Distribution of 7B2 (secretogranin V)-like immunoreactivity in the Japanese red-bellied newt (Cynops pyrrhogaster) pituitary.

In this study, we examined 7B2 (secretogranin V)-like immunoreactivity (IR) in the Japanese red-bellied newt (Cynops pyrrhogaster) pituitary. Results showed that the pars nervosa was filled with immunoreactive granules. In the pars intermedia, all melanotrophs showed 7B2-IR. In the pars distalis, immunoreactive cells were dispersed, and the 7B2-immunoreactive cells were also immunopositive for the beta-subunit of bullfrog luteinizing hormone (fLHbeta). 7B2-IR co-localized with fLHbeta-IR in the same secretory granules. Our results suggest that 7B2 may participate in the secretion processes of gonadotropins in the pars distalis.