幼龄红嘴相思鸟小脑皮层组织学结构

为了探讨不同日龄幼龄红嘴相思鸟（Leiothrix lutea）小脑皮质的组织学结构变化,本文分别以1、5、9日龄幼龄红嘴相思鸟为研究对象,通过H.E.和甲苯胺蓝法进行染色,光镜下观察红嘴相思鸟小脑冠状切面的显微结构。结果显示,1日龄时小脑皮层由外颗粒层（EGL）、浦肯野细胞层（PCL）和内颗粒层（IGL）3层构成,外颗粒层较厚且清晰,而浦肯野细胞层和内颗粒层界限不清楚;5日龄和9日龄时小脑皮质均可见外颗粒层、分子层（ML）、浦肯野细胞层和内颗粒层4层结构。对不同日龄红嘴相思鸟小脑皮质各层厚度进行单因素方差分析显示,随日龄增长,小脑皮质、分子层和内颗粒层厚度极显著增厚（P < 0.01）,浦肯野细胞体积也极显著增加（P < 0.01）;外颗粒层厚度变化不明显（P < 0.01）,呈现先增厚后变薄的趋势,与皮质厚度的比例逐渐减小。研究表明,幼龄红嘴相思鸟在出生后,随日龄增长,小脑皮质层逐渐发育成熟。内颗粒层与外颗粒层的相对变化规律表明内颗粒层细胞是由外颗粒层细胞迁移而来。     

幼龄红嘴相思鸟小脑皮质组织学结构

为了探讨不同日龄幼龄红嘴相思鸟(Leiothrix lutea)小脑皮质的组织学结构变化,分别以1、5、9日龄红嘴相思鸟为研究对象,通过H.E和甲苯胺蓝法进行染色,光镜下观察红嘴相思鸟小脑冠状切面的显微结构。结果显示,1日龄时,小脑皮层由外颗粒层(EGL)、浦肯野细胞层(PCL)和内颗粒层(IGL)3层构成,外颗粒层较厚且清晰,而浦肯野细胞层和内颗粒层界限不清楚;5日龄和9日龄时,小脑皮质均可见外颗粒层、分子层(ML)、浦肯野细胞层和内颗粒层4层结构。对3个日龄红嘴相思鸟小脑皮质各层厚度进行单因素方差分析,随日龄增长,小脑皮质、分子层和内颗粒层厚度极显著增厚(P0.01),浦肯野细胞体积也极显著增加(P0.01);外颗粒层厚度变化不明显(P0.05),呈现先增厚后变薄的趋势,与皮质厚度的比例逐渐减小。研究表明,幼龄红嘴相思鸟在出生后,随日龄增长,小脑皮质层逐渐发育成熟。内颗粒层与外颗粒层的相对变化规律表明,内颗粒层细胞是由外颗粒层迁移而来的。     

湖北兴山红嘴相思鸟繁殖生态初报

2005年4月～2007年8月,在湖北省兴山县龙门河地区,对红嘴相思鸟(Leiothrix lutea)的繁殖生态进行了初步研究。研究结果显示,红嘴相思鸟在此地区的繁殖时间为4月中旬至7月下旬。巢多营于山坡上、山谷中的乔木林、灌木林遮蔽下的箬竹(Indocalamus wilsoni)和小灌木上,也营巢于农田边、山间小路旁、林间空地的箬竹丛或灌丛中。巢材主要有细树枝、细树根、细藤、箬竹叶、茅草叶、细草茎、青苔等。雌雄鸟共同筑巢,筑巢过程较为迅速,一般5～7d即可完成。雌鸟每天产一枚卵,产卵时间一般在清晨。窝卵数3.41±0.80(n=61)。孵卵期11～13d(n=6)。雏鸟晚成性,雌雄共同育雏,育雏期9～10d。雏鸟发育十分迅速,但离巢时身体发育尚未完善。红嘴相思鸟在此地区的繁殖成功率约为22.95%(n=61)。     

高寒草甸三种雀形目雏鸟热调节机制的比较研究

３同巢型雏鸟大约在雏期的５０％开始出现调温机制。从变温到恒温的转变期呈现出两种发育趋势;黄嘴朱顶省发育迅速,角百灵和褐背拟地鸦发育缓慢。３种雏鸟产热量都随试验温度降低和日龄的增长而增加。但角百灵在３５℃时,产热量不随日龄增长而变化。     

白腰文鸟发声行为的神经发育

本文研究了 5～ 15 0日龄雄性白腰文鸟 (Lonchurastriataswinhoei)不同年龄段的声谱变化以及这种变化的神经调制机制。结果如下 :(1)HVC、RA和AreaX三个发声核团的神经联系基本接近成年鸟的水平后 ,幼鸟才开始学习鸣叫 (约 45日龄 ) ;(2 )HVC、RA和AreaX达到成年核团体积时 (约 80日龄 ) ,幼鸟才具有成年雄鸟的鸣叫模式 ;(3)发声控制核团的发育与核团间的神经支配有关 ,而基本不受鸣唱行为的影响 ,HVC、RA和AreaX的最快增长时间段各不相同 ,三个核团随年龄增长而呈现体积增长的显著变化 (one wayANOVA ,P <0 0 5 ) ,但各核团在任意两个时间段的体积差异并不都显著。结果提示 :发声行为产生的时间和发展与发声控制核团的发育、核团间的神经联系有关 ,最终的体积发育程度受内在遗传力的作用 ,同时可能还受神经核团建立正常神经联系时间的影响     

人工饲养大鸨雏鸟行为变化趋势及日节律

采用扫描取样法(scan sampling)和目标取样法(focal sampling)相结合观察大鸨(Otis tarda)雏鸟的行为,研究了大鸨雏鸟行为日节律及其行为随日龄增长的强度变化趋势。结果表明,大鸨雏鸟在1～3日龄休息行为、站立行为所占比例逐渐增多,蹲伏行为、鸣叫行为比例减少,随着日龄的增加,大鸨雏鸟的行为逐渐接近亚成体的行为,但整体还没有形成规律;大鸨雏鸟期行为主要由休息(51.7%)、站立(16.1%)和游走(18.8%)行为组成,其次为理羽(3.2%)和展翅(6.1%)行为。在雏鸟成长过程中,休息行为比例一直保持很高,觅食和理羽行为呈现明显的上升趋势,鸣叫和蹲伏行为逐渐减少。     

棕色田鼠雄性幼体不同发育期犁鼻器和副嗅球的组织结构

通过对出生后不同发育时期雄性棕色田鼠犁鼻器和副嗅球进行组织学观察, 探讨棕色田鼠出生后犁鼻器和副嗅球的发育规律。实验以出生后当天(0 日龄) , 5 日龄, 15 日龄, 25 日龄以及成年棕色田鼠为研究对象,副嗅球采用Pischinger 氏染色法染色, 犁鼻器用H. E. 染色法染色后进行组织学观察。结果显示, 棕色田鼠出生时, 犁鼻器和副嗅球就已具有成体的基本结构, 随着动物个体的发育, 犁鼻上皮逐渐增厚, 犁鼻管变长, 犁鼻上皮中神经元密度增加; 腺体逐渐增大, 犁鼻管腔填充物增多, 犁鼻管背外侧的静脉血管逐日增大, 管腔周围出现越来越多的血管; 副嗅球长宽都增加, 僧帽细胞层和颗粒细胞层逐渐增长, 各层细胞密度变化稍有不同;出生后15 日内, 僧帽细胞层细胞密度增加, 15 日龄以后又开始降低, 25 日龄及成体的僧帽细胞层细胞密度与5日龄的相似; 颗粒细胞层细胞密度持续增高。实验结果提示, 棕色田鼠5 日龄时, 犁鼻器和副嗅球已具有了完整的结构, 到25 日龄时可能达到了功能上的成熟。     

降钙素基因相关肽、P物质、甘丙肽和γ-氨基丁酸免疫阳性细胞在大鼠结合臂旁核的分布

应用免疫细胞化学ABC技术观察了降钙素基因相关肽,P物质、甘丙肽和γ-氨基丁酸免疫阳性胞体在大鼠结合臂旁核中的分布。降钙索基因相关肽阳性神经元分布于臂旁内侧核的腹侧部及外内侧亚核、臂旁外侧核的外外侧亚核、极外侧亚核,背外侧亚核及上外侧亚核,也分布于KllikerFuse核。P物质阳性胞体分布于臂旁内侧核内侧部和外内侧亚核、臂部外侧核的外外侧亚核及极外侧亚核,在腹外侧亚核中亦见个别细胞分布。甘丙肽阳性细胞的分布较为广泛,分布于臂旁外侧核和臂旁内侧核所有的亚核及Klliker-Fuse核中,γ-氨基丁酸阳性神经元在中尾部臂旁核中分布于臂旁外侧核背内侧部包括背外侧亚核、腹外侧亚核、内外侧亚核及结合臂背侧部;在嘴部和中嘴部臂旁核,GABA阳性胞体除位于臂旁外侧核背内侧部的背外侧亚核、腹外侧亚核、中央外侧亚核、上外侧亚核及内外侧亚核外,也出现于腹外侧部的外外侧亚核、臂旁内侧核内侧部及Klliker-Fuse核。     

白腰文鸟发声行为的性别差异及其机制

通过声谱分析,研究了５－１２０日龄雌、雄白腰文鸟（Lonchura striata swinhoei)的声谱变化,及该时段３个主要发声控制核团）ＨＶＣ、ＲＡ、Ａrea X)体积、睾丸（睾酮）的相应改变。结果如下：①４５日龄以前,雌雄鸟只能发出简单鸣叫（call),鸣声基本不会鸣唱。②雄性ＨＶＣ,ＲＡ,ＡreaX体积均比雌性大２－６部。３个核团的大小发育不完全一致。各核团的快速生长期与鸣唱学习的主要时段（６０－１２０日龄）不同步,说明核团的个体发育可能不完全受发声行为的影响。③睾丸的充分发育（１２０日龄后）及血液中具有较高的睾酮水平是雄鸟发出成熟鸣唱语句的重要条件。     

白琵鹭雏鸟的生长和恒温能力的发育

1994年和 1995年 4～ 6月在扎龙自然保护区 (4 7°2 9′N ,12 4°0 2′E)测定了 13只白琵鹭 (Platalealeucorodia)雏鸟的体重、体长、翅长、跗长和体温 ,以及环境温度。雏鸟生长符合逻辑斯谛模型 ,而 4～ 8日龄相对生长率最大。随着雏鸟日龄增大 ,体温稳步增加而且不随环境温度局部波动改变 ;冷暴露 2 5min后体温下降的幅度减小。孵出至 2 8日 ,雏鸟的体重与在巢内和冷暴露后的体温正相关 ,其体重和体长也与恒温指数正相关 ,雏鸟身体生长和恒温能力发育有某种同步关系 ,体现了晚成鸟的发育特点。     

Central connection of the optic, oculomotor, trochlear and abducens nerves in medaka, Oryzias latipes

Medaka (Oryzias latipes) is one of the few vertebrate experimental animals in which inbred lines have been established. It is also a species that has advanced in genetic studies in a manner comparable to zebrafish. This fish is therefore a good model for studying functional organization of the nervous system, but anatomical analysis of its nervous system has been limited to embryonic stages. In the present study, we investigated anatomy of cranial nerves in adult fish focusing on the visual function, using an inbred strain of medaka. Cranial nerves of medaka were labeled using biocytin, revealing a central distribution of retinofugal terminals, retinopetal neurons, and oculomotor, trochlear and abducens motor neurons. The optic nerve of the adult medaka was of a complete decussation type. Retinofugal terminals were located in 8 brain nuclei, the suprachiasmatic nucleus, nucleus pretectalis superficialis, nucleus dorsolateralis thalami, area pretectalis pars dorsalis (APd), area pretectalis pars ventralis (APv), nucleus of the posterior commissure (NPC), accessory optic nucleus, and the tectum opticum. Retinopetal neurons were identified in 6 brain nuclei, the ganglion of the terminal nerve, preoptic retinopetal nucleus, nucleus dorsolateralis thalami, APd, APv, and NPC. The oculomotor neurons were mostly labeled ipsilaterally and were located dorsomedially, abutting the fasciculus longitudinalis medialis in the mesencephalon. The trochlear nucleus was located contralaterally and dorsolaterally adjacent to the fasciculus longitudinalis medialis in the mesencephalon. The abducens nucleus was located ipsilaterally in a ventrolateral part of the rhombencephalic reticular formation. These results, generally similar to those in other teleosts, provide the basis for future behavioral and genetic studies in medaka.     

Brain morphology and immunohistochemical localization of the gonadotropin-releasing hormone in the bluefin tuna, Thunnus thynnus

The present study was focused on the morphology of the diencephalic nuclei (likely involved in reproductive functions) as well as on the distribution of GnRH (gonadotropin-releasing hormone) in the rhinencephalon, telencephalon and the diencephalon of the brain of bluefin tuna (Thunnus thynnus) by means of immunohistochemistry. Bluefin tuna has an encephalization quotient (QE) similar to that of other large pelagic fish. Its brain exhibits well-developed optic tecta and corpus cerebelli. The diencephalic neuron cell bodies involved in reproductive functions are grouped in two main nuclei: the nucleus preopticus-periventricularis and the nucleus lateralis tuberis. The nucleus preopticus-periventricularis consists of the nucleus periventricularis and the nucleus preopticus consisting of a few sparse multipolar neurons in the rostral part and numerous cells closely packed and arranged in several layers in its aboral part. The nucleus lateralis tuberis is located in the ventral-lateral area of the diencephalon and is made up of a number of large multipolar neurones. Four different polyclonal primary antibodies against salmon (s)GnRH, chicken (c)GnRH-II (cGnRH-II 675, cGnRH-II 6) and sea bream (sb)GnRH were employed in the immunohistochemical experiments. No immunoreactive structures were found with anti sbGnRH serum. sGnRH and cGnRH-II antisera revealed immunoreactivity in the perikarya of the olfactory bulbs, preopticus-periventricular nucleus, oculomotor nucleus and midbrain tegmentum. The nucleus lateralis tuberis showed immunostaining only with anti-sGnRH serum. Nerve fibres immunoreactive to cGnRH and sGnRH sera were found in the olfactory bulbs, olfactory nerve and neurohypophysis. The significance of the distribution of the GnRH-immunoreactive neuronal structures is discussed.     

The development of the static vestibulo-ocular reflex in the Southern Clawed Toad,Xenopus laevis

In the clawed toad, Xenopus laevis, the static vestibulo-ocular reflex appears in 3 days old tadpoles (developmental stage 42) (Fig. 2). The amplitude and gain of this reflex increase up to stage 52, and then decrease to an almost constant value at stage 60 and older tadpoles (Fig. 3). The most effective roll angle gradually increases during development (Fig. 4). The size of the sensory epithelia reaches the final value at the end of the premetamorphic period (stage 56) (Fig. 5). The small-cellular medial ventral vestibular nucleus (VVN) reaches its maximal number of neurons before the large-cellular lateral VVN. Cell death is more pronounced in the medial than in the lateral part of the VVN. In the dorsal vestibular nucleus (DVN), the numerical development of the small and large neurons is similar to that in the small-cellular medial and large-cellular lateral portion of the VVN (Fig. 7). The results demonstrate that labyrinth and oculomotor centres are anatomically connected before the labyrinth and the vestibular nuclei are fully developed. We discuss the possibility that the ciliary polarity pattern of the sensory epithelium is radial during the first period of life, and changes to the vertebrate fan-type pattern during the second week of life. According to the increase of gain during the first three weeks of life, an increase of the spontaneous activity of vestibular neurons may occur during this period.     

The distribution of melatonin binding sites in neuroendocrine tissues of the ewe

Specific high-affinity binding of 2-[125I]iodomelatonin (IMEL) was examined in 20-micrometer sections prepared from intact Suffolk ewes killed during late anestrus or the breeding season. The pars tuberalis contained by far the highest concentration of IMEL binding sites of all areas studied. Within the telencephalon, intense labeling was found in the mediolateral septum, the ventrolateral septal and septohypothalamic nuclei, the entorhinal cortex, the subiculum, and the inner and outer molecular layers of the hippocampus adjacent to the dentate gyrus. Melatonin binding in the medial preoptic nucleus, bed nucleus of the stria terminalis, and medial preoptic area was less striking but still distinct. Among diencephalic regions, melatonin binding sites existed in low concentrations in the anterior hypothalamus, the tuberal medial basal hypothalamus, and the paraventricular thalamic and supramammillary nuclei. Little binding was evident in the suprachiasmatic or ventromedial nuclei. In the midbrain, significant binding was restricted to the ventral raphe complex and the inferior colliculus. Little specific binding was found in the pars distalis or the pineal gland. The distribution of melatonin binding in the sheep brain is discussed in the context of the influence of this pineal hormone upon seasonal changes in neuroendocrine function.     

Effect of different photoperiods on the ultrastructure of the specific secretory cells and α-subunit mRNA level in the chicken pars tuberalis

The effect of different photoperiods on the specific secretory cells of the pars tuberalis was examined in male chicks. Animals were placed in one of three different photoperiod regimens: (1) normal control (light:dark = 12 h:12 h), (2) continuous light (L:D = 24 h:0), and (3) extended darkness (L:D = 1 h:23 h). The levels of common alpha-subunit mRNA in the pars tuberalis were examined by Northern blot analysis and compared with those in the pars distalis. In chicks exposed to continuous light for 1 week, alpha-subunit mRNA level in the pars tuberalis was decreased, although the level in the pars distalis was increased. Exposure to continuous light for 30 days also induced a decrease in alpha-subunit mRNA level in the pars tuberalis. On the other hand, in chicks exposed to extended darkness for 1 week, the alpha-subunit mRNA level of the pars tuberalis was markedly increased. In situ hybridization with digoxigenin-labeled common alpha-subunit cRNA probe also showed that the hybridization signals for alpha-subunit mRNA in the pars tuberalis cells become weak under continuous light for 30 days but they are very intense under extended darkness. Thus, the synthesis of alpha-subunits in the chick pars tuberalis was inhibited by continuous light but stimulated by extended darkness. These results were confirmed by semiquantitative electron-microscopic analyses. After exposure to continuous light for 30 days, many pars tuberalis (PT)-specific cells were filled with enlarged secretory granules, showing the reduction of secretory activity. On the contrary, extended darkness for 30 days induced hypertrophy of the PT-specific cells; the areas of cytoplasm and nucleus were significantly increased. In addition, secretory granules became small in size and exocytotic features were more frequent. Mitochondria and lysosomes were also increased in number. Thus, the synthetic and secretory activities of the PT-specific cells were increased under extended darkness. The data indicate that the specific cells of the pars tuberalis are responsive to photoperiodic changes in the chick.     

Early secretory activity in the hypothalamic nuclei and neurohypophysis in the rat; determined by selective staining

Visualization of stainable material in the neural lobe of the rat provided the most reliable index of the age at which secretory activity can first be recognized, though preceded by both hypothalamic synthesis and axonal transportation. A problem of interpretation was encountered in the neural lobes of fetal and infant animals, due to different staining responses obtained during this age period, to the two methods of staining employed; chrome alum hematoxylin-phloxin and aldehyde fuchsin after oxidation by either acidified potassium permanganate or performic acid. With aldehyde fuchsin the material of the neural lobe is stainable selectively from the eighteenth day of fetal life to adulthood. With hematoxylin phloxine the first staining response also occurred in the posterior lobe but much later, at the end of the first postnatal week. The staining situation in the pars neuralis has its counterpart in the differentiating hypothalamic nuclei; complicated by the differentiation of the supraoptic nuclei some days in advance of the paraventricular nuclei. After aldehyde fuchsin staining, evidences of neurosecretory activity were present in the perikarya of the supraoptic nuclei at birth, but mature neurons were rarely seen in the paraventricularis until at least 24 hours later. Nuclei of fetal hypothalami were not studied, but the demonstration of stainable material in the fetal neural lobes constitutes circumstantial evidence of functional competence of some neurons of either one or both types of nucleus, most likely the supraoptic.     

Topography of retinal axons in the diencephalon of goldfish

Summary The projections of horseradish peroxidase-filled axons from each quadrant of the retina were studied to determine whether retinal projections of goldfish are topographically organized in diencephalic target nuclei. A distinct topography of the dorsal, nasal, ventral and temporal retina exists in the lateral geniculate nucleus and in the dorsolateral optic nucleus of the thalamus. The projections of retinal quadrants show minimal spatial overlap in each of these nuclei. The suprachiasmatic nucleus of the hypothalamus is extensively innervated by ventral retinal fibers, whereas the nucleus is sparsely innervated by fibers from the other three retinal quadrants. A rudimentary topography also exists in the pretectum where the dorsal pretectal area receives projections primarily from the ventral retina and the ventral pretectal area receives projections mostly from the dorsal retina. These data show that retinal projections to some diencephalic nuclei are topographically organized.This work was supported by Research Grant EY-01426 to S.C.S.     

Physiology of lateral line mechanoreceptive regions in the elasmobranch brain

The physiology of mechanoreceptive lateral line areas was investigated in the thornback guitarfish, Platyrhinoidis triseriata, from medulla to telecephalon, using averaged evoked potentials (AEPs) and unit responses as windows to brain functions. Responses were analysed with respect to frequency sensitivity, intensity functions, influence of stimulus repetition rate, response latency, receptive field (RF) organization and multimodal interaction. 1. Following a quasi-natural vibrating sphere stimulus, neural responses were recorded in the medullary medial octavolateralis nucleus (MON), the dorsal (DMN) and anterior (AN) nucleus of the mesencephalic nuclear complex, the diencephalic lateral tuberal nucleus (LTN), and a telencephalic area which may correspond to the medial pallium (Figs. 2, 3, 13, 14, 15, 16). 2. Within the test range of 6.5-200 Hz all lateral line areas investigated responded to minute water vibrations. Best frequencies (in terms of displacement) were between 75 and 200 Hz with threshold values for AEPs as low as 0.005 microns peak-to-peak (p-p) water displacement calculated at the skin surface (Fig. 6). 3. AEP-responses to a vibrating sphere stimulus recorded in the MON are tonic or phasic-tonic, i.e., responses are strongest at stimulus onset but last for the whole stimulus duration in form of a frequency following response (Fig. 3). DMN and AN responses are phasic or phasic-tonic. Units recorded in the MON are phase coupled to the stimulus, those recorded in the DMN, AN or LTN are usually not (Figs. 5, 8, 9). Diencephalic LTN and telencephalic lateral line responses (AEPs) often are purely phasic. However, in the diencephalic LTN tonic and/or off-responses can be recorded (Fig. 11). 4. For the frequencies 25, 50, and 100 Hz, the dynamic intensity range of lateral line areas varies from 12.8 to at least 91.6 dB (AEP) respectively 8.9 and 92 dB (few unit and single unit recordings) (Fig. 7). 5. Mesencephalic, diencephalic, and telecephalic RFs, based on the evaluation of AEPs or multiunit activity (MUA), are usually contralateral (AN and LTN) or ipsi- and contralateral (telencephalon) and often complex (Figs. 10, 12, 16). 6. In many cases no obvious interactions between different modalities (vibrating sphere, electric field stimulus, and/or a light flash) were seen. However, some recording sites in the mesencephalic AN and the diencephalic LTN showed bimodal interactions in that an electric field stimulus decreased or increased the amplitude of a lateral line response and vice versa (Fig. 13 B).     

Selective spread of herpes simplex virus in the central nervous system after ocular inoculation.

The spread of herpes simplex virus (HSV) was studied in the mouse central nervous system (CNS) after ocular inoculation. Sites of active viral replication in the CNS were identified by autoradiographic localization of neuronal uptake of tritiated thymidine. Labeled neurons were first noted in the CNS at 4 days postinoculation in the Edinger-Westphal nucleus, ipsilateral spinal trigeminal nucleus, pars caudalis, pars interpolaris, and ipsilateral dorsal horn of the rostral cervical spinal cord. By 5 days postinoculation, additional sites of labeling included the seventh nerve nucleus, nucleus locus coeruleus, and the nuclei raphe magnus and raphe pallidus. None of these sites are contiguous to nuclei infected at 4 days, but all are synaptically related to these nuclei. By 7 days postinoculation, no new foci of labeled cells were noted in the brain stem, but labeled neurons were noted in the amygdala, hippocampus, and somatosensory cortex. Neurons in both the amygdala and hippocampus receive axonal projections from the locus coeruleus. On the basis of these findings, we conclude that the spread of HSV in the CNS after intracameral inoculation is not diffuse but is restricted to a small number of noncontiguous foci in the brain stem and cortex which become infected in a sequential fashion. Since these regions are synaptically related, the principal route of the spread of HSV in the CNS after ocular infection appears to be along axons, presumably via axonal transport rather than by local spread.     

Vocal reactions of chickens to midbrain stimulation with different electrical current parameters]

Vocal reactions of hens are realized via nucleus intercollicularis, nucleus mesencephalicus, nucleus isthmi (pars principalis magnocellularis), nucleus isthmi (pars principalis parvocellularis), formatio reticularis and other midbrain structures. These findings indicate a widespread representation of vocal centre in the midbrain of hens. Functional properties of these structures are different. Intercollicular and dorsal mesencephalic nuclei exhibit higher excitability as compared to isthmic nuclei and the reticular formation. Vocal reactions depend on the parameters of the electrical stimuli. The increase in the amplitude and frequency of stimulation facilitates vocal reaction and changes its pattern.