ULTRASTRUCTURAL MORPHOMETRY OF RAT NEUROHYPOPHYSIS

Abstract

Standard stereological methods were used to determine the morphometric parameters of the rat neurohypophysis. Thr percentage of total volume (0.57 mm3) occupied by the neurohypophyseal compartments were swellings (non-terminal dilatations), 16.41%; endings (terminal dilatations containing microvesicles but no neurotubules), 12.07%; axons, 13.95%; pituicytes, 28.67%; blood vessels, 7.44%; extracellular space, 15.08%; unclassified structures, 6.41%. One nerve cell projecting the neural lobe was calculated to have 1.84 .times. 103 endings and 4.36 .times. 102 swellings. The neural lobe contains 1.66 .times. 1010 neurosecretory granules of which 59% are found in swellings, 12% in axons and 29% in nerve endings. These values correspond to 2.24 .times. 103 and 2.58 .times. 102 neurosecretory granules per swellings and endings, respectively.