Short-term chorionic villi and amniotic fluid cultures.

Prenatal diagnosis of genetic disorders associated with specific biochemical, chromosomal, or molecular characteristics can be achieved from amniotie fluid (AF) or placenta (chorionic villus: CV) samples. Chorion material is usually obtained by sampling the placenta at the implantation site, during the first trimester (i. e., 9-12 wk), using either the transcervical or transabdominal route. The first method entails access to the placenta via the cervical canal, with aspiration through a metal cannula or a flexible catheter. Alternatively, the chorionic villi may be aspirated using a needle, which is passed through the abdominal wall. In both these methods, the positioning of the aspirating device must be made with the help of ultrasound scanning. Later pregnancies can only be sampled by the transabdominal route. Amniocentesis is usually performed at 16-18 wk of gestation by the transabdominal method.

In situ nick translation of human and mouse chromosomes detected with a biotinylated nucleotide.

In situ nick translation of human and mouse chromosome preparations has provided further evidence that DNase I sensitivity correlates with transcriptionally active chromatin. Chromosomes from differentiating cells and particular chromosome regions, known to differ in transcriptional activity, generally reveal predicted differences in relative DNase I sensitivity. The application of a biotinylated nucleotide in these studies provides a new level of cytological resolution and offers the potential for further refinement.

Effect of cannabinoids on spermatogenesis in vivo: a cytological study.

The cytogenetic effects of delta 9-tetrahydrocannabinol (THC) and cannabinol (CBN) (10 mg/kg) were investigated in hybrid mice of genotype (C57BL x C3H)F1. Mice were treated for 5 consecutive days with the specific cannabinoid; 16 days after the last treatment the meiotic cells were evaluated. Analysis of the spermatocyte bivalents at the first meiotic metaphase failed to reveal any numerical or structural abnormality. Contrary to previous reports we failed to find any major meiotic abnormalities associated with THC and CBN treatments. There was no evidence of ring or chain figures. The centromeric banding procedure (C banding) was used to support observations of Giemsa stained cells. It has previously been reported that cannabinoids suppress the incorporation of 3H-uridine into pachytene spermatocytes and round spermatids; the absence of chromosome aberrations in the present study suggests that an adverse effect appears to be present, but may be at a level other than cytogenetic.