便携式头颅固位仪的研制

众所周知,在头面部活体测量中,头的定位是决定测量正确与否的一个关键,为使所获取的图像位置恒定,具有科学性和可比性,我们研制了便携式头颅固位仪,现将设计要点、结构和功能报告如下。1　材料和结构头颅固位仪由头颅固位部分和连接部分组成,现分述如下:11　头颅固位部分头颅固位部分(图1)由硬质铝合金做成,由头架园盘和两侧头夹组成。园盘下有一通过园心的横杆,双侧头夹固定于其上;头夹可在横杆上滑动,以适应不同头型和脸型的需要。双侧头夹上有定位耳塞,耳塞可在头夹上上下移动。在耳塞平面上有定位眶针,通过一水平活动关节与耳塞相连。为…     

白桦雌花发育、大孢子发生及胚胎发育的解剖学观察

白桦雌花从开花到雌性器官的成熟需经历1个月左右的时间,解剖学观察表明：四月下旬越冬的雌蕊原基开始了活跃的分裂和分化。子房和柱头开始生长。四月末开花,五月初授粉。此后胚珠开始长大。五月中旬即分化形成珠被,珠心,珠被为单层珠被,胚珠为厚珠心胚珠,胚珠倒生,五月中下旬,珠心内产生大孢子母细胞,一周左右发育为成熟胚囊-七细胞八核胚囊,五月末完成双受精,白桦胚胎发育经过合子,原胚,球形胚,心形胚和鱼雷形胚等时期最后发育成熟,胚乳发育与胚胎同步,即受精的极核进行几次分裂后形成核型胚乳,胚乳核不断增多,在形成心形胚后胚乳细胞形成细胞壁。     

PHOTOCONTROL OF DEVELOPMENT OF EXCISED ERAGROSTIS EMBRYOS

• 1 Both the germination of intact seeds and the development of excised embryos depend on their after-ripening. Shortly after the harvest, the intact seeds of Eragrostis ferruginea are in dormancy and germinate neither in the light nor in the dark. The ability of seeds to germinate under both conditions, however, gradually increases with the progress of after-ripening. The development of excised embryos, on the other hand, is readily induced in the light and dark even shortly after the harvest. As the after-ripening proceeds, however, the ability of excised embryos to develop gradually decreases and is finally lost 18 months after the harvest. The after-ripened embryos whose ability to develop is completely reduced become light sensitive again when they are supplied with the yeast extract of a low concentration, and develop readily even in darkness at a high concentration of the extract.
• 2 The photorequirement for development of excised embryos is scarcely affected by oxygen concentrations, and the embryo growth can take place equally in both light and darkness in the atmosphere containing 100 to 10 percent of air, while it can not be induced in pure nitrogen.
• 3 The promotion of embryo development by light is observed at the time when the ability of embryos to develop declines. The effectiveness of the irradiation is very similar to that in intact seed germination.

     

DEVELOPMENT OF THE SEED OF SOLANUM PHUREJA

Dnyansagab , Vishnu R., and Delmer C. Cooper . (U. Wisconsin, Madison.) Development of the seed of Solanum phureja. Amer. Jour. Bot. 47(3) : 176—186. Illus. 1960.—Ontogeny of the seed of Solanum phureja Juz. et Buk. is described. The megagametophyte, during the course of its development, ruptures the nucellus and at maturity lies in direct contact with the inner layer (endothelium) of the single massive integument. The mature megagametophyte, a 7-celled structure, consists of a 3-celled egg apparatus, an endosperm mother cell with fused polar nuclei and 3 persistent antipodals. Both 2- and 3-celled mature pollen grains are formed within anthers of the same flower; hence this character cannot be considered of any taxonomic value. Double fertilization occurs between 24 and 72 hr. after pollination. A cellular endosperm is formed, the peripheral layer acting as an absorbing tissue during the early ontogeny of the seed. Later this layer becomes organized as an aleurone layer and thereafter the source of nutrients is via the basal portion of the endosperm immediately adjacent to the apical end of the vascular tissue of the developing seed. Embryo development follows the Nicotiana variation of the Solanad type. The mature testa is composed of an outer layer of thick-walled epidermal cells, an inner layer of thin-walled cells and an intervening mass of disorganized tissue. In those instances where the ovule or young seed aborts, the endothelial cells of the integument become hyperactive and proliferate to such an extent that the space formerly occupied by the gametophyte or the developing endosperm and embryo becomes completely filled with endothelial tissue.     

DEVELOPMENT OF THE FLAGELLAR APPARATUS OF NAEGLERIA

Flagellates of Naegleria gruberi have an interconnected flagellar apparatus consisting of nucleus, rhizoplast and accessory filaments, basal bodies, and flagella. The structures of these components have been found to be similar to those in other flagellates. The development of methods for obtaining the relatively synchronous transformation of populations of Naegleria amebae into flagellates has permitted a study of the development of the flagellar apparatus. No indications of rhizoplast, basal body, or flagellum structures could be detected in amebae. A basal body appears and assumes a position at the cell surface with its filaments perpendicular to the cell membrane. Axoneme filaments extend from the basal body filaments into a progressive evagination of the cell membrane which becomes the flagellum sheath. Continued elongation of the axoneme filaments leads to differentiation of a fully formed flagellum with a typical "9 + 2" organization, within 10 min after the appearance of basal bodies.     

KINETICS OF DEVELOPMENT OF EMBRYONIC ERYTHROID CELLS

Embryonic erythropoiesis is an intrinsically non-steady-state process. A method of non-steady-state analysis is employed to approximately determine the kinetics of maturation of embryonic erythroid cells during the hepatic phase of erythropoiesis in the mouse. It appears from this analysis that embryonic erythroid cells have significantly shorter maturation times than their adult counterparts. In the embryo, there is insufficient time for more than three divisions between the proerythroblast and the orthochromatic erythroblast.     

DEVELOPMENT OF THE ASCOCARP OF CERATOCYSTIS ULMI

Rosinski , Martin A. (U. Maine, Orono.) Development of the ascocarp of Ceratocystis ulmi. Amer. Jour. Bot. 48(4): 285–293. Illus. 1961.—A study of the development of the perithecium of Ceratocystis ulmi was conducted using classic histological techniques. This study revealed the presence of a singular combination of primitive and advanced characteristics. The perithecium possesses a simple centrum made up only of ascogenous hyphae and small, spherical asci, but croziers are formed prior to ascus formation, and the ascogenous hyphae are arranged in a hymenium. Since development of C. ulmi compares closely with most other accounts of development in other members of the genus Ceratocystis, it appears that Ceratocystis is a good taxon. In addition, because of its intermediate nature and because Ceratocystis is the type genus of the family Ophiostomataceae, this family should be placed in a separate order, the Ophiostomatales.     

胚珠发育的分子基础

胚珠作为胚囊的携带者,在植物的生殖过程中起重要作用。胚珠是种子的前身,它在受精后发育成种子。近年来通过诱变已创造出一些胚珠和胚囊发育异常的突变体,如ｓｉｎ１,ｂｅｌ,ｏｖｍ２,ｏｖｍ３。这几个突变体的表现型不但是珠被发育异常,而且胚囊不能形成或发育异常,最终结果是雌性不育。同时,已分别从蝶兰和矮牵牛的胚珠中分离出一批胚珠发育特异的基因,其中有关ＭＡＤＳＢｏｘ基因在胚珠形成和发育中的作用研究得比较清楚,基因转化工作证实胚珠的分化和形成受一类新的ＭＡＤＳＢｏｘ基因控制。     

流式细胞计的研制

流式细胞计是近年发展起来的一种综合应用光学机械,电子学,流体动力学,激光和计算机的高技术生物医学仪器。它在生物学基础研究和临床医学研究中有广泛的应用。我们最近研制成功国内首台多参数流式细胞计,并已通过中国科学院院级鉴定。本文介绍该仪器的原理,主要结构与技术要点和使用结果等,它将有助于我国流式细胞术及其应用研究工作的开展。