Date of Award

7-1964

Degree Name

Master of Arts

Department

Biological Sciences

First Advisor

Dr. Jean M. Lawrence

Second Advisor

Dr. Imy Holt

Third Advisor

Dr. Jack Wood

Fourth Advisor

Dr. Leo VanderBeek

Access Setting

Masters Thesis-Open Access

Abstract

Chapter I

Introduction

In the central nervous system of most animals which have been examined some neurons show cytological characteristics of gland cells. These cells are now recognized as a specialized cell type and designated neurosecretory cells.

These neurosecretory cells are capable of elaborating secretory material which is accumulated as granules in the body of the nerve cell and in the axon-endings. They release complex organic substances, neurohormones, which act as hormones and are often liberated into the blood stream (Welsh, 1958). These specialized neurons are capable of receiving impulses from other neurons although their axons do not end in contact with other neurons or effectors (Scharrer, 1959). Examples are the hypothalmus-pituitary axis of vertebrates and the sinus-x gland complex of crustaceans (Laverack, 1963).

In many of the invertebrates, especially Annelida, these neurosecretory cells make up a large proportion of the central nervous system (Hagadorn, 1959; Scharrer, 1959; Herlant-Meewis, 1961). According to Scharrer (1959) they may well be the only source of hormones in these organisms.

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