The effects of regular handling on fear responses in the domestic chick

Reduction of fear in the domestic chick by regular handling was assessed and an attempt was made to determine whether such an effect was due specifically to reduced fear of human beings or to a general reduction in fearfulness. Regular handling decreased the tonic immobility response, a fear-potentiated phenomenon, and increased approach to a human being, but had no effect on approach towards an inanimate object. These findings were common to three strains (two layer, one broiler), and suggest that handling does not depress general fearfulness, but specifically reduces fear of human beings, presumably through habituation.     

Growth and feeding of Echinostoma revolutum on the chick chorioallantois and in the domestic chick

Chemically excysted metacercariae of Echinostoma revolutum cultivated on the chick chorioallantois grew slowly until day 5, more rapidly between 5 and 7 days, and slowly between 7 and 10 days. Worms did not become ovigerous in this site by 12 days, at which time studies were terminated. In contrast, chemically excysted metacercariae reared in the domestic chick were ovigerous by day 9, at which time their mean body area was about 4 times greater than the largest chorioallantoic worms. Histochemical studies, solubility tests for hematin, and X-ray microanalysis of cecal contents showed that chorioallantoic-worms fed on blood from the vascular membrane, whereas chick-worms fed on host intestinal mucosa.     

Connections of the IMHV in the domestic chick Gallus domesticus

The responses to single electrical stimuli have been recorded from neurons in the brains of domestic chicks, by using an in vitro preparation consisting of a coronal slice taken from the forebrain. All slices were cut so that they contained the intermediate part of the medial hyperstriatum ventrale (IMHV). When such a slice is bathed in standard Krebs' solution there is no evidence that the excitation produced by a single stimulus can be transmitted more than 1 mm either towards or away from the IMHV. The addition of bicuculline methiodide (more than 3 x 10(-6) M) to Krebs' solution allows the excitation produced by a single stimulus to spread in all directions throughout the dorsal half of a coronal slice. At points remote (more than 1.5 mm) from the stimulated point, the magnitude of the spreading wave of excitation bears an all-or-nothing relation to the strength of stimulus used to excite it. This wave of excitation spreads from the excited point in all directions without attenuation at 0.9 +/- 0.017 (s.d.) m s-1 and consists of a prolonged burst of activity of the invaded neurons. The properties of coronal slices described above are also true of brain slices cut in a parasagittal plane. The spreading response to a single stimulus given in the presence of bicuculline, can be reduced in magnitude by the addition of AP-5 but it still spreads throughout the dorsal part of the slice at the same velocity. The response can be eliminated by the addition of kynurenic acid. The addition of curare to the bathing medium produces similar responses that spread in a similar fashion to those seen under bicuculline. These results suggest that the dorsal part of the forebrain of the domestic chick (in fact, the part derived from the embryological alar plate) contains a network of reciprocally connected local circuits. Transmission throughout the network is normally prevented by active inhibition.     

Neural mechanisms of learning: an analysis of imprinting in the domestic chick

Learning is a complex set of processes involving the acquisition and storage of information. Imprinting in the domestic chick was studied to analyse the neural basis of storage. The recently hatched chick learns the characteristics of a visually conspicuous object by being exposed to it. When a chick is trained in this way, biochemical changes can be detected in the dorsal part of the forebrain. Through a series of experiments it was shown that these changes are unlikely to be non-specific consequences of training, but more probably reflect some aspect of the storage process. By using a radioautographic technique to localize the brain region more precisely, part of the hyperstriatum ventrale was implicated in this process. Bilateral destruction of the region before imprinting prevented acquisition, and bilateral destruction after imprinting impaired retention. After exposure for 140 min to an imprinting stimulus there was an increase in the area of contact between presynaptic and postsynaptic elements in the region. This effect was found on the left side only. Sequential lesions to left and right sides confirmed that there is a hemispheric asymmetry in the role of the region in the storage of information. The area receives input from the visual pathways and possibly from other sensory pathways, and projects to regions that are thought to be involved in the control of locomotor and viscero-endocrine functions. The results afford an opportunity for the further analysis both of storage and of the whole set of neural processes that underlie imprinting in the domestic chick.U     

Correlations between the processes of cell differentiation and development of blood vessels in the (chick embryo) adenohypohhysis

Utilizing semi-thin and, respectively, thick sections after indian ink injections, we have analyzed morphohistogenesis and vessel development in the adenohypophysis of chick embryos from the 4th to the 19th incubation day. Our preliminary results indicate that a close correlation exists between cellular differentiation and vasculogenesis. Vessels begin to enter the gland only at the 6th day when the first endocellular granules become detectable, and, from the 10th day, they markedly increase in number and size, gradually acquiring a peculiar sinusoidal arrangement around cellular groups, as cell differentiation further progresses.     

Skin tension lines in the domestic pig.

The skin tension lines of the domestic pig have been mapped. With a 6mm punch biopsy, local relative skin forces can be determined. The influence of various factors (such as age, fat deposition, gascial attachments, and previous scarring) on the direction of the skin tension lines is discussed.     

Comparison of two sampling methods for domestic populations of Triatoma infestans in north-west Argentina

Abstract. In mud-and-thatch houses of Santiago del Estero Province, northwest Argentina, where no insecticides had been sprayed officially to control domestic infestations of the Chagas disease vector Triatoma infestans (Klug) (Hemiptera: Reduviidae), two knockdown (KD) insecticidal collection procedures were compared with the standard flush-out (FO) method for sampling T. infestans. Bugs were collected by FO using 0.2% tetramethrin in bedrooms of (1) 41 houses of Amama village employing 1 man-hour of capture effort per house, and (2) 19 houses of Trinidad and Mercedes villages employing 4 man-hours/house. From the same houses, 2-5 days after the manual FO collection, bugs were collected by KD indoor-spraying of deltamethrin 25mga.i./m² in Amama, or burning of one γ-HCH (=γ-BHC) fumigant tablet 3.1g of γ-isomer) per bedroom in Trinidad and Mercedes. The majority of infestations were detected by both methods, the proportion of positive houses being 81% at Amama and 95% at the other villages. Although the FO method was more sensitive, at least because it was applied first, the KD method detected infestations in 25% of houses where bugs were not found by FO. Bug densities estimated by FO or by subsequent KD in each house were significantly correlated: r = 0.795 for deltamethrin; r= 0.882 for y-HCH. Compared with FO collections of T.infestans large stages, i.e. adults plus fourth and fifth instar nymphs, the KD catch averaged 0.88x with deltamethrin and 0.57× with γ-HCH, regardless of the apparent population density of bugs per house. However, the KD method has practical advantages of speed and standardization.     

两种玻璃化胚胎冷冻方法对不同品系小鼠胚胎冷冻效果比较

目的探讨EFS和DAP两种玻璃化冷冻方法对不同品系小鼠胚胎冷冻的效果。方法6个品系小鼠（KM、ICR、BALB／c、C57BL／6J、OB／OB、LAP／~TAOF59）的2-cell胚胎分别用EFS和DAP两种玻璃化冷冻方法进行冷冻和复苏,比较两种冷冻方法的胚胎复苏率和着床率。结果6个品系小鼠冷冻胚胎EFS方法的平均复苏率为69．97％（47．9％～83．6％）,DAP方法的平均复苏率47．23％（26．3％-76．7％）,EFS方法明显优于DAP方法。其中KM、ICR和BALB／c小鼠EFS方法的冷冻复苏率显著高于DAP方法（P〈0．01）;冻融胚胎移植后EFS方法的平均着床率27．23％（1．75％一45．0％）,DAP方法的平均着床率31．43％（7．0％一46．3％）。除KM、ICR小鼠外,其他4个品系小鼠的着床率DAP方法高于EFS方法。结论KM和ICR远交群小鼠胚胎适合用EFS方法冷冻保存;C57BL／6J、OB／OB、LAP／aTAOF59三个品系小鼠DAP方法优于EFS方法,但差异不大;BALB／c小鼠两种玻璃化冷冻方法的冻融胚胎着床率均较低,需进一步研究。     

Prenatal light exposure affects early feather-pecking behaviour in the domestic chick

Recently we proposed that early feather pecking is a form of social exploration. Social recognition, important for exploration, is a lateralized function in the domestic chick. Lateralization of functions can be influenced by light exposure late in embryonic development. Therefore, we investigated whether this light exposure affected early posthatching feather-pecking behaviour in domestic chicks, Gallus gallus domesticus. White leghorn embryos either were exposed to light or remained in darkness in the last week of incubation. After hatching, they were housed in groups of two light-exposed and two dark-incubated chicks. Light-exposed chicks showed more feather pecking than did their dark-incubated cagemates. Dark-incubated chicks preferred to direct feather pecks to unfamiliar peers than to familiar peers; light-exposed chicks showed no preference. These effects were present in the first week after hatching and remained at least another 3 weeks. These results support the hypothesis that early gentle feather pecking is part of the normal behavioural repertoire of young chicks and influences social exploration. We discuss a possible mechanism underlying these results. We also suggest that it may be worthwhile not to expose embryos to light during the last week of incubation when housing hatchlings in commercial conditions, where feather pecking is a serious problem.     

Scanning electron microscopy of Echinostoma revolutum (Trematoda) during development in the chick embryo and the domestic chick

Fried B. and Fujino T. 1984. Scanning electron microscopy of Echinostoma revolutum (Trematoda) during development in the chick embryo and the domestic chick. International Journal for Parasitology14: 75–81. Scanning electron microscopy (SEM) was used to study the development of chemically excysted metacercariae of Echinostoma revolutum on the chick chorioallantois. SEM studies were also made on preovigerous adults of E. revolutum grown in the domestic chick. During worm development on the chorioallantois the tegument changed from smooth to granular and sensory papillae on the suckers became well-defined. As worms developed on the chorioallantois the cephalic collar spines became thicker and more curved and the tegumentary spines showed marked changes in shape, size and distribution on both ventral and dorsal aspects of the body. Changes in the surface ultrastructure of worms grown on the chorioallantois were essentially similar to those observed in preovigerous worms from chicks.     

Pathological effects of Echinostoma caproni (Trematoda) in the domestic chick

Domestic chicks experimentally infected with Echinostoma caproni for 2 weeks showed a dilated ileum, unkempt feathers, watery diarrhoea, and weight loss. The ileum from infected and control chicks was fixed in 10% neutral buffered formalin, and prepared as 10 microns paraffin sections stained in haematoxylin and eosin, Papanicolau, periodic acid-Schiff, picro-ponceau, and alcian blue. The infected ileum showed atrophic villi, hypertrophied circular musculature with collagen-like fibres and haemorrhagic zones. The brush borders of epithelial cells and goblet cells were absent in the mucosa of the infected ileum. Worms in contact with host mucosa showed tissue plugs in the suckers. The cephalic spines of worms abraded the host mucosa.