RESUMO
The sinus nerve or sympathetic trunk was stimulated unilaterally in one group of adult cats or Syrian hamsters while in another group the sinus nerve or sympathetic trunk was cut unilaterally and the animals were given reserpine. In a third group, atropine was administered prior to sinus nerve stimulation. All tissues were processed for the detection of primary monoamines. The carotid bodies on the operated sides were compared with those on the unoperated sides of the same animal in order to determine if amine depletion occurred following the experimental procedures. After sinus nerve stimulation alone, the density of the granules in the glomus cells was decreased, but changes were not noted in the granules following sympathetic nerve stimulation. Sinus nerve stimulation after atropine administration resulted in no change in granule density. Sinus nerve transection followed by reserpine treatment resulted in a greater decrease in granule density on the unoperated than on the operated side. Transection of the sympathetic components to the carotid body followed by reserpine injections resulted in a decrease in granule density in the glomus cells on both the operated and unoperated sides. These results suggest that the sinus nerve must be intact for reserpine to exert an effect and that the sinus nerve may contain efferent fibers which modulate amine secretion.
Assuntos
Corpo Carotídeo/inervação , Estimulação Elétrica , Nervo Glossofaríngeo/citologia , Aminas/análise , Animais , Atropina/farmacologia , Corpo Carotídeo/análise , Corpo Carotídeo/citologia , Corpo Carotídeo/efeitos dos fármacos , Gatos , Grânulos Citoplasmáticos/efeitos dos fármacos , Denervação , Eletrofisiologia , Nervo Glossofaríngeo/fisiologia , Histocitoquímica , Métodos , Microscopia Eletrônica , Fibras Nervosas Mielinizadas/efeitos dos fármacos , Neurônios Eferentes/efeitos dos fármacos , Reserpina/farmacologiaRESUMO
The carotid bodies from control, reserpine-treated, and hypoxia-treated hamsters were fixed with phosphate-buffered glutaraldehyde and osmium tetroxide, s-Collidine-buffered osmium tetroxide, or phosphate-buffered glutaraldehyde followed by potassium dichromate incubation. Following glutaraldehyde-osmium tetroxide fixation no differences in density or population of the electron-opaque granules in the glomus cells of either control or experimental animals were observed. With s-Collidine-buffered osmium tetroxide and the glutaraldehyde-dichromate technique a marked decrease in density without an appreciable reduction in number of granules was noted after reserpine treatment, while in hypoxia-treated hamsters the density and population of the granules were not different from those of the controls. The results indicate that reserpine depletes the amines without granule disappearance and that hypoxia does not affect the amine content of the granules. It is suggested that following glutaraldehyde-osmium tetroxide double fixation, persistence of the density of the granules in reserpine-treated animals is due primarily to the nonamine content, and that the amines in the glomus cells are probably not directly involved in the respiratory reflex.
RESUMO
Adult Syrian hamsters were given a subcutaneous injection of reserpine 3 days before an intraperitoneal injection of (3)H-3,4 dihydroxyphenylalanine or (3)H-5, hydroxytryptophan and the carotid bodies were subsequently prepared for electron microscopic radioautography. Other Syrian hamsters were given a subcutaneous injection of reserpine and the carotid bodies were subjected to a sensitive cytochemical test for the detection of unsubstituted amines. These studies were made to determine whether the labeled amine precursors were incorporated into the cells and to see whether the parenchymal cells were affected by reserpine treatment. Material from hamsters treated first with reserpine and subsequently injected with (3)H-3,4 dihydroxyphenylalanine or (3)H-5, hydroxytryptophan exhibited reduced grains of silver over the cells which were associated mainly with the dense cores of the cytoplasmic granules. These studies offer evidence that the granules of the carotid body incorporate catecholamine and indolamine precursors. Material from hamsters incubated for the presence of unsubstituted amines gave a positive reaction (opaque cytoplasmic granules) for catecholamines but not for indolamines. The latter substances may not be present in quantities sufficient to register a positive reaction in the cytochemical test. The opaque granules, indicative of the presence of catecholamines, decreased in density after reserpine treatment. 5 days after one reserpine injection the granules had regained opacity and were comparable to those seen in the control cells.
Assuntos
5-Hidroxitriptofano/metabolismo , Aminas/análise , Corpo Carotídeo/metabolismo , Catecolaminas/análise , Grânulos Citoplasmáticos/metabolismo , Di-Hidroxifenilalanina/metabolismo , Neurotransmissores/metabolismo , Animais , Corpo Carotídeo/efeitos dos fármacos , Cricetinae , Indóis , Microscopia Eletrônica , Reserpina/farmacologia , TrítioRESUMO
Substance P-immunoreactive (SP-1) structures in the carotid bodies of rats and cats were examined with the light and electron microscopes. In both species SP-I varicose nerve fibers were located singly in the interstitial connective tissue in close association with blood vessels. They were small unmyelinated fibers enveloped in a common Schwann cell sheath with other SP-negative fibers. Some of SP-I fibers contained large dense-cored granules and small clear vesicles in addition to microtubules and mitochondria and probably represented nerve fiber varicosities. The latter often were found incompletely invested by Schwann cell sheaths. SP-fibers were found occasionally in the envelopes of supporting cells at the periphery of parenchymal cell groups. However, none of the nerve terminals making synaptic contacts with glomus cells exhibited SP-like immunoreactivity. In cat carotid bodies some glomus cells showed moderate to intense SP-like immunoreactivity. The intense SP-I glomus cells displayed numerous dense-cored vesicles of 85 to 140 nm in diameter and frequently showed synaptic contacts with SP-negative nerve terminals. In rat carotid bodies we were unable to detect consistent SP-immunoreactivity in glomus cells. Our results do not favor the hypothesis that SP is a neurotransmitter/modulator in the chemoreceptor afferents synapsing on glomus cells in either the cat or rat carotid body. However our results support the hypothesis that SP in cat glomus cells may play a role in the modulation of chemoreceptor activity.
Assuntos
Corpo Carotídeo/química , Substância P/análise , Animais , Corpo Carotídeo/citologia , Corpo Carotídeo/ultraestrutura , Gatos , Feminino , Imuno-Histoquímica , Masculino , Fibras Nervosas/química , Ratos , Ratos EndogâmicosRESUMO
Utilizing electron microscopic observation, several contacts between small, granule-containing cells (SGC) and postganglionic neurons (PGN) in the celiac ganglion of the guinea pig have been observed. A SGC in very close association with a PGN was seen to receive a distinct synaptic contact that contained many vesicles with dense cores. This contact was morphologically unlike cholinergic synapses previously reported on chromaffin cells. Because the SGC and PGN were clearly separated by a thin rim of satellite cell cytoplasm mutual to both cells, it is not known how or if the SGC would possibly exert a synaptic or paracrine effect on the PGN. Also, intraganglion SGC existed as large well-vascularized islands within the celiac ganglion. These intraganglion clusters sometimes contained more than 50 cells and perhaps could be considered to function as localized neuroendocrine components within the ganglion by secreting granule products into the nearby blood vessels for local or distant effects, although this certainly is not known. This work reports a unique synaptic ending upon a single-occurring SGC, which, in turn, closely approximates a ganglion neuron in a soma-somatic relationship. In addition, a very close association (but no actual contact) was observed between granule-containing processes, presumably emanating from the intraganglion clusters, and PGN. Whatever the function of ganglionic SGC may be, the exact relationship between SGC and PGN presumably would be of great interest and potential importance.
Assuntos
Comunicação Celular , Grânulos Cromafim/ultraestrutura , Sistema Cromafim/ultraestrutura , Gânglios Simpáticos/ultraestrutura , Animais , Feminino , Cobaias , Masculino , Artéria Mesentérica Superior/inervaçãoRESUMO
The ultrastructure of substance P-containing nerve terminals synapsing on catecholamine neurons in the rat commissural subnucleus of the nucleus tractus solitarii (NTScom) was studied using a double immunocytochemical labeling technique. Although there were numerous tyrosine hydroxylase-immunoreactive (TH-I) somata present, substance P immunoreactive (SP-I) cell bodies were only occasionally found in the NTScom. At the light microscopic level, many SP-I terminals were seen closely associated with TH-I dendrites and somata. At the electron microscopic level, SP-I terminals synapsing on TH-I structures were also readily encountered. SP-I terminals contained small, clear, and predominantly spherical vesicles (32 +/- 4 nm diameter), as well as large dense-cored vesicles approximately 100 nm in diameter. Postsynaptic TH-I dendritic profiles of various calibers and somata were encountered. These postsynaptic TH-I structures often showed postsynaptic densities. The morphological features of the SP-TH synapses in the present study, that is, the size of synaptic vesicles and the presence of postsynaptic densities, are quite different from those of central carotid sinus afferent synapses reported in our previous study [Chen et al. (1992), J. Neurocytol., 21:137-147]. Therefore, most of the SP terminals of the SP-TH synapses in the NTScom appear not to originate from the carotid sinus afferents. SP-I second-order neurons of the carotid sinus afferent pathway [Chen et al. (1991), J. Auton. Nerv. Syst., 33:97-98] may be one of the possible sources of such terminals.
Assuntos
Catecolaminas/análise , Núcleo Solitário/química , Substância P/análise , Sinapses/ultraestrutura , Vias Aferentes/ultraestrutura , Animais , Tronco Encefálico/química , Tronco Encefálico/ultraestrutura , Feminino , Técnicas Imunoenzimáticas , Microscopia Imunoeletrônica , Neurônios/química , Neurônios/ultraestrutura , Terminações Pré-Sinápticas/química , Terminações Pré-Sinápticas/ultraestrutura , Ratos , Ratos Endogâmicos WKY , Núcleo Solitário/ultraestrutura , Tirosina 3-Mono-Oxigenase/análiseAssuntos
Ligases/análise , Fígado/enzimologia , Nucleotídeos de Adenina/metabolismo , Adenosina Trifosfatases/metabolismo , Animais , Bicarbonatos/metabolismo , Membrana Celular , Núcleo Celular , Coenzima A/biossíntese , Meios de Cultura , Citoplasma , Retículo Endoplasmático , Repressão Enzimática , Ácidos Graxos/biossíntese , Substâncias de Crescimento/metabolismo , Técnicas Histológicas , Técnicas In Vitro , Fígado/citologia , Magnésio/metabolismo , Manganês/metabolismo , Microscopia Eletrônica , Mitocôndrias Hepáticas/enzimologia , Fosfatos/metabolismo , Proteínas/metabolismo , Ratos , SolubilidadeAssuntos
Adenosina Trifosfatases/metabolismo , Ventrículos Cerebrais/ultraestrutura , Animais , Barreira Hematoencefálica , Capilares/enzimologia , Glicosídeos Cardíacos/toxicidade , Membrana Celular/enzimologia , Ventrículos Cerebrais/enzimologia , Cães , Epêndima/enzimologia , Epêndima/ultraestrutura , Neuroglia/enzimologia , Neurônios/enzimologia , Vômito/induzido quimicamenteAssuntos
Sistema Cromafim/inervação , Terminações Nervosas/citologia , Sinapses/citologia , Anatomia Comparada , Animais , Axônios , Catecolaminas/análise , Cricetinae , Citoplasma , Grânulos Citoplasmáticos/análise , Retículo Endoplasmático , Feminino , Haplorrinos , Histocitoquímica , Humanos , Recém-Nascido , Lisossomos , Microscopia Eletrônica , Microtúbulos , Mitocôndrias , Gravidez , Coelhos , Ribossomos , Células de Schwann/citologia , Membranas Sinápticas , Vesículas SinápticasAssuntos
Sistema Cromafim/ultraestrutura , Paragânglios Cromafins/ultraestrutura , Envelhecimento , Animais , Aorta Abdominal , Capilares , Catecolaminas , Núcleo Celular/ultraestrutura , Tecido Conjuntivo/ultraestrutura , Grânulos Citoplasmáticos/ultraestrutura , Cães , Paragânglios Cromafins/anatomia & histologia , Paragânglios Cromafins/irrigação sanguínea , Espaço RetroperitonealRESUMO
Horseradish peroxidase (HRP)-conjugated alpha-bungarotoxin (alpha Bgt) was used to localize alpha Bgt-acetylcholine receptor sites in the rat carotid body. Two types of glomus cell were differentiated on the basis of the staining of their plasma membranes by the conjugate: type A, devoid of staining or only partly stained; and type B, exhibiting staining over the entire cell surface. The parts of type A glomus and supporting cells stained were always in direct apposition to type B glomus cells. It is concluded that type B glomus cells are possibly the only cell types exhibiting specific binding sites of alpha Bgt. Other morphological characteristics and quantitative studies indicated that the type A and type B glomus cells presented in this study were equivalent to those described in the rat carotid body by other investigators (McDonald & Mitchell, 1975). alpha Bgt-HRP staining facilitated the observation of the distribution pattern of glomus cells in the parenchyma: type A glomus cells were arranged in groups and often showed polarity toward neural elements and sinusoidal capillaries; and clusters of type B glomus cells were frequently situated in a demilune -like fashion over groups of type A glomus cells. Because of differences in morphology, synaptology, alpha Bgt-binding affinity, and polarity toward the blood vessels, we propose that type A and type B glomus cells in the rat carotid body represent functionally distinct cell types.
Assuntos
Bungarotoxinas/metabolismo , Corpo Carotídeo/citologia , Acetilcolina/fisiologia , Animais , Fibras Autônomas Pré-Ganglionares/metabolismo , Sítios de Ligação , Corpo Carotídeo/fisiologia , Histocitoquímica , Microscopia Eletrônica , Terminações Nervosas/metabolismo , Ratos , Ratos Endogâmicos , Transmissão SinápticaRESUMO
The Golgi complex in the Sertoli cell of the Syrian hamster is well developed and consists of stacks of cisternae and associated vesicles. The inner- and outermost cisternae of the Golgi stacks are usually moderately dilated and exhibit numerous fenestrations. The middle portions of the intermediate cisternae are greatly flattened and not fenestrated, but toward the periphery these cisternae gradually become dilated and show a few fenestrations. On the inner aspect of the Golgi stacks the following structures are seen frequently: (1) one or two series of linearly arrayed circular profiles some of which are interconnected by tubules; (2) networks of anastomosing tubules with circular or oval meshes (800 to 1200 A in diameter); and/or (3) irregularly disposed tubules. The circular profiles and tubules are approximately 450 A in diameter. Acid phosphatase activity was localized in these anastomosing tubules when the tissues were incubated for more than one hour in a modified Gomori's medium (Barka and Anderson, 1963). Strong thiamine pyrophosphatase activity was demonstrated in the inner one to three cisternae of the Golgi stacks but not in the associated tubules. The system of the Golgi associated tubules is morphologically and histochemically distinct from the Golgi stacks and is probably equivalent to the Golgi-endoplasmic reticulum-lysosome system (GERL) in other cell types. The three dimensional aspects of the GERL-equivalent system are discussed.
Assuntos
Complexo de Golgi , Monoéster Fosfórico Hidrolases/análise , Células de Sertoli/ultraestrutura , Fosfatase Ácida/análise , Animais , Cricetinae , Retículo Endoplasmático/enzimologia , Complexo de Golgi/enzimologia , Histocitoquímica , Lisossomos , Masculino , Microscopia Eletrônica , Pirofosfatases/análise , Células de Sertoli/enzimologia , Tiamina PirofosfatoRESUMO
The subclavian glomera (aortic bodies) of young New Zealand white rabbits were studied with the light, fluorescence, and electron microscopes. Two cell types were identified: type I, granule-containing (chief) cells, and type II, agranular (sustentacular) cells. The type I cells possessed large nuclei, the normal complement of cytoplasmic organelles and numerous electron-opaque cytoplasmic granules. The type II cells were agranular with attenuated cytoplasmic processes which partially or completely ensheathed the type I cells. The glomera were well vascularized. Capillary endothelial cells contained numerous pinocytotic vesicles, but few fenestrae. Two profiles of nerve terminals were observed. One, apposing the type I cells, contained numerous electron-lucent vesicles, several dense-cored vesicles, mitochondria and possessed membrane specializations resembling those usually observed in synaptic zones. The other profile contained abundant mitochondria and a few electron-lucent and dense-cored vesicles. Structural specializations were not observed on the apposed membranes of these terminals or adjacent to type II cells. Fluorescence histochemistry revealed an intense yellow-green fluorescence in the glomera, which indicated the presence of biogenic amines, possibly primary catecholamines or an indolamine. The electron-opaque granules observed in the type I cells were believed to be the storage sites for these amines. The subclavian glomera were found to be morphologically similar to the carotid body which is a known chemoreceptor.
Assuntos
Corpos Aórticos/ultraestrutura , Paragânglios não Cromafins/ultraestrutura , Coelhos/anatomia & histologia , Artéria Subclávia/inervação , Animais , Corpos Aórticos/análise , Corpos Aórticos/fisiologia , Aminas Biogênicas/análise , Células Quimiorreceptoras/ultraestrutura , Grânulos Citoplasmáticos/ultraestrutura , Feminino , Masculino , Mitocôndrias/ultraestruturaRESUMO
Mitotic activity often has been reported in embryonic and fetal sympathetic neuroblasts, principal sympathoblasts, and primitive sympathetic cells in various species at different stages of development. Postnatal adrenal medullary cells also are known to undergo mitosis, but such dividing capabilities rarely have been observed in the true postnatal extraadrenal chromaffin system. Although few in number, this work nevertheless has clearly identified such cells in varying stages of the mitotic cycle in the young dog, Syrian hamster, mouse, rabbit, and rat. The dividing cells were noted in paraaortic chromaffin organs, paraganglia, and within the inferior mesenteric ganglion as well. They displayed the morphological character usually associated with their adrenal medullary catecholaminergic counterparts, including numerous dense-cored vesicles known to be the harbingers of catecholamines and various peptides. Nerve endings were not noticed upon the mitotic cells. The phenomenon of dividing extraadrenal chromaffin cells augments existing data and perhaps suggests that these cells are more endocrine than neural in type and subservient to the adrenal medulla in its classic endocrine function.
Assuntos
Sistema Cromafim/citologia , Mitose , Animais , Sobrevivência Celular , Sistema Cromafim/ultraestrutura , Cricetinae , Cães , Glucocorticoides/fisiologia , Camundongos , Necrose , Fatores de Crescimento Neural/fisiologia , Coelhos , RatosRESUMO
The carotid baroreceptor field of normotensive (NTR) and spontaneously hypertensive rats (SHR) examined in this study extends for about 0.5 mm along the length and about 1/3 to 1/2 of the circumference of the wall of the internal carotid artery opposite to the carotid body. The vascular wall of the baroreceptor field exhibits neither a marked dilation to form a carotid sinus nor histological differences in the intima and media compared to other parts of the carotid artery. Histologically the adventitia of the baroreceptor field is characterized by (1) an increased thickness and by less well developed elastic lamellae in comparison with other parts of the arterial wall, (2) a profuse blood and nerve supply, and (3) a richness of cellular elements. The presumptive baroreceptor terminals are localized in the inner 1/3 of the adventitia and display local enlargements that appear to show preferential association with the cell body or processes of the Schwann cell but not with other components of the adventitia. the enlargements are characterized by an accumulation of very densely packed mitochondria, and glycogen particles. No morphological alterations were noted in the baroreceptor terminals of SHR except for proliferated basal laminae that invest the terminals. Our work does not support the concept that resetting of the baroreceptors is due to degeneration of the terminals.
Assuntos
Artéria Carótida Interna/inervação , Hipertensão/patologia , Pressorreceptores/ultraestrutura , Animais , Artéria Carótida Interna/ultraestrutura , Corpo Carotídeo/ultraestrutura , Tecido Elástico/ultraestrutura , Fibras Nervosas/ultraestrutura , Organoides/ultraestrutura , Pressorreceptores/irrigação sanguínea , Ratos , Células de Schwann/ultraestruturaRESUMO
Subendocardial cells of the right ventricular myocardium of the West African bat, Pipistrellus pipistrellus, were investigated at the ultrastructural level. The prominent features of these cells include a well-developed T-tubule system and numerous mitochondria with closely packed cristae. Additionally, the cells display large stores of lipid bodies. These unusual features confirm that Purkinje cells are heterogeneous in structural detail. From the paucity and poor structure of myofibrils of these cells, it is likely that the T-tubules may have a primary nutritional role in the regulation of electrolytes in an animal in which the cardiac cycle is particularly rapid. The well-developed mitochondria and the large stores of lipid bodies are appropriate for such active cells in which metabolism is probably of the aerobic type.
Assuntos
Quirópteros/anatomia & histologia , Ramos Subendocárdicos/ultraestrutura , Animais , Lipídeos/análise , Masculino , Microscopia Eletrônica , Mitocôndrias Cardíacas/ultraestrutura , Miofibrilas/ultraestrutura , Ramos Subendocárdicos/químicaRESUMO
Immunocytochemical localization of dopamine beta-hydroxylase (DBH) was used to study the synthesis and storage sites of norepinephrine (noradrenaline) in the rat and cat carotid bodies. In the rat carotid body some parenchymal cells exhibited strong DBH-like immunoreactivity (DBH-I), while others displayed only faint DBH-I. In a typical parenchymal cell cluster, most cells with strong DBH-I were irregular in shape and appeared to partially surround those with weak DBH-I which usually were rounded in contour. In the cat carotid body most parenchymal cells showed a strong to moderate DBH-I. In both the rat and cat carotid bodies varicose nerve fibres with DBH-I were associated primarily with blood vessels. All autonomic ganglion cells examined, which were associated with the rat carotid body, showed DBH-I. Electron microscopy revealed that most DBH-I in the strongly positive cells of the rat carotid body was associated with dense granules (possibly corresponding to dense-cored vesicles of various sizes), although some was found in other sites. In oval cells with less DBH-I, reactivity resided in some of the large granules. In the cat carotid body the glomus cells contained more granules of various sizes and shapes than did those of the rat carotid body. Most of the cat glomus cell granules exhibited DBH-I activity. Our results indicate that some of glomus cells in the rat and most of the glomus cells in the cat contain DBH and therefore may be sites of norepinephrine synthesis.
Assuntos
Corpo Carotídeo/enzimologia , Dopamina beta-Hidroxilase/metabolismo , Norepinefrina/análise , Animais , Reações Antígeno-Anticorpo , Corpo Carotídeo/ultraestrutura , Gatos , Dopamina beta-Hidroxilase/imunologia , Soros Imunes/análise , Imunodifusão , Técnicas Imunoenzimáticas , Ratos , Ratos EndogâmicosRESUMO
The distribution of Mg++-activated ATPase was determined with light and electron microscopy in normal and degenerating seminferous tubules. In the normal animals ATPase was localized in the interface between spermatids and Sertoli cells, in association with the cytoplasmic filaments contained within Sertoli cell processes, and in the lymphatic endothelium. ATPase activity increased in degenerating tubules as observed by light microscopy. Electron microscopic investigations of the degenerating tubules which contained only spermatogonia and Sertoli cells revealed reaction product on the outer surface of the Sertoli cell processes and within the interface between adjacent Sertoli cells. Reactaction product was also observed in the Sertoli cell processes between the cytoplasmic filaments and the cell membrane. Where filaments were absent in Sertoli cell processes, no reaction product was observed. These electron microscopic studies indicate that the increase in ATPase activity in testicular degeneration is probably a relative increase due to a loss of the germinal elements of the tubular epithelium and subsequent apposition of the Sertoli cell processes. We speculate that the ATPase activity localized within the Sertoli cell processes may be involved in providing an energy source for filament motility.
Assuntos
Adenosina Trifosfatases/metabolismo , Testículo/enzimologia , Animais , Membrana Celular/ultraestrutura , Cricetinae , Sistema Linfático/ultraestrutura , Masculino , Epitélio Seminífero/ultraestrutura , Túbulos Seminíferos/ultraestrutura , Células de Sertoli/enzimologia , Células de Sertoli/ultraestrutura , Espermátides/ultraestrutura , Doenças Testiculares/enzimologia , Testículo/ultraestruturaRESUMO
Young male and female New Zealand white rabbits were given a daily subcutaneous injection of reserpine (Serpasil, Ciba; 3 mg/kg) for two days and were sacrificed 24 hours after the last injection. The subclavian glomera (aortic bodies) were processed for electron microscopy to determine the effects of this biogenic amine depleting agent on the electron-opaque cytoplasmic granules of the parenchymal type I cells. Observations of glutaraldehyde-osmium tetroxide fixed glomera from reserpinized animals showed a slight decrease in granule density of the type I cells. Glomera fixed in glutaraldehyde and incubated in potassium dichromate (pH 4.1) demonstrated a reduction in granule opacity following reserpine treatment. Control glomera incubated in potassium dichromate displayed electron-opaque granules. These results indicate that reserpine does deplete the amines without granule disappearance or changes in granule population. The positive reaction of the control tissue granules to potassium dichromate incubation suggests that the predominant biogenic amines in the electron-opaque granules are unsubstituted monoamines. Persistence of the opaque granules following reserpinization and glutaraldehyde-osmium tetroxide double fixation, may be due to amine-binding protein within the granules. The mode of granule depletion could not be ascertained with certainty.