Schatten G, Schatten H
Scan Electron Microsc. 1983(Pt 3):1403-13.
Scanning electron microscopy (SEM) has been successfully employed for the study of several surface-mediated events during fertilization and early development in sea urchins. In addition to basic morphological descriptions of the sperm, the extrusion of the acrosomal process has been documented with SEM. During sperm incorporation, short microvilli are found to elongate around the successful sperm. In eggs denuded of vitelline layers, in which the elevation and hardening of this fertilization coat is prevented, numerous long microvilli have been shown to cluster around and elongate over the entering sperm during sperm incorporation. Following sperm incorporation and the elevation of the fertilization coat, scanning electron microscopy has been utilized to study the bursts of elongation of the previously short egg microvilli. These microvilli appear to undergo two bursts in length due primarily to the new assembly of microfilaments in the egg cortex. Cytokinesis occurs shortly after the second burst of microvillar elongation. The morula stage is characterized by loosely attached cells which become more closely apposed in subsequent cell divisions to result in the hollow blastula. The ciliated blastula hatches from the fertilization coat, whereupon gastrulation occurs, resulting in a free-swimming, feeding larval stage. This paper reviews the surface alterations and the contribution of scanning electron microscopy to the study of these surface alterations, from fertilization through early development.
扫描电子显微镜（SEM）已成功用于研究海胆受精和早期发育过程中的几种表面介导事件。除了对精子进行基本的形态学描述外，顶体突起的挤出也已通过扫描电子显微镜记录下来。在精子纳入过程中，发现短微绒毛会围绕成功纳入的精子伸长。在去除卵黄膜层的卵子中，受精膜的隆起和硬化受到抑制，在精子纳入过程中，大量长微绒毛会聚集在进入的精子周围并在其上伸长。在精子纳入和受精膜隆起之后，扫描电子显微镜已被用于研究先前短的卵微绒毛的伸长爆发。这些微绒毛的长度似乎经历两次爆发，这主要是由于卵皮质中微丝的新组装。胞质分裂在微绒毛伸长的第二次爆发后不久发生。桑葚胚阶段的特征是细胞松散附着，在随后的细胞分裂中这些细胞彼此靠得更近，从而形成中空的囊胚。有纤毛的囊胚从受精膜中孵化出来，随后发生原肠胚形成，形成自由游动、摄食的幼虫阶段。本文综述了从受精到早期发育过程中的表面变化以及扫描电子显微镜对这些表面变化研究的贡献。
