Development into blastocysts of bovine oocytes cryopreserved by ultra-rapid cooling

The objective of the research described was to devise an efficient procedure to cryopreserve in vitro-matured bovine oocytes, using in vitro fertilization (IVF) and development of resultant zygotes into blastocysts as criteria of oocyte survival. Oocytes at metaphase II were found to be extremely sensitive to chilling. Cooling them to O degrees C for as little as 5 sec significantly decreased their capability to cleave and develop further after IVF; after 80 sec at 0 degrees C, only approximately 10% of chilled oocytes developed into blastocysts. Oocytes were also adversely affected by brief exposures to 4 M and 5.5 M ethylene glycol (EG) solutions supplemented with sucrose; after being suspended in either of these EG solutions in plastic straws and plunged directly into liquid nitrogen (LN2), few of the oocytes were fertilized and developed. To "outrace" chilling injury, oocytes contained in < 1 microliter of EG solution were placed onto electron microscope grids and plunged directly into N2 slush or LN2. After such ultra-rapidly cooled oocytes were warmed, 30% of them cleaved after IVF, and half of these developed into blastocysts-- survival rates equivalent to those for oocytes that had been exposed to EG without any cooling. This method offers promise as a novel way to cryopreserve bovine oocytes.     

The organization and postnatal development of the commissural projection of the rat somatic sensory cortex

Anterograde and retrograde tracing experiments have been used to demonstrate the origin and terminal distribution of commissural fibers in the first somatosensory cortex (SI) of the rat. The commissural fibers originate from pyramidal cells of all layers, but predominantly from layers III and V. The fibers terminate in a series of approximately vertical bands. In each of these there are concentrations of terminals extending from the inner portion of the molecular layer to the deep portion of layer III as well as in the superficial part of layer V, and in layer VI. Discrete vertical bands of cortex are reciprocally connected across the midline to give both the origin and terminal regions of the projection a patchy or "columnar" appearance. The commissural fibers arise from and terminate in areas of the cortex that lie between and alongside the aggregations of granule cells that distinguish SI of the rat. No commissural fibers terminate within the aggregations of layer IV cells themselves but the more superficial terminal ramifications may come to overlie these aggregations. A heterotopic projection to the contralateral second somatosensory cortex has been observed and is similar in form to the homotopic projection to SI. Many commissural fibers have crossed the midline in the corpus callosum by the day of birth but lie in the underlying white matter and do not enter the cortical plate until at least the third postnatal day. During the first postnatal week these fibers grow somewhat diffusely into the maturing cortex and their topographic and laminar pattern of distribution attains its adult characteristics by the end of the first week. Commissural axons, thus, arise from immature cells but the maturation of cell form seems to precede the ingrowth of these axons and the acquisition of commissural synapses.     

Professional drivers: protection needed for a high-risk occupation

"On the job" motor vehicle deaths number more than 4,000 annually in the U.S. and comprise nearly one-third of all work-related deaths. Yet the Department of Labor has set no standards relating to on-the-road safety of the millions of workers whose jobs entail large amounts of driving, and Department of Transportation standards affecting occupational safety cover only drivers in interstate commerce. Drivers of some commercial vehicles, such as heavy trucks, are at special risk of injury because trucks have usually been exempted for many years from federal motor vehicle safety standards--such as standards for brakes and seatbelts--designed to prevent crashes or protect occupants in crashes. Observations based on a series of 150 fatal crashes involving tractor trailers illustrate the need for better protection of this large population of high-risk workers. Clarification of responsibility within the various federal agencies and application of available knowledge and technology are essential.     

Effect of caging variables on body weight and weight gain in mice

The effects on body weight of mixing litters to attain constant density of mice per cage, as opposed to housing litters in separate cages, was studied. Mixing litters resulted in a decreased weight gain between 21 and 42 da of age and a decreased adult body weight at 63 da of age compared to housing litters in separate cages, whether the separately housed litters were allowed to vary in density or not. Mixed litter housing also increased the variance of the body weight measures among males. Housing litters separately, even if it entails variable density of housing, appears to be the preferred method for studies involving inheritance of body weight.     

Immunocytochemical studies on Schistosoma mansoni. II. Soluble cercarial antigens in cercarial and schistosomules

The localization of soluble, cercarial antigen preparation (CAP) in cercariae and schistosomules of Schistosoma mansoni was performed at the light and electron microscope levels using the unlabeled antibody method. Reaction produce was observed associated with the contents of the pre- and postacetabular glands and with the filamentous coat of mature cercariae. No reaction product was observed associated with the glycoacalyx of schistosomules. However, several schistosomules did retain remnants of their filamentous coats and reaction product was observed associated with those remains. CAP components were also observed in the area surrounding the intrasporocyst cercariae.     

Retroperitoneal germinoma marked by elevated serum lactic dehydrogenase

A case of primary retroperitoneal germinoma is presented in which markedly elevated serum lactic dehydrogenase levels were present before diagnosis, but declined to normal with abdominal irradiation. It is the first report of lactic dehydrogenase serving as a tumor marker in germinoma.