Fig. 1

Schematic of the transverse sections through the forebrain (a–d) and sagittal section of the pituitary gland (e) of Clarias batrachus showing the organization of tyrosine hydroxylase (TH) immunoreactive (ir) cell bodies (filled circles) and fibers (dashed lines and dots). TH cell bodies are seen in the anterior (NPPa) and posterior (NPPp) subdivisions of the nucleus preopticus periventricularis (NPP). The photomicrograph of the brain of C. batrachus at the top shows the levels of transverse sections used for depicting the TH immunoreactivity. In the pituitary gland, a dense innervation of TH-ir fibers is seen in the proximal pars distalis (PPD). Immunofluorescence photomicrographs through the POA of male (f, h) and female (g, i) C. batrachus showing TH-ir neurons (arrows) in the NPPa (f, g) and NPPp (h, i). j Semiquantitative image analysis of the number (mean ± SEM) of TH neurons in the NPPa and NPPp in both the sexes. Note the presence of more number of TH-ir neurons in the NPPa of female fish. P < 0.05. NS non-significant. Scale bar = 1 mm in (a–d) and the photomicrograph of the brain at top , 500 μm in (e), and 25 μm in (f–i)