Área de Biología Celular, Departamento de Anatomía, Biología Celular y Zoología, Facultad de Ciencias, Universidad de Extremadura, Badajoz 06006, Spain.
Center of Marine Sciences, Universidade do Algarve Campus de Gambelas, Faro 8005-139, Portugal.
Tissue Cell. 2024 Jun;88:102417. doi: 10.1016/j.tice.2024.102417. Epub 2024 May 27.
In this work we present a detailed study of the major events during retinal histogenesis of the cuttlefish Sepia officinalis from early embryos to newly hatched animals and juveniles. For this purpose, we carried out morphometric and histological analyses using light and scanning electron microscopy. From St19, the first embryonic stage analysed, to St23/24 the embryonic retina is composed of a pseudostratified epithelium showing abundant mitotic figures in the more internal surface. At St24 the first photoreceptor nuclei appear in the presumptive inner segment layer, while an incipient layer of apical processes of the future rhabdomeric layer become visible at St25. From this stage onwards, both the rhabdomeric layer and the inner segment layer increase in size until postnatal ages. In contrast, the width of the supporting cell layer progressively decreases from St25/26 until postnatal ages. S. officinalis embryos hatched in a morphologically advanced state, showing a differentiated retina even in the last stages of the embryonic period. However, features of immaturity are still observable in the retinal tissue during the first postnatal weeks of life, such as the existence of mitotic figures in the apical region of the supporting cell layer and migrating nuclei of differentiating photoreceptors crossing the basal membrane to reach their final location in the inner segment layer. Therefore, postnatal retinal neurogenesis is present in juvenile specimens of S. officinalis.
在这项工作中，我们对乌贼（Sepia officinalis）从早期胚胎到刚孵化的幼体和幼体的视网膜发生过程中的主要事件进行了详细研究。为此，我们使用光镜和扫描电子显微镜进行了形态计量学和组织学分析。从分析的第一个胚胎阶段 St19 到胚胎期 St23/24，胚胎视网膜由具有丰富有丝分裂图的假复层上皮组成。在 St24，第一批光感受器核出现在预期的内节层中，而未来的纤毛层的顶端过程的初始层在 St25 时变得可见。从这个阶段开始，纤毛层和内节层的大小都增加，直到出生后年龄。相比之下，从 St25/26 到出生后年龄，支持细胞层的宽度逐渐减小。S. officinalis 胚胎以形态上先进的状态孵化，甚至在胚胎期的最后阶段也表现出分化的视网膜。然而，在出生后的头几周的视网膜组织中仍然可以观察到不成熟的特征，例如在支持细胞层的顶端区域存在有丝分裂图和正在分化的光感受器的迁移核穿过基底膜到达它们在内节层中的最终位置。因此，S. officinalis 幼体存在出生后视网膜神经发生。
