Retinotopy in the optic chiasm of chicks and its significance in an undesirable complication of lesioning the supraoptic decussation

Bilateral disruption, or one-sided transection of the basal optic root with a partial injury of this tract of retinal fibres on the other side, abolished vertical, but spared horizontal optokinetic head-nystagmus. Horizontal nystagmus could not be evoked when the ventral part of the pretectum was injured and the basal optic root was transected on the same side. The lesions were checked by the cobalt-filling technique. It is concluded that the basal optic nucleus mediates stimuli which evoke vertical optokinetic head-nystagmus in frogs.     

Asymmetry in the chicken forebrain during development and a possible involvement of the supraoptic decussation

During the first week of post-hatch life, the chicken forebrain is asymmetrically susceptible to the action of cycloheximide. Between days 2 to 8 treatment of the left hemisphere, but not the right, causes long-lasting changes in behaviour. The right hemisphere is susceptible on days 10 and 11. These developmental events may be related to a significant loss of fibers in the supraoptic decussation, which occurs around the same time.     

Development of the supraoptic decussation in the chick (Gallus gallus)

Summary The developing supraoptic decussation (SOD), a major interhemispheric tract in birds, has been implicated in both transfer of visual information and in the modulation of brain asymmetry. Moreover little is known of its morphology during development. We have examined the development of the chick SOD, which consists of three subregions; dorsal, ventral and subventral SOD. In the dorsal SOD the total number of fibres reach 968000 on the 19th day of incubation (E-19), falling to 570000 by the 8th day after hatching (P-8). In the ventral SOD, the number of fibres at E-19 reach 660000, followed by a gradual reduction in their number to about 490000 at P-22. In the subventral SOD the number of fibres estimated was 87000 at E-15 falling to about 36000 at P-1. Compared with adult levels, there is, respectively, a drop in the number of fibres of 44%, 25% and 69% in the dorsal, ventral and subventral SOD during development. At E-19 in both the dorsal and ventral SOD there is qualitative evidence of axonal loss; disrupted axonal profiles, increased extracellular space and cells containing lysosomal cytoplasmic inclusions indicative of macrophages. Differences were also observed in the pattern of myelination, the dorsal, ventral and subventral SOD were shown to myelinate at different rates. Thus, in a single named tract, the SOD, there are major differences in the onset, rate and extent of fibre loss and myelogenesis within its three subregions. The functional implications of these differences are considered.     

Histometric study of age related changes in the thoracic aorta of Gallus gallus (Linnaeus, 1758)

Summary The authors have studied the quantitative variations of elastic and collagenous fibers, muscle cells and cellular population in the mesarteria of the middle portion of the thoracic aorta of Gallus gallus from 1 day to 36 months of age. A histometric method has been employed, using an integrating eyepiece I (Zeiss Oberkochen) for the countings.The results obtained show that the concentration of elastic fibers increases from the first to the 30th day of age, decreasing from this point until 36 months while that of the collagenous fibers increases during the first and second period. The muscular tissue increases its concentration from the 30th day to 36th month, while the cellular population decreases from the 15th to 30th day, then remaining, stable until 36 months. From the variations pointed out here for the different elements studied between 30 days and 36 months of age, only those of the eollagenous fibers were linear with age.     

The effect of imprinting training on hyperstriatal EEG in young domestic chicks (Gallus domesticus)

Duration of low amplitude (< 50 μV) hyperstriatal EEG activity is both a treatment and stimulus-specific indicator of imprinting training in domestic chicks. Trained birds exhibited sustained EEG arousal in the presence of the imprinted stimulus whereas both they and control birds evinced temporary desynchronization when presented with a strange stimulus. The EEG pattern observed in the chicks was virtually identical to that obtained in domestic turkeys tested under similar conditions.     

The histogenesis of the isthmic nuclei in chick embryos (Gallus domesticus)

Summary The neuromeric mes-rhombencephalic boundary runs between the oculomotor and trochlear nuclei. During morphogenesis the m ₂-segment is reduced to a cellfree mantle demarcating a morphological mes-rhombencephalic border. The floor plate and glycogen-containing raphe extend rostralwards to terminate at the level of the m ₂-segment ventromedially.The isthmic migration commences within the dorsal and dorsolateral rhombencephalic cell columns caudal to the emergence of the trochlear nerve. The neuroblasts migrate radially out from the synthetic zone of the neural epithelium into the mantle constituting the isthmic migration. The latter migrate longitudinally en masse rostralwards into the mantle below the optic lobe. The m ₂-segment can, however, be identified as a morphological border between the mesencephalic and isthmic (rhombencephalic) mantles throughout the early embryogenesis.The isthmic migration subdivides into a tectal and a tegmental nuclear group. Both groups contribute to the formation of the isthmic nuclei. The caudal portion of the mesencephalic tectal mantle contributes to a mesencephalic isthmic nucleus: Nucleus isthmi principalis mesencephali (magnocellularis).     

背侧抑制性轴突导向蛋白对鸡胚后脑内23C10阳性神经元轴突投射的影响

目的:初步探讨背侧抑制性轴突导向蛋白即draxin对鸡胚后脑23C10阳性神经元轴突投射过程中的调控作用。方法:对HH13-14发育阶段的正常鸡胚后脑内进行跨膜型和分泌型draxin质粒转染,通过免疫组织化学染色方法,观察HH25-26发育阶段鸡胚23C10阳性神经元轴突的投射情况;应用活组织离体培养方法,检测draxin对鸡胚后脑神经元轴突生长的影响。结果:跨膜型draxin过表达后,有较多23C10阳性神经元的轴突异常投射到同侧后脑背侧部;分泌型draxin过表达后,有少部分23C10阳性神经元的轴突异常投射到同侧后脑背侧部;正常鸡胚和空白质粒过表达对照组均未观察到异常投射的神经元轴突。鸡胚后脑活组织离体培养中,draxin显著抑制体外培养组织内树突的生长,而对照组可见体外培养的组织内有大量树突形成。结论:draxin对鸡胚后脑内23C10阳性神经元的轴突投射具有抑制性导向作用。     

The development of eye movements in the zebrafish (Danio rerio)

We investigated the development of oculomotor activity in zebrafish embryos and larvae of ages 48-96 hrs postfertilization (hpf). The optokinetic response (OKR: smooth tracking movements evoked by a rotating striped drum) improved steadily after its onset at 73 hpf, and by 96 hpf had a achieved a gain (eye velocity/drum velocity) of 0.9, comparable to adult performance. Reset movements (the fast phase of optokinetic nystagmus) developed over 75–81 hpf. The vestibuloocular reflex (VOR: compensatory eye movements evoked by passive rotation of the head) developed over 74–81 hpf, and the associated reset movements, over 76–81 hpf. The VOR was qualitatively normal in dark-reared fish, which excludes an essential role for visual experience in its early development. Spontaneous saccadic movements (the fast shift of eye position) appeared between 81 and 96 hpf, and at 96 hpf had maximum velocities that were comparable to adults. These results are compared to, and found to be incompatible with, two earlier ideas of motor development: behavioral “differentiation” and “encephalization.” © 1997 John Wiley & Sons, Inc. Dev Psychobiol 31: 267–276, 1997     

Genetic background effects on dental and other craniofacial abnormalities in homozygous small eye ( Pax6 Sey /Pax6 Sey ) mice

 Small eye (Pax6 ^Sey ) is a semi-dominant mutation affecting development of the eyes, brain and nasal structures. The mutant phenotype arises from defects within the Pax6 gene and several mutant alleles have been identified. A previous study reported that Pax6 ^Sey /Pax6 ^Sey homozygotes, in a random-bred stock, had a median cartilaginous rod-like structure in the nasal region and 80% had supernumerary upper incisor teeth. In this study we show that supernumerary upper incisor teeth and a previously unreported nasal capsule-derived cartilaginous ’spur’ occur in compound heterozygous Pax6 ^Sey-Neu /Pax6 ^Sey and homozygous Pax6 ^Sey /Pax6 ^Sey fetuses from several strains of mice. The frequencies of the abnormal phenotypes were not related to allele type but showed variable penetrance, which was dependent on genetic background. The median nasal cartilaginous rod-like structure was present in all homozygous small eye fetuses. The Pax6 ^Sey /Pax6 ^Sey homozygote may provide insight into the complex gene interactions involved in eye, nasal and craniofacial morphogenesis. Accepted: 28 April 1997     

Autoradiographic localization of receptors for neuropeptide Y (NPY) in the brain of broiler and leghorn chickens (Gallus domesticus)

Broiler and leghorn chickens show an extreme difference in ingestive and reproductive behavior. As neuropeptide Y (NPY) influences both behaviors the goal of this study was to elucidate the distribution, expression and affinity of NPY binding sites in broiler and leghorn chicken brain. By means of in vitro autoradiography, sections of chicken brains were incubated with ³H-NPY as tracer and NPY as displacer. Scatchard analysis revealed a curvilinear plot suggesting two subtypes of the NPY binding site in the chicken brain, a high affinity one (K_D = 2–4 nM) and one with a lower affinity (K_D = 18–24 nM). Binding sites for NPY are localized with high density in the different subdivisions of the neostriatum and the hyperstriatum, the cerebellum, the nucleus septalis lateralis and medialis, the nucleus ruber and the nucleus tractus solitarii. A lower density of NPY binding sites was found in the different subdivisions of the striatum, the nucleus mesencephalicus lateralis pars dorsalis, the paleostriatum, the archistriatum intermedium pars ventralis, the nucleus geniculatus lateralis, the nucleus taeniae, the locus ceruleus, the nucleus rotondus, the nucleus habenularis medialis, the nucleus dorsomedialis anterior (rostralis) thalami, the pituitary and the area of the hypothalamus with its nuclei such as the nucleus paraventricularis magnocellularis and the nucleus preopticus medialis. Comparison of the localization of NPY binding sites in the brains of broilers and leghorns showed no differences but the density of both receptor types is two to three times higher in broilers than in leghorns.     

Comparative distribution of NADPH-diaphorase activity and tyrosine hydroxylase immunoreactivity in the diencephalon and mesencephalon of the domestic chicken (Gallus domesticus)

We described the distribution of NADPH-diaphorase-containing neurons in relation to tyrosine hydroxylase immunoreactivity in the diencephalon and mesencephalon of the chicken. In the diencephalon, both markers were found in the lateral hypothalamus, dorsal hypothalamic area, hypothalamic periventricular nucleus, paraventricular nucleus and mamillary area. A close examination showed that the fine distribution of these markers differed slightly, so that they were never observed in the same neurons. In the mesencephalon, NADPH-diaphorase and tyrosine hydroxylase immunoreactivity were found in the ventral pedunculopontine area (nucleus tegmenti pedunculopontinus pars compacta, adjacent areas surrounding the quintofrontal tract and the nucleus mesencephalicus profundus ventralis), the coeruleus complex (locus coeruleus, ventral and dorsal subcoeruleus nuclei), the ventral tegmental area and the central gray. The majority of these neurons contained either diaphorase or tyrosine hydroxylase. Nevertheless, in a few cases both markers appeared to colocalize in the same neuron, typically in large perikarya of the ventral pedunculopontine area.Abbreviations AVT Ventral tegmental area of Tsai - DAB diaminobenzidine - DHA dorsal hypothalamic area - DMA anterior dorsomedial thalamic nucleus - DMP posterior dorsomedial thalamic nucleus - DSV ventral supraoptic decussation - GCt central gray - ICH intercalated hypothalamic nucleus - IH inferior hypothalamic nucleus - LHy lateral hypothalamic area - LoC locus coeruleus - ML lateral mamillary nucleus - MM medial mamillary nucleus - MPv ventral part of the deep mesencephalic nucleus - nI interstitial nucleus of Rendahl - NADPH-d NADPH-diaphorase - NGS normal     

Vitreous cytology in asteroid hyalosis and observations on interpretation of cytologic findings in specimens of the posterior (vitreous) compartment of the eye

Cytologic methods have been used in the pathologic investigation of the posterior (vitreous) compartment of the eye in specimens obtained by fine-needle aspiration, as well as by surgical procedures. The vitreous body, which is in a semiliquid gel state, lends itself to pathologic investigation by cytologic methods. We report on a case of reparative eye surgery for complications of previous cataract extraction; vitrectomy was performed for vitreous opacities, which, by cytologic examination, were diagnostic of asteroid hyalosis, a relatively uncommon condition affecting the elderly. The cytologic findings diagnostic of this disease are described. Observations are made on the cytologic findings commonly encountered in specimens obtained from the posterior (vitreous) compartment of the eye.     

The effect of temperature on myogenesis in embryonic development of the Atlantic salmon (Salmo salar L.)

Summary From fertilisation to hatching one group of salmon embryos was reared at ambient temperatures (fluctuating around 1.6° C) and another at 10° C. At Gorodilov stages 28, 30 and 33 transverse sections of whole embryos were obtained for light and electron microscopy. Total cross-sectional areas, fibre numbers, fibre diameters and myofibrillar areas of the white muscle of m. lateralis were measured. At hatching (stage 33, which occurred much earlier at the higher temperature), the higher temperature embryos had significantly larger (P< 0.01) but fewer (P< 0.05) muscle fibres. These larger fibres contained significantly more myofibrillar material (P< 0.05) than the smaller fibres of the lower temperature embryos. Lesser differences were found at pre-hatching stages. Higher temperatures caused myofibre hypertrophy to increase at a greater rate than hyperplasia. Hence, the cellularity of the tissue produced under the different temperature regimes was quite different.     

The normal haematology of great skuas (Catharacta skua) in the wild

Routine haematological investigations were carried out on 102 wild adult great skuasCatharacta skua. No sex- or age-related differences were detected in any of the parameters measured. There are very few sets of haematological reference ranges published for seabirds from the northeastern Atlantic. Given the recent pollution threats in this region, the reference ranges presented for this species could be a valuable tool in future conservation efforts.     

The formation of the allantoic placenta in the golden hamster (Mesocricetus auratus)

Summary The processes of attachment, implantation and placentation in the golden hamster (Mesocricetus auratus) have been re-examined. Blastocyst attachment occurs at 4.0 days P.C. and complete interstitial implantation is attained by 5.5 days P.C. At 6.15 days P.C. the trophoblast of the träger breaks into the uterine lumen which becomes filled with blood clot. The advancing träger uses this blood clot as a bridge to reach the decidua basalis, lying on the opposite side of the uterine cavity, at 8.5 days P.C. Thus the uterine lumen becomes obliterated opposite each conceptus by the formation of the allantoic placentas which are vascularised by 8.5 days P.C. Non-glandular extensions of the glandular interlocular lumina penetrate between the decidua capsularis and the muscularis of the antimesometrial wall of the uterus from the 8th day P.C. onwards. On the 14th day P.C. the parietal wall of the yolk sac and its thin covering layer of decidua capsularis disappear to form a completely inverted yolk sac placenta. This places the yolk sac cavity in continuity with the non-glandular extensions of the uterine lumen and re-establishes complete continuity of the uterine lumen.     

The effects of 2,3-butanedione monoxime (BDM) on the force-velocity relation in single muscle fibres of the frog

The effects of 2,3-butanedione monoxime (BDM) on the forcevelocity relaion were studied in single fibres from the anterior tibialis muscle of Rana temporaria (2.2 μm sarcomere length, temperature 1.9-2.4 d?C). BDM (1.0 and 1.8 mM) suppressed the maximum tetanic force (P_o) and the maximum speed of shortening (V_max), and increased the main curvature of the force-velocity relation. The biphasic shape of the forcevelocity curve was maintained well in the presence of BDM, but the interrelation between the two portions of the forcevelocity relation was significantly changed. Caffeine (0.5 mM) added in the presence of BDM increased the initial rate of rise of force during twitch and tetanus, increased the twitch amplitude, but did not affect the maximum tetanic force. The latter finding suggests that the contractile system was fully activated during tetanus in the presence of BDM. The results support the view that BDM affects the cross-bridge function by exerting a direct action upon the contractile apparatus. The decrease in tetanic force and the change of the force-velocity relation induced by BDM may be interpreted to show that a larger fraction of the attached cross-bridges is in a state of low force production under the influence of BDM. This view is further supported by the observation that the instantaneous stiffness of the muscle fibre is reduced proportionally less by BDM than the tetanic force.     

The effect of 2,5-di-(tert-butyl)-1,4-hydroquinone on force responses and the contractile apparatus in mechanically skinned muscle fibres of the rat and toad

Summary In this study, we investigated the effect of the Ca²⁺ pump inhibitor, 2,5-di-(tert-butyl)-1,4-hydroquinone on the function of the contractile apparatus, Ca²⁺ uptake, the permeability of the sarcoplasmic reticulum to Ca²⁺ and excitation-contraction coupling, in mechanically skinned muscle fibres of the rat and toad. 2,5-di-(tert-butyl)-1,4-hydroquinone had no significant effect on the maximum force and Ca²⁺ sensitivity of the contractile apparatus in rat and toad fibres at concentrations of 20 and 5 M respectively. In rat fibres, 2,5-di-(tert-butyl)-1,4-hydroquinone was found to inhibit sarcoplasmic reticulum Ca²⁺ loading in a dose dependent manner, with a half maximal effect at 2 M. In toad fibres, 5 M 2,5-di-(tert-butyl)-1,4-hydroquinone completely blocked sarcoplasmic reticulum Ca²⁺ loading. Exposure to 5 mM BAPTA revealed a small resting sarcoplasmic reticulum Ca²⁺ leak in unstimulated rat fibres. This Ca²⁺ leak was not significantly affected by the presence of 20 M 2,5-di-(tert-butyl)-1,4-hydroquinone, suggesting that 2,5-di-(tert-butyl)-1,4-hydroquinone does not substantially block or activate the sarcoplasmic reticulum Ca²⁺ release channels. Depolarisation-induced force responses elicited in rat and toad skinned fibres were not significantly affected by 0.5 M 2,5-di-(tert-butyl)-1,4-hydroquinone. In the rat fibres, 5 and 20 M 2,5-di-(tert-butyl)-1,4-hydroquinone greatly increased the peak and duration of initial depolarisation-induced force responses, while subsequent responses were reduced. 2,5-di-(tert-butyl)-1,4-hydroquinone did not affect excitation contraction coupling, as depolarisation-induced force responses similar to initial controls could be elicited after 2,5-di-(tert-butyl)-1,4-hydroquinone exposure, provided that the initial Ca²⁺ release in 2,5-di-(tert-butyl)-1,4-hydroquinone was chelated with 0.5 mM EGTA (to prevent Ca²⁺-dependent damage) and the sarcoplasmic reticulum was reloaded with Ca²⁺. In the toad fibres, 5 M 2,5-di-(tert-butyl)-1,4-hydroquinone had a similar effect on depolarisation-induced force responses to that observed at 20 M 2,5-di-(tert-butyl)-1,4-hydroquinone in rat fibres. This study shows that 2,5-di-(tert-butyl)-1,4-hydroquinone specifically and reversibly inhibits the sarcoplasmic reticulum Ca²⁺ pump in skeletal muscle and therefore, 2,5-di-(tert-butyl)-1,4-hydroquinone could be a valuable tool for investigating the role of the sarcoplasmic reticulum in Ca²⁺ homeostasis in skeletal muscle.     

The first record of Macrogyrodactylus species (Monogenea, Gyrodactylidae) on freshwater fishes in Senegal with the description of Macrogyrodactylus simentiensis sp. nov., a parasite of Polypterus senegalus Cuvier

The first record of monogenean parasites of the genus Macrogyrodactylus Malmberg, 1957 on freshwater fish in Senegal is presented. Macrogyrodactylus congolensis Prudhoe, 1957 from the skin and Macrogyrodactylus heterobranchii N’Douba et Lambert, 1999 from the gills of Clarias anguillaris L. were found, representing new host records for these parasites. On Polypterus senegalus Cuvier, three Macrogyrodactylus species were identified, Macrogyrodactylus polypteri Malmberg, 1957, Macrogyrodactylus simentiensis sp. nov. and Macrogyrodactylus sp. M. simentiensis sp. nov. can be readily distinguished from the other Macrogyrodactylus species by the size of its hamuli and the shape of its marginal hook sickles. The marginal hooks on the anterolateral lobes of M. simentiensis differ in size and shape from those on the posterior margin of the haptor. Measurements and drawings of the haptoral sclerites of all five identified species are provided.     

The development of the tooth pattern and dentigerous bones in Polypterus senegalus (Cladistia, Actinopterygii)

The formation sequence of the tooth-bearing bones and the tooth pattern in early ontogeny of Polypterus senegalus is investigated using transparent preparation, histological sections, and SEM. During the attachment step of the yolk-sac larva the first dermal bones and teeth are formed. Teeth appear simultaneously in the areas of the maxillary, dentary, dermopalatine, prearticular, and coronoid 1 along with the first separate anlagen of these bones. A monostichous arrangement of primary teeth is established on the maxillary, dentary, and dermopalatine. Polystichous tooth arrangements do not occur before the early pterolarval phase, and then only in connection with bones of the palate and inner dental arcades. Especially pronounced is the influence of tooth formation on the structure of the parasphenoid that becomes much thickened by accretion of denticulate platelets, but we found neither evidence for a distinct vomeral contribution to the parasphenoid, nor a composite origin of the ectopterygoid in ontogeny. First replacement teeth are found in association with the maxillary and dentary as early as the late apterolarval phase. Primary teeth are of a single general type, whereas from the pterolarval phase onward three tooth types can be distinguished that are restricted to certain tooth bearing bones. Relatively late in ontogeny, dermo-metapterygoid and entopterygoid become formed and colonised by teeth, whereas first branchial teeth and tooth plates appear earlier during the first phase of extrinsic larval feeding. Characteristics of development of the dentition are discussed in comparison with character states of other better known fossil and recent taxa among Actinopterygii and Sarcopterygii. Compared to the assumed basic pattern of actinopterygian fishes, Polypteriformes show a derived condition with respect to structure, arrangement, replacement, and differentiation of teeth, which arises in sequence during larval development. This also corresponds to observed changes of feeding behaviour and functional demands during larval life.