Showing papers by "Yonsei University published in 1973"

Volume changes during the preimplantation stages of mouse egg development.

Abstract: A study of the preimplantation changes of mouse eggs is presented. Data on the largest and smallest diameters of the inner and outer surface of the zona pellucida were analyzed by computer. Measurements were made during the following stages of egg growth: germinal vesicle ovulated but unfertilized egg ovulated and fertilized egg 2-cell embryo on Day 2 of pregnancy 4- to 8-cell embryos on Day 3 of pregnancy and the morulablastocyst on Day 4 of pregnancy. The diameter of the vitellus of the ovarian oocyte was the largest of any stage measured whereas the diameter of the zona pellucida of the oocyte was the smallest. The total volume of the oocyte increases considerably by the time of ovulation and increases only slightly after fertilization. It then decreases until the 4- to 8-cell stage of development. The volumes of the entire egg intrazonal cavity zona pellucida perivitteline space and the vitellus were measured during the initial 18 hours of development following ovulation and fertilization. 6 hours after ovulation the total fertilized egg is reduced in volume as is the volume enclosed by the zona pellucida. The egg remains relatively constant in volume for 6 more hours and then shrinks again. No changes occurred in the total volume and intrazonal cavity of unfertilized eggs 6 hours after ovulation. The unfertilized egg reduces slightly until 9 hours when it suddenly expands beyond the size of the fertilized egg. The perivitteline space in fertilized and unfertilized eggs increases with time while the zona pellucida gradually decreases in the fertilized egg but increases in the unfertilized egg prior to the 1st cleavage. The vittelus of the fertilized egg shrinks at a relatively constant rate whereas transient swelling was observed in the unfertilized tubal egg. Temperature differences had no effect on the size of fertilized and unfertilized eggs. The results give further evidence of an increased metabolic capability of the mouse embryo between the 2-cell stage and the 8-cell stage. Possible reasons for the observed changes are discussed in relation to the literature.

Fine Structures Of Trichomonas Tenax And Trichomonas Hominis

Abstract: Trichomonas tenax(T. tenax) and Trichomonas hominis (T. hominis) were collected, cultured and sampled for comparative microscopical studies using electron microscope. 1. Both flagellates were oval in shape and surrounded by a distinct outer membrane. Five recurrent flagella and one anterior flagellum had, each, 9 paris of peripheral and 1 pair of central fibrils, Undulating membrane was curved over the recurrent flagella, and bended in the middle at right angles with cell surface. Cytostome, engulfing bacteria, was observed in T. hominis. 2. In the cytoplasm, there were fine dense glycogen particles, and vacuoles containing ingested materials. Dense pigment rods were also observed in both flagellates, but the rods were not distributed around the vacuoles in T. hominis. 3. In T. tenax axostyle appeared as a cup-shaped structure comprising a single row of 41 fibrils, each about 120 a in diameter. It enclosed glycogen particles, and the open side was faced to the nucleus. 4. Endoplasmic reticulum was observed around the nucleus, but it was less developed in T. hominis. 5. Nucleus was ovoid having double nuclear membrane, which was clearly defined in T. hominis. 6. Blepharoplast, parabasal body, Golgi appartus and mitochondrion was not observed in both flagellates.

Analog simulation for spatio-temporal characteristics of visual system

Abstract: In this paper, the function of visual system was mainly analysed by spatio-temperal characteristics based upon Enroth's model, Broca-Sulzer phenomenon and Mach effect. (a) In order to get the excitatory and inhibitory potential of intermediate cell layer in the retina, the exponential value exp {(FM/kT)-Imn} was calculated based on the physiological theory in neuro-phenomena. (b) To show the visual characteristics by the analog simulation for generating stimulus waveforms and analysis, the visual adaptation was recorded as electrical stimulation in the form of step functions. Furthermore, it was shown that there was a satisfactory agreement within experimental errors between those data obtained and the theoretical values, which is psycho-physiological.