The comb jelly Mertensia ovum, widely distributed in Arctic regions, has recently been discovered in the northern Baltic Sea. We show that M. ovum also exists in the central Baltic but that the population consists solely of small-sized larvae (less than 1.6 mm). Despite the absence of adults, eggs were abundant. Experiments revealed that the larvae were reproductively active. Egg production and...

There are two populations of sperm in bull semen. One consists of X-chromosome-bearing sperm; the other consists of Y-chromosome-bearing sperm. In contrast, all cattle ova contain an X chromosome. That is why when an X-chromosome-bearing sperm fertilizes the ovum a female (XX) develops, and when a Y-chromosome-bearing sperm fertilizes the ovum, a male (XY) develops. Ratios of the number of male...

to develop until the tenth or twelfth week, the case usually terminates in rupture of the tube, with its well-known symptoms. But at an earlier period than this, during the first five or six weeks, other changes may take place, involving both the developing ovum and the tube in which it is contained. Of these changes, one of the most important and interesting is that of tubal abortion. We may, ...

BACKGROUND We aimed to investigate whether multifetal pregnancies are at risk of more pregnancy complications in women of advanced age after ovum donation. METHODS Pregnancy outcome in women after ovum donation aged 40 and above was extracted. Labor and delivery data as well as antenatal records of women carrying twins were compared with those of singletons, as well as to a control group of a...

Phosphate esters in polyhydroxylated systems are normally blighted by uncontrolled migration under a variety of reaction conditions. Cesium fluoride is demonstrated as a reagent to control migration of primary phosphates during transesterifications. This allows easy exchange of phosphoryl protecting groups enabling enhanced synthetic strategic flexibility and regioselective phosphate installati...

Vacant and blighted urban land is a widespread and potentially risky environmental condition encountered by millions of people on a daily basis. About 15% of the land in US cities is deemed vacant or abandoned, an area roughly the size of Switzerland. In a citywide cluster randomized controlled trial, we investigated the effects of standardized, reproducible interventions that restore vacant la...

I'HIS paper is based on a review of all cases of multiple pregnancy occurring in the Belfast Maternity Hospital, Townsend Street, and the Royal Maternity Hospital, Belfast, during the last ten years 1927-36. During this period, 164 mothers were delivered of twins, and one mother was delivered of triplets, i.e., 165 mothers gave birth to 331 babies. The number of twin pregnancies over this perio...