162 



HYPOPHYSIS AND GONADOTROPHIC HORMONES 



H. Lactation 205 



XIII. The Human Hypophysis 206 



A. Structure 206 



B. Specific Basophil Types in the 



Human Hypophj'sis 206 



C. Differential Staining of Basophil 



Cells in the Human Pars Dis- 

 talis 207 



D. Functions of the Basophil Cells of 



the Human Pars Distalis 209 



1. The 5-cell 209 



2. The blue /3-cell 209 



3. The 7-cell 209 



E. The Amphophil Cells of Russfield. 209 



F. The Purple /3-Cell in the Cushing 



Syndrome 210 



G. Crooke's Cell Changes Produced 



by Corticosteroid or Cortico- 



trophin Administration 211 



H. Changes in the Purple /3-Cells in 



Addison's Disease 212 



I. The Pharyngeal Hypophysis 212 



XIV. Electron Microscopy of the 



Adenohypophysis 212 



A. Endoplasmic Reticulum 213 



B. Golgi Region or Zone 213 



C. Palade Granules 222 



D. Secretory Granules 222 



E. Microvilli 223 



XV. The Neurohypophysis and Neuro- 

 hypophyseal Secretion 223 



A. Neurosecretory Phenomena in the 



Hypothalamus and Neurohy- 

 jiophysis 223 



B. The Chemical Nature of the Stain- 



able Neurosecretory Material . . 227 



C. The Physical Form of Neurosecre- 



tion in the Neurohypophysis: 

 the Secretory Granule 227 



D. The Hormone Content of Nemo- 



secretory Granules 228 



E. The Distribution of Oxytocin and 



Vasopressin 228 



F. Inferences Concerning Rate of 



Secretion from Cytologic and 



Histochemical Studies 229 



XVI. References 229 



I. Introduction 



The aim of this chapter is to present cer- 

 tain morphologic characteristics of the hy- 

 pophysis. Emphasis is given to those aspects 

 of the structure which are, in the light of 

 modern knowledge, of importance in eluci- 

 dating the functions of this organ. Although 

 the study of morphologic features does not 

 by itself provide clear answers to questions 

 concerning the endocrine functions of the 

 hypopliysis, it is evident that the morpho- 

 logic peculiarities of the gland are related 

 to its functions, and that the consideration 

 of morphologic data in conjunction with the 



evidence derived from physiologic observa- 

 tions does assist in the construction of ac- 

 ceptable hypotheses concerning these func- 

 tions. 



11. Embryonic Development 



The adenohypophysis is derived from 

 Rathke's pouch, a process of epithelial tis- 

 sue derived from the buccal ectoderm. The 

 distal portion of this process forms a hollow 

 structure which lies in close contact with 

 the infundibulum. The infundibulum is an 

 outgrowth of neural tissue from the floor of 

 the third ventricle, and differentiates into 

 the neurohypophysis. 



The work of Burch (1946) suggested that 

 contact of the epithelial element with the 

 neural element was necessary for the differ- 

 entiation of the adenohypophysis from the 

 former. He found in the frog {Hyla regilla) 

 that translocation of the infundibulum or of 

 the epithelial anlage, at a stage in develop- 

 ment before these elements made contact, 

 prevented the differentiation of the epithe- 

 lial element. The pars intermedia did not 

 develop, nor did acidophil and basophil cells 

 appear in the epithelial cell mass. These re- 

 sults must, however, be reconsidered in view 

 of the later findings of Etkin (1958). Etkin 

 succeeded in transplanting the epithelial 

 anlage at the earliest possible stage, and 

 found that this does not prevent the differ- 

 entiation of a pars intermedia. The devel- 

 opment of normal pigmentation showed that 

 the pars intermedia so differentiated func- 

 tioned in its transplanted position and, in 

 the later tadpole stages, pigmentation was 

 greater than normal, indicating hyperf unc- 

 tion of the pars intermedia such as develops 

 in the differentiated pars intermedia which 

 is subsequently transplanted in the frog. 

 Etkin's experiments were done with the wood 

 frog, Bana sylvatica, but it is unlikely that 

 the differences are due to species differences. 

 Etkin observed differentiation of a jmrs dis- 

 talis, but no chromophil cells were present 

 at the stages examined. These chromophil 

 cells usually do not appear until a later stage 

 in normal animals. It has, therefore, not yet 

 been demonstrated that a full differentiation 

 of a functional pars distalis can occur with- 

 out continued contact with the infundibu- 



