Map kinase activation and RAF-1 synthesis in blue fox oocytes is controlled by cumulus granulosa cells

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Eggs of Paracentrotus lividus were pretreated with doses of trypsin that brought about a dissolution of the vitelline membrane, whereas the cytoplasm often exhibited a certain excess gelation as described in a previous paper [27]. In these eggs an expulsion of the cortical granules takes place; these are converted into rods and plates. Above the region of sperm entry the particles are closely aggregated, whereas they are dispersed in a more distal region and absent in the region opposite to that of sperm entry.In eggs approaching cytoplasmic cleavage the rods and plates move in the direction of the cleavage plane, where they accumulate and aggregate. The rods and plates move in a layer that is outside the egg surface but follow the movements of this latter. The particles carry out a certain Brownian movement which is damped when the furrow formation begins. After completion of the furrow the Brownian movement increases again and the particles are dispersed over the egg surface. In preparation for the second cleavage the accumulation of the rods and plates toward the cleavage plane is repeated. The degree of aggregation of the particles is variable. In many cases the aggregated particles bridge over the cleavage furrow like a continuous membrane, whereas the poles are devoid of particles. In many eggs of this kind bulges are formed at the division poles.The movements of cortical granules toward the cleavage furrow are also observed in eggs where the formation of a fertilization membrane occurs. Under certain circumstances a number of cortical granules do not join the membrane and are not converted into rods and plates. Accumulation of the granules toward the division plane and changes in their Brownian movement are also observed here.Partial fertilization of eggs was caused by temporary warming of the eggs soon after insemination [3, 26]. In these eggs the membrane covers only a certain region of the egg. If a division furrow appears in the neighbourhood of the border of the fertilization membrane, this latter expands so as to cover also the adjacent part of the furrow.The elevation of the fertilization membrane may be prevented by pipetting the eggs 30 seconds after insemination into the slit between coverslip and slide. These eggs divided and it is described how the fertilization membrane may bulge and become more refractive above the cleavage furrow.The phenomena described may be the due to the action of a gelating factor that plays a role both infertilization and cytoplasmic cleavage. The gleating factor may also be of importance for the cortical movements occurring in connection with cleavage [4–10]. Similar movements are noted to occur also toward the region of sperm attachment. The nature of the gelating factor is discussed on the basis of data showing that certain doses of trypsin are able to activate a gelating factor in the egg [27]. This factor has probably the nature of an enzyme.Certain additional observations are reported in order to demonstrate that considerable movements of the cortical layer may be induced in oocytes.