Larsen J H, Schroeder P C, Waldo A E
Cell Tissue Res. 1977 Jul 19;181(4):505-18. doi: 10.1007/BF00221772.
Low concentrations of cytochalasin B (CCB) are known to inhibit ovulation in the frog, Hyla regilla. Examination of amphibian thecal cell ultrastructure reveals filaments (average diameter 71 A) arranged in bundles parallel to the surface of the oocyte. These filaments are often associated with hemidesmosome-like plaques on the basal plasmalemma, While individual filaments appear unaltered morphologically by CCB (1-5 microgram/ml), their organization into bundles, apparent relationship to the hemidesmosomes, and the highly contorted configuration of the thecal cells after oocyte expulsion, suggest that a nonmuscular contractile system residing within the follicle plays a fundamental role in ovulation. Our data suggest that the flattened epitheloid thecal cells shorten all axes that run parallel to the oocyte surface via filament bundle contractions, while they remain tightly bound together by macular attachment plaques. These cells thus increase in height to become cuboidal-low columnar in shape; the area covered by the base of each is greatly reduced. As this "thecal sac" decreases in size, the compression generated by the contractile mechanism forces the oocyte through the enzymatically weakened apex of the follicle and ovulation results.
已知低浓度的细胞松弛素B（CCB）可抑制蛙类（雨蛙）排卵。对两栖动物卵泡膜细胞超微结构的检查发现，细丝（平均直径71埃）成束排列，与卵母细胞表面平行。这些细丝常与基底质膜上类似半桥粒的斑块相关联。虽然单个细丝在形态上未被CCB（1 - 5微克/毫升）改变，但其聚集成束、与半桥粒的明显关系以及卵母细胞排出后卵泡膜细胞的高度扭曲形态，表明卵泡内存在的非肌肉收缩系统在排卵中起基本作用。我们的数据表明，扁平的上皮样卵泡膜细胞通过细丝束收缩缩短所有与卵母细胞表面平行的轴，同时它们通过斑状附着斑块紧密结合在一起。因此，这些细胞高度增加，变成立方形 - 低柱状；每个细胞底部覆盖的面积大大减小。随着这个“卵泡膜囊”尺寸减小，收缩机制产生的压力迫使卵母细胞通过卵泡酶解弱化的顶端，从而导致排卵。
