1) for 3 or more days caused a decline in basal Isc and PD (the PD often reversed with the serosal side becoming electronegative) and a drop in resistance. However in these preparations, the amiloride-sensitive Isc was significantly elevated which could be accounted for by an increase in net Na flux. 3. No significant change occurs in net flux of Cl or K although unidirectional fluxes in both directions were increased for both ions in birds given dexamethasone for 3 days. 4. A disparity between the basal Isc and the amiloride-sensitive Isc appeared in these preparations from dexamethasone injected birds reflecting the transport of other ions, possibly HCO3- or H+. The possible role of corticosterone in mineral metabolism of birds is discussed.

Amiloride↗

Studies on the livestock of Southern Darfur, Sudan, VII. Production of poultry under simulated traditional conditions.

Observations were made on egg production, egg hatchability and fertility, liveweight and growth characteristics of domestic fowls, Muscovy ducks and pigeons kept under simulated traditional conditions in Southern Darfur. Fowl and ducks produced about 50 eggs a year in 4 1/2 clutches spaced at 80 day intervals and pigeons 17 in 8 1/2 clutches at 43 day intervals. First eggs were laid at about 240 days by the fowls, 213 days by ducks and 132 days by pigeons. The annual weight of eggs produced was 2,013 3,596 and 286 g for fowl, ducks and pigeons respectively, being 1.53, 2.33 and 0.88 times the mean adult female body weight for each species. Fertility and hatchability of eggs were higher in fowls than ducks which were in turn higher than in pigeons. Early growth in pigeons was very rapid. Muscovies achieved mature body weights at about 20 weeks while mature weights in fowls were achieved much later in males than in females.

Animals↗

Livestock production in central Mali: ownership, management and productivity of poultry in the traditional sector.

A survey of small-scale poultry production in an urban and two agropastoral systems covered 381 households. Less detailed information was also obtained from a small sample in a transhumant pastoral system. More households owned poultry in the rice (89.5%) than in the millet (81.1%) or urban (57.1%) systems. Domestic fowl were commonest in all systems followed by pigeons, Guinea fowl and then ducks, although the last were absent from the millet zone. Most families kept only one species but there was more diversification in the rice system. Flock sizes were largest in the rice system for fowls, Guinea fowl and pigeons while duck flocks averaged more birds in the urban area. Females predominated in all species except pigeons where sex ratios were about equal. Management practices in relation to housing, feeding, health care and consumption and marketing are described. Productivity figures relating to egg production, egg size, hatchability, growth and mortality are provided.

Animal Husbandry↗

Immunoreactivities to protein gene product 9.5, neurofilament protein and neuron specific enolase in the ovary of the sexually immature ostrich (Struthio camelus).

The innervation of the ovary has been studied in various species of birds and mammals. Despite the fact that the innervation of any organ is an essential factor in controlling its growth and function, no information is available on the distribution of nerve fibers in the ovary of the sexually immature ostrich. Thus, the present study was undertaken to investigate the distribution of nerve fibers in the ovary of the sexually immature ostrich, using antibodies against neurofilament protein type M of 160 kD (NP), protein gene product 9.5 (PGP 9.5) and neuron specific enolase (NSE). A total of 26 sexually immature female ostriches, aged between 12 and 14 months were used in the present study. Immunostaining was performed using a LSAB plus kit (Dakocytomation, Denmark). Antibodies against NP and PGP 9.5 were used at dilutions of 1:25 and 1:50, respectively. A ready-to-use solution containing antibodies against NSE was also used. Strong immunostaining for NP, PGP 9.5 and NSE was observed in nerve bundles, which coursed through the ovarian stalk and extended into the medulla and cortex. In addition, NSE immunoreactive nerve cell bodies were observed in the cortex and medulla. NP, PGP 9.5 and NSE immunoreactive nerve fibers were present in the thecal layer of the follicular wall. The current study has highlighted the distribution of NP, PGP 9.5 and NSE-immunoreactive nerve fibers in the ovary of the sexually immature ostrich. The findings of the present study suggest that the distribution of nerve fibers in the immature ostrich is similar to that of the domestic fowl.

Animals↗

Expression of the dentin matrix protein 1 gene in birds.

The emergence of jawed vertebrates was predicated on the appearance of several innovations, including tooth formation. The development of teeth requires the participation of several specialized genes, in particular, those necessary for the formation of hard tissues--dentin, enamel, and cementum. Some vertebrates, most conspicuously birds, secondarily lost the tooth-forming ability. To determine the fate of some of the tooth-forming genes in the birds, we tested a domestic fowl cDNA library for the expression of the dentin matrix protein 1 (DMP1) gene. The library was prepared from the poly(A+) RNA isolated from the jaws of 11- to 13-day-old embryos and the testing was carried out by the polymerase chain reaction with degenerate primers designed on the basis of the available mammalian and reptile sequences. A chicken homologue of the DMP1 gene identified by this approach was shown to be expressed in the jaws and long bones, the same two tissues as in mammals. The chicken DMP1 gene has an exon/ intron organization similar to that of its mammalian and reptile counterparts. The chicken gene contains three short highly conserved segments, the rest of the gene being poorly alignable or not alignable with its mammalian or reptilian homologues. The distribution of similarities and dissimilarities along the gene is indicative of a mode of evolution in which only short segments are kept constant, while the rest of the gene is relatively free to vary as long as the proportion of certain amino acid residues is retained in the encoded polypeptide. The DMP1 gene may have been retained in birds because of its involvement in bone formation.

3' Untranslated Regions↗

The effect of infusion of hypertonic saline on glomerular filtration rate and arginine vasotocin, prolactin and aldosterone in the domestic chicken.

Domestic fowl were infused for 60 min with isotonic saline followed by 90 min with hypertonic saline. Plasma electrolyte concentrations, osmolality and haematocrit were measured. Urine electrolyte excretion rates, osmolar output and urine flow rates were also monitored. From these results fractional excretions of electrolytes were calculated. The renal function markers inulin and rho-amino hippuric acid were infused to enable the measurement of glomerular filtration rate and plasma clearance of rho-amino hippuric acid, respectively. Plasma samples were also taken to assay for the hormones prolactin, aldosterone and arginine vasotocin. Plasma electrolytes and osmolality, fractional excretion of electrolytes and osmolar output all increased, while haematocrit decreased, throughout the experiment. However, no significant change was found in urine flow rate and little change was seen in glomerular filtration rate. The clearance of rho-amino hippuric acid, which provides an indication of renal plasma flow, increased during hypertonic saline infusion. Plasma concentrations of aldosterone and prolactin decreased during the experiment and plasma concentrations of arginine vasotocin increased. Infusion of hypertonic saline had no consistent effect on glomerular filtration rate, which may be due to conflicting influences of expansion of the extracellular fluid volume and increased plasma osmolality.

Aldosterone↗

Cellular localization of growth hormone receptors/binding proteins in immune tissues.

It is well established that the activity and proliferation of lymphoid cells and lymphoid organs are stimulated by growth hormone. These actions on lymphoid cells may be direct or mediated by actions on the epithelial and non-immune tissue cells that regulate immune function. The occurrence and cellular localization of growth hormone receptors in immune tissues has therefore been investigated to determine the target-sites of growth hormone action. Growth hormone receptor mRNA was first detected by Northern blotting in the spleen, bursa of Fabricius, and thymus of domestic fowl. In addition to the 4.4-kb transcript thought to encode the full-length growth hormone receptor, smaller transcripts of 2.8 kb and 1.0 kb, which may encode growth hormone-binding proteins, were also occasionally observed. Further analysis using the polymerase chain reaction revealed that mRNA sequences encoding the extracellular and intracellular domains of the growth hormone receptor were present in all tissues and highly homologous with hepatic transcripts. Translation of these transcripts also occurs in immune tissues, since immunoreactive growth hormone-binding proteins or growth hormone receptors of approximately 56 kDa were detected in hepatic, splenic, thymic, and bursal extracts. Immunocytochemistry of these tissues subsequently revealed that macrophages probably contain the bulk of this immunoreactivity, although some thymic medullary epithelial cells (including Hassall's corpuscles) and splenic ellipsoids and interdigitating cells were also immunoreactive. This immunoreactivity is present in immune tissues of newly hatched and adult chickens. Importantly, B-lymphocytes were rarely, if ever, immunoreactive, and T-lymphocytes containing growth hormone receptors or binding proteins were not observed. These results suggest that a number of primary (thymus and bursa) and secondary (spleen) lymphoid tissues in the chicken contain growth hormone receptors and are thus target-sites for growth hormone action. The distribution of growth hormone receptor/growth hormone-binding protein immunoreactivity in these tissues would further suggest that growth hormone plays a major role in macrophage proliferation and/or activity and may indirectly affect lymphocyte maturation and storage via effects on thymic and splenic stromal cells.

Animals↗

The demonstration of very low density lipoprotein in the basal lamina of the granulosa layer in the hen's ovarian follicle.

The isolated basal lamina from the granulosa layer in ovarian follicles of the domestic fowl contains an abundance of spherical particles with a modal cross-sectional diameter of 25-30 nm. The lipid in this basal lamina is predominantly triacylglycerol and its total fatty acid composition resembles that of plasma very low density lipoprotein (VLDL). Immunodiffusion studies and immunoelectrophoresis indicated that this basal lamina contains diffusible antigen identifiable with plasma VLDL. Perfusion with an alkaline buffer displaced the particles from the basal lamina and subsequent perfusion with plasma VLDL in an acidic buffer resulted in the reappearance of particles of similar size and form. Alternatively, when the perfused basal lamina was subsequently perfused with VLDL-free serum, few particulate structures were observed. Measurements of total and VLDL triacylglycerol together with electron microscope studies of the untreated and of the perfused basal lamina provided further evidence for the identification of the majority of particles with plasma VLDL. Other particulate lipoprotein is most probably plasma low density lipoprotein (LDL). These studies demonstrated that this basal lamina is permeable to the circulating VLDL of the laying fowl.

Animals↗

Indomethacin attenuation of celiac blood flow hyperemia following glutathione depletion.

The effect of glutathione (GSH) depletion on mean celiac blood flow (MCBF) was determined in domestic fowl. Diethyl maleate (DEM, 1 mL/kg body wt) decreased hepatic and duodenal GSH to approximately 15% of control. This GSH depletion was associated with an increase in MCBF and decreases in mean arterial blood pressure (MABP) and celiac vascular resistance (CVR). While indomethacin attenuated the rise in MCBF, this cyclooxygenase inhibitor had no effect on the decrease of MABP or CVR which occurred following DEM treatment. The results indicate that GSH depletion may increase vasodilatory prostaglandin synthesis since elevations in MCBF were attenuated by cyclooxygenase inhibition.

Animals↗

Degeneration patterns in the chicken central nervous system induced by ingestion of the organophosphorus delayed neurotoxin tri-ortho-tolyl phosphate. A silver impregnation study.

Exposure to certain organophosphorus compounds results in a neurological condition known as organophosphorus-induced delayed neurotoxicity (OPIDN). OPIDN is characterized clinically by an initial post-exposure delay period of 8-14 days after which signs of progressively developing ataxia and paralysis of the hindlimbs are observed. Although several studies have reported the presence of degeneration induced by organophosphorus delayed neurotoxins in specific central nervous system (CNS) structures, none have systematically examined CNS changes seen in the most frequently studied animal model for OPIDN--the domestic fowl. In the present study, we assessed the location and extent of anterograde degeneration in the chicken CNS following exposure to tri-o-tolyl phosphate (TOTP). All birds were dosed with 500 mg TOTP/kg body weight and killed after post-exposure periods of 1, 2, 3, or 4 weeks. The brains and spinal cords were processed with Fink-Heimer and Nissl stains. In the spinal cord, axon degeneration was noted in the fasciculus gracilis at cervical levels two weeks after exposure to TOTP. At 3 weeks, degeneration was also present in the cervical part of the dorsal spinocerebellar tract, in the lumbar part of the medial pontine-spinal tract, and in lamina VII in the lumbar ventral horn. In the medulla, moderate amounts of terminal and preterminal degeneration appeared at two weeks in the lateral vestibular, gracile, external cuneate, and lateral cervical nuclei. Lesser amounts of degeneration were noted in the solitary, inferior olivary, and raphae nuclei, in the medial, descending and lateral vestibular nuclei, and in the lateral paragigantocellular, gigantocellular, and lateral reticular nuclei. Fiber degeneration was also present in the medullary portions of the dorsal and ventral spinocerebellar tracts and spinal lemniscus. In the cerebellum, moderate amounts of terminal degeneration appeared in the deep cerebellar nuclei at one week while moderate mossy fiber degeneration was first noted in the granular layers of cerebellar folia I-V at 3 weeks. These results indicate (1) that, in the CNS, axonal and terminal degeneration resulting from TOTP intoxication appears to be confined to the spinal cord, medulla and cerebellum, (2) that the time of onset of degeneration in different fiber tracts and nuclei ranges from one to three weeks post-exposure, and (3) that the delay in the appearance of clinical signs of OPIDN is consistent with the delayed onset of degeneration in many of the affected CNS fiber systems.

Animals↗

The binding of very low density and low density lipoproteins to the plasma membrane of the hen's oocyte. A morphological study.

The binding of lipoproteins to the oocyte plasma membrane of the domestic fowl (Gallus domesticus) was examined by electron microscopy in preparations of the ovarian follicle in the main phase of yolk formation. Numerous particles, 26 nm in diameter, were present on the untreated membrane. They were dissociated from the membrane by incubation at 4 degrees C in buffer at pH 6.2 and with heparin at pH 7.4. Added calcium was not required for binding, though the number of bound particles was reduced by treatment with EDTA. Very low density (VLD) lipoproteins from laying hen's plasma were found to bind to the denuded membrane and to correspond in size to the native particles. The results suggest that the binding characteristics are similar in quality to those determined for the binding of low density (LD) lipoproteins to mammalian cells. The oocytes, however, bound 100-fold more particles per unit length of membrane. VLD and LD lipoproteins from immature hens also adhered to the denuded membrane, although their apoprotein composition was very different from that of laying hen VLD lipoproteins. LD lipoproteins from immature hens and VLD lipoproteins from laying hens both contained apo-B, which formed about 80 and 35%, respectively, of the total apolipoproteins. Apo-VLDL-II is the other major apoprotein identified in laying-hen VLD lipoproteins. Apo-VLDL-II was not positively identified as a component of immature-hen LD lipoproteins and could only have been present as a minor component.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Stimulation of growth hormone secretion by human pancreatic growth-hormone-releasing factor and thyrotrophin-releasing hormone in anaesthetized chickens.

Sodium pentobarbitone anaesthesia depressed the concentration of growth hormone (GH) in the plasma of young (6 weeks of age) and old (22-30 weeks of age) domestic fowl. In both cases the concentration was reduced (P less than 0.05) within 10 min and had declined (P less than 0.001) to stable low levels (less than 5 ng/ml) within 50 min. The intravenous administration of synthetic human pancreatic growth-hormone-releasing factor (hpGRF) (10 micrograms/kg) (2 X 10(-9) mol/kg) increased (P less than 0.01) the GH concentration in both the young and old birds. This effect was observed irrespective of whether the birds were conscious or anaesthetized. The magnitude of the response in conscious young birds (164 ng/ml) was, however, greater (P less than 0.01) than that in anaesthetized chicks (64 ng/ml). The response in anaesthetized adult fowl (18.8 ng/ml) was also less (P less than 0.05) than that in their conscious counterparts (42.8 ng/ml). The GH response in conscious and anaesthetized 6-week-old birds to hpGRF was greater (P less than 0.01) than that in the corresponding adult birds. Thyrotrophin-releasing hormone (TRH) (10 micrograms/kg (2.8 X 10(-8) mol/kg); iv) also provoked (P less than 0.01) GH secretion in conscious and anaesthetized young birds and in anaesthetized (but not conscious) adults. Anaesthesia blunted (P less than 0.01) the GH response to TRH in the immature cockerels, although the response was greater (P less than 0.05) than that in anesthetized adults.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia↗

The effect of a single injection of thyrotrophin on serum concentrations of thyroxine, triiodothyronine, and reverse triiodothyronine in the immature chicken (Gallus domesticus).

Immature domestic fowl were given a single injection of 0.1 or 0.25 IU bovine thyrotrophin (TSH)/kg body wt by the intramuscular route and serum concentrations of thyroxine (T4), 3,5,3'-triiodothyronine (T3), and 3,3',5'-reverse T3 (rT3) were measured during the following 24 hr. The increase in T4 was markedly greater than that of T3. Serum rT3 concentration increased after an injection of 0.25 IU TSH/kg but the maximal concentration (75 pg/ml) was very low.

Age Factors↗

Comparisons of avian renal responses to bovine parathyroid extract, synthetic bovine (1-34) parathyroid hormone, and synthetic human (1-34) parathyroid hormone.

The structure of avian parathyroid hormone (PTH) is only partially known, therefore studies of the avian renal responses to PTH have been conducted using bovine parathyroid extract (bPTE), synthetic human PTH (h(1-34)PTH), and synthetic bovine PTH (b(1-34)PTH). In vitro studies indicate that these peptides may have quite different chick kidney receptor binding affinities and adenylate cyclase activation potencies. In the present study, the in vivo renal responses to bPTE, b(1-34)PTH, and h(1-34)PTH have been compared in immature domestic fowl. The following parameters were evaluated: glomerular filtration rates; renal plasma flow rates; urine pH; and fractional excretion of sodium, potassium, chloride, calcium, magnesium, and inorganic phosphate. Overall, the different hormonal peptides elicited qualitatively similar responses: they all were phosphaturic, natriuretic, diuretic, hypomagnesiuric, hypocalciuric, and kaliuretic. This is the first study to show an effect of PTH on renal magnesium transport in avian species. Quantitative comparisons make it clear that bPTE is more natriuretic and diuretic, but less phosphaturic than either b(1-34)PTH or h(1-34)PTH. A temporal dissociation of the phosphaturic response from the other mineral and electrolyte responses suggests that the phosphaturic response is mediated by a separate mechanism.

Animals↗