Handl Claudia H, Todt Christiane
Department of Evolutionary Biology, University of Vienna, A-1090 Vienna, Austria.
J Morphol. 2005 Jul;265(1):28-42. doi: 10.1002/jmor.10336.
In the molluscan class Solenogastres, different types of foregut glands vary in number, structure, and location within the foregut. The present article describes their anatomy and cytology and intends to clarify their confused terminology. Pharyngeal glands, esophageal glands, and the more complex dorsal and ventrolateral foregut glands can be distinguished. The ventrolateral foregut glands (ventral foregut glandular organs, ventral salivary glands of auct.), in the literature subdivided previously into four types, are revisited here in the context of current vertebrate gland terminology. The results of recent investigations are added to earlier ones, and a classification system for these multicellular glands is proposed. This system is based on cytological characters of glandular cells (intra- or extraepithelial), characters of the associated musculature (inner or outer musculature), location of the gland relative to the pharynx epithelium (endoepithelial or exoepithelial), characters of the gland openings (paired or unpaired), morphology of the gland duct (simple or branched), and some additional features like the arrangement of glandular cells along the gland ducts. Gross morphology and anatomy of ventrolateral foregut glands constitute useful taxonomic characters in determining higher taxa (family level), and finer details of the anatomy and cytology are useful in determining lower levels (genus and species). Possible pathways for the evolution of the different gland types of Solenogastres in relation to foregut glands present in the other molluscan clades are presented. The importance of ventrolateral foregut gland characters for phylogenetic considerations within the Solenogastres is discussed.
在软体动物的沟腹纲中，不同类型的前肠腺在数量、结构以及在前肠内的位置上存在差异。本文描述了它们的解剖结构和细胞学特征，并旨在厘清其混乱的术语。可以区分出咽腺、食管腺以及更为复杂的背侧和腹外侧前肠腺。腹外侧前肠腺（腹侧前肠腺器官，作者所称的腹侧唾液腺），在文献中先前被细分为四种类型，本文在此根据当前脊椎动物腺体术语对其进行重新审视。将近期研究结果与早期研究结果相结合，并提出了这些多细胞腺体的分类系统。该系统基于腺细胞的细胞学特征（上皮内或上皮外）、相关肌肉组织的特征（内部或外部肌肉组织）、腺体相对于咽上皮的位置（上皮内或上皮外）、腺体开口的特征（成对或不成对）、腺管的形态（简单或分支）以及一些其他特征，如腺细胞沿腺管的排列方式。腹外侧前肠腺的大体形态和解剖结构在确定较高分类阶元（科级）时构成有用的分类学特征，而解剖学和细胞学的更细微细节在确定较低分类阶元（属和种）时则很有用。本文还展示了沟腹纲不同腺体类型相对于其他软体动物类群中存在的前肠腺可能的进化途径。讨论了腹外侧前肠腺特征在沟腹纲系统发育研究中的重要性。
