Histology and Immunohistochemical Analyses in the Brain of Juvenile Chinese Alligator

In current study, we used Nissl staining to examine the histological structure of the juvenile Chinese alligator brain, and immunohistochemistry (IHC) staining to detail the serotonin (5-hydroxytryptamine, 5-HT) localization and morphology of neurons belonging to the serotonergic system. Nissl staining revealed that the Chinese alligator brain was divided into four regions (telencephalon, diencephalon, brainstem, and cerebellum) and a connected ventricular system (containing the pair of lateral ventricles, third ventricle, fourth ventricle and the aqueduct). According to the IHC results, 5-HT immunoreactive (5-HT-IR) neurons were primarily observed in the cerebral cortex, the hypothalamic paraventricular nucleus (PH), tectum and tegmentum of the optic lobes, the medial longitudinal fasciculus (Flm) of medulla oblongata and the cerebellar cortex. 5-HT-IR fibers were mostly located lateral to the hypothalamic paraventricular nucleus (PH), in the medial vestibular nucleus (MVe) of the medulla oblongata, and in the choroid plexus (CP) of the lateral ventricles. Additionally, our findings paralleled those results of other reptiles; nevertheless, some distinctions in terms of both histological architecture and function were identified. The layering of the cerebral cortex and tectum, as well as the arrangement of Purkinje cells, differed between reptile brains. The distribution of 5-HT-IR neurons varied in the layer of cerebral and cerebellar cortex when compared to other reptiles. Within the diencephalon, 5-HT-IR neurons formed distinct nuclei in the hypothalamic paraventricular nucleus (PH), but few in the infundibular recess. KEY WORDS: Chinese Alligator brain; Nissl staining; Immunohistochemistry (IHC); 5-HT-IR neurons. Utilizamos la tincion de Nissl para examinar la estructura histologica del cerebro juvenil del caiman chino y la tincion inmunohistoquimica (IHC) para detallar la localizacion y morfologia de la serotonina (5-hidroxitriptamina, 5-HT) de las neuronas que pertenecen al sistema serotoninergico. La tincion de Nissl revelo que el cerebro del caiman chino estaba dividido en cuatro regiones (telencefalo, diencefalo, tronco encefalico y cerebelo) y un sistema ventricular conectado (que contiene el par de ventriculos laterales, el tercer ventriculo, el cuarto ventriculo y el acueducto). Segun los resultados de IHC, las neuronas inmunorreactivas 5-HT (5-HT-IR) se observaron principalmente en la corteza cerebral, el nucleo paraventricular (PH) hipotalami