一种游仆虫棘毛基部纤维的形态及其在形态发生过程中的演化

游仆虫皮层棘毛基部纤维包括纵纤维、前纵纤维和放射纤维:额腹棘毛基部后纵纤维一般长而粗大,前纵纤维次之,放射纤维较细小;横棘毛基部前纵纤维几乎纵贯额腹横棘毛区皮层,而放射纤维较为细小;尾棘毛基部仅与一类更为细小的放射纤维相联系。不同额腹棘毛基部的同种纤维大小、形态不尽一致,各种纤维由棘毛基部区向皮层细胞质多个方向伸展,表现出极性和不对称性。并且额腹横棘毛基部纤维相互交联在一起,导致这一皮层区域形成强大的棘毛基部纤维网络。 游仆虫形态发生中,横棘毛原基向皮层裂口上方伸出一束粗大的纤毛芽时,先后发生模棘毛原基前纵纤维芽、额腹棘毛原基后纵纤维芽,以及这些棘毛原基放射纤维芽。纤维芽的发育顺序是从左列棘毛原基开始,到右侧的棘毛原基。这种纤维物质生长的顺序性,与新棘毛原基的发生和分化是相一致的。并且额腹棘毛基部后纵纤维和横棘毛基部前纵纤维形成中显示出极性和方向性,纤维物质生长伸长的方向与相应的新棘毛迁移方向相反。 老棘毛基部纤维在游仆虫形态发生过程中必然要退化。我们推测,其瓦解过程与细胞分化中老棘毛逐渐失去功能是有联系的。

THE MORPHOLOGY OF CIRRAL-BASE-ASSOCiATED FIBERS IN EUPLOTES SP.AND THEIR MORPHOGENESIS

The cortical cirral-base-associated fibers (CF) in Euplotes sp. are. anterior longitudinal fibers (AF), posterior longitudinal fibers (PF), and radiating fibers (RF). Among them, the PF of frontoventral cirri (FVC) base are generally longer and thicker; while the AF are smaller; and, the RF are the thinnest and smallest ones. The AF of transverse cirri (TC) base almost spread through the whole cortical region of froritoventral and transverse cirri (FVTC); and their RF are thinner and smaller. Caudal cirri base are associated only with some RF, further thinner and smaller. Similar fibers, base-associated with different FVC, are different in size and shape. They extend from their cirral-base in various orientations, towards cortical cytoplasm, with apparent polarity and asymmetry. The fibers from FVTC base are heavily entangled, forming a strong net-work of base-associated fibers in their cortical region. During morphogenesis of Euplotes sp., when the primordia of TC developed a bundle of thick cilia buds, extending towards the cortical fissure, the AF buds of TC primordia, PF buds of FVC primordia, and their RF buds, were developed successively. The fiber buds of left column cirral primordia developed first, then, developed those of the right column. The order of fiber material growth in coincidence with the development and differentiation of new cirri primordia. Also, in the formation of PF of FVC bases and AF of TC bases,polarity and orientation are displayed, i. e., the directions of fiber material growth are opposite to that of their corresponding new cirri migration. Old CF arc doomed to degenerate during morphogenesis of Euplotes. It is supposed that their degenerating process are related to the gradual lose of old cirri's functions during cell differentiation.