Anisogamy is the occurrence within a population of two gamete types of different size, a very common condition both in plants and in animals. This paper shows conditions that anisogamy without disassortative fusion (pseudoanisogamety) should be favoured by individual natural selection; the results obtained analytically below are in basic agreement with those obtained through the use of numerica...

BACKGROUND Cytoplasmic defects are thought to cause aneuploidies in oocytes and embryos and oocyte 'reconstruction' by germinal vesicle (GV) transfer may circumvent such defects. In mice 'reconstructed' oocytes undergo meiosis and fertilize normally, but early embryonic development is compromised if their ooplasm matured in vitro. This study employs sequential MII spindle and/or pronucleus (PN)...

Pittard, James (Yale University, New Haven, Conn.), John S. Loutit, and Edward A. Adelberg. Gene transfer by F' strains of Escherichia coli K-12. I. Delay in initiation of chromosome transfer. J. Bacteriol. 85:1394-1401. 1963.-Two different F' strains were found to transfer both F-merogenote and chromosomal markers to recipient strains. When zygotes having received different chromosomal markers...

The challenge of the case presented was threefold: congenital absent uterus (Mayer-Rokitansky-KustnerHauser syndrome), a request for surrogacy, and teratozoospermia in the husband (6% normal morphology according to the Tygerberg strict criteria). Surrogacy was dealt with by means of guidelines proposed by the SA Law Commission after a surrogate mother was found. The gestational carrier was sync...

The microinjection method for production of transgenic farm animals requires specialized techniques and results in intolerably low production efficiencies. We investigated whether or not co-injection of foreign DNA constructs with restriction endonuclease into the pronucleus of mouse zygotes would improve the integration frequencies of foreign DNA into the host genome. Two kinds of DNA construc...

Although, the first transgenic animal was produced more than 30 years ago, there are still many factors limiting efficiency of transgenesis. One of them is the low rate of transgene incorporation into the genome of microinjected eggs. This mini-review summarizes recent research methods based on pronuclear microinjection of rabbit fertilized eggs in order to reach higher efficiency of transgene ...

Once ingested by mosquitoes, malaria parasites undergo complex cellular changes. These include zygote formation, transformation of zygote to ookinete, and differentiation from ookinete to oocyst. Within the oocyst, the parasite multiplies into numerous sporozoites. Modulators of intracellular calcium homeostasis A23187, MAPTAM, and TMB-8 blocked ookinete development as did the calmodulin (CaM) ...

BACKGROUND Embryos selection is crucial to maintain high performance in terms of pregnancy rate, reducing the risk of multiple pregnancy during IVF. Pronuclear and nucleolar characteristics have been proposed as an indicator of embryo development and chromosomal complement in humans, providing information about embryo viability. METHODS To correlate the zygote-score with the maternal age and ...

OBJECTIVES To study the potential of embryo transfer after 3, 4 or 5 days of embryo culture under the German embryo protection law according to which only a maximum of three zygotes are allowed to be cultured for embryo transfer. STUDY DESIGN In a prospective study, 273 patients with assisted reproductive treatment were randomly allocated for transfer on days 3, 4 or 5. Pregnancy and implanta...

OBJECTIVES In assisted reproductive technology, it is important to choose high quality embryos for embryo transfer. The aim of the present study was to determine the grade A embryo count and factors related to it in infertile women. MATERIALS AND METHODS This historical cohort study included 996 infertile women. The main outcome was the number of grade A embryos. Zero-Inflated Poisson (ZIP) r...