Witold Stefański Institute of Parasitology, Polish Academy of Sciences, 51/55 Twarda Street, 00-818, Warsaw, Poland.
Laboratoire de Biodiversité et Ecosystèmes Aquatiques, Département des Sciences de la Vie, Faculté des Sciences de Sfax, BP 1171, 3000, Sfax, Tunisia.
Parasitol Res. 2019 Feb;118(2):493-504. doi: 10.1007/s00436-018-6180-4. Epub 2018 Dec 26.
Vitellogenesis and vitellocytes of Cainocreadium labracis were studied by transmission electron microscopy (TEM) and TEM cytochemistry. Four developmental stages were distinguished during vitellogenesis: (I) stem cell of high nucleo-cytoplasmic ratio; (II) early differentiation with chief activity focused on the beginning of protein synthesis and shell globule formation; (III) advanced differentiation with rapid intensification of protein synthesis, progressive fusion of single shell globules into large globule clusters, and formation of unsaturated lipid droplets surrounded by β-glycogen particles; and (IV) mature vitellocyte. Early vitellogenesis with vitellocyte maturation consists of: (1) increase in cell volume; (2) increased development of large, parallel cisternae of GER with production of proteinaceous granules; (3) development of small Golgi complexes that package granules; and (4) within vacuoles, progressive enlargement of proteinaceous granules into shell globule clusters formed during vitellogenesis. Three types of inclusions accumulate in large amounts in mature vitelline cells: (1) shell globule clusters, important component in the formation of egg shell; (2) numerous unsaturated lipid droplets. Though fewer, there are also diphasic droplets consisting of saturated and unsaturated lipids in the same droplet, and (3) a relatively small amount of β-glycogen particles, usually surround a few groups of lipid droplets. The β-glycogen and lipid droplets are nutritive reserves for embryogenesis. General pattern and functional ultrastructure of vitellogenesis greatly resemble those observed in some lower cestodes, such as bothriocephalideans and diphyllobothrideans. Variations and differences in the amount of lipids and of glycogen during vitellogenesis in lower cestodes and other trematodes are compared and discussed.
利用透射电子显微镜（TEM）和 TEM 细胞化学技术研究了 Cainocreadium labracis 的卵黄发生和卵黄细胞。在卵黄发生过程中区分出四个发育阶段：（I）核质比高的干细胞；（II）早期分化，主要活动集中在蛋白质合成和壳球形成的开始；（III）晚期分化，蛋白质合成迅速增强，单个壳球逐渐融合成大球簇，并形成不饱和脂滴，被β-糖原颗粒包围；（IV）成熟的卵黄细胞。早期卵黄发生和卵黄细胞成熟包括：（1）细胞体积增大；（2）GER 的大平行嵴增加，产生蛋白质颗粒；（3）小高尔基体复合体的发育，包装颗粒；（4）在液泡内，蛋白质颗粒逐渐增大，形成卵黄发生过程中的壳球簇。在成熟的卵黄细胞中积累了大量的三种内含物：（1）壳球簇，是形成卵壳的重要成分；（2）大量不饱和脂滴。虽然较少，但也有二相滴，由同一滴中的饱和和不饱和脂质组成，（3）相对少量的β-糖原颗粒，通常围绕着几组脂滴。β-糖原和脂滴是胚胎发生的营养储备。卵黄发生的一般模式和功能超微结构与一些较低的绦虫（如 Bothriocephalideans 和 Diphyllobothrideans）非常相似。在较低的绦虫和其他吸虫中，卵黄发生过程中脂类和糖原的数量的变化和差异进行了比较和讨论。
