HYPOPHYSEAL MORPHOLOGY 



201 



characterized as /^-cells by Romeis. The 

 S-cells of Romeis do not invade the neural 

 lobe. 



The assays of Morris and his associates 

 were concerned with intermedin and cor- 

 ticortrophin, and show that the invading 

 basophil cells were not responsible for corti- 

 cotrophin production. Although no informa- 

 tion is available concerning the other hor- 

 mones, it is virtually certain that the cells 

 which secrete intermedin in the human will, 

 like the cells secreting intermedin in other 

 vertebrates, be responsible for this secretion 

 only. In man this intermedin secretor is 

 heavily granulated and stains strongly by 

 PAS or by trichrome methods, as does the 

 pars intermedia cell of the cat. It is par- 

 ticularly liable to retain the red stain of the 

 trichrome method, a tendency which is 

 greatly strengthened after fixation in Helly's 

 fluid. Herlant (personal communication) 

 has found that the staining of ^-cells in the 

 human pars distalis by aldehyde-fuchsin is 

 greatly diminished or even fails entirely 

 after fixation in Helly's fluid. This be- 

 havior of the intermedin secretors of the 

 liuman pars distalis is also found in the cells 

 of the pars intermedia of the rat, which 

 stain intensely with aldehyde-fuchsin after 

 formol-sublimate fixation but stain very 

 weakly after Helly fixation (Fig. 3.17). It 

 has not been determined whether this be- 

 havior is a general one for intermedin- 

 secreting cells. 



In the human pars distalis the inter- 

 medin-secreting basophils are the most con- 

 spicuous of the basophil cells. Their preva- 

 lence is consistent with the high intermedin 

 content of the human hypophysis (Land- 

 grebe and Mitchell, 1958). Their failure to 

 respond in sympathy with disturbances of 

 gonadotrophin and thyrotrophin secretion, 

 which has apparently set the human pitui- 

 tary apart from those of experimental ani- 

 mals, need no longer be a stumbling block 

 now that the nature of these conspicuous 

 basophilic cells is recognized. Obviously the 

 source of thyrotrophin and gonadotrophin 

 must be sought in glycoprotein-containing 

 cells other than the intermedin secretors. 



It is possible that some species which have 

 a discrete pars intermedia may also have 

 some dispersed pars intermedia cells in the 



pars anterior. Landgrebe, Ketterer and 

 Waring (1955) have referred to such an 

 invasion of the pars anterior in some breeds 

 of pigs. 



XI. The Pars Tuberalis 



The pars tuberalis consists of a layer of 

 adenohypophyseal cells which surrounds the 

 neural stalk and covers the surface of the 

 median eminence of the tuber cinereum. It 

 is composed almost entirely of cells of a 

 single type which, from the absence of 

 specific granules of the kind seen in anterior 

 lobe cells, are classed as chromophobes. 

 There are, in addition, small numbers of 

 typical basophil cells which, according to 

 Romeis (1940), do not differ in any respect 

 from the basophil cells of the anterior lobe. 

 Acidophil cells apparently identical with the 

 cells in the anterior lobe are extremely rare. 

 In the larger animals, the pars tuberalis 

 cells are arranged in cords and follicular 

 structures ; the latter enclose small amounts 

 of colloid. No specific hormone has been 

 demonstrated in the pars tuberalis other 

 than small amounts of activities probably 

 due to contamination with adjacent anterior 

 lobe or pars intermedia tissue. The function 

 of the pars tuberalis is at present unknown. 

 It may be that it is the source of some 

 trophic influence which is carried to the 

 anterior lobe by the hypophyseal portal 

 system. 



XII. Cytologic Changes Accompanying 



Secretory Responses Concerned 



with Reproductive Function 



A. SEXUAL MATURATION IN THE RAT 



Sexual maturation in the male rat is ac- 

 companied by a gradually increasing con- 

 tent of glycoprotein in the gonadotrophs. 

 In the female, however, the reaction is en- 

 tirely different. Maturation is accompanied 

 by a considerable degranulation of gonado- 

 trophs. This degranulation occurred be- 

 tween the ages of 35 and 42 days in the 

 observations of Siperstein, Nichols, Gries- 

 bach and Chaikoff (1954), and, in a num- 

 ber of their rats degranulation of the pe- 

 ripheral gonadotrophs which are thought 

 to be follicle stimulating in activity, was 

 found to have preceded the degranulation 

 of the central gonadotrophs. This observa- 



