ULTRASTRUCTURAL OBSERVATIONS ON THE DISCHARGE OF TWO KINDS OF GRANULES IN THE FERTILIZED EGGS OF CYPRINUS CARPIO AND CARASSIUS AURATUS

This paper describes mainly ultrastructural evidence on the discharge of two kinds of granules, CA and CB, as well as the cortical alveoli in an egg of the common carp and the goldfish. The cortical alveoli (about 2–28 μ in diameter) and CA-granules (about 0.4–2 μ in diameter) are located in the cortical cytoplasm of the mature egg, and the latter is distinguishable in size and texture from the former which contains an eccentric core at the very least as a basal internal structure. The CB-granules (about 100–950 mμ in diameter) appear in small or large clusters in the cortical cytoplasm after fertilization, being formed in connection with constriction or pinching-off of dilated tubular elements. After fertilization the cortical alveoli, CA- and CB-granules are discharged at different times. The new plasmalemma of a fertilized egg appears to be a joint production of the original plasmalemma and the limiting membranes of the cortical alveoli, CA- and CB-granules.     

SPERM PENETRATION AND THE FORMATION OF A FERTILIZATION CONE IN THE COMMON CARP EGG*

Sperm penetration and the formation of a fertilization cone in the micropylar canal of the egg of the common carp were examined by electron microscopy. The overwhelming majority of inseminated eggs fixed without immersion in fresh water showed that the first spermatozoon had penetrated into the ooplasm before the cortical reaction had occurred, and in many cases had formed a fertilization cone to plug the micropylar canal. At this stage the sperm head was usually located at the base of the cone, and the tail part did not participate in the formation of the cone. Inseminated eggs fixed soon after immersion in fresh water showed that the elevation of the fertilization membrane and the simultaneous recession of the fertilization cone often permitted the penetration of a few supernumerary spermatozoa into the perivitelline space near the micropylar canal, but polyspermic fertilization was never observed. The mechanism of the block to polyspermy in the egg of the common carp is discussed in connection with the fertilization cone.     

Late Jurassic decapod crustaceans from northeast Japan

Abstract: Astacidean and thalassinidean macrurans (Glyphea sp., ?Eryma sp. and Protaxius sp.) and a new longodromitid crab, Planoprosopon kashimaensis, are recorded from the Upper Jurassic (upper Kimmeridgian to lower Tithonian) of Fukushima Prefecture, northeast Japan. Material was collected from the Tatenosawa Sandstone Member of the Nakanosawa Formation, Somanakamura Group, from which abundant Tethyan‐type marine invertebrates are known. Planoprosopon kashimaensis sp. nov. closely resembles P. heydeni (von Meyer), a common form in the Upper Jurassic of the Tethyan realm in Europe, and represents the oldest record of a brachyuran from the circum‐Pacific region. Similarities to contemporaneous decapod assemblages in southern Germany indicate that closely comparable, parallel decapod faunas in the Tethyan realm, inclusive of brachyurans, had already been established in the western circum‐Pacific region by the Late Jurassic.     

一种新型网膜对SARS冠状病毒的抑制作用

利用光触媒钛羟基磷灰石网膜（PTAF）具有吸附和酶催化的特点,研究其对SARS病毒的抑制作用.实验结果表明在紫外照射条件下,PTAF膜对SARS冠状病毒的抑制率为100％.在没有紫外照射的条件下,PTAF膜对SARS冠状病毒的抑制率为99.99％, 与对照组相比,PTAF膜抑制病毒的效率是HAF膜的1 000倍以上.研究结果提示,PTAF在预防SARS冠状病毒及其他病毒性疾病流行方面有潜在的应用价值.     

Response to Sperm Penetration of the Cortex of Eggs of the Fish, Plecoglossus altivelis

The response of the egg to sperm penetration was examined in eggs of the fish, Plecoglossus altivelis , by scanning electron microscopy. Eggs responded to sperm penetration by forming a fertilization cone at a "sperm entry site", which is a specialized structure in the egg surface under the micropyle. Within one minute, the fertilization cone showed dramatic morphological changes from its earliest appearance, through full two-storied growth to its marked recession. The sperm entry site in the egg surface is discussed as a morphologically specialized organ responsible for the entrance of a fertilizing spermatozoon. The morphological characteristics of the egg and sperm are also described.     

ENZYMO-CYTOCHEMICAL OBSERVATIONS ON THE CORTICAL CHANGE IN THE EGGS OF CYPRINUS CARPIO AND CARASSIUS AURATUS

Acid phosphatase (AcPase) and cholinesterase (ChE) activities were examined by ultracytochemical techniques in the mature unfertilized and the fertilized eggs of Cyprinus carpio and Carassitus auratus , to reveal the differences among three kinds of structures, cortical alveoli, CA- and CB-granules, which discharge their contents on fertilization into the perivitelline space. Deposits of the reaction product for AcPase activity are localized on the plasmalemma of unfertilized eggs, in the cortical alveoli, cytoplasmic matrix, lamellae of the Golgi apparatus and sometimes in multivesicular bodies but not in CA- and CB-granules, mitochondria, rough endoplasmic reticulum or on the plasmalemma of fertilized eggs. Deposits of the reaction product for ChE activity are localized on the inner surface of the plasmalemma, in the cytoplasmic matrix, in mitochondria and on a small number of tubular or cisternal membranes of the endoplasmic reticulum in mature unfertilized eggs, and on the outer surface of the limiting membrane of CB-granules and on membranous structures (possibly Golgi lamellae) associated with their formation, in fertilized eggs. The deposits on the plasmalemma rapidly disappear almost completely, with discharge of the cortical alveoli soon after fertilization, but they are again seen on the inner surface of the plasmalemma when emiocytotic discharge of the CB-granules begins about 10 min after fertilization.     

Ultracytochemical Modifications of Surface Carbohydrates in Fertilized Eggs of the Common Carp

The surface of the plasma membrane of unfertilized and fertilized carp eggs was examined by four cytochemical techniques, colloidal thorium, colloidal iron, ruthenium red and phosphotungstic acid stainings, to determine the carbohydrate moieties. The surface of the plasma membrane of unfertilized eggs stained only with colloidal iron, which was heterogeneously deposited: no deposits were seen on the plasma membrane near overlying cortical alveoli. In fertilized eggs, the membrane was stained by all four methods. These ultracytochemical modifications of the surface of the plasma membrane may be caused by participation of the limiting membranes of secretory organelles, probably by turnover of the inner surface of the limiting membranes. Neuraminidase treatment of fertilized eggs eliminated the deposits of colloidal iron on the surface of the plasma membrane and caused an increase in stainability with ruthenium red. Treatment with neuraminidase or trypsin prevented the staining with phosphotungstic acid.     

Ultrastructure and Ultracytochemistry of Fertilization Envelope Formation in the Carp Egg

This paper describes ultrastructural and ultracytochemical events occurring during the process of transformation of the vitelline envelope (VE) into the fertilization envelope (FE) in the egg of Cyprinus carpio. The VE is composed of four layers, except the micropylar region. The outermost (first) layer can be subdivided into a double layer (upper and lower halves) by cytochemical differences. The upper half is more protein-rich and positive for acid phosphatase (AcPase) activity, while the lower one is more carbohydrate-rich and negative for AcPase.
The most striking differences between the VE and the FE appear in the first layer component and the thickness. The FE first layer, ultrastructurally and cytochemically consisting of a single layer, gradually grows to be about five-fold as thick as the VE first layer by 40 min after fertilization. This may be due to displacement of the former VE first layer by deposits of the cortical alveolar exudate.     

Microtubule Formation in Regenerating Terminal Buds of the Silurid Fish, Corydoras aeneus

Regenerating terminal buds of Corydoras aeneus were observed by electron microscopy to determine how terminal buds developed with respect to microtubule formation. After surgical removal of the fish barbel, it and the terminal bud began to regenerate 1.5 weeks later at 25°C. The regenerating terminal buds were ovoid in shape and contained three types of cells. The first type of cell had extended cellular processes which contained numerous microtubules and tubules. A bundle of three or four microtubules ran parallel to the long axis of the cellular process. Receptor villi protruded from the cell two weeks later, suggesting that it is a receptor cell. The second cell type, which appeared 1.5 weeks after barbel removal, had numerous microtubules oriented along the long axis of the cellular process; and numerous dense granules appeared two weeks later, suggesting that it is a supporting cell. The third type of cell observed was a basal cell without cellular processes. These results suggest that microtubule formation plays an important role in the elongation of regenerating terminal buds.