Pars nervosa hypophyseos in chronic audiovibratory stress.

In the nervous part of the hypophysis, significant decrease in the quantity of neurosecretion, hypertrophy, and frequent findings of mitosis of adenopituicytes occur under the influence of noise and vibrations. In chronic audiovibratory stress, the phenomenon of hyperplasia of adenopituicytes and intracytoplasmic presence of structural elements of neurosecretory fibres in disintegration are noticeable. Heterogeneity of neurosecretory fibres is characteristically manifested in the presence of dilated Herring bodies with preserved structure, occurrence of nerve swellings very variable in structure, with numerous polymorphous inclusions and autolytic bodies, or with large vacuoles, few secretory granules and few mitochondria. There are some endings of neurosecretory fibres with many clear microvesicles and few granules, as well as the endings abounding only in clear microvesicles, particularly in pericapillary spaces. The results obtained point to strong stress-inducing effects of noise and vibrations upon the nervous part of the hypophysis.