MORPHOLOGICAL CHANGES OF THE SURFACE OF THE EGGS OF RANA AMURENSIS DURING FIRST CLEAVAGE BY FLUORESCENCE MICROSCOPY——RECEPTORS OF WHEAT GERM AGGLUTININ AND SOYBEAN AGGLUTININ

Receptors of wheat germ agglu-tinin (WGA) and soybean agglutinin (SBA) are present on the denuded living egg surface of Rana amurensis.Before cleavage these receptors dis-tribute evenly all over the animal pole (Plate I.Fig.1).At the onset of cleavage,numerous bright fluores-cent granules which correspond to the protrusions in the scanning ele-ctron microscope (10),are seen on the cleavage stripe and many bright ra-diated rays which is identified as folds,are visible on the side of the cleavage stripe (Plate I.Fig.2).Soon after,the new membrane hav-ing much less FITC-lectins binding ability,appears and divides the clea-vage stripe into 3 bright lines.The middle one is the primitive contrac-tile ring.While the cleavage goes on,the new membrane increases gra-dually (Plate I.Fig.3).However,when the denuded eggs are immersed in high concentration of WGA (500γ/ml) before cleavage,the new mem-brane appears only for a short time,then vanishes,leaving a black streak (Plate I.Fig.6 b,d).These results are in line with those found in newt's eggs (5).In high concentration of SBA (100 γ/ml) the new membrane exposed continuously but in a much smaller schedule.The contractile ring initially working normally,fails to work,and the new membrane bulges out (Plate II.Fig.7 8).Finally the new membrane disappears as those in WGA (Plate.I.Fig.6 a c are untreated control). In a few FITG-SBA stained eggs,a large dark halo,its center often coincides with the center of the furrow,appears quickly (Plate II.Fig.12),and persists for several minutes to more than one hour,so that it may overlap with the halos seen on the second cleavage stripes.The darker overlapping area gradually decreases and disappear eventually while the ??halos on the second cleavage furrows move away.Sometimes a bright halo may be seen on the egg surface.As the halo contracts,it becomes brighter and brighter.Finally many radiated stripes and a nipple-like structure are found in the center of the halo (Plate II.Fig.10-11).A few receptors,however,remains or lags behind dur-ing the contraction of the bright halo.This indicates that the receptor can become mobile or increase its moving rate under certain condition.The increasing of fluorescence,however,is not always resulting from the mo-vement of the receptor but from the movement of cell surface.By push-ing the evenly distributed fluorescent egg surface,many brighter lines appear at the folded places.This is explain-ed in figure 1.Increasing in fluores-cent intensity due to the fold of egg surface is also present naturely suchas the bright radiated rays and gra-nules at the cleavage stripe. Fig.1.Digrammatical representative of the dif-ferent intensity of fluorescence on the plain and fold region."A" Plain region."B" Fold or protuberant region."." FITC-lectin binding site."I" Transverse section,binding sites inequal distance."II" Top view.Binding sites becoming dense or fluorescence becoming brighter in B region.Indicating the increase of the intensing of fluo-rescence resulting from the move-ment of the binding sites itself.