Immunocytochemical and Ultrastructural Identification of Pituitary Cell Types in the Protogynous Thalassoma duperrey during Adult Sexual Ontogeny

Abstract

Protogynous wrasses (Thalassoma duperrey): females (F), primary males (PM) along with a few terminal-phase males (TM) and sex-changed males (SM), were used to characterize the topographical organization of the pituitary. In general, immunocytochemical and ultrastructural features of the adenohypophyseal cell types of the saddleback wrasse pituitary resemble those of other teleosts. In the rostral pars distalis (RPD), corticotropic cells were found bordering the neurohypophysis (NH) and surrounding the centroventrally located prolactin cells. Thyrotropic cells formed a small group in the anteriodorsal part of the rostral and proximal pars distalis (PPD). The somatotropic cells were distributed in large clusters, mostly organized in cell cords around the interdigitations of the NH of the dorsal PPD. Cells containing gonadotropin Ib subunit were localized in the dorsal parts of the PPD, in close association with somatotropic cells and gonadotropin IIb subunit containing cells were seen in the centroventral parts of the PPD and along the periphery of the pars intermedia (PI). The pars intermedia was composed of melanotropic cells and somatolactin cells that lined the neurohypohysis.Distinct ultrastructural differences in corticotropic and somatotropic cells were not observed between the four groups. In all groups, prolactin cells in the ventral-most RPD could be immature cells or actively secreting prolactin. Gonadotropic II cells of PM and F had relatively higher incidence of "nuclear budding" and cell organelles compared to TM and SM. Besides gonadotropic, the active melanotropic and somatolactin cells might be associated with some aspect(s) of reproduction.

Immunocytochemical identification of adenohypophyseal cells in the pirarucu (Arapaima gigas), an Amazonian basal teleost

“…GH cells were located mainly in the dorsal central PD and were arranged in thin strands in the ventral part of A. gigas pituitary gland. This distribution is in agreement with other teleosts, as reported previously (see Ball and Baker 1969;Holmes and Ball 1974;Schreibman et al 1973) and in more recent studies (Parhar et al 1998;Rendón et al 1997;Rodríguez-Gómez et al 2001;Sánchez Cala et al 2003;Segura-Noguera et al 2000;Vissio et al 1997), although some variations may occur, depending on the species and developmental stage (García-Hernández et al 1996;Villaplana et al 2000;Sánchez Cala et al 2003).…”

“…These cells have previously been demonstrated in the RDP of many other teleosts (Arana et al 1997;Batten 1986;Parhar et al 1998;Rodríguez-Gómez et al 2001;Sánchez Cala et al 2003;Segura-Noguera et al 2000), where they were arranged as a compact mass, in follicles, in both, or in thick strands (see Agulleiro et al 2006). The follicular arrangement of PRL cells present in salmonids and ancient teleost species such as the eel (Arakawa et al 1992;Grandi et al 2003;Ingleton and Stribley 1977), which is considered a basal feature, was not found in A. gigas pituitary.…”

A systematic immunohistochemical survey of the distribution patterns of GH, prolactin, somatolactin, β–TSH, β–FSH, β–LH, ACTH, and α–MSH in the adenohypophysis of Oreochromis niloticus, the Nile tilapia

“…Human β-TSH antisera have been reported to cross-react well with teleost TSH (for a review, see Agulleiro et al 2006); this has also been found here in tilapia. We have not observed cross-reactivity between antisera to β-TSH and GTH II (β-LH) as described in several studies (García-Hernández et al 1996;Parhar et al 1998;Segura-Noguera et al 2000) but between the antisera directed against GTH I and GTH II. A moderate crossreactivity (10% and 12%, respectively) between these antisera has previously been observed (Suzuki et al 1988).…”

“…A few more extensive studies have been performed (e.g. García-Hernández et al 1996;Grandi and Chicca 2004;Laiz-Carrión et al 2003;Naito et al 1993;Parhar et al 1998Parhar et al , 2002Sánchez Cala et al 2003;Segura-Noguera et al 2000;Weltzien et al 2003b;Yan and Thomas 1991) but no thorough investigation has localised all pituitary hormones by immunohistochemistry on consecutive sections.…”

“…In the protogynous teleost wrasse Thalassoma duperrey, all adenohypophyseal hormones were investigated but cross-reactivities between β-TSH and the gonadotropin GTH II (β-LH) antisera had to be considered (Parhar et al 1998); however, the study mainly characterised endocrine cells at the ultrastructural level and only selected hormones were presented by light microscopy. In an ontogenic study on sturgeon, Acipenser naccarii, the appearance and distribution of all adenohypophyseal hormones including β-endorphin were monitored but, as the main focus was laid on early development, the demand for investigations of the hormone expression pattern in adults was stressed (Grandi and Chicca 2004).…”