Kleineidam C, Romani R, Tautz J, Isidoro N
Theodor-Boveri-Institut, Lehrstuhl für Verhaltensphysiologie und Soziobiologie, Am Hubland, 97074, Würzburg, Germany.
Arthropod Struct Dev. 2000 Jan;29(1):43-55. doi: 10.1016/s1467-8039(00)00012-8.
The sensilla ampullacea on the apical antennomere of the leaf-cutting ant Atta sexdens were investigated regarding both their responses to CO2 and their ultrastructure. By staining the sensillum during recording, we confirmed that the sensilla ampullacea are responsible for CO2 perception. We showed that the sensory neurons of the sensilla ampullacea are continuously active without adaptation during stimulation with CO2 (test duration: 1 h). This feature should enable ants to assess the absolute CO2 concentration inside their nests. Sensilla ampullacea have been found grouped mainly on the dorso-lateral side of the distal antennal segment. Scanning and transmission electron microscopic investigations revealed that the external pore opens into a chamber which connects to the ampulla via a cuticular duct. We propose protection against evaporation as a possible function of the duct. The ampulla houses a peg which is almost as long as the ampulla and shows cuticular ridges on the external wall. The ridges are separated by furrows with cuticular pores. The peg is innervated by only one sensory neuron with a large soma. Its outer dendritic segment is enveloped by a dendritic sheath up to the middle of the peg. From the middle to the tip numerous dendritic branches (up to 100) completely fill the distal half of the peg. This is the first report of a receptor cell with highly branched dendrites and which probably is tuned to CO2 exclusively.
对切叶蚁Atta sexdens顶端触角节上的壶形感器进行了研究，涉及它们对二氧化碳的反应及其超微结构。通过在记录过程中对感器进行染色，我们证实壶形感器负责二氧化碳感知。我们发现，在用二氧化碳刺激期间（测试持续时间：1小时），壶形感器的感觉神经元持续活跃且无适应性。这一特性应能使蚂蚁评估巢穴内的绝对二氧化碳浓度。壶形感器主要集中在触角远端节段的背外侧。扫描电镜和透射电镜研究表明，外部小孔通向一个腔室，该腔室通过角质化导管与壶腹相连。我们认为导管可能具有防止蒸发的功能。壶腹内有一个栓柱，其长度几乎与壶腹相同，外壁上有角质化脊。这些脊由带有角质化小孔的沟隔开。栓柱仅由一个具有大细胞体的感觉神经元支配。其外部树突段被一个树突鞘包裹至栓柱中部。从栓柱中部到顶端有许多树突分支（多达100个），完全充满了栓柱的远端一半。这是首次报道具有高度分支树突且可能专门对二氧化碳进行调谐的受体细胞。
