Structural foundations of the releasing pattern and transport route for hormone granules of neurohypophysis
- VernacularTitle:神经垂体激素颗粒释放形式和转运途径的结构基础
- Author:
Xinhua SHEN
;
Baozhi WANG
;
Lei CAO
- Publication Type:Journal Article
- From:
Chinese Journal of Tissue Engineering Research
2005;9(17):219-221
- CountryChina
- Language:Chinese
-
Abstract:
BACKGROUND: The basic way for the releasing pattern of secretory granules of neurohypophysis is still not clear, neither is the extracellular normal transport route of neurohypophysis polypeptide hormones to enter the cerebrospinal fluid.OBJECTIVE: To provide the morphological evidences for the structural foundations of the releasing pattern and extraeellular normal transport route for secretory granules or polypeptide hormones of neurohypophysis by observing the structure of rats' neurohypophysis.DESIGN: Randomized controlled study.SETTING: Department of human anatomy in a university.MATERIALS: The experiment was completed in the Department of Human Anatomy of Hebei Medical University from May 2003 to January 2004. Twelve healthy clean grade adult male Sprague-Dawley rats with a body mass of about 300 g were supplied by the Experimental Animal Center of Hebei Province.METHODS: The 12 rats were randomly divided into 3 groups with 4 rats in each group. The neurohypophysises of each group were respectively observed with light microscope, transmission microscope and scanning electron microscope.MAIN OUTCOME MEASURES: The microstructure and ultrastructure of the neurohypophysis.RESULTS:All 12 rats entered the final analysis. In the coronary section of rat hypophysis, pars distalis, pars intermedia and pars nervosa were discernable under the light microscope. Under the transmission electron microscope, the neurohypophysis was composed of unmyelinated nerve fibers, pituicytes and connective tissue abound in blood capillaries. The endothelium of the blood capillary belonged to the fenestrated type(50 nm), separated from perivascular space by basement membrane. The intact secretory granules (100 -300 nm) coated with membrane existed not only in the endings of the unmyelinated nerve fibers but also occasionally in perivascular space. Under the scanning electron microscope, the pituitary capsule was composed of simple squamous epithelial cells and subepithelial connective tissue. Many irregular epithelial openings(2-5 μm) were observed among epithelial cells. Secretory granules were seen frequently near the epithelial opening.CONCLUSION: The releasing pattern of secretory granules or polypeptide hormones of neurohypophysis involves a whole-releasing pattern together with granular membrane. After released into perivascular space, they enter easily into cerebrospinal fluid via interspace of tissue and epithelial openings rather than into blood circulation through the walls of capillaries, and then into the cerebrospinal fluid.
