Ultrastructure of the adenohypophysis in the teleost Poecilia latipinna

Abstract

In the sailfin molly, Poecilia latipinna, seven morphological endocrine cell-types could be distinguished with the electron microscope. Each of these was identified with one of the seven cell-types distinguished with the light microscope, to most of which endocrine functions have previously been allocated. Corticotrophs and prolactin cells form the rostral pars distalis, and the proximal pars distalis consists of an outer layer of gonadotrophs and an inner zone containing growth hormone cells and thyrotrophs. The pars intermedia contains two cell-types, of uncertain function. Stellate cells (interstitial cells) occur throughout the adenohypophysis, but are most numerous and prominent in the rostral pars distalis. The inner proximal pars distalis contains a cell-type not previously distinguished in this species with the light microscope, the Z-cell, which could be aminergic. The ultrastructural features of each cell-type are described in detail, and discussed in comparisons with the homologous cells described in other teleosts. There is good agreement for different teleosts in the ultrastructural details of each cell type.

Immunocytochemical and ultrastructural characterization of melanotropin and adrenocorticotropin cells from the mediterranean yellowtail (Seriola dumerilii, Risso 1810)

“…However, in Gasterosteus aculeatus the secretory granules were evenly distributed (Benjamin, 1974). The round secretory granules with varying electron-dense content and a narrow clear halo were similar to those described in a number of teleosts (Schreibman et al, 1973;Benjamin, 1974;Holmes and Ball, 1974;Betchaku and Douglas, 1980;Quesada et al, 1988), although a wide separation of the secretory granule core from its limiting membrane has been described in some species (Dharmamba and Nishioka, 1968;Abraham, 1971;Cook and van Overbeeke, 1972;Benjamin, 1974;Leatherland et al, 1974;Batten et al, 1975). However, the semicore osmiophilic inclusion seen in some granules of the M. yellowtail ACTH cells has not been described in the teleosts so far studied.…”

“…ACTH cells in the M. yellowtail were separated from the NH by a continuous basal lamina as in other teleosts (Benjamin, 1974;Batten et al, 1975;Batten, 1986;Quesada et al, 1988). The secretory granules were accumulated in the pole of the cell near the NH, as in Sparus aurata (Quesada et al, 1988) and P. latipinna (Batten, 1986).…”

“…Teleostean MSH cells, as found in the M. yellowtail, are characterized by small secretory granules in the Golgi area and variably sized, round secretory granules of varying electron density and content appearance dispersed throughout the cytoplasm (Leatherland, 1970b;Benjamin, 1974;Thornton and Howe, 1974;Batten et al, 1975;Follénius and Dubois, 1976;van Eys, 1980;Quesada et al, 1988). A few rod-shaped secretory granules were found in P. latipinna (Batten et al, 1975).…”

“…A few rod-shaped secretory granules were found in P. latipinna (Batten et al, 1975). The variable electron density of the secretory granules of MSH cells has been attributed to cell activity variations, to fixation conditions (Thornton and Howe, 1974), and to the granule maturation process (Follénius and Dubois, 1976).…”

“…However, although the ultrastructure of the putative MSH and ACTH cells has been described in a number of teleost species (Benjamin, 1974;Leatherland et al, 1974;Thornton and Howe, 1974;Batten et al, 1975;Follénius and Dubois, 1976;van Eys, 1980;Quesada et al, 1988), only a few immunocytochemical ultrastructural studies have been performed (van Eys, 1980;Batten, 1986).…”