Newsletter

Table of Contents

17.01.2002

Newsletter No.13

The G-spot does not exist
Sperm characteristics in fertile and infertile couples
Early embryo cleavage is a strong indicator of embryo quality in human IVF
Developmental ability of chromosomally abnormal human embryos to develop to the blastocyst stage.

1. The G-spot does not exist

The G-spot (Grafenberg-spot) is an allegedly highly erogenous area on the anterior wall of the human vagina. Since the concept first appeared in a popular book on human sexuality in 1982, the existence of the spot has become widely accepted, especially by the general public. For example, more than 60% of American and Canadian women do believe in the existence of this spot. The article reviews the behavioural, biochemical, and anatomic evidence for the reality of the G-spot, which includes claims about the nature of female ejaculation. The evidence is far too weak to support the reality of the G-spot. Specifically, anecdotal observations and case studies made on the basis of a tiny number of subjects are not supported by subsequent anatomic and biochemical studies.

Hines TM (2001) The G-spot: a modern gynaecologic myth. Am J Obstet Gynecol. 185:359-62.

2. Sperm parameters in fertile and infertile men

Sperm measurements that discriminate between fertile and infertile men are not well defined. The authors evaluated two semen specimens from each of the male partners in 765 infertile couples and 696 fertile couples. The female partners in the infertile couples had normal results on fertility evaluation. The subfertile ranges were a sperm concentration of less than 13.5x106 per millilitre, less than 32 percent of sperm with motility, and less than 9 percent with normal morphologic features. The fertile ranges were a concentration of more than 48.0x106 per millilitre, greater than 63 percent motility, and greater than 12 percent normal morphologic features. Values between these ranges indicated indeterminate fertility. There was extensive overlap between the fertile and the infertile men within both the subfertile and the fertile ranges for all three measurements. Although each of the sperm measurements helped to distinguish between fertile and infertile men, none was a powerful discriminator. The percentage of sperm with normal morphologic features had the greatest discriminatory power. Threshold values for sperm concentration, motility, and morphology can be used to classify men as subfertile, of indeterminate fertility, or fertile. None of the measures, however, are diagnostic of infertility.

Guzick DS et al. (2001) Sperm Morphology, Motility, and Concentration in Fertile and Infertile Men N. Engl. J. Med. 345: 1388-1393

Early embryo cleavage is a strong indicator of embryo quality in human IVF and IVF/ICSI

In order to reduce multiple pregnancy rate by selecting only one or two embryos for transfer criteria are required which allow to select those embryos that provide the highest chance of resulting in a pregnancy. Selecting of an embryo can start as early as the PN-stage (pronuclear scoring), by judging the quality of a day 3 embryo or by selecting blastocysts. The authors of the two papers report that early cleavage is another strong indicator of the quality of the embryo. Early cleavage embryos resulted in significantly higher pregnancy rates than later cleavage.

Lundin K, Bergh C, Hardarson T. (2001) Early embryo cleavage is a strong indicator of embryo quality in human IVF. Hum Reprod. Dec;16(12):2652-2657.

Bos-Mikich A, Mattos AL, Ferrari AN. (2001) Early cleavage of human embryos: an effective method for predicting successful IVF/ICSI outcome. Hum Reprod. 16:2658-2661

4. Developmental ability of chromosomally abnormal human embryos to develop to the blastocyst stage.

A correlation between morphology, developmental competence and chromosome abnormalities is established. However, embryo selection remains one of the most arduous tasks in assisted reproduction. The authors have undertaken this study in order to determine which chromosomal abnormalities are compatible with development to the blastocyst stage. Embryos diagnosed by preimplantation genetic diagnosis (PGD) as chromosomally abnormal or unsuitable for transfer were cultured to day 5 or 6. Morphology and development were observed daily. After extended culture, embryos were fixed and analysed by two rounds of FISH with the same probes used for PGD. Even though there is a strong selection against chromosomally abnormal embryos, extended culture to day 5 or 6 cannot be used as a reliable tool to select against clinically relevant chromosome abnormalities such as trisomies.

Sandalinas M, Sadowy S, Alikani M, Calderon G, Cohen J, Munne S. (2001) Developmental ability of chromosomally abnormal human embryos to develop to the blastocyst stage. Hum Reprod. Sep;16(9):1954-1958.

Gerhard Leyendecker