Fine structure of pars neuro-intermedia of the loach,Misgurnus fossilis L.

Summary Two types of glandular cells are present in the pars intermedia of the loach, Misgurnus fossilis. Basophils are characterized by the presence in their cytoplasm of numerous secretory granules containing electron-dense and homogeneous material and by scarce endoplasmic reticulum. Weak acidophils contain in their cytoplasm abundant endoplasmic reticulum and numerous granules of different electron densities.The distal part of the neurohypophysis is composed of several types of neurosecretory axons, strongly branched pituicytes, numerous capillaries, and connective tissue elements. The axon terminals form the neuroglandular, neurovascular and neurointerstitial contacts. Some axon terminals are closely apposed to the basement membrane separating neurohypophysis from meta-adenohypophysis. At points of absence of continuity of this membrane, some neurosecretory axons become directly contiguous with cytoplasmic membranes of the intermedia cells.The investigation was partly supported by a research grant from the Zoological Committee of the Polish Academy of Sciences.