This study was carried on the tongues of ten normal, healthy and adult fruit bats (Rousettus amplexicaudatus, also known as the nyap biasa bat) in Yogyakarta, Java Island, Indonesia. The tongue was protrusible, elongated and flat with a rounded apex, and its width and thickness increased gradually towards to lingual root. There were two main types of lingual papillae, mechanical (filiform) and gustatory (fungiform and circumvallate). The tongue was divided into three parts (apex, corpus and radix), and then, each part was subdivided into three regions (two lateral regions and a median region). There were six subtypes of the filiform papillae—three types on the anterior part (small, scale‐like and giant), one type on the middle part (leaf‐like papillae) and two types on the posterior part (rosette‐shaped filiform and conical filiform papillae)—in addition to transitional papillae presented on the corpus and radix. Two types of gustatory papillae were represented by a small number of fungiform papillae that are scattered among the filiform papillae on the lingual apex and corpus, while three circumvallate papillae on the posterior part are arranged in a “V” shape pointing directly at the larynx.

There are vast numbers of bats, in terms of both individuals and species, in Indonesia, although the precise species count is currently unknown. These bats demonstrate great variation in feeding patterns, with some being insectivorous, frugivorous, nectareating or carnivorous. One of the insectivorous bats found on Java Island, Indonesia, is the Javan pipistrelle (Pipistrellus javanicus). This paper presents a detailed morphological description of the tongue and lingual papillae of P. javanicus, using scanning electron microscopy (SEM) and light microscopy (LM). Macroscopically, the elongated tongue of P. javanicus can be divided into three sections: the apex, corpus and radix. On the dorsal part of the tongue (corpus), there is a prominence called the mediodorsal lobe, the lobe begin from the end of apex. On the radix, in the medial part, we describe the presence of a sulcus medianus. The SEM and LM observations show that the apex of the tongue bears three types of papillae: crown filiform, pronged filiform and fungiform. The corpus bears conical and fungiform papillae, whereas the radix bears vallate, large filiform, small filiform and fungiform papillae. Taken together, these results contribute to research on the tongue anatomy and feeding habits of the bat.

Background:Rousettus amplexicaudatus is one of the old world fruit bats, commonly known in Javanese word as codot belongs to Order Chiroptera and suborder Megachiroptera. R. amplexicaudatus possessed an outstanding visual ability, which helps in the process of searching for food. Those activities process and save within the brain involving the learning and memory activities. Learning and memory activities are centered around the hippocampus with the help of serotonergic nerve.Aim:This study conducted to identify the morphology and distribution of serotonergic nerve (5-hydroxytryptamine) in the hippocampus of R. amplexicaudatus, which related to the function of serotonin within the learning and memory process.Materials and Methods:Five R. amplexicaudatus bats were brought from Gunung Kidul cave, Yogyakarta, Java Island, Indonesia. The bats were anesthetized using ketamine and xylazine. R. amplexicaudatus then perfused intracardially. The brain samples were collected processed into paraffin block, and a further cut in 8 µm thickness serially. The tissue slides were stained using hematoxylin-eosin, cresyl echt violet, and immunohistochemistry with rabbit’s anti-serotonin (1:200). The results observed and analyzed quantitatively and qualitatively using image J (https://imagej.nih.gov/ij/) (Bethesda, Maryland, USA) and GraphPad Prism 7 (La Jolla, CA, USA).Results:The hippocampus of R. amplexicaudatus composed of the dentate gyrus (DG), hippocampus proper (cornu ammonis 3 [CA3], and CA1 as the main area for learning memory), and subiculum. On the DG serotonin immunoreactive cells found within the granular layer (132±35.03 cells/mm2), polymorphic stratum (86.33±11.23 cells/mm2), and molecular layer (93±1 cells/mm2). Meanwhile, on CA3 area, the immunoreactive cells for serotonin found in each stratum. The number of immunoreactive cells on each stratum from highest to the lowest are stratum pyramidal 123.33±15.88 cell/mm2, stratum molecular 63±13.11 cell/mm2, stratum lucidum 62.67±8.08 cell/mm2, stratum radiatum 55.33±510.21 cell/mm2, stratum oriens 48±3.46 cell/mm2, and stratum alveus 28.67±2,52 cell/mm2. In addition, in CA1 also hampers the immunoreactive cells in the pyramidal stratum, molecular, lucidum, oriens, radiatum, and alveus layer, respectively, of each 91±27.40 cell/mm2, 60.33±20.65 cell/mm2, 53.67±4.51 cell/mm244.33±10.40 cell/mm2, 41.33±5.51 cell/mm2, and 27±4 cell/mm2.Conclusion:Taking together the distribution of serotonin-immunoreactive cells in the hippocampus of R. amplexicaudatus mostly found on CA3 followed by CA 1 and DG.