Comparative ultrastructural study on merkel cells and dermal basal cells in poultry (Gallus domesticus)

Summary Basal cells of the hard palate epithelium have been examined electronmicroscopically. Secretory granules, morphologically similar to those of the Merkel cells, occur in the groups of basal cells. A comparison concerning the cytoplasmic qualities of the two cell types is given, and the possibility of a cytogenetical or physiological relationship between the Merkel cells and the basal cells is discussed.Supported by the Agricultural Research Council of Norway.     

Ontogeny of magnetoreception in chickens (Gallus gallus domesticus)

Chickens are precocial birds, capable of moving independently from within a few hours of hatching, and thus provide a useful model to investigate the development of magnetoreception in young birds. Chicks show some sharply-timed behavioural changes at around 11 days of age that may be indicative of improvements in navigation ability around this age. We trained Young (<10 days, n = 7) and Old (11 days or older, n = 6) chicks to find a hidden imprinting stimulus behind one of four screens in a square arena. Once criterion was reached, the directional choices of chicks were recorded in unrewarded tests in the geomagnetic field and in an experimental field shifted by 90° clockwise. These tests were separated with rewarded training trials to avoid extinction. In the first, and the first 3 tests, no indication was found that chicks chose the correct unimodal magnetic direction. Instead, in all tests, Old chicks preferred the screens in the same magnetic axis as the training direction in tests in the geomagnetic and shifted experimental fields significantly more than Young chicks (P < 0.05). Choices of Young chicks were no different to chance in tests, whereas choices by Old chicks were significantly different from chance (P < 0.05). Our findings support the hypothesis that magnetoreception appears in the second week of life in the chicken. It is, however, unclear when a truly directional magnetic response (i.e. an unimodal, rather than axial, response in our test) develops that could be used by the chicks for accurate navigation.     

鸡内金中氨基酸及营养元素含量的测定

采用日立 835 - 5 0型氨基酸自动分析仪和岛津Z - 80 0 0型原子吸收分光光计。测定了鸡内金中氨基酸和营养元素的含量 ,结果表明 :鸡内金中营养元素钾、钙、镁、铜、锌、铁、锰含量分别为 36 9.5 0、12 0 .5 6、470 .77、31.89、32 .42、5 5 9.6 4、8.11mg/kg ;氨基酸总量为 86 .92 4% ,必需氨基酸占氨基酸总量的 30 .2 6 4%。     

Genistein affects testosterone secretion by Leydig cells in roosters (Gallus gallus domesticus)

Genistein is one of non-steroidal phytoestrogens present in soya and soybean products as well as in other legumes. Phytoestrogens possess estrogen-like biological activity and may influence human and animal reproduction. The aim of this study was to examine the effect of genistein on testosterone (T) secretion by isolated Leydig cells in roosters. Genistein (5-50 microM) inhibited (p<0.05) in vitro basal and LH-stimulated T secretion by Leydig cells in a dose dependent manner. No significant effect of lavendustin C (inhibitor of PTK, a non-phytoestrogen) on the T production was observed. In conclusion, genistein, present in commercial poultry feeds, may influence testicular steroidogenesis but its effect on reproductive performance of roosters requires further examinations.     

Genetic characterization of Bhutanese native chickens based on an analysis of Red Junglefowl (Gallus gallus gallus and Gallus gallus spadecieus), domestic Southeast Asian and commercial chicken lines (Gallus gallus domesticus)

The genetic diversity of Bhutanese chickens needs to be understood in order to develop a suitable conservation strategy for these birds in Bhutan. In this, work, we used microsatellite markers to examine the genetic diversity of Bhutanese chickens. Four Bhutanese chicken varieties (Black plumage, Frizzle, Naked neck and Red Junglefowl-like, corresponding to Yuebjha Narp, Phulom, Khuilay and Seim, respectively), two subspecies of Red Junglefowl (Gallus gallus gallus and Gallus gallus spadecieus), two varieties of Thai native chickens (Pradhu Hang Dam and Chee; Gallus gallus domesticus) representing the Southeast Asian domestic chicken, and two commercial lines (Broiler and Single Comb White Leghorn) were genotyped with 18 microsatellites that included 16 loci recommended by the FAO/ISAG for investigations of genetic variability in chickens. All loci were polymorphic, with the number of alleles ranging from six (MCW0111) to 23 (MCW0183). Substantial genetic variation was observed in all populations, with the Bhutanese native chicken Yuebjha Narp (Black plumage chicken) showing the lowest genetic variability. Despite extensive intrapopulation variation, the genetic differentiation among 10 populations was moderate. A neighbor-joining tree revealed the genetic relationships involved while principal component analysis showed that Bhutanese native chickens should be given priority in conservation efforts because of their genetic distinctiveness. Chee chickens are especially valuable as a reservoir of predomestic diversity, as indicated by their greater genetic variation and their position in the phylogenetic tree.     

Regressive post-hatching development of acetylcholinesterase-positive neurons in the pineal organs of Coturnix coturnix japonica and Gallus gallus

Summary Distribution and number of acetylcholinesterase-positive neurons were studied in the Japanese quail and the domestic fowl during the post-hatching period by means of the acetylcholinesterase method. For comparison, the development of the catecholamine-containing (sympathetic) pinealopetal fibers of the domestic fowl was demonstrated with the use of the glyoxylic acid method. The number of acetylcholinesterase-positive ganglion cells in the pineal organs of both avian species decreased rapidly after hatching, with a concentration of these elements in the basal portion (stalk) of the pineal organ.In 3-day-old chickens, perivascular catecholamine-containing nerve fibers penetrate the antero-lateral walls of the pineal organ and are found exclusively in the interfollicular and perivascular tissues. In 13-day-old and adult fowl, these fibers increase in number and terminate not only in the interfollicular space but also in the neuroepithelial parenchyma of the pineal body.The ontogenetic regression of the sensory structures paralleled by an expanding sympathetic innervation in the pineal organ of a galliform species resembles somewhat the process of phylogenetic transformation leading from pineal sense organs to pineal glands.This work was supported by a grant (No. 56480080) from the Ministry of Education, Science and Culture of Japan.Fellow of the Alexander von Humboldt Foundation (1982).     

The action of insulin in the morphogenesis of Gallus gallus domesticus embryos]

Aspects concerned with morphogenesis of Gallus gallus domesticus, avail studies related to the action of the insulin in the topography and embryonic structures. At the temperature of 37.5 degrees C, eggs were incubated during 24 h, injected with 5 ml of swine insulin in three concentrations and reincubated for more 72 h. The morphological characteristics of 80 embryos were evaluated and, according to the presented organization, classified in 5 morphogenetic levels. It was registered generalized dysmorphism (4th level) in 21 embryos that went through the tests with insulin. Standard morphogenesis (1st level) and located dysmorphism (3rd level) were verified among those from the control experiments. Those individuals concerned with the 4th level, showed reduced dimension of the body and were characterized by anterior-dorsal limits organized in a cephalic projection, and also presented alterations in the posterior-ventral region. These features evidence a pattern of abnormality in the determination of the cephalic-caudal axis and indicate a specific action of the insulin in the embryonic morphogenesis, in the period of 96 hours of incubation.     

A cytoarchitectonic scheme for the spinal cord of the domestic fowl, Gallus gallus domesticus: lumbar region.

In Nissl stained and silver impregnated transverse sections of the chick spinal cord it is possible to subdivide the gray matter of the lumbar region into ten cytoarchitectonically discrete regions or laminae. The laminae are basically similar in both brachial and lumbar regions of the chick cord, with minor exceptions in the dorsal horn. The laminar scheme postulated for the chick cord is , with the exception of the glycogen body and orientation of laminae 1, 2 and 3 in the dorsal horn, similar to the laminar scheme proposed by Rexed (1954) for the cat.     

Development of cholinergic chronotropic control in chick (Gallus gallus domesticus) embryos

In chick (Gallus gallus domesticus) embryos, instantaneous heart rate begins to fluctuate with the appearance of rapid, transient decelerations at around the end of the second week of incubation. Previously, it was shown that instantaneous heart rate decelerations were eliminated by administration of atropine and concurrently heart rate baseline was elevated in late embryos. Because the previous study lacked statistical treatment and there has been recent controversy over the development of tonic vagal control of the heart, we reexamine the hypothesis that transient decelerations of instantaneous heart rate are mediated by vagus nerve and the vagal tone begins to appear at around the end of the second week of incubation. Atropine administration tests were conducted for sixty-seven 11- to 14-day-old and 18-day-old embryos in total. Heart rate decelerations appeared sporadically in three out of ten 12-day-old embryos, but the difference of mode heart rate before and after administration of atropine was not significant. Seven out of nine 13-day-old embryos and all nine 14-day-old embryos showed heart rate decelerations and the difference of mode heart rate before and after atropine administration was significant. In late (18-day-old) embryos, magnitude and frequency of instantaneous heart rate decelerations further increased with additional appearance of transient, irregular accelerations. Administration of varying doses of atropine completely eliminated the heart rate decelerations and elevated the heart rate baseline more markedly than in young embryos, indicating the maturation of vagal tone late in incubation.     

Depolarisation and repolarisation sequences of ventricular epicardium in chickens (Gallus gallus domesticus)

Activation and recovery sequences were mapped by means of 64-channel synchronous recording of extracellular potentials on ventricular epicardium in chickens. Ventricular epicardium was depolarized due to multiple breakthroughs. The recovery of ventricular epicardium occurs from the apex to the base of heart and does not repeat the activation sequence. Gradients of repolarisation exist over the ventricular epicardium in birds. Repolarisation pattern of ventricular epicardium depends primarily on intrinsic spatial heterogeneities of ARIs over epicardium.     

Cell number and sex ratio in unfertilized chicken eggs (Gallus gallus domesticus)

In chickens and other birds, females have two different sex chromosomes (ZW), whereas males carry two homologous sex chromosomes (ZZ). The primary sex ratio can thus be determined by genetic analysis of the sex chromosome of the ovum before fertilization. Sex diagnosis is more reliable when there are more cells, i.e. sufficient DNA, for the analysis. In this study, eggs from virgin hens were incubated for 3 days and the number of cells in the germinal discs was counted. A median of 2.5 cells was counted with a range of two to 20 cells. We also counted cells in the germinal discs of unfertilized eggs of inseminated hens and recorded a median of three cells and a range of two to 40 cells. Sex diagnosis based on polymerase chain reaction (PCR) amplification of Z and W chromosomes specific fragments from the CHD1 gene in 30 incubated eggs obtained from 35-week-old virgin hens gave a ratio of 13 Z to 15 W chromosomes with two samples undetermined.The unfertilized eggs of three groups of chickens were subjected to sex diagnosis to supplement the sex ratio data of an incubation experiment (see companion paper). The high proportion of Z chromosomes diagnosed in all three groups by two independent gene products suggests a sex difference on developmental potential and/or a sex chromosome segregation biased toward males in unfertilized eggs especially at the beginning of reproduction.     

Sex inversion in domestic chicken (Gallus gallus domesticus) by letrozole and tamoxifen

In multicellular organisms, determination of sex identity is a complex, multistage process. Sex hormones are synthesized in gonads and fulfill the role of inductors in this process. The effect of androgen is currently well studied. However, the participation of estrogen in the formation of female gonads and female sex on the whole is not much known. Here, we present the results of experimental sex inversion by inhibition of aromatase (an enzyme involved in estrogen synthesis) and tamoxifen (a modulator of estrogen receptors) in chick embryos. It was shown that masculinization depended on the dose of the substance and quantity of injections. Inhibition of aromatase did not block the meiotic prophase in oogoniums. It has been suggested that retinoic acid and estrogens have different mechanisms of effect on oogenesis. Proteins and nucleoproteins interacting with estrogen receptor 1 and their gene localization in human and chicken genomes have been shown for the first time.