Figure 2

Figure 2. Age-related changes of NPY immunoreactivity in the brain of zebrafish. (A–C) Transverse sections of the brain of a 6-month-old zebrafish. (A) Overview of NPY immunoreactivity in the hypothalamic area (lateral and dorsal periventricular hypothalamus) and in the midbrain tegmentum of 6-month-old zebrafish. Positive neurons are distributed in the lateral hypothalamus, in the proximity of the preglomerular nucleus and along the ventricle. Abundant varicosities are distributed in the hypothalamus and over the entire tegmentum. (A1) Higher magnification of NPY positive neurons along the ventricle and in the proximity of the preglomerular nucleus. (B) Packed immunoreactive varicose fibers in the semicircular tori. (C) Overview of the optic tectum and the midbrain tegmentum displaying staining in a few neurons of the periventricular grey zone and in varicose fibers over the different layers of the optic tectum, numerous positive neurons along the ventricle and in the proximity of the preglomerular nucleus. (D–E1) Transverse sections of the brain of a 36-month-old zebrafish. (D) Overview of NPY immunoreactivity in the hypothalamic area (lateral and dorsal periventricular hypothalamus) and in the midbrain tegmentum of 36-month-old zebrafish. Few intensely immunostained neurons localized in the lateral and dorsal hypothalamus. Strong immunoreactivity in abundant varicosities distributed in the hypothalamus and projecting fibers toward the optic tectum and over the entire tegmentum. (D1) Higher magnification of projecting fibers toward the optic tectum. (D2) Higher magnification of abundant varicosities distributed in the hypothalamus. (E) Overview of NPY immunoreactivity in fibers in the optic tectum and in varicosities and neurons in the tegmentum. (E1) NPY immunostaining in the optic tectum layers (asterisks) and in a few cells of the periventricular grey zone. Scale bars 100 µm.