Hans Wilhelm Michelmann

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Infertility affects 13-18% of couples and growing evidence from clinical and epidemiological studies suggests an increasing incidence of male reproductive problems. There is a male factor involved in up to half of all infertile couples. The pathogenesis of male infertility can be reflected by defective spermatogenesis due to failure in germ cell(More)
BACKGROUND Patients increasingly use health portals and Web-based expert forums (ask-the-doctor services), but little is known about the specific needs of Internet users visiting such websites, the nature of their requests, or how satisfied they are with Internet health experts. OBJECTIVE The aim of this study was to analyze the information requests of(More)
During intracytoplasmic sperm injection (ICSI) approximately 10% of all injected oocytes degenerate. The reason for this process is unknown. It has been speculated that the mechanical procedure of the insertion of the ICSI needle induces injuries to the zona pellucida which lead to the death of the cell. By scanning electron microscope (SEM), it could be(More)
BACKGROUND Both healthy and sick people increasingly use electronic media to obtain medical information and advice. For example, Internet users may send requests to Web-based expert forums, or so-called "ask the doctor" services. OBJECTIVE To automatically classify lay requests to an Internet medical expert forum using a combination of different(More)
Sperm cells from 45 infertile patients were investigated for disomy rates of chromosomes 1, 7, 10, 17, X and Y as well as for diploidy by single- and double-target in-situ hybridization. The patients who attended the infertility clinic were aged 23-46 years. Semenograms showed that the patients had oligo-, astheno-, oligoastheno-, oligoterato-,(More)
Human oocytes from the same as well as from different patients have an extremely heterogeneous morphology of the zona pellucida surface as shown by scanning electron microscopy. For years it has been believed that this heterogeneous morphology plays an important part in the sperm-oocyte interaction. It was the aim of this investigation to analyse the(More)
BACKGROUND This is the first study of the effect of epidermal growth factor (EGF) on marmoset monkey oocytes matured in vitro. METHODS We have evaluated the effects of 10 ng/ml EGF in combination with 1 or 10 IU/ml of gonadotrophins (FSH/hCG 1:1 ratio) during in vitro maturation (IVM) of marmoset oocytes. Immature cumulus-oocyte complexes (COCs) were(More)
Interaction between the spermatozoon and the zona pellucida during the first steps of fertilization was analysed on approximately 500 polyploid and unfertilized IVF oocytes by scanning electron microscopy (SEM). Oocytes demonstrate high inter- and intra-individual variations in size and morphology which do not correlate either with the maturity of the(More)
Infertility affects 13 – 18% of couples and growing evidence from clinical and epidemiological studies suggests an increasing incidence of male reproductive problems. There is a male factor involved in up to half of all infertile couples. The pathogenesis of male infertility can be reflected by defective spermatogenesis due to failure in germ cell(More)
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