Division of Veterinary Anatomy and Developmental Biology, Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland.
Anat Histol Embryol. 2024 Jul;53(4):e13077. doi: 10.1111/ahe.13077.
The endangered Saimaa ringed seal (Pusa hispida saimensis) is an endemic freshwater subspecies inhabiting Lake Saimaa in Finland. The Baltic ringed seal (Pusa hispida botnica) inhabits the brackish Baltic Sea, which is almost entirely landlocked. Recent research shows that Saimaa and Baltic ringed seals may be genetically even further apart from each other than from other ringed seal subspecies. We documented histologically the integument microstructure of Saimaa and Baltic ringed seals to determine whether the geographic and genetic isolation was manifested as variation in the integument microstructure of these subspecies adapted to icy aquatic environments. The skin structures of these subspecies were similar to those of other phocids. The association of the sweat glands with hair follicles in both subspecies suggested that they were small apocrine sweat glands described previously in terrestrial or aquatic mammals. None of the apocrine glands had large lumina, and some of the ducts were relatively straight and short. Further studies analysing the mode of secretion, for example, apocrine versus eccrine, in the sweat glands are necessary to confirm the types of sweat glands in seals.
濒危的塞马环斑海豹（Pusa hispida saimensis）是一种仅分布于芬兰塞马湖的淡水亚种。波罗的海环斑海豹（Pusa hispida botnica）栖息在几乎完全被陆地环绕的咸水波罗的海。最近的研究表明，塞马环斑海豹和波罗的海环斑海豹在遗传上可能比其他环斑海豹亚种彼此之间更为疏远。我们通过组织学记录了塞马环斑海豹和波罗的海环斑海豹的表皮微观结构，以确定地理和遗传隔离是否表现为适应冰冷水生环境的这些亚种的表皮微观结构的变化。这些亚种的皮肤结构与其他海豹科动物的皮肤结构相似。两种亚种的汗腺与毛囊的关联表明它们是小的顶泌汗腺，之前在陆地或水生哺乳动物中已有描述。没有一个顶泌腺有大的腔，有些导管相对直且短。进一步的研究分析汗腺的分泌方式，例如顶泌腺与外分泌腺，对于确认海豹的汗腺类型是必要的。
