SPERMIOGENESIS IN THE PULMONATE SNAIL, EUHADRA HICKONIS II. STRUCTURAL CHANGES OF THE NUCLEUS

In accordance with the characteristic shape of the nucleus and degree of condensation of the nuclear substance, spermiogenesis in Euhadra hickonis can be roughly divided into four stages. The chromatin in the highly polymorphic nucleus of the first stage, early spermatid, forms relatively thick (ca. 50 nm) fibrils which associate here and there into irregular clumps. In the next stage, the spermatid nucleus becomes conspicuously spherical, its contents appear more finely homogeneous and the irregular clumps of chromatin are few. In the third stage, the nucleus gradually takes on an ellipsoidal shape as the antero-posterior axis shortens. The anterior part of its envelope becomes structurally modified in preparation for the adherence to it of the developing acrosome, and an implantation fossa forms posteriorly at the center of a second area where the nuclear envelope has been modified. The diameter of the chromatin fibrils again increases and those near the implantation fossa become oriented perpendicular to the nuclear envelope.
As the nucleus elongates in the fourth stage, a concentric sheath of microtubules closely surrounds it. These appear to depolymerize as the nuclear elongation proceeds, so that they are no longer present in the head region of the mature spermatozoon. The diameter of the chromatin fibrils increases to about 10 nm and they become oriented parallel to the long axis of the cell. With the decrease in the nuclear volume the fibrils unite laterally to form longitudinal sheets, and these finally merge in the mature spermatozoon into a mass of very dense chromatin without perceptible internal structure.     

MOTILITY AND LOCOMOTION OF EMBRYONIC CELLS OF THE MEDAKA, ORYZIAS LATIPES, DURING EARLY DEVELOPMENT

The motility and locomotion of embryonic cells of the medaka, Oryzias latipes , were studied in situ with time-lapse cinematography.
In the early morula (128-cell stage), the surface of the blastomeres begins to undulate gently. By the early blastula stage, these undulations increase gradually in amplitude, and blebs appear. These blebs protrude and retract rapidly. In the mid-blastula stage they are found in most of the blastomeres. Some are found adhering to the surfaces of other cells. Blebs often expand into elongate lobopodia. Cell locomotion is first evident in the mid-blastula stage and continues throughout gastrulation and afterward. The cells move in the direction of the protrusion. In the late blastula a number of blastomeres locomote in random directions. In the thickening stage, when blastoderm epiboly begins, the cells with lamellipodia or elongate filopodia increase gradually in number, and in the early gastrula most cells change into this form. The motility, rate of movement, and mode of locomotion of embryonic cells during early development are described in detail.     

甜叶菊的受精作用及胚和胚乳的早期发育

成熟胚囊被珠被绒毡县包围,由卵器、具次生核的中央细胞以及数目为1至6个反足细胞组成。传粉后6小时左右,雌、雄性核融合。配子融合同精核与次生核的融合几乎同时发生;精核与次生核融合速度快于配子融合。甜叶菊受精作用属于有丝分裂前类型。传粉后8小时左右,初生胚乳核分裂,其分裂方向可与胚囊长轴平行或垂直,从而形成最初的两个胚乳细胞。胚乳细胞前5次分裂是同步的。心形胚阶段,胚乳细胞呈现被消化吸收的迹象。胚乳发育属细胞型。传粉后10小时左右,合子第一次分裂,为横分裂。胚胎发育属紫菀型。     

QUANTITATIVE CHANGES IN NUCLEAR DNA ACCOMPANYING POSTGERMINATION EMBRYONIC DEVELOPMENT IN VANDA (ORCHIDACEAE)

Nuclear DNA was measured cytophotometrically in sections and isolated nuclei of the developing embryo of Vanda. The data were interpreted in terms of developmental stage and spatial relationships of the nuclei within the embryo. An equal amount of DNA was found in all meristematic nuclei regardless of the developmental stage of the embryo and was taken as the 2C value. Most of the nuclei in the parenchymatous region fell into the discrete DNA classes, 2C, 4C, and 8C. A significant number, however, had DNA contents above 8C but could not be grouped into classes based on a whole-number multiple of 2C. Nuclear size was found to vary in direct proportion to DNA content through 8C. Above 8C, correlation between nuclear size and DNA content was poor. The amount of DNA in the nuclei of the parenchymatous region was shown to increase in direct proportion to the distance of the nucleus from the meristem. The average amount of DNA in parenchymal nuclei above 8C was found to increase with the developmental stage of the embryo. Mechanisms which might account for the observed changes in DNA per nucleus are discussed.     

真水狼蛛胚胎发育过程中形态和主要化学物质含量的变化

采用常规石蜡切片和液体石蜡透明卵壳的方法,系统地观察了真水狼蛛的胚胎早期,体节期,胚胎速转期和幼虫期4个发育阶段的形态特征和发育过程,并测定了胚胎发育过程中卵的内主要化学物质含量的变化,在28度时,真水狼蛛的卵从产卵到孵化共需144小时,其中胚胎早期42小时,体节期33小时,胚胎逆转期27小时,在胚胎逆转期后进入前幼虫期,前幼虫期42小时,真水狼蛛的胚胎逆转现象很明显,表明真水狼蛛的进化程度较高,在胚胎发育过程中,卵的含水量,含脂量和卵重在胎发育24hr后开始下降,卵的蛋白质含量在48小时后也开始下降,含糖量下降不明显。     

小鼠卵母细胞成熟和受精过程中Ca^2＋分布变化的研究

用焦锑酸钾原位定位法、膜结合Ｃａ＾２＋荧光探针金霉素标记法,分别在电镜和光镜水平对小鼠卵成熟和卵受精过程中结合态Ｃａ＾２＋的分布及其变化进行了研究,发现：１）Ｃａ＾２＋分布于线粒体、胞质、内质网囊泡、微绒毛和透明带等部位,其中以线粒体基质中分布密度为最大;２）减数分裂Ｉ中、后期于纺锤体极区结合有较多的Ｃａ＾２＋;３）生发泡、纺锤体和原核内膜结合态Ｃａ＾２＋含量很少,但纺锤体和原核周围分布较多;４）     

SOME NUCLEAR CHANGES ACCOMPANYING DEVELOPMENT IN THE ENDOSPERM OF GLEDITSIA AND PODOPHYLLUM

The development of the endosperm in Gleditsia is marked by the growth of the average nucleus from 141 μ³ on June 12 to 978 μ³ on July 14. At the time of formation of a cellular endosperm the average nuclear volume commences dropping and by July 20 reaches an average of 224 μ³ throughout the endosperm. In Podophyllum at the time of cell formation the average nuclear volume begins to drop from a value of about 2850 μ³ and falls to a value of from 500 μ³ to 770 μ³, the latter estimates depending upon the mode of fixation of the material. The volume decrease in the Podophyllum endosperm nucleus is accompanied by a fall in mean relative DNA content of the average nucleus, as determined by microspectrophotometry with the two wavelength method. The possibility of degeneration of some of the higher “ploid” types is considered, as well as depolyploidization.     

小麦×长穗偃麦草的受精和早期胚胎发育

用石蜡切片法,对小麦（Ｔｒｉｔｉｃｕｍａｅｓｔｉｖｕｍ）和长穗偃麦草（Ｅｌｙｔｒｉｇｉａｅｌｏｎｇａｔａ）杂交的受精和早期胚胎发育进行了观察。结果表明,长穗偃麦草花粉在小麦柱头上萌发良好,花粉管可顺利长入花柱和胚囊。观察的１７０个小麦子房中,１７６５％发生了双受精,产生了胚和胚乳;９４１％发生了单卵受精,只产生胚而无胚乳;４７１％发生了单极核受精,只产生胚乳而无胚;总受精率为３１７７％;成胚率为２７０６％。由于胚乳的缺乏或发育异常及败育,最终难以获得有生活力的种子。为小麦与长穗偃麦草远缘杂交提供了细胞胚胎学证据。     

CHANGES IN THE CARBOHYDRATES, PROTEINS AND NUCLEIC ACIDS DURING SEED DEVELOPMENT IN OPIUM POPPY

This investigation is concerned with the major changes in thelevels of carbohydrates, proteins, nucleic acids and some enzymesin the ovules of Papaver somniferum at various stages of seeddevelopment. Of the soluble sugars, fructose and glucose arepresent in large amounts up to the free nuclear stage of theendosperm but decrease rapidly when the latter turns cellular;then sucrose becomes most abundant. At this time the concentrationof insoluble carbohydrates is almost one-seventh that of solubleand the activities of - and ß-amylases are at theirhighest. The nitrogen in the seed is accumulated in two phases,the first coinciding with the development of endosperm and thesecond with the development of embryo. Cell wall formation inthe coenocytic endosperm is accompanied with a marked decreasein the soluble nitrogen. The activity of glutamic-alanine transaminaseincreases concurrently with the increase of protein in the ovules.The maximal RNA content is attained after the ovules have completedtheir increase in size but prior to the deposition of proteinaceousreserves in the endosperm. The amount of DNA increases withthe growth of endosperm but decreases during the maturationof embryo. Both ribonuclease and deoxyribonuclease show twopH optima corresponding to pH 5.5 and 7.5 (ribonuclease) and5.0 and 7.5 (deoxyribonuclease). Their activities seem to becorrelated to the levels of nucleic acids. ¹ Present address: AEC Plant Research Laboratory, Michigan StateUniversity, East Lansing, Mich., U.S.A.     

CHANGES IN ACTIVITIES OF CREATINE KINASE, ARGININE KINASE AND THEIR MULTIENZYME FORMS DURING EMBRYONIC AND LARVAL DEVELOPMENT OF SEA URCHINS

The presence and the changes of CPK and APK have been studied during larval development through metamorphosing of Hemicentrotus pulcherrimus, Anthocidaris crassispina and Pseudo-centrotus depressus . While no CPK activity was found in the unfertilized eggs and the embryos of early developmental stages, APK was quite active throughout these stages. At the late 8-armed pluteus stage just prior to metamorphosis, CPK first became active. Electrophoretically this CPK was identical with one of three CPK forms of sperm, tube feet and esophagus but not with two CPK forms of lantern muscle. APK in the unfertilized eggs and early embryos was electrophoretically separated into two distinct molecular forms, one of which disappeared during the late larval stages. The persisting form of larval APK was identical with a single APK form present in the adult muscular tissues.     

雌核发育和两性融合发育鱼卵调控精核受精发育的生化特性研究

两性融合生殖的鱼卵受精后,精核能疏松、解凝,形成雄性原核：雌核发育银鲫卵子受精后,精核发育受到抑制,无法形成原核。采用显微注射去膜精核以及细胞学和电镜观察的方法,本文对两类鱼卵受精后精核早期发育的生化性质进行了初步探讨,并着重研究了雌核发育银鲫卵子控制精核发育的生化特征。实验结果显示,两性融合生殖鱼类卵质中,一定量的Ｃａ２＋的存在,二硫键的还原作用对于精核的发育显然是必要的;而在雌核发育银鲫卵中,Ｃａ２＋的功能和二硫键的还原作用与精核发育受到抑制之间并无直接联系。银鲫卵质中似乎显示出异常的磷酸酶脂解活性,导致磷酸化过程无法进行,使精核解凝受到阻碍。另外,两性融合生殖的鱼卵重质层中具有大量诱导精核原核化的有关因子,而银鲫卵质中则缺少该因子（或活性极低）。银鲫卵质中还可能缺乏某些与雄性原核的核膜重组装有关的大分子物质。     

CHANGES OF CHROMOSOMES DURING THE EARLY NEURAL DEVELOPMENT OF A JAPANESE NEWT, CYNOPS PYRRHOGASTER

The karyotype of Cynops pyrrhogaster was determined on the mitotic chromosomes in the presumptive neural area of an early gastrula. 24 chromosomes of a diploid set consisted of 8 metacentric and 4 submetacentric pairs. Individual chromosomes were identified on the basis of their morphology and characteristic C-binding patterns. Sex chromosomes were not identified. Total length of the haploid chromosome set in the presumptive neural area decreased remarkably from morulae to gastrulae, further continued to decrease up to neurulae and thereafter remained unchanged till tail-buds. Chromosome shortening occurring from morulae to gastrulae was accompanied with a prominent decrease in chromosome volume, keeping chromosome width constant. Shortening took place evenly along the longitudinal axis of a chromosome. When gastrulae and neurulae were compared concerning their positions of the appearance of the C-bands, the basic pattern remained unchanged. In certain chromosomes, the number of C-bands decreased as the result of their fusion, as gastrulae proceeded to neurulae.     

METABOLISM DURING EMBRYONIC AND METAMORPHIC DEVELOPMENT OF INSECTS

1. For species of insects that deposit their eggs on foliage, as Leptinotarsa decemlineata, Crioceris asparagi, and Anasa tristis, the rates of metabolism as measured by the CO₂ output or the oxygen intake indicate, during embryonic development, a short formative period, followed by a very active extended growth. Those species that deposit their eggs in the soil, as Cotinis nitida and Popillia japonica, show that the formative period is greatly extended and the growth period similarly lengthened. 2. It has been shown from metabolism experiments that intensive histolysis occurs during the prepupal period and becomes less intensive during pupal development. 3. Metabolism experiments show a greater amount of energy change during embryonic development as compared to the energy developed during metamorphosis. This is shown by the greater CO₂ output and by the oxygen intake. 4. Low respiratory quotients, varying from 0.42 to 0.71, have been obtained during the embryonic and pupal development of insects, resembling similar low quotients obtained with hibernating forms. 5. Changes from a neutral to an acid reaction (pH 6.8 to 5.9) have been observed to take place in some species during prepupal and early pupal development. As metamorphosis is completed a converse change occurs (pH 5.9 to 6.8). Changes in pH from an acid to neutral reaction were also observed to take place in some species, as Cotinis nitida and Hylemyia cilicrura, during embryonic development.