IHEM   20887
INSTITUTO DE HISTOLOGIA Y EMBRIOLOGIA DE MENDOZA DR. MARIO H. BURGOS
Unidad Ejecutora - UE
artículos
Título:
Effect of the Photoperiod and Administration of Melatonin on the Pars Tuberalis of Viscacha (Lagostomus maximus maximus): An Ultrastructural Study
Autor/es:
EDITH PEREZ ROMERA,; FABIAN MOHAMED; TERESA FOGAL; SUSANA DOMINGUEZ,; RAMON PIEZZI; LUIS SCARDAPANE
Revista:
ANATOMICAL RECORD
Editorial:
WILEY-LISS, DIV JOHN WILEY & SONS INC
Referencias:
Año: 2010 vol. 293 p. 871 - 878
ISSN:
0003-276X
Resumen:
The pituitary pars tuberalis (PT) is a glandular zone exhibiting welldefined
structural characteristics. Morphologically, it is formed by specific
secretory cells, folliculostellate cells, and migratory cells coming from the
pars distalis. The purpose of this work was to investigate differences in specific
cellular characteristics in the PT of viscachas captured in summer
(long photoperiod) and winter (short photoperiod), as well as the effects of
chronic melatonin administration in viscachas captured in summer and
kept under long photoperiod. In summer, the PT-specific cells exhibited celllike
characteristics with an important secretory activity and a moderate
amount of glycogen. In winter, the PT-specific granulated cells showed ultrastructural
variations with signs of a reduced synthesis activity. Also, PT
showed a high amount of glycogen and a great number of cells in degeneration.
After melatonin administration, the ultrastructural characteristics
were similar to those observed in winter, but the amount of glycogen was
higher. These results suggest possible functional implications as a result of
morphological differences between long and short photoperiods, and are in
agreement with the variations of the pituitary-gonadal axis, probably in
response to the natural photoperiod changes through the pineal melatonin.
The ultrastructural differences observed in PT, after melatonin administration,
were similar to those observed in the short photoperiod, thus supporting
the hypothesis that these cytological changes are induced by melatonin.
Anat Rec, 293:871878, 2010. VVC 2010 Wiley-Liss, Inc.VVC 2010 Wiley-Liss, Inc.
Key words: Lagostomus maximus maximus;Lagostomus maximus maximus;