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 31 毫秒
1.
长吻鮠精巢及精子结构的研究   总被引:11,自引:0,他引:11  
长吻鮠精巢高度分支呈指状。后1/3紫红色,由上皮细胞组成,既不产生精子,也不贮存精子。精巢的内部结构为叶型,由体细胞和生殖细胞构成,小叶的基本单位是小囊。精子头短而圆,主要为核占据,无顶体,核凹窝十分发达,有中心粒帽;尾极长,具侧鳍,轴丝基部有发达的囊泡状结构和线粒体。  相似文献   

2.
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   

3.
本文就以下几方面对我国植物生态学和地植物学作了回顾与展望。一、回顾:1.亚热带和热带森林区的植被研究。2.温带森林区的植被研究。3.温带草原区的植被研究。4.温带荒漠区的植被研究。5.青藏高寒高原区的植被研究。6.中国植被及其地理、分区和植被图研究。7.环境植物学的研究等。二,展望1.植被基本理论的研究2.植被图志的编制和植被制图学研究 3.栽培植物群落和经济植物生态学特性研究4.实验群落学和植物生理生态学研究5.陆地生态系统的结构和功能的研究6.环境保护的植物生态学研究7.植物和植物群落指示性研究  相似文献   

4.
四川自贡大山铺蜀龙动物群——简报Ⅲ.蜥脚类   总被引:4,自引:2,他引:2  
本文记述了中侏罗世蜥脚类一新属种——巴山酋龙(Datousaurus bashanensts gen. et sp. nov.)对李氏蜀龙(Shunosaurus lii)的特征进行了补充,讨论了它们在蜥脚类进化过程中的位置。  相似文献   

5.
马蹄香大小孢子发生及雌雄配子体形成   总被引:1,自引:0,他引:1  
马蹄香(Sarumahenryi,Oliv.)花药壁的发育属双子叶型。花粉母细胞减数分裂为同时型,四分体主要为四面体形,少数为左右对称式排列。腺质绒毡层,其细胞可排列为不规则的两层,双核或多核。到单细胞花粉阶段,绒毡层细胞内切向壁上出现许多乌氏体。成熟花粉为2细胞型,圆球状,具单萌发沟。雌蕊6心皮,上部彼此分离、下部联合。倒生胚珠,双珠被,厚球心。胚囊发育蓼型。成熟胚囊为七细胞结构,但两个助细胞退化较早。  相似文献   

6.
本文详细描述了菱臼齿兽耳区各个部分的基本结构;并指出了耳区结构与某些啮齿类的相似性,以及中耳鼓泡组成成份与戈壁(犭亚)兽(Anagale gobiensis)的区别。  相似文献   

7.
本文对糖密草(MelinisminutifloraBeauv.)的幼穗分化发育及花和果实的形态作了研究,将幼穗分化发育过程划分为以下九个时期:第一苞原基形成期;第一次枝梗原基形成期;第二、三次枝梗原基形成期;小穗及颖花原基形成期;雌、雄蕊原基形成期;花粉母细胞形成期;花粉母细胞减数分裂期;花粉充实期;花粉成熟期。全过程历时约需42d.从抽穗到颖果成熟约需50d。糖蜜草的花序为圆锥花序。每花序有可育花2000—3000朵.小穗是由小穗轴、内外颖片、不育花外稃和小花构成。小花包括有内外稃各一片、一鳞被、雄蕊三枚和一枚雌蕊,颖果千粒重为91mg。  相似文献   

8.
鳗鲡肝脏、脾脏显微与超微结构   总被引:27,自引:0,他引:27  
郭琼林  卢全章 《动物学报》1994,40(2):125-130
经光镜和电镜观察发现:鳗鲡肝脏的肝小叶不规则。肝细胞胞质内富含多种细胞器及包含物。胆小管由2—4个肝细胞围成,相邻肝细胞间有连接复合体封闭胆小管。肝血窦为有孔型、孔处无隔膜,内有巨噬细胞。窦周隙明显,未见贮脂细胞。肝细胞向胆小管腔与窦周隙面伸出许多指状微绒毛。脾脏内白髓中淋巴细胞聚集成群,未见明显脾小结、淋巴鞘。红髓由脾索与脾窦组成,动脉分支末端(壁厚的毛细血管)可开放于红髓,无明显巨噬细胞中心。脾窦及脾小动脉内皮细胞通常为长杆状、沿血管纵向平行排列。脾窦为有孔型,孔处可见薄的隔膜。脾小动脉内皮外为2—5层平滑肌(多数为纵行)。  相似文献   

9.
芒苞草形态学和胚胎学研究:Ⅱ.花药和胚珠发育的研究   总被引:3,自引:0,他引:3  
李平  高宝莼 《植物研究》1992,12(4):389-398
芒苞草成熟胚珠为倒生型,薄珠心,双珠被。胎座为侧膜胎座向中轴胎座的过渡类型。胚囊发育为单孢蓼型。 成熟胚囊由印器,具二极核的中央细胞及三个反足细胞组成。助细胞呈倒梨形,极性不明显,珠孔端壁有角状的丝状器。中央细胞的二极核在受精前融合为次生核。 花药具二个小孢子囊,花药壁层为单子叶型,具分泌型绒毡层,小孢子母细胞减数分裂时,胞质分裂为连续型,四分体是左右对称式排列,成熟花粉粒为二细胞的。 在花药与胚珠发育过程中,多糖物质的消长是有规律的变化。  相似文献   

10.
红皮树胚胎发育   总被引:3,自引:0,他引:3  
本文报道红皮树(Styrax suberifoltus Hook.et Arn.)大小孢子发育和早期胚胎发生。子房具胚珠20—23枚,胚珠横生,珠被二层,薄珠心,孢原细胞直接起大孢子母细胞作用。合点端大孢子具功能。胚囊发育为正常型。成熟胚囊具大量淀粉粒。小孢子形成为同时型,成熟花粉为二细胞型。传粉后、受精前两个助细胞在形状和对苏木精着色程度上有显著区别。胚乳发育为细胞型。在合子分裂前,胚乳细胞增至约26个时,暂时停止分裂。苏木精对细胞质不易着色,似解体细胞。有胚乳吸器。  相似文献   

11.
新疆蒙古族体质人类学研究   总被引:41,自引:11,他引:30  
1991年对新疆伊犁20-55岁的蒙古族人群进行了活体观察(533例)和活体测量(209例)。结果表明,蒙古族的主要特征是:黑发直发,黑褐色眼,90%以上的个体眼内角有蒙古褶,大多为狭鼻型,突唇者居多,约50%个体耳廓在达尔文结节,耳垢大多是干型。头面部指数分型,大多属圆头型。身材较高大,平均身高男1690毫米,女1565.1毫米,身材在中等以上者占大多数(男81.2%,女73.9%)体格健壮,平  相似文献   

12.
The structure of the flagellar apparatus in the excavate flagellate Parabodo nitrophilus Skuja has been studied. Two smooth heterodynamic flagella emerge from the bottom of the flagellar apparatus. The kinetosomes connected by their proximal ends lie under an acute angle to each other and bear against the plate on the anteior wall of kinetoplast. The dorsal and ventral rootlets emerge from the kinetosomes and are transformed into dorsal and ventral bands. The latter accompanies the posterior flagellum. The MTR band begins inside the wall of the flagellar pocket. The upper part of the cytopharynx is armored by MTR and FAS bands, cross-banded fibril and structure, and additional microtubules. The MTR band and three additional microtubules surround the bottom part of cytopharynx. The mitochondrium contains compact kinetoplast and discoid cristae. The resemblance of Parabodo nitrophilus with other free-living kinetoplastids is discussed.  相似文献   

13.
四川自贡发现合川马门溪龙新材料   总被引:1,自引:0,他引:1  
叶勇  欧阳辉  傅乾明 《古脊椎动物学报》2001,39(4):266-271,T001
记述了产自四川自贡上侏罗统的一具较完整的蜥脚类恐龙骨架 ,将其归入合川马门溪龙 (Mamenchisaurushochuanensis)中。新材料的发现弥补了合川种正型标本的不足 ,对合川种的特征作了重要补充 ,同时也使我们对马门溪龙的末端尾椎形态有了新的认识。  相似文献   

14.
The absorption of H2O and D2O was studied in seeds with different reserve food materials represented by barley and rice (starch), linseed and mustard (fat) and mung, and kidney beans (protein). Respiration rate and respiratory quotient during absorption were also measured. The results indicate that the water absorption profiles of the starchy and fatty seeds are essentially similar but differ from that of The proteinaceous type. Initial hydration is relatively incomplete in D2O in all The seeds to varying degrees the latter being maximum in The proteinaceous and minimum in The starchy seeds. The respiration rate is lower in D2O while The R.Q. values are higher for The first hour but lower later on. The results, in part, help explain The varying effects of D2O on The germination of different types of seeds. These studies also support The earlier reported preference (Cope et al. 1965) by the higher plant systems for protium.  相似文献   

15.
泥螺生殖系统的组织学   总被引:6,自引:2,他引:4  
泥螺为雌雄同体。生殖系统包括交媾器和生殖器本部。交媾器包括刺激器、阴茎和摄护腺;生殖器本部主要包括两性腺、缠卵腺和蛋白腺。刺激器和阴茎都具有非常发达的肌肉组织,腔壁游离面具纤毛。阴茎腔壁为单层柱状细胞;摄护腺被膜为一层薄的肌纤维,里面具有许多分泌细胞;缠卵腺被膜为单层扁平上皮,下层为环肌,腺体组织由分泌小管构成。蛋白腺主要由皮质层和导管层组成,皮质层内充满了分泌细胞,导管层由许多分泌小管构成,管壁为柱状腺细胞。  相似文献   

16.
The ultrathin structure of the amoeboid flagellate Thaumatomonas coloniensis Wylezich et al. has been studied. The cell is surrounded by somatic scales forming on the surface of the mitochondria. The heterodynamic flagella emerge from the small flagellar pocket. Both flagella are covered by pineal scales and thin twisted mastigonemes. The kinetosomes lie parallel to each other. The transitional zone of the flagella carries the thin-walled cylinder. The transversal plate of the flagella is above the cell surface. The flagellar root system consists of three microtubular bands and a fibrillar rhizoplast. The vesicular nucleus and Golgi apparatus are of the usual structure. The mitochondria contain tubular cristae. The extrusive organelles (kinetocysts) contain amorphous material and a capsule; they are located in cytoplasm. The capsule consists of a muff and cylinder. Osmiophilic bodies of various shapes contain crystalloid inclusions. The pseudopodia capturing the bacteria emerge from the ventral groove. The groove is armored by the two longitudinal groups of the close situated microtubules. Microbodies and symbiotic bacteria have not been discovered. The resemblance of Th. coloniensis with other thaumatomonads is discussed.  相似文献   

17.
鞑靼滨藜(Atriplex tatarica L.)药壁4层细胞,中层1层;绒毡层腺质型。孢原细胞1列或2弄;同花药异花粉囊小孢子母细胞减数分裂为同步,同花粉囊减数分裂大部分同步,部分非同步;四分孢子多为四面体形,少数是左右对称形,胞质分裂同时型;成熟花粉粒为风状饰纹,3-细胞型;单子叶型药壁。弯生胚珠,厚珠心型;双珠被,四分子孢子直线。反足细胞受精前退化,属蓼型胚囊。胚的发育为藜型,胚乳细胞在球  相似文献   

18.
利用石蜡切片法对中华花龟的心脏、肝脏、脾脏、肺和肾脏等组织器官进行了组织学观察.结果显示心肌的特点是暗带较窄,心肌纤维束状排列.肝脏分3叶,肝实质内结缔组织少,肝小叶分界不清楚.脾脏分被膜和实质两部分,实质由白髓和红髓构成,白髓包括椭球周围淋巴鞘(PELS)和动脉周围淋巴鞘(PALS),红髓由脾索和脾窦组成,未发现淋巴小结和生发中心.肺一对,为长形扁平囊,肺泡囊状,肺泡内可见管壁的结节状膨大.肾脏由肾小体、颈段、近曲小管、中间段、远曲小管和收集管6部分构成,肾小体由肾小球和肾小囊组成,在肾小体附近可见致密斑样结构.  相似文献   

19.
This paper presents a detailed report on the developmental progresses of the microsporangium and its microspores in Azolla filiculoides Lam., and shows the morphologicaI structures of the respective developmental stares with the aid of scanning electron photographs. The entire developmental progress may be divided into six stages: ( 1 ) The microspore mother cell initiating stage The microsporangium initial on the placenta of the sporocarp gave rise a sporogenous cell, and then divided four times to form sixteen microspore mother cells; (2) The meiotic stage–The microspore mother cells initiated meiosis inside their calIose walls. The radial and inner tangential walls of the tapetum were dissolved at the same time and followed by the formation of a sporoplasmodium; (3) The microspore shrinking Ⅰ–After the callose walls of tetrads was dissolved, those microspores that just released from the callose walls shrunk intensely and became spherical later again. The sporoderm of microspores was principally synthesized in this stage, and the volume of microspores became evidently increased. The microspores then gradually moved to the periphery of the sporoplasmodium; (4) The microspore shrinking Ⅱ-Each microspore formed a large vacuole and gave rise the second contraction. The periphery of the sporoplasmodium was gradually dissolved; (5) The massulae forming stage–The sporoplasmodium was dissolved successivelly, and the undissolvable granules and organelle membrane residues. became aggregated into the compartmental layer, and the microsporangium was divided into several large vesicles, each vesicle will form a massulae; (6) The microspore germinating stage–The ,natured microspores inside the massulae each gave rise an androgonial initial which divided two times to form four antherozoid mother cells and then gave rise the antherozoids. The relationships between the various morphological structures and their functions in the microsporangium developmental progress have breify discussed. In addition, our viewpoints have compared with those of previous investigations.  相似文献   

20.
应用扫描电镜(SEM)与透射电镜(TEM)观察了黄姑鱼和大黄鱼精子的超微结构。结果显示,黄姑鱼和大黄鱼精子无论在形态、大小还是超微结构上都十分相似。黄姑鱼和大黄鱼精子均由头部、中段和尾部(鞭毛)3部分组成。精子头部形状近似椭圆形,无顶体,细胞核呈肾形。中心粒复合体位于细胞核背侧,近、远端中心粒相互垂直,远端中心粒分化成基体并形成轴丝。中段的袖套呈筒状,4~5个圆形的线粒体围绕轴丝呈环形排列。精子尾部为单鞭毛,轴丝为典型“9+2”结构,鞭毛表面质膜形成不规则侧鳍。  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