The cortical granules of hamster ova were ruptured in vitro by electrical stimulation (standard treatment was 150 V, 1\m=.\0msec). Approximately 8 min were required for the cortical granule material so released to induce a complete zona reaction. The active material from the cortical granules was released into the medium from vitelli and was shown to act directly on the zona pellucida and on mo...

background: this study is the first research investigating the possible effect of pulsed power signals on the characteristics of cortical bone by comparing the mechanical properties of this type of bone pre and post expose to pulsed power. methods: a positive buck-boost converter was applied to generate adjustable high voltage, high frequency pulses (up to 500 v and 10 khz). the functional beha...

The number of conditions in which abnormal adrenal cortical function can occur is an ever-widening field, including certain well recognized endocrine abnormalities in addition to extremes of environment, trauma, "non-specific " disease processes, and surgical procedures which may excite the so-called " stress reaction " (Selye, 1946). In addition, alteration in adrenal cortical activity seems t...

Fusion of capacitated spermatozoa with the vitelline membrane, but not actual penetration, appears to initiate the cortical reaction in hamster eggs. The reaction can be artificially induced by the application of positively charged particles to the vitelline surface, a situation which may normally be prevented by the zona pellucida. Exposure of hamster eggs to neuraminidase, to lectins (concana...

Egg envelope or otherwise called zona radiata (ZR) is an acellular area that originates next to oolemma externally. It grows and thickens gradually from oolemma and follicular epithelium both. Microscopic studies on the tissue sections hava shown that during developmental stages of oocytes, ZR could not be observed at stage I (Primary growth stage) in Acipenser persicus. It appeared in stage ...

We investigated the effects of neonatal optic nerve transection on cortical acetylcholinesterase (AChE) activity in hooded rats during postnatal development and following behavioral manipulation after weaning. AChE reaction product was quantified on digitized images of histochemically stained sections in layer IV of primary somatic sensory, primary visual and visual association cortex. Rats wit...

Anterior-posterior polarity in the Caenorhabditis elegans zygote depends on two groups of PAR proteins, as well as on cortical flow. Recent work now demonstrates that this polarization results from a transition in a bistable reaction-diffusion system of PAR proteins that is triggered by cortical flow.