Ultrastructural Study of Two Gonadotrophs in Rats Bearing an Adrenocortical Carcinoma (Snell 494)
Iwao Nakayama, MD, PhD and Peter A. Nickerson, PhD
Two morphologically distinct gonadotrophs have been identified in the anterior pituitary of rats bearing the Snell 494 tumor. Type 1 gonadotrophs first showed ultrastructural alterations at 4 weeks after implantation of the tumor. Numerous large 300 to 600 mu granules appeared in type 1 cells. The opacity of the granules was variable, and they sometimes contained non-membrane-bounded spherical inclusions. These granules were dispersed among more electron-opaque, 200-mu granules usually seen in gonadotrophs. A third granule approximately 500 to 600 mu in diameter was apparently a lysosome-derived structure. Type 2 gonadotrophs first showed changes after 4 weeks, but the alterations were especially prominent by 8 to 10 weeks. No large granules characteristic of type 1 cells were seen in type 2 cells. By 8 to 10 weeks, very few 200-mu granules were observed in the cytoplasm of type 2 cells. The endoplasmic reticulum was dilated in most type 2 cells; frequently, the cisternae were dilated considerably, forming large lake-like areas. Hypertrophic rough endoplasmic reticulum and the presence of intracisternal granules within cisternae of the rough reticulum suggest that type 2 cells were stimulated by the tumor. Changes in gonadotrophs were undoubtedly produced by the large amount of corticosterone secreted by the tumor. The corticosterone may well act directly on the hypothalamushypophyseal axis or it could act indirectly on the ovary; ovarian steroids would then exert a feedback effect. The ovary was atrophic and did not contain maturing Graafian follicles or corpora lutea. In somatotrophs, the number of secretory granules increased, probably reflecting suppression of hormonal release by corticosterone (Am J Pathol 71:279-294, 1973).
SIX DISTINCT HORMONES are secreted by cells in the adeno- hypophysis.1,2 Of these hormones, it is generally agreed that ACTH, growth hormone, thyrotropin and prolactin are produced by separate cell types.3-5 The cells secreting each of these four hormones have been well-identified ultrastructurally by several characteristics:3-8 cell shape, diameter and location of secretory granules and amount and distribution of rough endoplasmic reticulum. It is still unclear whether follicle stimulating hormone (FSH) and luteinizing hormone (LH) are produced by a single cell in the anterior pituitary.4 In an immuno-
From the Department of Pathology, State University of New York at Buffalo, Buffalo, NY.
Supported by Research Grant HL 06975 from the National Heart and Lung Institute; Dr. Nakayama is the recipient of a Bertha P. and Henry C. Buswell Fellowship from the State University of New York at Buffalo.
Accepted for publication Jan 22, 1973.
Address reprint requests to Dr. Peter A. Nickerson, State University of New York at Buffalo, Department of Pathology, Bell Facility, 180 Race St, Buffalo, NY 14207.
chemical study, Nakane7 has proposed that FSH and LH are pro- duced by a single type of cell. Other investigators 8,9 have claimed to be able to distinguish FSH and LH-producing cells by electron mi- croscopy. However inasmuch as there is some doubt as to the site of FSH and LH production, the term gonadotroph usually is utilized to designate FSH and LH-producing cells. Secretory granules in gon- adotrophs of the rat are 200 mu in diameter;4 dilation of endoplasmic reticulum usually varies from one cell to another.4
The response of gonadotrophs to various experimental procedures has suggested that two morphologically distinct types of gonadotrophs can be recognized.10,11 Nakayama, Nickerson and Skelton1º reported that methylandrostenediol, a synthetic androgen, induced changes in the ultrastructure of a gonadotroph which they considered to be the FSH-producing cell. Ultrastructural identification of the FSH-se- creting cell was supported by reports that androgen causes an in- creased FSH content 12 but a decreased LH content.13 We have tried to substantiate our previous study 10 that there are two different types of gonadotrophs and have sought another experimental procedure to separate gonadotrophs by differences in morphology. Snell and Stew- art 14 have developed an autonomous, transplantable corticosterone- secreting tumor in the rat which is designated as the Snell 494 tu- mor.15 Studies in our laboratory were begun to determine the effect of corticosterone from rats bearing the 494 tumor on ACTH-secreting cells. In further studies, however, two morphologically distinct gona- dotrophs were observed in tumor-bearing rats which will be described in this report.
Materials and Methods
The Snell 494 adrenal cortical tumor was obtained from Dr. Robert Ney, Department of Medicine, University of North Carolina. Thirty female rats weighing approximately 250 g were obtained from the Charles River Breeding Co, North Wilmington, Mass. For transplantation, the tumor was minced in medium 199 and injected subcutaneously in the flank. Rats were divided into two groups: Group 1 consisted of 15 untreated non-tumor-bearing control rats; 15 animals in Group 2 received the tumor. Animals were caged individually and maintained in a room with constant temperature (22.5 C) and humidity. All animals were given lab chow and water ad libitum.
Three controls and 3 tumor-bearing animals were sacrificed at 3, 4, 6, 8 and 10 weeks. Rats were sacrificed by decapitation; the pituitary gland was removed within 20 seconds following decapitation and fixed in 3% purified glutaraldehyde (Ladd Research Industries, Burlington, Vt) buffered to pH 7.3 with 0.1 M phosphate. The pituitary was transferred to a drop of fixative, sep- arated into 8 to 10 small pieces and then placed in fresh fixative for an addi- tional 4 hours. The tissues were washed overnight in 0.1 M phosphate buffer
(pH 7.3) at 4 C, and then postfixed in 2% osmium tetroxide for 2 hours, de- hydrated in ethanol, infiltrated with propylene oxide, propylene oxide: resin (1:1) and embedded in a mixture of Epon 812 and Araldite.16
Thin sections were cut with a diamond knife on a Porter-Blum MT-1 ultra- microtome. Sections were double stained with methanolic uranyl acetate 17 followed by lead citrate.8 Micrographs were taken with a Siemens 101 electron microscope.
Ovaries were weighed fresh, fixed in 10% neutral formalin and stained wtih hematoxylin and eosin for light microscopic observation. Data was expressed as the mean ± standard error of the mean.
Results
The ovarian weights from control animals did not differ significantly from one another at any period of observation. The calculated com- posite mean for controls was 134.9 ± 8.9 mg. Ovarian weight in tumor-bearing rats decreased by 4 weeks after transplantation (113.3 ± 10.9 mg), although the decrease was not significant. At 6, 8 and 10 weeks, the weight of the ovaries was significantly smaller (P < 0.001) with values of 63.0 ± 13.8 mg, 44.6 ± 5.8 mg and 47.6 ± 5.3 mg, respectively.
The reduced weight of the ovary was reflected in marked histologic changes. No maturing Graafian follicles or corpora lutea were ob- servable in the ovaries of tumor-bearing rats (Figure 1), in contrast to the numerous follicles (Figure 2) and corpora lutea seen in control rats.
Gonadotrophs in Controls
Only one type of gonadotroph could be identified, by electron microscopy, in the anterior pituitary of control rats (Figure 3). Gona- dotrophs were the largest cell type in the adenohypophysis of normal female rats. Most gonadotrophs were located adjacent to capillaries (Figure 3). The cell was usually round or oval, but occasionally ir- regular or stellate. The nucleus was generally localized to one pole of the cell and was round or elliptical in shape. Size and location of secretory granules was one of the most useful criteria for identification of gonadotrophs. The granules were round, especially electron opaque and membrane bound (Figure 3). The diameter of granules was ap- proximately 200 mu; secretory granules were dispersed randomly throughout the cytoplasm (Figure 3). The number of the secretory granules, however, varied widely from one gonadotroph to another, even in the same animal.
In gonadotrophs with numerous secretory granules, the granules often aggregated into distinct groups in several focal areas of the cell.
Several dense bodies, 600 mu in diameter, were often dispersed among the secretory granules (Figure 3). Dilation of cisternae of the endoplasmic reticulum was more variable in gonadotrophs than in any other cell type in the anterior pituitary of normal rats. The rough endoplasmic reticulum in most gonadotrophs was slightly (Figure 3) to moderately dilated. Vesicular, distended rough reticulum, comprising a large part of the cytoplasm and similar to that seen soon after gonadectomy,19 was rarely observed in gonadotrophs of control rats. Distended short cisternae of rough endoplasmic reticulum were gen- erally dispersed throughout the cytoplasm, although long parallel cis- ternae of rough endoplasmic reticulum were located near the cell membrane in some gonadotrophs (Figure 3).
The Golgi complex occupied much of the cytoplasm in one pole of the cell in gonadotrophs (Figure 3). Each Golgi complex consisted of several cisternae with a concave and convex surface (Figure 3). The convex surface was slightly distended and many vesicles were closely associated with the peripheral cisternae of the Golgi apparatus (Fig- ure 3). A very low, electron-opaque material was observed within Golgi cisternae. Cisternae comprising the concave surface were flat- tened and contained a few newly forming immature granules.
Gonadotrophs in Tumor-Bearing Rats
Noticeable changes in gonadotrophs were first observed at 4 weeks after tumor transplantation. The ultrastructural changes included al- terations in number and size of secretory granules as well as structure of the rough endoplasmic reticulum. The gonadotrophs have been divided conveniently into type 1 and type 2 cells based upon differ- ences in ultrastructure. Four other cell types could be identified in the anterior pituitary of tumor-bearing animals at 10 weeks and were distinct from gonadotrophs. The morphology of the ACTH-secreting cells, thyrotrophs and mammotrophs will not be described, inasmuch as the cells have been well characterized in previous studies.3-5 The ultrastructure of somatotrophs in tumor-bearing rats will be described briefly.
Type 1 Cells
Type 1 gonadotrophs first appeared in the adenohypophysis of ani- mals bearing the adrenal cortical carcinoma at 4 weeks after tumor transplantation. Three different sizes and types of secretory granules were observed in type 1 gonadotrophs. The diameter of most secre- tory granules was 200 mu (Figure 4). A second type of especially
large secretory granule was a distinguishing feature of type 1 cells (Figure 4). The second type of granule was large and spherical with diameters ranging from 300 to 600 mp (Figure 4). Many granules were located near the Golgi complex. However the number of large granules varied from one cell to another, even in the pituitary of the same animal. The density of large granules was distinctly less than that of the 200-mu secretory granules (Figure 4). At high magnifica- tions, the large secretory granules closely resembled those in gonado- trophs from animals treated with methylandrostenediol, a synthetic androgen.10 The matrix of some large granules was of greater electron opacity than that of other large granules. Many granules possessed non-membrane-bound spherical inclusions (Figure 4). The inclusions resembled typical secretory granules of gonadotrophs because of their electron opacity, spherical shape and diameter of approximately 200 mu. A third class of large granules was approximately 500 to 600 mu in diameter and possessed a homogeneously electron-opaque matrix. However the matrix was less opaque than that of 200-mu secretory granules and the granules resembled lysosomal derived structures.
Cisternae of rough endoplasmic reticulum in type 1 cells were very flat and short (Figure 4). The rough endoplasmic reticulum was scat- tered throughout the cytoplasm, although no parallel arrays of the rough reticulum were seen.
At 4 weeks, numerous 200-mu secretory granules were dispersed throughout the cytoplasm of type 1 cells. The large 300- to 600-mu secretory granules were also interspersed among the smaller 200-mu ones. At later periods after tumor transplantation, the number of the large secretory granules apparently increased, whereas the number of 200-mu granules decreased (Figure 4).
Changes in gonadotrophs became more pronounced especially at 8 and 10 weeks after tumor transplantation. Total granules appeared to be decreased for the most part at 8 and 10 weeks. A reduction in the size of the cell as well as the Golgi region was a consistent finding. Fewer type 1 cells could be seen on the microscope screen in a single thin section than at 4 weeks. Some nuclei in type 1 cells were irregularly shaped and were characterized by indentations of the nu- clear membrane. Profiles of rough endoplasmic reticulum became progressively shorter and more flattened.
Type 2 Gonadotrophs
Type 2 cells were not readily identifiable until after type 1 gona- dotrophs first appeared at 4 weeks. At 4 weeks, type 2 cells were
identical in fine structure to gonadotrophs observed in control rats. Type 2 cells were readily recognizable because secretory granules were approximately 200 mu in diameter, in contrast to those in type 1 cells where larger granules were observed. The most important dis- tinguishing feature was that no large secretory granules seen in type 1 gonadotrophs were ever observed in type 2 cells during any period. A few dense lysosomally derived dense bodies were dispersed through- out the cytoplasm, but were distinctly different from large secretory granules in type 1 gonadotrophs. At later periods after tumor trans- plantation, the ultrastructure of type 2 cells (Figure 5) differed markedly from that in gonadotrophs of control rats. Dilation of cis- ternae of rough endoplasmic reticulum in type 2 cells varied from one cell to another, even in the same animal (Figure 5). Parallel arrays of rough endoplasmic reticulum composed of several cisternae occas- ionally were observed near the cell membrane.
At later periods after tumor transplantation, the ultrastructure of type 2 cells differed markedly from gonadotrophs in control rats. A transition was observed in which type 2 cells gradually changed in ultrastructure. Type 2 cells became transformed into larger cells with dilated rough endoplasmic reticulum (Figure 5). By 8 to 10 weeks, type 2 cells became hypertrophic and were the largest cell type in the adenohypophysis. Secretory granules decreased in number and disap- peared almost entirely from many cells (Figure 5). However, a few secretory granules were usually aligned adjacent to the cell membrane. The Golgi complexes were enlarged and many immature granules were observed in and around the Golgi complex ( Figure 5).
Much of the cytoplasm was occupied by enlarged, dilated rough endoplasmic reticulum. The degree of dilation of the endoplasmic reticulum varied considerably from one cell to another even at 10 weeks. Some cells had large lake-like areas of rough reticulum (Figure 6), reminiscent of those seen in the pituitary of castrated rats.19 In- tracisternal granules were frequently present within the distended rough endoplasmic reticulum (Figure 7) and were non-membrane- bound and appeared as spheroid electron-opaque structures.
Somatotrophs in Tumor-Bearing Animals
Alterations in the ultrastructure of somatotrophs were particularly evident at 8 and 10 weeks after implantation of the tumor. Secretory granules approximately 350 mul in diameter virtually filled the entire cytoplasm (Figure 8). Only a few cisternae of rough endoplasmic reticulum were scattered among the granules ( Figure 8).
Discussion
Two morphologically distinct cells have been identified in the an- terior pituitary gland of rats bearing the 494 adrenocortical carcinoma. These cells are considered to be gonadotrophs because they were distinct from the four other parenchymal cells of the anterior pituitary gland. All the other cell types of the pituitary-ie, ACTH-secreting cells, thyrotrophs, mammotrophs, somatotrophs and chromophobes could be recognized in tumor-bearing animals.
Gonadotrophs have been designated as type 1 and type 2, inasmuch as there is uncertainty in the literature as to the identity of the two cells.4,7 Ultrastructural characteristics for the identification of gona- dotrophs have not been well established. Two gonadotrophic hormones, FSH and LH have been identified in endocrinologic studies.1,2 How- ever, it is unclear at present whether FSH and LH are synthesized and secreted by a single cell type in the anterior pituitary gland. Sev- eral investigators have separated FSH- and LH-producing cells by differences in ultramicroscopic morphology.8,9 Kurosumi and Yashi- hiko 9 showed distinct FSH- and LH-producing cells in rats. How- ever, Nakane 7 has utilized immunocytochemical methods for elec- tron microscopy and suggested that FSH and LH are produced by a single type of cell. Nonetheless, it should be mentioned that two anti- gens have not yet been identified simultaneously in a single cell type in the electron microscopic procedure.
The 494 tumor secretes large quantities of corticosterone.15 Snell and Stewart 14 reported a spontaneous tumor in a female Osborne-Mendel rat. The tumor became autonomous and was transplanted; it usually becomes large about 8 weeks after transplantation. We have implanted cells suspended in medium 199 in the present study. This procedure contrasts with the method of Ney 20 in which a core of the tumor is transplanted by a trochar. With a large number of cells in a fairly well- intact tumor core, the mass becomes large by several weeks after transplantation. It was our hope to extend the period of tumor growth over a longer period in an attempt to study progressive changes in ultrastructure of the pituitary gland.
The size of type 1 cells became progressively smaller concomitant with growth of the tumor. The appearance of large secretory granules in type 1 cells suggests that the cell responds to corticosterone by formation of large granules. It is likely that the alteration in ultra- structure of gonadotrophs in tumor-bearing animals is produced by corticosterone. The corticosterone could act directly on the pituitary
gland, although it probably affects the pituitary gland through the hypothalamus.21 Another possibility that cannot be excluded is that the corticosterone acts directly on the ovary and reduced ovarian steroids would then act through feedback loop on the hypothalam hypophyseal axis. This concept finds support in the extreme atrophy of the ovary with no maturing follicles or corpora lutea after 8 to 10 weeks of tumor growth.
We cannot be certain as to whether corticosterone acts directly on the ovary or whether it affects the hypothalamuseal axis. Undoubtedly both mechanisms play some part in producing the changes in ultrastructure. To our knowledge, there have been no studies of the effect of massive, prolonged doses of corticosterone on the content of FSH and LH in the pituitary gland of the rat. In the mouse, Miyake 22 reported that injection of desoxycorticosterone ace- tate for 10 days induced a slight inhibition of gonadotrophins. How- ever McCann and Ramirez 23 reported little change in content of LH in rats given cortisol in a study by bioassay. Eleftherion and Church 24 reported that repeated exposure to stress increases plasma LH but decreases pituitary LH. However, Roger 25 reported that desoxycorti- costerone decreased LH secretion. The effect of prolonged corticos- terone has not been characterized in recent studies employing the radioimmunoassay procedure. Furthermore, the effect of continuously high levels of corticosterone would be difficult to duplicate by injec- tion alone because fluctuation of hormone levels would undoubtedly occur with injection.
It is suggested that type 1 cells produce FSH, whereas type 2 cells produce LH. The basis for this tentative identification of cells comes from a study reported previously from our laboratory.1º In that study, methylandrostenediol (MAD) was injected into female rats. FSH- producing cells in that study were characterized by especially large secretory granules which were identical to those within type 1 cells in the present study. Type 2 cells on the other hand were similar to another type of cell (types 1-4) in androgen-treated animals.10 With androgen, it is clear that FSH content of the pituitary gland increases, whereas LH content decreases concomitant with release of the hor- mone. If a similar mechanism for formation of large granules is opera- tive in 494-tumor bearing animals, the enlarged granules could well form by fusion of smaller granules. It is uncertain whether or not this mechanism is operative in the present study.
The decrease in number of both large and small granules at later periods (8 to 10 weeks), suggests strongly a process of involution in
type 1 cells. Type 2 gonadotrophs on the other hand became pro- gressively larger in size, contained extensive rough endoplasmic re- ticulum and became depleted of secretory granules by 10 weeks. These findings are consistent with hyperactivity of the cell.
Type 2 cells were somewhat similar to gonadectomy cells observed by Farquhar and Rinehart.19 Endoplasmic reticulum was dilated and the cell enlarged considerably. This change may reflect hyperactivity of the cell. Another indication of hyperactivity is the presence of in- tracisternal granules within the lumen of rough endoplasmic reticulum. The significance of intracisternal granules is not well established, al- though they could well signify a rapid synthesis of hormone. The usual route of protein synthesis in parenchymal cells of the pituitary 26 as well as other cells 27 involves condensation of immature granules within the Golgi apparatus to form large, membrane bounded mature gran- ules. Such a mechanism might be bypassed in the hyperstimulated type 2 gonadotrophs. Farquhar and Rinehart 28 have reported intracis- ternal granules in the pituitary of thyroidectomized animals.
Somatotrophs were also suppressed. Numerous secretory granules accumulated within the cytoplasm. The increased number of gran- ules correlates well with assay data which indicates that corticoster- oids suppress the release of growth hormone.2º
References
1. Harris GW, Donovan BT: The Pituitary Gland, Vol 1. Berkeley, Uni- versity of California Press, 1966
2. Turner CD: General Endocrinology, Fourth edition. Philadelphia, W. B. Saunders Co, 1966
3. Nakayama I, Nickerson PA, Skelton FR: An ultrastructural study of the adrenocorticotrophic hormone-secreting cell in the rat adenohypophysis during adrenal cortical regeneration. Lab Invest 21:169-178, 1969
4. Farquhar MG: Processing of secretory products by cells of the anterior pituitary gland, Memoirs of the Society for Endocrinology No. 19, Sub- cellular Organization and Function in Endocrine Tissues. Edited by H Heller, K Lederis. London, Cambridge University Press, 1971, pp 79-124
5. Herlant M: The cells of the adenohypophysis and their functional sig- nificance. Int Rev Cytol 17:299-382, 1964
6. Barnes BG: Electron microscopic studies on the secretory cytology of the mouse anterior pituitary. Endocrinology 71:619-628, 1962
7. Nakane PK: Classifications of anterior pituitary cell types with im- munoenzyme histochemistry. J Histochem Cytochem 18:9-20, 1970
8. Kurosumi K: Functional classification of cell types of the anterior pi- tuitary gland accomplished by electron microscopy. Arch Histol Jap 29: 329-362, 1968
9. Kurosumi K, Yashihiko O: Electron microscopy of two types of gon-
adotrophs in the anterior pituitary glands of persistent oestrous and di- oestrous rats. Z Zellforsch 85:34-46, 1968
10. Nakayama I, Nickerson PA, Skelton FR: An electron microscopic study of the changes in ACTH- and FSH-producing cells during development of methylandrostenediol hypertension in the rat. Am J Pathol 58:377- 401, 1970
11. . Heap PF, Lederis K, Neumann F: Effects of cyproterone on the ultra- structure of the rat adenohypophysis.4 pp 147-160
12. Bogdanove EM: Analysis of histophysiologic responses of the rat hy- pophysis to androgen treatment. Anat Rec 157:117-136, 1967
13. Hellbaum AA, Greep RO: Qualitative changes induced in gonado- tropic complex of pituitary by testosterone propionate. Endocrinology 32:33-40, 1943
14. Snell KC, Stewart HL: Variations in histologic pattern and functional ef- fects of a transplantable adrenal cortical carcinoma in intact, hypophy- sectomized, and newborn rats. J Natl Cancer Inst 22:1119-1155, 1959
15. Johnson DR, Snell KC, Francois D, Heftmann E: In vitro metabolism of progesterone-4-14C in an adrenocortical carcinoma of the rat. Acta En- doctrinol (kbh) 37:329-335, 1961
16. Mollenhauer HH: Plastic embedding mixtures for use in electron micros- copy. Stain Technol 39:111-114, 1964
7. Stempak JG, Ward RT: An improved staining method for electron micros- copy. J. Cell Biol 22:697-701, 1964
18. Reynolds ES: The use of lead citrate at high pH as an electron-opaque stain in electron microscopy. J Cell Biol 17:208-212, 1963
19. Farquhar MG, Rinehart JF: Electron microscopic studies of the an terior pituitary gland of castrate rats. Endocrinology 54:516-541, 1954
20. Ney RL, Hochella NJ, Grahame-Smith DG, Dexter RN, Butcher RW: Abnormal regulation of adenosine 3’, 5’-monophosphate and corticos- terone formation in an adrenocortical carcinoma. J Clin Invest 48:1733- 1739, 1969
21. Yates FE: Physiological control of adrenal cortical hormone secretion, The Adrenal Cortex. Edited by AB Eisenstein. Boston, Little, Brown and Company, 1969, pp 133-183
22. Miyake T: Inhibitory effect of various steroids on gonadotrophin hy- persecretion in parabiotic mice. Endocrinology 69:534-546, 1961
23. McCann SM, Ramirez VD: The neuroendocrine regulation of hypoph- yseal luteinizing hormone secretion. Recent Prog Horm Res 20:131-181, 1964
24. Eleftheriou BE, Church RL: Effects of repeated exposure to aggression and defeat on plasma and pituitary levels of luteinizing hormone in C57BL16J mice. Gen Comp Endocrinol 9:263-266, 1967
25. Roger F-H: Inhibition de la sécrétion d’hormone luteotrophe hypophysaire (LH) par l’acétate de désoxycorticostérone chez le rat mâle châtré. Ann Endocrinol (Paris) 29:647-651, 1968
26. Farquhar MG: Origin and fate of secretory granules in cells of the an- terior pituitary gland. Trans NY Acad Sci 23:346-351, 1961
27. Caro LG, Palade GE: Protein synthesis, storage and discharge in the pancreatic exocrine cell: an autoradiographic study. J Cell Bioll 20:473- 495, 1964
8. Farquhar MG, Rinehart JF: Cytologic alterations in the anterior pitui- tary gland following thyroidectomy: an electron microscope study. Endocrinol- ogy 55:857-875, 1954
29. Pecile A, Muller, E: Suppressive action of corticosteroids on the secre- tion of growth hormone. J Endocrinol 36:401-408, 1966
Acknowledgments
The authors are grateful to Mrs. Neonile Fylypiw, Mr. Luther Joseph, Mrs. Geneva Joseph, Mrs. Elisabeth Lawson and Mr. Robert Linsmair for skilled technical assistance.
[Illustrations follow]
Legends for Figures
Fig 1-Central section from atrophic ovary of tumor-bearing animal at 10 weeks after implantation. No maturing Graafian follicles are observable (x 17).
Fig 2-Central section from ovary of non-tumor-bearing control animal at 10 weeks. Follicles (F) and corpora lutea (CL) are observable (x 17).
Fig 3-Gonadotroph from control animal sacrificed at 4 weeks. Secretory granules (SG) approximately 200 mu in diameter are dispersed throughout the cytoplasm. Parallel cisternae of rough endoplasmic reticulum (ER) can be observed near the cell mem- brane. The lumen of the rough reticulum is somewhat distended. A few large lysosomal-derived structures (LY) are seen within the cytoplasm. An extensive Golgi complex (G) forms an incomplete ring-like structure within the cytoplasm (x 11,500).
CL
SG
ER
C
LY
Fig 4-Type 1 gonadotroph in tumor-bearing animal at 8 weeks following implantation. Many large 300 to 600 mu granules (GR) are dispersed among smaller 200 mu gran- ules. A few cisternae of rough endoplasmic reticulum (ER) are observable. The Golgi complex forms an incomplete ring. C=capillary (x 10,100). Inset-The second ☒ class of large granules (GR) can be seen in detail. There is a variable electron opacity of granules with a highly dense matrix whereas others have a lighter opacity. Dense struc- tures can be observed within the matrix of one granule (arrow) (x 13,800). ☒
Fig 5-Type 2 gonadotroph (GO) in tumor-bearing animal at 8 weeks. Only a few gran- ules are seen in one gonadotroph whereas there are more granules in an adjacent cell. Endoplasmic reticulum (ER) is hypertrophic. The cisternae contain a homogeneous, lightly electron-opaque matrix. A large lysosome-derived structure (LY) can be seen in the cytoplasm (x 10,600). Inset-Small immature secretory granules (IG) appear ☒ near the cisternae of the Golgi apparatus (G). Vesicles (V) are also clearly associated with Golgi cisternae (x 14,300). ☒ ☒
GR
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C
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