Balles S, Maas U, Sehn E, Dorn A
Institut für Zoologie, Johannes Gutenberg-Universität, D-55099 Mainz, Germany.
J Morphol. 2002 Jan;251(1):22-37. doi: 10.1002/jmor.1072.
The gonads of Lampyris noctiluca are sexually undifferentiated during the first larval instars. They consist of many gonadal follicles that include the germ stem cells enclosed by the somatic cells of the follicle wall. Follicle wall cells are more numerous at the follicle apices than at the distal parts, but different cell types cannot be distinguished. In male larvae, the appearance of apical follicle tissue, derived from follicle wall cells, marks the onset of testis differentiation. When maximally expressed, the apical tissue occupies about the upper half of the testis follicles and can be observed in larvae of the fifth and sixth instar. The apical tissue is characterized by its "light" appearance (due to poor stainability) caused by the small number cellular organelles, especially a paucity of free ribosomes. Maximal expression of the apical tissue must be very brief, since in most examined fifth and sixth instar larvae the apical tissue is partly or mostly translocated into the center of the upper half of the follicles and spermatogonia then occupy the apical follicle tips. During and after translocation apical cells form projections that grow around clusters of spermatogonia (spermatocysts). Thus, the apical cells transform into spermatocyst envelope cells. They retain their "light" appearance but undergo dramatic subcellular differentiation: smooth ER becomes extremely prominent, forming stacks and whorls of parallel cisternae. Golgi complexes are also conspicuous. The cellular organization suggests secretory activity. The possibility of ecdysteroid production and its function is discussed. The spermatocyst envelope cells persist into the pupal stage. When spermiohistogenesis takes place in cysts, cyst envelope cells show signs of regression. At all stages of testis development apical cells and their derivatives, the spermatocyst envelope cells, phagocytize degenerating spermatogonia. Although this is an important task of these cells, the impressive formation of sER in the cyst envelope cells is indicative of an additional, as yet unknown, function.
黄萤的性腺在第一龄幼虫期是未分化的。它们由许多性腺滤泡组成，这些滤泡包含被滤泡壁体细胞包围的生殖干细胞。滤泡壁细胞在滤泡顶端比在远端部分更多，但无法区分不同的细胞类型。在雄性幼虫中，源自滤泡壁细胞的顶端滤泡组织的出现标志着睾丸分化的开始。当顶端组织最大程度表达时，它占据睾丸滤泡的上半部分左右，并且可以在第五和第六龄幼虫中观察到。顶端组织的特征是其“浅色”外观（由于染色性差），这是由于细胞器数量少，尤其是游离核糖体缺乏所致。顶端组织的最大程度表达一定非常短暂，因为在大多数检查的第五和第六龄幼虫中，顶端组织部分或大部分转移到滤泡上半部分的中心，然后精原细胞占据滤泡顶端。在转移期间和之后，顶端细胞形成围绕精原细胞簇（精囊）生长的突起。因此，顶端细胞转变为精囊包膜细胞。它们保持“浅色”外观，但经历了显著的亚细胞分化：滑面内质网变得极其突出，形成平行扁平囊泡的堆叠和螺旋。高尔基体也很明显。细胞组织表明有分泌活动。讨论了蜕皮甾类产生的可能性及其功能。精囊包膜细胞持续到蛹期。当精细胞发生在囊中时，囊包膜细胞显示出退化的迹象。在睾丸发育的所有阶段，顶端细胞及其衍生物，即精囊包膜细胞，吞噬退化的精原细胞。尽管这是这些细胞的一项重要任务，但囊包膜细胞中滑面内质网的显著形成表明还有一项额外的、尚未知晓的功能。
