首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 427 毫秒
1.
Summary The differentiation of the spermatid, especially in reference to the formation of the flagellum, and transformation of the shape of the nucleus was investigated in the domestic fowl.In the early stage of the spermatid, a prominent Golgi apparatus appears around the centrioles. The Golgi vesicles then surround the axial-filament complex which develops from the distal centriole. These vesicles fuse to form continuous membrane at the earliest stage of flagellar formation, and in the succeeding stage Golgi lamellae are attached to the plasma membrane of the developing flagellum. From these observations, it is assumed that Golgi apparatus may be a source of the membrane system of the flagellum.The microtubules distributed around the nucleus form the circular manchette. The anterior region of the nucleus with the manchette is cylindrical in shape and the posterior region without it remains irregular in shape. When the circular manchette has been completed, the whole nucleus acquires a slender cylindrical shape. The circular manchette then changes into the longitudinal manchette. The nuclei of spermatids without a longitudinal manchette are abnormal in shape. In view of these observations it is assumed that the nuclear shaping of the spermatid may be accomplished by circular manchette and the maintenance of shape of the elongated nucleus by longitudinal manchette.The authors wish to thank Mr. Takayuki Mori for his helpful suggestions and technical advices  相似文献   

2.
Chosen at random 38 diastolic preparations of human hearts from persons having not any cardiac pathology, as demonstrate the postmortem examination, have been investigated. The left ventricle casts have been made during the first 24 hours after death according to a strictly fixed technique by means of filling the cardiac chambers with polymere mass--protacryl--under a physiological pressure of the diastolic filling. The trabecules are arranged as a spiral from the apex of the ventricle up to the atrioventricular fibrous ring, with approaching the apex the spiral step increases and the trabecules straighten. The left ventricle cast is devided into some planes, the envelopes and the trabecularity lines are measured. Average values of the shift in the trabecularity lines I, II, III and in the cross sections B, C, D, E are defined in relation to the plane A and in every case in relation to the previous plane Cn-1. The data obtained are presented in tables and diagrams. The greatest shift demonstrate the trabecularity lines I running predominantly along the posterior wall of the left ventricle in the planes B and which are situated nearer to the atrioventricular ring projection. Owing to the presence of the spiral-shaped course of the trabecules, it is possible to suppose that it influences the blood stream twisting clockwise in the left ventricle during the diastole phase. This indicates the necessity to work out some new constructions of artificial cardiac valves, securing the twisted blood stream. The condition mentioned should be taken into consideration while making prostheses of the cardiac valves.  相似文献   

3.
The spinal cord in 25 non-inbred dogs has been studied macro-microscopically. The dissymmetry in the arrangement level in the right and left root bases on the dorsal surface of the spinal cord is much greater than on the ventral surface. The same as in the human being, the dissymmetry is the greatest in the thoracic part (as compared to other spinal parts). On the ventral surface of the spinal cord both along the anterior and posterior margin of the root bases, there is a right-sided dissymmetry (with cranial shift); on the dorsal surface it is present only at the roots along the posterior margin. The dissymmetry of the dog spinal cord is quantitatively estimated along its whole extension.  相似文献   

4.
The paper presents results of miospore studies on Carboniferous strata from drillings made in the last 20 years in several regions in marginal zones of the East-European Platform in Poland (Lublin Coal Basin, Warsaw, Płock, and Bydgoszcz regions, and western Pomerania). In that area the Carboniferous is represented by Dinantian and Silesian strata, from the Tournaisian to Westphalian D.Because of differences in geological development of the Carboniferous and in composition of microfloristic assemblages from strata of that age in the above mentioned regions the first stage of the studies had to be aimed at compilation of local palynostratigraphic schemes for individual regions. The next stage involved compilation of a regional palynostratigraphic scheme for the whole area of Polish margin of the East-European Platform. The scheme comprises 16 spore zones of the concurrent-range-zone type: 6 for the Dinantian and 10 for Silesian. The detailed characteristics of miospore assemblages and age correlations of the zones are given.The proposed scheme was subsequently compared with that proposed for the Carboniferous in western Europe. The comparison showed marked similarities in ranges of taxa diagnostic for individual stratigraphic units in both schemes.  相似文献   

5.
This study aimed to analyze the aqueous humor (AH) and the vitreous body (VB) of the eye of the adult frog Rana temporaria L. as a representative species of amphibians, which lead a semi-terrestrial life. The presence of collagen, albumin, uric acid and electron donors was shown in both media; however, there are slight differences in their concentrations. To determine collagen, a spectral-fluorescent probe, cyanine dye, was used. The presence of collagen in AH of the frog was found at the first time. The total content of electron donors (ascorbic and uric acids, tryptophan, and tyrosine) in VB and HA was roughly estimated at ~ 1.5 × 10− 4 mol/L. Both VB and AH absorb light in similar UV regions. The total protein and albumin contents in AH were found to be somewhat higher than those in VB. The uric acid content was at an equally low level in both intraocular media. It is supposed that the similarity of VB and AH compositions shown in this work is due to some exchange between VB and AH contents in the course of accommodation. The role of intraocular fluids in physiological functions of the eye and in protecting the retina against UV light is discussed.  相似文献   

6.
K. Hausmann 《Protoplasma》1979,100(2):199-213
Summary The membranes of the pellicle of the ciliatePseudomicrothorax dubius are investigated using thin section electron microscopy and freeze-fracture replicas. The plasma membrane is covered by a surface coat and is connected to the outer alveolar membrane by short, sometimes branched, bridges. The inner alveolar membrane is coated on both sides. The epiplasm lies in intimate contact with the cytoplasmic surface of this membrane, and there is a corresponding deposit on the other surface. This deposit is regularly striated.The epiplasmic layer and the alveoli are interrupted at sites of cytotic activity,e.g., the attachment sites of trichocysts, the cytoproct, and the parasomal sacs. The striated deposit ends where the epiplasm ends, indicating a direct relationship between these two epimembranous layers.There is a deposit along the sides of the first part of the tip of the trichocysts, and in this region the trichocyst membrane is free of intramembranous particles.The membrane of the parasomal sacs has a coat on both surfaces. That on the extraplasmic surface is similar to the surface coat of the plasma membrane. The origin of the cytoplasmic coat is unknown. The cytotic activity of these sacs is indicated by their highly irregular profiles.  相似文献   

7.
The yeast Candida tropicalis, Candida utilis, Trichosporon cutaneum were cultivated on the synthetic medium containing additions of group B vitamins (biotin, thiamin) and glucose, glycerol of lactic acid as the sole source. The protein content, amino acid composition, nucleic acids and complex B vitamins were identified in the resultant biomass. The carbon source in the medium affected these indices. The protein and nucleic acid content also depended on the yeast strain.  相似文献   

8.
In the bottlenosed dolphin (Tursiops truncatus) the hypothalamic corpus mammillaris has been studied using interperpendicular, sagittal, frontal and horizontal serial sections, impregnated in silver and stained with cresil-violet. Comparatively small dimentions of the corpora mammillaria in the bottlenosed dolphin are explained by presence of only two nuclei, medial and lateral. The lateral nucleus is nearly three times as large as the medial one. The size of the neurons in the medial nucleus is on the average two times as large as that of neurons in the lateral nucleus. The density of the neural cells distribution is a little greater in the lateral nucleus. The structure of the bottlenosed dolphin corpora mammillaria is compared with similar structures in other animals and the human being.  相似文献   

9.
The figure of tetrahedron is formed in certain species of Plectus and in Tobrilus gracilis at the stage of 4 blastomeres rather than a rhombus which is formed in most highly organized nematodes. The analysis of the Nematoda's embryogenesis allows to conclude that tetrahedron, rhombus as well as some other figures play the role of preblastula sustaining the most expedient disposition of the first blastomers for transition to the formation of the blastula. With the increasing organization of nematodas the tetrahedron preblastula turns into a rhombic, linear-rhombic and at last in aphelenchoid-tylenchoid one. The character of the distribution of structural elements of organs and tissues of the definitive animal in the cytoplasm of the egg of Plectus and Tobrilus confirms the rightness of the division of the class of nematodas into subclasses Enoplia and Chromadoria rather than subclasses Adenophorea and Secernentea.  相似文献   

10.
A Vercelli  C Cracco 《Acta anatomica》1989,134(3):177-183
The mean area of the neuromuscular endplates and the acetylcholinesterase (AChE) activity at the myotendinous junction of the ischiocavernosus muscle were studied in normal, castrated and testosterone-treated castrated Wistar rats by the Koelle method. The mean endplate area was found to be smaller in castrated rats, compared to normal ones (p less than 0.001), while testosterone treatment restored its normal size (0.8 greater than p greater than 0.7). The terminal AChE activity in castrated rats was as strong and spread as in juvenile ones, while it was almost absent in normal and in testosterone-treated castrated rats. The same parameters were examined in the tibialis anterior muscle of the same rats, chosen as a specimen of 'nonhormone-dependent' muscle, without finding any difference among the single groups.  相似文献   

11.
The electrical activity of the sphincter of Oddi and gastro-intestinal tract had been recorded on 21 negative atropineesterase conscious rabbits by means of chronically implanted electrodes located in the digestive wall. An analysis of the action of different spasmolytic and analgesic drugs was realized. Electromyograms of the sphincter of Oddi presented (a) isolated or in series spike potentials occurring independently of electrical activities of the duodenum (b) recurring spike potentials correlated with intestine spikes. The independent activity of the sphincter of Oddi was not controlled by the cholinergic system, contrary to the intestine-dependent activity (effect of the fempiverinium, atropine like drug). The pitofenone had inhibited the spike potentials of both the sphincter and intestine because its papaverinic effect. The noramidopyrine, analgesic drug without morphine-like effects, had induced activation and inhibition at low and high posology respectively.  相似文献   

12.
The optimal shape of the front profile of the thick lens in the eye of the scallop,Pecten is theoretically, geometric optically investigated as a function of the refractive index of the lens and the retina, as well as of the geometrical parameters of the eye. The shape of the theoretical front surfaces is compared with that of the real, experimentally determined front face of the lens. The degree of correction of the lens for spherical aberration of the reflecting spherical mirror in thePecten eye is examined. The optimal shape of the front profile of the lens depends strongly on a set of parameters, such that a certain fine tuning is required among them to assure a full correction for spherical aberration. The extreme variability of the eye parameters and the shape of the front face of the lens in the scallop is inconsistent with this fine tuning requirement. The degree of correction of thePecten lens for spherical aberration might not be as good as it could be, a possible biooptical reason for which is discussed.  相似文献   

13.
The causes of differences in the reaction of spermatozoa of the fresh-water (morpha leiurus) and marine (m. trachurus) forms of three-spined stickleback Gasterosteus aculeatus to the high sea water salinity (the upper limit of spermatozoan motility being 18% and 52%, resp.) were investigated. The experiments with solutions of pure NaCl, CaCl2, MgCl2, KCl, LiCl (25 g/l) have shown that the movement of spermatozoa of m. leiurus is inhibited by NaCl only. The inhibition of chlorine channels of the plasma membrane by a specific inhibitor furosemide has shown that the activity of spermatozoa of m. leiurus is suppressed by the high Na+ concentrations. The experiments with ATP have revealed no differences in the activity of Na pump between the spermatozoa of mm. trachurus and leiurus. Amyloride, an inhibitor of Na channels, at a concentration of 1.10(-5) M relieved the inhibiting effect of the high Na+ concentrations on the activity of spermatozoa of m. leiurus. The differences in the reaction of spermatozoa of two forms of the stickleback appear, to be determined by differences in Na channels of the plasma membrane.  相似文献   

14.
N A Dmitrieva 《Tsitologiia》1986,28(7):745-748
The developing taste buds of vallate papillae were studied with electron microscope in rats during the first 7 days after birth. Two types of cells--light and dark--are identified in the taste buds of a one day old animal. The apical parts of dark cells are characterized by numerous dark granules. A distinguishing feature of light cells is the presence of synaptic contacts with afferent intragemmal nerves. On the 4th day of development on the top of the apical parts of the cell, a microvillar apparatus is seen to form, which does not yet communicate with the oral cavity. On the 7th day, basal cells appear in the taste buds. Some of these cells are seen mitotically dividing. The differentiated microvillar apparatus now communicates with oral cavity. The structure of the taste buds is getting similar to that in the adults. The structural and functional peculiarities of the developing taste buds are discussed in association with the period of ontogenesis under consideration.  相似文献   

15.
The electrophoretical polymorphisms of some blood proteins were studied in the Talysh population of Pirasora situated in South-East Azerbaidjan. We calculated the gene frequencies of these polymorphisms and determined the genetic distances between the Talyshes and some Iranian populations of North, Central and South Iran, Afghans, and three populations of Azerbaijan. The Talyshes are very close to Iranians of Shiraz, whereas they are distant from the Azerbaijanians. Anthropological investigations showed that the Caucasoids and Mongoloids lived in the Aragvi Basin since the Eneolithic period. This was stated by Alexeev (1974), who emphasized the mixture of the Caucasus populations from ancient times on. We calculated the genetic distances between the Caucasus populations and numerous populations of other geographic regions, considering 28 alleles of 12 loci of blood group, serum protein and red cell enzyme polymorphisms and constructed the dendrogram of these populations. The position of the Caucasus populations in the dendrogram corresponds on principle to the earlier anthropological observations. The clustering of the Caucasoid populations corresponds completely with anthropological and historical data, and supports our earlier hypothesis (Nazarova 1999) concerning the differentiation of Caucasoids, Northern Mongoloids and Amerinds from the populations, which inhabitated Asia in palaeolithic times.  相似文献   

16.
On the origin of the Hirudinea and the demise of the Oligochaeta   总被引:10,自引:0,他引:10  
The phylogenetic relationships of the Clitellata were investigated with a data set of published and new complete 18S rRNA gene sequences of 51 species representing 41 families. Sequences were aligned on the basis of a secondary structure model and analysed with maximum parsimony and maximum likelihood. In contrast to the latter method, parsimony did not recover the monophyly of Clitellata. However, a close scrutiny of the data suggested a spurious attraction between some polychaetes and clitellates. As a rule, molecular trees are closely aligned with morphology-based phylogenies. Acanthobdellida and Euhirudinea were reconciled in their traditional Hirudinea clade and were included in the Oligochaeta with the Branchiobdellida via the Lumbriculidae as a possible link between the two assemblages. While the 18S gene yielded a meaningful historical signal for determining relationships within clitellates, the exact position of Hirudinea and Branchiobdellida within oligochaetes remained unresolved. The lack of phylogenetic signal is interpreted as evidence for a rapid radiation of these taxa. The placement of Clitellata within the Polychaeta remained unresolved. The biological reality of polytomies within annelids is suggested and supports the hypothesis of an extremely ancient radiation of polychaetes and emergence of clitellates.  相似文献   

17.
Summary The epithelial reticular cells of the thymic medulla of the golden hamster were studied by electron microscopy. On the basis of their structural details two cell types are distinguished, although the two types are similar in basic structure. The cells of one type are more extended in shape and darker in appearance. They are connected with one another by their cytoplasmic processes, forming a reticulum in the medulla. Thus they appear to play a supporting role as do the cortical epithelial reticular cells. The other cell type is larger, more rounded and lighter. The characteristic feature of this cell type is an abundance of vesicular structures, which occur as vesicles or vacuoles of varying sizes. In addition, an enormous, intracytoplasmic ciliated cyst is occasionally encountered in the latter cell type. The cyst may be regarded as representing a specialized form of the vesicular structures. The possible functional significance of the latter cell type is discussed in relation to recent concepts concerning the mechanism of thymic function.Dedicated to Professor W. Bargmann, under whose guidance my thymus studies were begun, in honor of his 60th birthday (T. Ito).  相似文献   

18.
The analysis of the spread of bacteria of the genus Acinetobacter among the invertebrate animals of the Bay of Peter the Great (the Sea of Japan): in bivalved mollusks, sea cucumbers and sea urchins Acinetobacter bacteria were detected more often than in cushion stars and crustaceous animals. The biological properties of 45 isolated bacteria were studied with the use of a wide variety of tests. The study revealed that 9% of Acinetobacter cultures isolated from marine animals had pronounced beta-hemolysis.  相似文献   

19.
Summary The choriocapillaris is a fenestrated capillary bed located posterior to the retinal pigment epithelium. It serves as the main source of supply to the photoreceptors, retinal pigment epithelium, and other cells of the outer retina. The permeability of these capillaries to intravenously injected ferritin (MW — approx. 480,000; mol. diam. 11 nm) was examined in the mouse, rabbit, and guinea pig, each of which is characterized by a different type of retinal vascularization. In all three species, the bulk of the ferritin remained in the capillary lumina, where it appeared to be blocked at the level of the diaphragmed fenestrae. Some ferritin was present in endothelial cell vacuoles. The results confirm previous work on the rat choriocapillaris and indicate that the barrier function of the choriocapillary endothelium is present even among species in which the retinal circulation differs significantly.Supported by NIH grant EY03418  相似文献   

20.
DNA contents in squashed cells of the adult frog hypothalamic preoptic region (HPR) were measured using the Feulgen and UV cytophotometry techniques. The histone-DNA ratio in the cell nucleus was determined by means of a combined Feulgen-heparin-Alcian blue staining procedure. The nuclei of the vast majority of HPR cells have a diploid DNA content. However, in cells of this group the mean values of DNA amount and the distribution range were always higher than those in hepatocytes used as a diploid standard. Such a heterogeneity in DNA content in the diploid part of HPR cell population could apparently suggest some differences in the nuclear chromatin arrangement to be always higher in spring before the frog spawning, and it seems to be characteristic of this type of cells. About 1 per cent of cells with hyperdiploid surplus of DNA (H2c cells) as well as of tetraploid cells (4c and 2c X 2 cells) is found in HPR in frogs sacrificed both in winter and in summer. The quota of these cells has no reference either to the frog's age or to the annual cycle. The fact that the mean DNA values in H2c and 4c cells are much higher than in the standard cannot be explained by the presence of different amounts of nuclear proteins only. It is suggested that at least some part of the highest DNA values may be due to an actual extra DNA synthesis in a small constantly existing pool of HPR cell population.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号