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Nicholas Hind 《Curtis's Botanical Magazine》1996,13(4):195-199
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羚牛(Budorcas taxicolor)部分脏器特点的观察 总被引:2,自引:2,他引:0
本文对2只羚牛的雌性生殖器官及肝、肾、脾等脏器进行了形态描述,并与黄牛及羊的相应器官进行了比较,为探讨羚牛的分类地位提供了解剖学资料。 相似文献
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巨龙竹生殖器官形态结构及雌、雄配子体的发育 总被引:2,自引:0,他引:2
通过石蜡切片的方法对巨龙竹生殖器官结构、大小孢子的发生和雌、雄配子体的发育过程进行了观察研究。 巨龙竹为一心皮组成的单室单子房,子房内具有一个胚珠,倒生、双珠被、厚珠心。大孢子母细胞减数分裂形成线形排列的4个大孢子,合点端大孢子具功能。胚囊的发育为蓼型,具多个反足细胞。巨龙竹的花药壁由4层结构组成,包括表皮、药室内壁、中层、绒毡层;花药壁发育为单子叶型,绒毡层为腺质型。小孢子母细胞减数分裂中的胞质分裂为连续型,四分孢子为四面体型;成熟花粉粒为2细胞型,具1个萌发孔。小穗发育雌雄异熟,雌蕊的发育早于雄蕊的发育。 相似文献
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短柄五加大,小孢子发生和雌,雄配子体发育的研究 总被引:6,自引:2,他引:4
短柄五加花药5枚,每个花药四个花粉囊。小孢子母细胞减数分裂时,胞质分裂为同时型,产生正四面体形的四分体。花药壁由表皮、药室内壁、中层和绒毡层四层细胞组成,其发育类型为双子叶型。腺质绒毡层,其细胞为二核。三细胞型花粉。子房5室,每室两个胚珠,上胚珠败育,下胚珠可育。下胚珠倒生,具单珠被,厚珠心。大孢子母细胞减数分裂形成线性排列的四个大孢子,雌配子体发育属蓼型。开花当天,花粉散开,雌配子体尚未成熟,处 相似文献
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维吾尔族的体质特征研究 总被引:37,自引:12,他引:25
1991年5月,对新疆伊梨维吾尔族529人(男271,女258)进行了活体观察和测量。观察29项,测量92项。维吾尔族的主要特征是:黑直发,黑褐色眼,眉毛较浓密,大都有上眼脸皱褶,鼻根中等偏高,大多为直形鼻,鼻尖向前,鼻基部下垂,大多有达尔文结节,耳垢湿型。头面部指数分型,属于特短头型,阔头型和高头型。身材中等偏高,平均身高男168.6毫米,女1578.8毫米。 相似文献
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严重缺碘对体质及遗传性状影响的研究 总被引:3,自引:2,他引:1
对严重缺碘地区一个容貌特殊,身材较矮,智力低下的人群进行了体质特征及遗传性状的研究,并与国内有关本地区的调查资料进行了对照,提出人类体质特征和遗传性状除与人种、地理环境异同直接相关外,人体不可缺少的微量元素的摄入水平在一定程度上对其也产生影响。并且认为同一人种、民族居住同一地理位置所产生的体质差异应从水文、地质、生活方式、生活水平的不同进行综合分析。 相似文献
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The skull of Morganucodon 总被引:3,自引:0,他引:3
K. A. KERMACK F.L.S. FRANCES MUSSETT H. W. RIGNEY S.V.D. F.L.S. 《Zoological Journal of the Linnean Society》1981,71(1):1-158
Morganucodon is a triconodont (atherian) mammal from the Lower Jurassic. Two species are described: M. oehleri from China and M. watsoni from Wales. The skull in M. walsoni is 26 mm long; M. oehleri is slightly larger. The dentition is differentiated functionally into incisors, canines, premolars and molars. The pineal foramen is closed. The prefrontals, postfrontals and postorbitals are lost. Septomaxilla, quadratojugal, tabular and pterygoid flanges are retained. The bony external nares are unpaired. The nasal cavity had the mammalian complement of turbinals. The posterior palate has ridges and troughs similar to those in tritylodonts, triconodonts and multituberculates. The alisphenoid ascending process is narrow and is not in contact with the anterior lamina of the petrosal, lying lateral to it. There is a cavum epiptericum, as in late therapsids. The anterior lamina forms the lateral braincase wall, perforated by the foramina pseudovale and pseudorotundum. There is a squamosal-dentary articulation, but the reptilian jaw joint is retained. The ear resembles that in later therapsids, with the tympanum in the lower jaw. The small quadrate was moveable, buttressed medially be a large stapes. Sound conduction from the tympanum was via articular, quadrate and stapes. The systematic position of Morganucodon is discussed. 相似文献
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The microfilaria of Brugia pahangi is a differentiated nematode larva. The basic nematode body plan is present showing cuticle, hypodermis, dorsal, ventral, and lateral cords, muscle cells, longitudinal nerves, papillary nerves, amphids and phasmids. Secretory granules are present in ganglionic cells and in axons in the nerve ring. There is no differentiated pseudocoelom. There is only a single row of muscle cells between each pair of cords. The excretory cell complex is similar in structure to the hypodermal gland cells of other nematodes. The alimentary canal of the microfilaria is very much modified. The pharyngeal cells are attached to the pharyngeal thread which is circular in cross section and there is no pharyngeal musculature. The intestine is represented by the solid mass of the inner body within paired intestinal cells. The intestine is separated from the rectum. The three rectal cells form a syncytium of villi in the anal vesicle. The structure in Brugia is related to the ultrastructure of other microfilariae and it is concluded that the evolution of the modifications of the basic larval structure is due to the small size of these nematodes as a consequence of their adaptation to a parasitic mode of life in the capillaries of the vertebrate host with transmission through an intermediate arthropod vector. 相似文献
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对3例川金丝猴的内分泌腺作了观察。位于垂体窝内的垂体呈扁圆球形,前后径平均为8.0mm,横径为9.0mm,垂直径为4.5mm;松果体呈扁圆锥形,松果体脚很短,松果体隐窝很小;左肾上腺呈等腰三角形,右肾上腺呈直角三角形;连接甲状腺左、右叶的峡为纤维峡,仅1mm宽;1例川金丝猴有3个甲状旁腺(左侧1个,右侧2个);胸腺右叶较长,伸至颈部形成颈叶。此外,对右肾上腺方位、形态特征的形成也作了讨论。作者认为疣猴类右肾上腺这一特征与它们胃的膨大有关。 相似文献
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扬子鳄视觉器官组织学研究 总被引:11,自引:0,他引:11
本文用光镜和电镜研究了扬子鳄(Alligator sinensis)的组织学,同时测量了其眼球的一些光学参数.扬子鳄眼球呈扁圆球形,角膜径与球径的比值为1:1.44;晶状体与角膜的比值为1:1.40。角膜内具鲍氏膜;虹膜内的括约肌、睫状体内的睫状肌均属横纹肌,视细胞椭圆体内线粒体嵴突与线粒体长轴相平行,这与报道的其它鳄类不同。虹膜内未见扩瞳肌纤维,角膜缘缺巩膜小骨片,晶状体环垫薄,因而其视觉调节能力仍然很弱。视网膜中视细胞由视杆细胞、单锥细胞、双锥细胞组成,其中以视杆细胞占多数。视细胞与神经节细胞核比值平均为2.5:1,表明扬子鳄的组织结构与其弱光视觉相适应。 相似文献
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本文记述了在江西弋阳石溪组发现的一中华弓鳍鱼。其形态特征虽与华北的师氏中华弓鳍鱼很相似,但又有很明显的差别,因此建立一新种——Sinamia poyangica, sp. nov.。在此基础上,对中华弓鳍鱼的形态变异和石溪组的时代作了讨论,并对师氏中华弓鳍鱼的复原图提出了修正的建议。 相似文献
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通过青海锡铁山铅、锌矿区植物群落和植物中铅,锌含量特征的调查研究表明:该区植被为荒漠植被类型。矿带上的植物群落与非矿带上的相比较,群落中种属数目更少,覆盖度更低,植物生长更低矮。植物灰分中的锌含量(平均)为125.9—1144ppm。膜果麻黄(Ephedra przewalskii)含量最高,变化范围最大,为86.11—5871.88ppm。植物中的铅含量为31.32—1129.6ppm。黑柴(Sympegma regelii)含量较高,变化最大,平均为746ppm,极值为14.3—5561.70ppm。在矿带上含量最高,非矿带对照区含量最低。植物及其生长的土壤中金属元素含量之间的关系,无论是铅还是锌含量都有很好的线性关系。膜果麻黄、黑柴、优若藜(Eurotia ceratoides)和中亚紫菀木(Asterothamnus centrali-asiaticus)等植物相关系数均达显著相关水平(α≤0.05)。 这在植物地球化学勘探上是非常有用的。例如中亚紫菀木和琵琶柴(Reaumuria soongorica)中铅的植物地球化学异常,准确地圈出了铅、锌矿的位置,衬度高,异常范围与矿化区基本吻合。 相似文献
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江苏泗洪下草湾中中新世脊椎动物群——6.鸟纲 总被引:6,自引:0,他引:6
本文记述了近年来在江苏泗洪下草湾组中补采到的6种鸟类,其中包括天岗琵鹭 Platalea tiangangensis sp. nov.和松林庄古石鸡 Palaeoalectoris songlinensis gen. et sp. nov.,前者系琵鹭属迄今最早的记录,后者为雉科鹑族目前已知最早的成员. 相似文献
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The Receptor-Mediated Activation of Tyrosine Hydroxylation in the Superior Cervical Ganglion of the Rat 总被引:10,自引:5,他引:5
Takeyuki Ikeno Geneva Dickens Tom Lloyd Gordon Guroff 《Journal of neurochemistry》1981,36(5):1632-1640
The addition of carbachol to superior cervical ganglia causes a rapid increase in tyrosine hydroxylation in situ. The increase occurs in ganglia from both newborn and adult animals, and in ganglia from animals pretreated with reserpine. The increase is not due to increased transport of the substrate. The increase is dependent upon the presence of calcium, and is additive to the stimulation produced by dibutyryl cyclic AMP. The stimulation seems specific for tyrosine hydroxylation; dopamine beta-hydroxylation is not increased. Preincubation experiments suggest that the carbachol-induced stimulation is due to a change in the availability of, or the affinity of the enzyme for, reduced pterin cofactor. The stimulation is inhibited by atropine and also by low concentrations of phenoxybenzamine or haloperidol, which suggests that it is caused by an action of carbachol on the interneurons in the ganglia. 相似文献
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The ovules of Amentotaxus are 2–2.5 cm in length and about 1.3 cm in width. Aril, which contains about 14—17 secretory canals in transection, is com- posed of parenchyma. The vascular bundles are absent in aril. The integument is com- posed of ceils of outer, middle, and inner regions. The middle region of the integument is about 10 cells in thickness. The Integuments are basally parenchymatous before pollination and then the cells become elongating and thickenning in middle region after pollination. Finally the micropylar canal is forced to be closed. In addition, there are 8–14 vascular bundles with centripetal xylem arranged in a ring in integument. One of the most remarkable feature of the ovule is that there is a pollen chamber formed at the top of nucellus before pollination. At this time because epidermis of nucellus does not disintegrate, the pollen chamber looks like conical in longitudinal section. After pollination the pollen chamber was becoming closed due to elongation and thickenning of cells in the middle region of integument. At the base of ovule there are 4–5 pairs of bracts which contain a larger secretory cavity and a centripetal xylem in a vascular bundle. It is interesting that wax layer of 30–40 μm thick is covered on the surface of integument, aril and bract. Usually 3–4 microsporangia which are hypodermal in origin, occur in abaxial side of a microsporophyll. In some cases the tapetum is partly enlarging and extruding into the developing tetrahedral tetrads. The mature pollen comprises an antheridial initial and a tube cell. About 20 pollen grains may germinate in the same ovule. The megaspore divide successively 8 times to produce 256 nuclei and then cell wall formation takes place. The female gametophyte is about 830–908 μm in length and 500 μm in width. The archegonia are single, terminal, and 6–7 in number. The mature archgonium, with ventral canal nucleus, is about 430 μm in length and 80–108 μm in width. The female gametophyte is often growing against the upper part of the nuceilus and makes the cells of the latter gradually to be disintegrated. The ovule construction of Amentotaxus is in some degree similar to that of Ginkgo in having a comparatively well developed pollen chamber. The mature pollen of Amentotaxus, which is similar to that of Cephalotaxus is composed of 2-cells. In sum, Amentotaxus perhaps is the most primitive genus in Taxaceae and it is closely related to Cephalotaxus. 相似文献