Bairati A, Comazzi M, Gioria M
Dipartimento di Fisiologia e Biochimica Generali, Sezione di Istologia e Anatomia Umana, Università degli Studi di Milano, Italy.
Tissue Cell. 2001 Oct;33(5):426-38. doi: 10.1054/tice.2001.0197.
We studied the ultrastructure of the subepidermal connective tissue (SEC) in different zones of the integument in terrestrial, marine and freshwater gastropods (eight species). In all cases, the SEC was a layer of loose connective tissue between the basal membrane (BM) of the epidermis and the connective tissue of the deeper muscle layers. It was of monotonous structure and not differentiated into layers such as are found in mammalian dermis. The extracellular matrix (ECM) consisted of a network of collagen fibrils of variable diameter, with abundant anchoring devices and proteoglycans. In six species, variables quantities of haemocyanin were present within haemocoelic sinuses present in the SEC. The thickness and density of the BM varied from species to species, as well as within species in the various zones of integument. The ultrastructure of the lamina densa (LD) was indistinguishable from that of BM in bivalves and similar to that in mammals, although basotubules and double pegs were absent. An irregularly spaced lamina lucida was usually present and was often shot thorough with filaments and small protrusions of the LD that connected with epithelial plasma membrane or with hemidesmosomes. A lamina fibroreticularis was not present. LD protrusions characterize the connection between BM and the ECM of SEC. In the terrestrial gastropods, a spongy matrix with ultrastructure closely similar to LD occupied large tracts of the SEC. In the mantle region of Arion rufus, the integumental SEC contained large cavities filled with spherical concretions, probably representing rudiments of a shell. In the mantle where the integument contained abundant muscle fibres, the BM was thick and directly connected to the ECM of the SEC which consisted of compact laminae of collagen fibrils with abundant anchoring devices. Along the edge of the foot of Patella ulyssiponensis, the SEC contained a layer of paramyosinic muscle fibres adhering to the epidermis. No differences or gradations in integumental SEC structure could be related to the phylogenetic position of the species examined.
我们研究了陆生、海洋和淡水腹足类动物（8个物种）体表不同区域的表皮下结缔组织（SEC）的超微结构。在所有情况下，SEC都是表皮基底膜（BM）与更深层肌肉层的结缔组织之间的一层疏松结缔组织。它结构单一，未分化成哺乳动物真皮中那样的层。细胞外基质（ECM）由直径可变的胶原纤维网络组成，有丰富的锚定装置和蛋白聚糖。在6个物种中，SEC中的血腔窦内存在不同数量的血蓝蛋白。BM的厚度和密度因物种而异，在同一物种的体表不同区域也有所不同。双壳类动物的致密层（LD）超微结构与BM无法区分，与哺乳动物的相似，不过没有基底小管和双钉。通常存在一层间隔不规则的透明层，且常常有细丝和LD的小突起贯穿其中，这些突起与上皮质膜或半桥粒相连。不存在纤维网状层。LD突起是BM与SEC的ECM之间连接的特征。在陆生腹足类动物中，一种超微结构与LD非常相似的海绵状基质占据了SEC的大片区域。在红蛞蝓的外套膜区域，体表SEC包含充满球形凝结物的大腔，可能代表壳的雏形。在体表含有丰富肌纤维的外套膜处，BM较厚，直接与SEC的ECM相连，SEC由带有丰富锚定装置的紧密胶原纤维层组成。沿着乌利西髌骨螺足部边缘，SEC包含一层附着于表皮的副肌球蛋白肌纤维。所研究物种的体表SEC结构的差异或渐变与系统发育位置无关。
