Maliković Jovana, Schönbächler Katja, Destro Ana Luiza F, Wolfer David P, Amrein Irmgard
Division of Functional Neuroanatomy, Institute of Anatomy, University of Zürich, Zürich, Switzerland.
Bat Conservation Switzerland, Zürich, Switzerland.
Front Neuroanat. 2025 Aug 13;19:1641787. doi: 10.3389/fnana.2025.1641787. eCollection 2025.
Even though bats are the second most speciose group of mammals, neuroanatomical studies of their hippocampus are rare, particularly of small echolocating bats. Here, we provide a qualitative and quantitative neuroanatomical analysis of the hippocampus of small echolocating bats (Phyllostomidae and Vespertilionidae). Calcium-binding proteins revealed species- and family-specific patterns for calbindin and calretinin. Interneuron staining for both proteins was very rare in phyllostomids, while calretinin marked subpopulations of CA3 pyramidal neurons in both families. Parvalbumin expression was consistent across bats and similar to other species. A unique calretinin-positive calbindin-negative zone was observed at the superficial boundary of the CA3 pyramidal cell layer in phyllostomid bats. This zone defined a gap between pyramidal cells and the zinc-positive mossy fibers. We hypothesize that this gap might either stem from calretinin-positive afferents displacing the zinc-positive mossy fiber boutons, or from a complete segregation of neurochemically distinct mossy boutons. Furthermore, we observed a distinct dorsoventral shift in the length of the upper and lower blade of the granule cell layer in all species. In terms of hippocampal neuron numbers, bats were characterized by a rather small granule cell and subicular neuron population, but a well-developed CA3. In a correspondence analysis, preferred diet segregated phyllostomids into a hilus-dominant omnivorous and frugivorous species group, and a subiculum-dominant group containing vampire bats and nectivorous species. Although the two families overlapped considerably, the cellular composition of the phyllostomid hippocampus can be described as output dominant, while in vespertilionids neuron populations on the hippocampal input side are more dominant. Neuroanatomical and ecological variability and unique traits within echolocating bats as shown here can provide a rich source for investigating structure-function relationships.
尽管蝙蝠是哺乳动物中第二大物种丰富的类群，但对其海马体的神经解剖学研究却很罕见，尤其是对小型回声定位蝙蝠的研究。在此，我们对小型回声定位蝙蝠（叶口蝠科和蝙蝠科）的海马体进行了定性和定量的神经解剖学分析。钙结合蛋白揭示了钙结合蛋白和钙视网膜蛋白的物种及科特异性模式。在叶口蝠科中，这两种蛋白的中间神经元染色非常罕见，而钙视网膜蛋白标记了两个科中CA3锥体神经元的亚群。小白蛋白的表达在蝙蝠中是一致的，且与其他物种相似。在叶口蝠科蝙蝠的CA3锥体细胞层表面边界观察到一个独特的钙视网膜蛋白阳性、钙结合蛋白阴性区域。这个区域界定了锥体细胞和锌阳性苔藓纤维之间的间隙。我们推测，这个间隙可能源于钙视网膜蛋白阳性传入纤维取代了锌阳性苔藓纤维终扣，或者源于神经化学上不同的苔藓终扣的完全分离。此外，我们在所有物种中都观察到颗粒细胞层上下叶片长度的明显背腹移位。就海马神经元数量而言，蝙蝠的特点是颗粒细胞和下托神经元群体相对较小，但CA3发达。在对应分析中，偏好的饮食将叶口蝠科分为一个以齿状回为主的杂食性和食果性物种组，以及一个以下托为主的包含吸血蝙蝠和食蜜物种的组。尽管这两个科有相当大的重叠，但叶口蝠科海马体的细胞组成可描述为输出占主导，而蝙蝠科中海马输入侧的神经元群体更为占主导。此处所示回声定位蝙蝠的神经解剖学和生态变异性以及独特特征可为研究结构 - 功能关系提供丰富来源。
