Choroidal and iris angioarchitecture of the newt: A scanning electron-microscopic study of vascular corrosion casts

The corrosion cast technique provided for the first time an excellent three-dimensional visualization of the vascular pattern of the choroid and iris in the newt eye. The results show the presence of a single arterial afference to the choroidal and iris capillaries: the ophthalmic artery is the origin fo both ciliary arteries and the long posterior ciliary artery. Slightly behind the equatorial circumference of the eyeball the venous drainage consists of a single vessel on the dorsal side and two distinct vessels on the ventral one. It receives blood from both iris and choroid. The surface of the plastic endocasts shows some details of fine luminal structures of the endothelial cells. Shallow depressions may be regarded as imprints of endothelial cell nuclei, and they are distinctly different for arteries and capillaries. The angioarchitecture of the newt eye differs from that of brain in that hairpin-shaped capillary loops are not observed at all.     

Transdifferentiation of larval Xenopus laevis iris under the influence of the pituitary

Fragments of larval Xenopus laevis dorsal iris implanted together with the pituitary into the tail fin transdifferentiate into neural retina. On the contrary, in the control experiments the implanted tissues, dorsal iris alone, pituitary, or dorsal iris with liver fragments, do not undergo any retinal transformation.     

Transdifferentiation of larvalXenopus laevis iris under the influence of the pituitary

Summary Fragments of larvalXenopus laevis dorsal iris implanted together with the pituitary into the tail fin transdifferentiate into neural retina. On the contrary, in the control experiments the implanted tissues, dorsal iris alone, pituitary, or dorsal iris with liver fragments, do not undergo any retinal transformation.     

Organization of contralateral and bilateral projections of corticospinal tracts in cats]

In Cats with a previous spinal lesion (C 6) saving only a lateral or ventral funiculus, a caudal horseradish peroxidase injection (C 8-Th 1) reveals that some cortical zones (lateral sigmo?d gyrus, medial part of the posterieur sigmo?d gyrus, medial part of the dorsal bank of the cruciate sulcus) send spinal projections, only contralaterally, by way of the dorsolateral funiculus, whereas other cortical zones (anterior sigmo?d gyrus, middle part of the posterior sigmo?d gyrus, lateral parts of the dorsal and ventral bank of the cruciate sulcus) send bilateral spinal projections by way of the ventral and dorsolateral funiculi.     

Induction of the mesoderm and primordial germ cells by the endoderm of Pleurodeles waltlii (Amphibia, Urodele): development during gastrulation]

Blastulae ectoderm is combined with dorsal or ventral endoderm from blastulae, gastrulae and early neurulae. In vitro culture reveals the presence of different mesodermal structures whose nature is connected with the endoderm origin site. Primordial germ cells differentiate essentially in the recombinates including ventral endoderm. The inducing capacity of this latter concerning germ cells is maximum at the beginning of gastrulation, then decreases during it and finally disappears at the onset of neurulation.     

Recurrent inhibition of the monosynaptic reflex in the upper caudal cord of the cat

Summary In spinal cats both ipsi- and contralateral antidromic volleys in the 3rd sacral ventral roots produce recurrent inhibition of the monosynaptic reflex evoked by stimulation of the 1st caudal dorsal root and recorded from the corresponding ventral root.     

Recurrent inhibition of the monosynaptic reflex in the upper caudal cord of the cat.

In spinal cats both ipsi- and contralateral antidromic volleys in the 3rd sacral ventral roots produce recurrent inhibition of the monosynaptic reflex evoked by stimulation of the 1st caudal dorsal root and recorded from the corresponding ventral root.     

Production of temperature signals in the peripherally denervated spinal cord of the dog

Summary Selective warming of the spinal cord with ventral and dorsal roots cut can generate panting in the conscious dog.     

Mitosenverteilung in der larvalen Rumpfepidermis vonSalamandra maculosa Laur.

Summary In the larval epidermal trunk region ofSalamandra maculosa, the total number of mitoses of both sides is approximately the same. This applies to the differentiated Leydig cells as well as to the rest of the epidermis cells.With respect to the meristic segmentation of the trunk, we find within the single segments a regular rise of the mitotic rate, which alternates from one side to the other.From the total number of mitoses found in the epidermis of the trunk, approximately 40% can be accounted for to the dorsal and 60% to the ventral region of the trunk. The number of cells is the same for both the ventral and dorsal region.     

A simple approach to the toad's (Bufo melanostictus) nerve muscle preparation.

A simple and modified dorsal approach method has been made in the toad's (Bufo melanostictus) sciatic gastrocnemius nerve-muscle preparation. This method incurs less blood loss, time consumption, nerve damage and visceral spoil compared to conventional ventral approach method.     

A simple approach to the toad's (Bufo melanostictus) nerver muscle preparation

Summary A simple and modified dorsal approach method has been made in the toad's (Bufo melanostictus) sciatic gastrocnemius nerve-musle preparation. This method incurs less blood loss, time consumption, nerve damage and visceral spoil compared to conventional ventral approach method.     

Distribution of thyrotropin releasing hormone (TRH), alpha-melanocyte-stimulating hormone (alpha-MSH) and somatostatin in the skin of the green frog (Rana esculenta)]

High concentrations of Thyrotrophin-Releasing Hormone (TRH) have been found in the dorsal skin of the Frog Rana esculenta, lower levels being measured in the ventral skin. alpha-MSH and somatostatin were undetectable in these tissues. Nor was TRH detected in the blood of these animals. The concentration of somatostatin in the pancreas was similar to that of the hypothalamus and twice or one hundred times higher than in the intestine or stomach respectively.     

Etude du développement des membres postériurs dePleurodeles waltlii Michah. (Amphibien,Urodèle) après la résection de l'épiderme du bourgeon

Summary Epidermis removal of the hind-limb bud of the newtPleurodeles waltlii throughout early stages of development is followed by the overlaying of stripped mesodermal bud by the epidermis of the dorsal and ventral fins. This removal never gives any deficiency of the proximo-distal sequence of the limb.     

针对东方人黑色虹膜识别的光谱选择

本文以东方人黑色虹膜作为研究对象,进行两方面研究:1)对于单一光谱照明,找到某一个最适合东方人黑色虹膜的光谱段;2)对于多个光谱照明,确定东方人黑色虹膜所需要的光谱段数量.第一部分研究中,采用改进的卷积矩阵与频谱能量相结合的算法,对虹膜纹理质量进行评估;采用改进2-DGabor与1-DLog-Gabor相结合的编码方法,获得虹膜匹配性能的指标.实验显示:针对单一光谱照明,700nm对于东方人的黑色虹膜是最优的光谱段.第二部分研究中,采用改进multi-group(2D)2PCA算法,基于多光谱虹膜图像的最大不相关性进行层次聚类分析.实验显示:针对多个光谱照明,3个主聚类可以最好地描述从545nm到940nm的所有光谱段.以上研究在该领域内具有开拓性,解决了东方人黑色虹膜多光谱采集与识别的基础问题,为东方人黑色虹膜的多光谱融合提供了理论依据.     

Selective antagonism by Mg2+ of amino acid-induced depolarization of spinal neurones.

In the isolated frog or rat spinal cord, low concentrations of Mg2+ (0.5-1.00 mM) markedly depress, in a substantially Ca2+-independent manner, ventral root depolarizations produced by dorsal root stimulation and by certain amino acids (e.g. N-methyl-D-aspartate and L-homocysteate) but do not depress depolarizations produced by other excitatory amino acids (e.g. kainate and quisqualate). L-Aspartate-induced depolarizations are more sensitive to Mg2+ then are L-glutamate-induced depolarizations.     

A sensorory input inhibiting heart rate in an insect,Rhodnius prolixus

The dorsal vessel of the blood feeding insect,Rhodnius prolixus, was found to increase or decrease its rate of contraction in response to a number of different stimuli. Handling increased contraction rates whereas tactile stimulation of the ventral abdominal cuticle inhibited contraction. Injection of very low concentrations of serotonin or of high concentrations of octopamine enhanced the inhibitory effect, apparently by acting via the nervous system. Higher concentrations of serotonin increased heart rate by acting directly on the myocardium. The inhibitory response is suggested to be one facet of a generalised thigmotactic response.     

Selective antagonism by Mg2+ of amino acid-induced depolarization of spinal neurones

Summary In the isolated frog or rat spinal cord, low concentrations of Mg²⁺ (0.5–1.00 mM) markedly depress, in a substantially Ca²⁺-independent manner, ventral root depolarizations produced by dorsal root stimulation and by certain amino acids (e. g. N-methyl-D-aspartate and L-homocysteate) but do not depress depolarizations produced by other excitatory amino acids (e. g. kainate and quisqualate). L-Aspartate-induced depolarizations are more sensitive to Mg²⁺ then are L-glutamate-induced depolarizations.Acknowledgment. We thank D. J. Oakes for skilled technica assistance. This work was supported by the Medical Research Council.     

Adrenergic supersensitivity of the pupil in idiopathic headache.

In idiopathic headache (IH) sufferers, phenylephrine and fenfluramine induce a pupillary dilatation respectively greater and lesser than in controls. The difference may be due to a supersensitivity of the iris alpha adrenoceptors caused by a deficiency of noradrenaline in the iris adrenergic nerve terminal of the IH sufferer. These findings seem to support the hypothesis of a brain receptorial, monoamine supersensitivity in IH.     

Transdifferentiation of larvalXenopus laevis iris implanted into the amputated hindlimb

Summary Fragments of larvalXenopus laevis iris, autoplastically implanted into the stump of the amputated hindlimb, transdifferentiated into neural retina. However, when such iris fragments were implanted into the caudal fin, no transdifferentiative process was observed.Supported by grant from the P.I. ministry.     

Adrenergic supersensitivity of the pupil in idiopathic headache

Summary In idiopathic headache (IH) sufferers, phenylephrine and fenfluramine induce a pupillary dilatation respectively greater and lesser than in controls. The difference may be due to a supersensitivity of the iris alpha adrenoceptors caused by a deficiency of noradrenaline in the iris adrenergic nerve terminal of the IH sufferer. These findings seem to support the hypothesis of a brain receptorial, monoamine supersensitivity in IH.This study was supported by a grant from the National Research Council, Rome, Italy.