Structure and fine structure of the hypophyseal pars distalis in endigenous African species of the genus Tilapia

1974 ◽  
Vol 149 (2) ◽  
Author(s):  
JohnF. Leatherland ◽  
J.N. Ball ◽  
Mohammed Hyder
Keyword(s):  
Fine Structure ◽  
Pars Distalis ◽  
African Species

Effect of thyroxine on the ultrastructure of the hypophyseal proximal pars distalis in Tilapia zillii

1975 ◽  
Vol 53 (6) ◽  
pp. 686-690 ◽  
Author(s):  
John F. Leatherland ◽  
Mohamed Hyder
Keyword(s):  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Cell Types ◽  
Pars Distalis ◽  
Tilapia Zillii ◽  
Thyroid Axis ◽  
And Control ◽  
Granule Release

The effects of exogenous L-thyroxine on the fine structure of the proximal pars distalis cells were examined in Tilapia zillii. In thyroxine-treated animals the thyrotrophic cells appeared marginally smaller and less active whereas the somatotrophs appeared markedly more active, with increased endoplasmic reticulum, larger mitochondria, and more granule release when compared with the same cell types in control animals. The gonadotrophs were similar in appearance in both thyroxine-treated and control groups.The possible interrelated activity of the somatotrophs and the TSH–thyroid axis is discussed.

Stellate Cells in the Pituitary Gland of the Salamander

1968 ◽  
Vol 26 ◽  
pp. 160-161
Author(s):  
Robert R. Cardell
Keyword(s):  
Fine Structure ◽  
Pituitary Gland ◽  
Stellate Cell ◽  
Secretory Granules ◽  
Present Report ◽  
Stellate Cells ◽  
Secretory Cells ◽  
Pars Distalis ◽  
Pericapillary Space ◽  
Basement Lamina

The fine structure of five cell types in the pars distalis of the salamander [Notophthalmus (Triturus) viridescens viridescens] pituitary gland has been described. Four of these possess characteristic secretory granules (figure 1) and apparently they are involved in the synthesis and secretion of pituitary hormones. The other cell (Cell type #5 or “stellate cell”) does not possess characteristic secretory granules (figures 1 and 2) and they show a morphology which does not suggest a secretory function. The present report extends the observations on the fine structure of the stellate cell and considers, in addition, the distribution of this cell throughout the pars distalis.The stellate cell displays many slender, cytoplasmic extensions which penetrate between the secretory cells (figure 1). These extensions contact processes from other stellate cells and desmosomes are found at the points of contact. Moreover, desmosomes are frequently located between the stellate cells and the secretory cells (figure 2). Thus, the stellate cells are not only linked to each other throughout the pars distalis, but to each secretory cell as well. Stellate cell processes contact the outer basement lamina of the pericapillary space and often such processes follow the contour of the basement lamina for considerable distances. They do not penetrate, however, into the pericapillary space.

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