(n.) One of the smaller cells, or blastomeres, resulting from the complete segmentation of a telolecithal ovum.
Example Sentences:
(1) In Strongylocentrotus droebachiensis, a micromere-specific protein of 133 K molecular weight (MW) was identified.
(2) The most extensively studied example is the specification of the mesodermal stem cell in Lymnaea and Patella, which occurs between 5th and 6th cleavage through an interaction between one macromere and a large number of micromeres.
(3) From the early beginning of the 32-cell stage, all four macromeres introdude far into the interior and tough the centrally radiating cells of the first quartet of micromeres.
(4) We suggest that the fibrillar meshwork is needed for macromere elongation toward the micromeres and that the basal lamina-like layer is involved in the determination process itself.
(5) Ilyanassa obsoleta larvae have two calcium carbonate-containing organs, shell and statocyst, which are derived from five micromere cells (2a, 2c, 2d, 3c, 3d).
(6) During the fifth cleavage interval in equally cleaving embryos, one of the vegetal macromeres makes exclusive contacts with the animal micromeres, and this macromere will give rise to the mesodermal precursor cell at the next division, thereby identifying the dorsal quadrant.
(7) Mesomere-mesomeres (which divide equally) and macromere-micromeres (which divide unequally) are compared in terms of their asters (both mitotic and so-called interphase asters), spindle apparatus, and contractile ring.
(8) Caulobothrium longicolle (Linton, 1890) and Phyllobothrium gracile (Weld, 1855) (Cestoda: Tetraphyllidea, Phyllobothriidae) have the same embryonic development with the following characteristic data: --a small number of vitelline cells (2 or 3) pass with the zygote in the ootype;--a non operculate thin egg-shell;--the entire and equal zyhote cleavage following by unequal divisions leading to the formation of four blastomere types (Macromeres, secondary Macromere, Mesomeres and Micromeres);--the differentiation of two syncytial embryonic envelopes during the preoncospheral phase.
(9) To examine competence in this system we have exposed cultured sea urchin micromeres to an inducing medium containing horse serum for various periods of time and have identified a period when micromeres are competent to respond to serum and form spicules.
(10) In Arbacia punctulata, four high molecular weight (HMW) proteins are detected on the surface of isolated micromeres--but not on mesomere-macromere fractions.
(11) Quantitation of immunofluorescence and three-dimensional reconstruction techniques demonstrate that micromere centrosomes differ from macromere centrosomes in two respects: (1) micromere spindle poles contain less centrosomal material than macromere poles, and (2) micromere centrosomes undergo a specific filiform elongation during late anaphase and telophase.
(12) A complementary DNA (cDNA) library was generated from cytoplasmic polyadenylated RNA isolated from differentiated micromere cultures of Strongylocentrotus purpuratus.
(13) Lineages of the first quartet micromeres were followed using Lucifer Yellow dextran as a tracer.
(14) The role of unequal cleavage in echinoid micromere determination was investigated by equalizing the fourth and fifth cleavages with brief surfactant treatment.
(15) We show that in sea urchin embryos, the daughter cells of the small micromeres become part of the coelomic sacs, in contrast to the long-held view that these sacs are purely of macromere origin.
(16) A procedure is described for large-scale isolation of micromeres from 16-cell stage sea urchin embryos.
(17) A method was developed for isolating large quantities of micromeres from the 16-cell stage of the sea urchin, and measurements were made of their ability to incorporate C(14)-L-valine into protein as compared with that of a mixed suspension of micromeres, mesomeres, and macromeres.
(18) Using this method, we fractionated the three different blastomere types of the 16-cell sea urchin embryo, the micromeres, mesomeres, and macromeres, achieving 96, 94, and 96% mean purities, respectively.
(19) Spicule formation of micromere-derived cells was enhanced by anti-FAPS.
(20) pHPSMC mRNA was detected in micromeres in vitro after 48 h of culture, but it was not found in blastomeres immediately after isolation.
Ovum
Definition:
(n.) A more or less spherical and transparent mass of granular protoplasm, which by a process of multiplication and growth develops into a mass of cells, constituting a new individual like the parent; an egg, spore, germ, or germ cell. See Illust. of Mycropyle.
(n.) One of the series of egg-shaped ornaments into which the ovolo is often carved.
Example Sentences:
(1) A specimen of a very early ovum, 4 to 6 days old, shown in the luminal form of imbedding before any hemorrhage has taken place, confirms that the luminal form of imbedding does occur.
(2) The results indicate that the sperm swelling test and the zona-free hamster ovum penetration assay are evaluating different functional qualities of sperm that are apparently not associated with each other.
(3) This study documents a molecular change in the murine ovum related to its exposure to oviductal fluid.
(4) The OCI-related membrane appeared a cause of OCI interference with fimbrial ovum capture by preventing the contact between the fimbrial cilia and the cumulus oophorus.
(5) Also, for determination of the fertilizing capacity of the semen, a zona-free hamster ovum penetration test was done in 49 men, while 14 men were studied by determination of the fertilization of human oocytes in vitro.
(6) The antiprogesterone RU 486 was utilized to evaluate the possible role of progesterone in ovum maturation, ovulation, fertilization, and embryo cleavage.
(7) It is suggested that the beta inhibitory activity of the uterus and the alpha excitatory activity of the rest of the oviduct are involved in the regulation of ovum transport.
(8) Among antigens possible unique to the reproductive process, sperm antigens, antigens of seminal plasma and of the ovum, antigens of placental hormones and of placenta specific proteins appear suitable targets of the production of fertility regulating vaccines.
(9) The preovulatory surge of gonadotropins activates a cascade of proteolytic enzymes resulting in the rupture of the follicular wall and the release of a fertilizable ovum during ovulation.
(10) The development of vaginal ultrasound transducers has facilitated ovum pick-up (OPU) by providing higher precision and less trauma than are found with laparoscopy and other ultrasound-assisted techniques.
(11) In Johnson v. Calvert, a surrogate mother in California failed to gain custody of the child she bore after gestating an embryo from the ovum and sperm of the couple who hired her.
(12) Risk factors that may theoretically alter ovum quality or the hormonal environment include ovulation induction, fertilization in vitro, delayed ovulation, and transperitoneal ovum migration.
(13) Thus, spermatozoa deposited in the vicinity of the USHG immediately following oviposition (to simulate a release of spermatozoa from this region) can be transported to the infundibulum and effectively fertilize the next ovum ovulated.
(14) However, they do not as yet permit a judgment as to the degree that ovum pickup through a fistula was impaired.
(15) We evaluated the differences between this group and those patients presenting either with a blighted ovum or beyond the first trimester, as well as the outcome of those patients with spotting early in gestation.
(16) It is too soon to learn whether this method will be reversible, but use of silastic should prevent adhesions while providing another mechanical barrier between ovum and sperm.
(17) Indomethacin was effective in preventing follicular rupture and ovum extrusion when administered simultaneously with gonadotropin.
(18) A 33% clinical pregnancy rate per ovum pick-up was achieved with the Buserelin-hMG treatment.
(19) The pregnancy rates were higher than a matched IVF series in the male factor and female ASAB groups and reached statistical significance for the ovum donation group.
(20) Lamellar structures, therefore, are considered to be storage material chiefly used in the second half of the cleavage for developmental processes in the rat ovum.