Relationship between the golgi apparatus, gerl, and secretory granules in acinar cells of the rat exorbital lacrimal gland

The method of secretory granuleformation in the acinar cells of the rat exorbital lacrimal gland was studied by electron microscope morphological and cytochemical techniques. Immature secretory granules at the inner face of the Golgi apparatus were frequently attached to a narrow cisternal structure similar to GERL as described in neurons by Novikoff et al. (Novikoff, P. M., A. B. Novikoff, N. Quintana, and J.-J. Hauw. 1971. J. Cell Bio. 50:859-886). In the lacrimal gland. GERL was located adjacent to the inner Golgi saccule, or separated from it by a variable distance. Portions of GERL were often closely paralleled by modified cisternae of rough endoplasmic reticulum (RER), which lacked ribosomes on the surface adjacent to GERL. Diaminobenzidine reaction product of the secretory enzyme peroxidase was localized in the cisternae of the nuclear envelope, RER, peripheral Golgi vesicles, Golgi saccules, and immature and mature secretory granules. GERL was usually free of peroxidase reaction product or contained only a small amount. Thiamine pyrophosphatase reaction product was present in two to four inner Golgi saccules; occasionally, the innermost saccule was dilated and fenestrated, and contained less reaction product than the next adjacent saccule. Acid phosphatase (AcPase) reaction product was present in GERL, immature granules, and, rarely, in the innermost saccule, but not in the rest of the Golgi saccules. Thick sections of AcPase preparations viewed at 100 kV revealed that GERL consisted of cisternal, and fenestrated or tublular portions. The immature granules were attached to GERL by multiple connections to the tublular portions. These results suggest that, in the rat exorbital lacrimal gland, the Golgi saccules participate in the transport of secretory proteins, and that GERL is involved in the formation of secretory granules.     

Cytochemical studies of GERL and its role in secretory granule formation in exocrine cells

Synopsis the structure and cytochemistry of GERL was studied in several different exocrine secretory cells, including the exorbital lacrimal gland, parotid, lingual serous (von Ebner's), submandibular, and sublingual salivary glands, and exocrine pancreas of the rat; the lacrimal, parotid and pancreas of the guinea-pig; and the lacrimal gland of the monkey. GERL was morphologically and cytochemically similar in all cell types studied. It was located in the inner Golgi region and consisted of cisternal and tubular portions. Immature secretory granules were in continuity with GERL through multiple tubular connections. Modified cisternae of endoplasmic reticulum, with ribosomes only on one surface, closely paralleled parts of GERL. GERL and immature granules were intensely reactive for acid phosphatase activity, while the inner Golgi saccules were reactive for thiamine pyrophosphatase and nucleoside diphosphatase activities. In the rat exorbital lacrimal and parotid glands, reaction product for endogenous peroxidase, a secretory enzyme, was present in the endoplasmic reticulum, Golgi saccules, immature and mature secretory granules. GERL was usually free of reaction product or contained only a small amount. The widespread occurrence of GERL in secretory cells, and its intimate involvement with the formation of granules, suggest that it is an integral component of the secretory process.     

Cytochemical localization of acid phosphatase and trimetaphosphatase activities in exocrine acinar cells

Acid phosphatase activity, a lysosomal marker, is commonly demonstrated using the Gomori technique with cytidine 5'-monophosphate or beta-glycerophosphate as substrate. Using this lead capture method on mouse and rat exorbital lacrimal, parotid, and pancreatic acinar cells, reaction product was localized in GERL, forming secretory granules, and secondary lysosomes. However, a different cytochemical localization was observed for inorganic trimetaphosphatase, another lysosomal enzyme. When the technique for trimetaphosphatase activity, a metal chelation method, was applied to exocrine acinar cells, reaction produce was conspicuously absent from GERL and forming secretory granules, but was present in secondary lysosomes, occasionally in Golgi saccules, and in previously unreported basal elongated lysosomes. The differences in the localization of the two enzymatic activities emphasizes the importance of employing more than one substrate where possible, and raises questions concerning the mechanism of delivery of acid hydrolases to secondary lysosomes.     

Ultrastructural localization of nicotinamide adenine dinucleotide phosphatase (NADPase) activity within columnar, goblet, and Paneth cells of rat small intestine

The distribution of nicotinamide adenine dinucleotide phosphatase (NADPase) activity was examined in epithelial cells of rat small intestine. Segments of ileum were fixed with glutaraldehyde and tissue chopper sections were incubated for up to 4 hr at pH 5.0 in cytochemical media prepared with NADP as substrate. NADPase activity was found primarily within the Golgi saccules of columnar, goblet, and Paneth cells. Columnar and goblet cells showed most of the NADPase activity within the saccules which were intermediate between the cis and trans faces of the Golgi stack. Paneth cells, however, showed the heaviest staining within saccules between the intermediate and innermost saccule at the trans aspect of the Golgi stack. Both columnar cells and Paneth cells also contained spotty, and sometimes heavy, deposits of reaction product within an occasional focal area of the GERL system and within an occasional lysosome. Control experiments indicated that the Golgi-associated NADPase activity was enhanced if cells were pretreated for about 12 hr with EGTA prior to incubation. No similar enhancement was apparent if the tissues were pretreated with DMSO. Furthermore, NADPase activity within the Golgi saccules could be inhibited completely by incubating intestinal epithelial cells with NADP in the presence of sodium fluoride or L(+)-tartrate.     

Golgi apparatus, GERL, and secretory granule formation within neurons of the hypothalamo-neurohypophysial system of control and hyperosmotically stressed mice

The vasopressin-producing neurons of the hypothalamo-neurohypophysial system are a particularly good model with which to consider the relationship between the Golgi apparatus nd GERL and their roles in secretory granule production because these neurons increase their synthesis and secretion of vasopressin in response to hyperosmotic stress. Enzyme cytochemical techniques for acid phosphatase (AcPase) and thiamine pyrophosphatase (TPPase) activities were used to distinguish GERL from the Golgi apparatus in cell bodies of the supraoptic nucleus from normal mice, mice hyperosmotically stressed by drinking 2% salt water, and mice allowed to recover for 5-10 d from hyperosmotic stress. In nonincubated preparations of control supraoptic perikarya, immature secretory granules at the trans face of the Golgi apparatus were frequently attached to a narrow, smooth membrane cisterna identified as GERL. Secretory granules were occasionally seen attached to Golgi saccules. TPPase activity was present in one or two of the trans Golgi saccules; AcPase activity appeared in GERL and attached immature secretory granules, rarely in the trans Golgi saccules, and in secondary lysosomes. As a result of hyperosmotic stress, the Golgi apparatus hypertrophied, and secretory granules formed from all Golgi saccules and GERL. Little or no AcPase activity could be demonstrated in GERL, whereas all Golgi saccules and GERL-like cisternae were TPPase positive. During recovery, AcPase activity in GERL returned to normal; however, the elevated TPPase activity and secretory granule formation seen in GERL-like cisternae and all Golgi saccules during hyperosmotic stress persisted. These results suggest that under normal conditions GERL is the predominant site for the secretory granule formation, but during hyperosmotic stress, the Golgi saccules assume increased importance in this function. The observed cytochemical modulations in Golgi saccules and GERL suggest that GERL is structurally and functionally related to the Golgi saccules.     

Ultrastructural and cytochemical studies of acid phosphatase and trimetaphosphatase in rat peritoneal mast cells developing in vivo

Summary The ultrastructural and cytochemical features of peritoneal mast cells of the rat were studied. Immature mast cells show specific cytoplasmic granules of different sizes, the smaller ones localized in the Golgi region. The rough endoplasmic reticulum and Golgi apparatus are well developed, and mitochondria are numerous. Nuclei show deep indentations. Acid phosphatase is present in the Golgi saccules, in GERL (Golgi apparatus-endoplasmic reticulumlysosome) and in some small granules. It is not present in mature granules. Trimetaphosphatase is present in the Golgi saccules, in GERL, in most immature granules and in some mature granules. These enzymes appear to be transported and packaged into granules by the Golgi apparatus, suggesting that the specific mast cell granules may be a form of lysosome. The results of this study are consistent with the hypothesis that peritoneal mast cells may be derived from macrophage-like precursors.     

Effects of secretory stimulation on the Golgi apparatus and GERL of rat parotid acinar cells

The structure and cytochemistry of the Golgi apparatus and GERL of rat parotid acinar cells was studied after in vivo secretory stimulation with isoproterenol. Discharge of mature secretory granules was complete within 1 hr after isoproterenol injection, but immature granules in the Golgi region or near the lumen were not released. At early times (1-5 hr) after isoproterenol, acid phosphatase (AcPase) activity was markedly increased in GERL and immature secretory granules compared to uninjected controls. GERL appeared increased in extent and numerous continuities with immature granules were observed. Reaccumulation of mature secretory granules was first evident at 5 hr, and was almost complete by 16 hr after isoproterenol. Thiamine pyrophosphatase (TPPase) activity, normally restricted to the trans Golgi saccules, was frequently present in immature granules during this time. Narrow cisternae resembling GERL, occasionally in continuity with immature granules, also contained TPPase reaction product. By 16-24 hr after stimulation, the activity and distribution of AcPase and TPPase were similar to control cells. These results demonstrate the dynamic nature of the Golgi apparatus and GERL in parotid acinar cells, and emphasize the close structural and functional relationship between these two structures.     

Intracellular transport of albumin through the secretory apparatus of rat liver parenchymal cells. An immunocytochemical study

The fine structural localization of albumin in rat liver parenchymal cells was determined by an improved immunocytochemical method and serial sectioning. Albumin in the secretory apparatus of the parenchymal cells was present in segments of the rough endoplasmic reticulum, interrupted with negative segments, in transport vesicles, Golgi saccules, finely anastomosed tubules and vesicles on the trans side of the Golgi complex, and in secretion granules. Horizontally sectioned Golgi saccules contained lipoprotein particles on one side and albumin on the other side. After transport, the vesicles that contained albumin fused with the so-called rigid lamellae on the trans-side of the Golgi complex. Ultrathin serial sections revealed no true structural continuity between the endoplasmic reticulum and the cis-aspect of the Golgi complex. We concluded that secretory proteins are transported from the endoplasmic reticulum to the Golgi complex by transport vesicles that bud from the endoplasmic reticulum and fuse with the Golgi saccules. These vesicles fuse regularly with the Golgi saccules on the cis-side and occasionally with tubular elements on the trans-aspect that may belong to the so-called GERL.     

Inorganic trimetaphosphatase as a histochemical marker for lysosomes in light and electron microscopy.

A new cytochemical method is presented for the light and electron microscopic localization of lysosomes in mineralized and soft tissues. Inorganic trimetaphosphate is used as substrate in a lead chelate incubation medium at pH 3.9. Lysosomes in several tissues are strongly reactive, and reaction product is frequently present in Golgi saccules and GERL. The reaction can be differentiated from acid glycerophosphatase activity, is relatively insensitive to fixation and demineralization procedures, and the reaction is often complete after short incubation times.     

Morphological and cytochemical alterations of the Golgi apparatus and GERL in rat parotid acinar cells during ethionine intoxication and recovery

The present electron microscopic cytochemical investigation was undertaken to characterize the alterations in the golgi apparatus and GERL of rat parotid acinar cells during ethionine intoxication and recovery. Although the Golgi apparatus and GERL were reduced in size, and some broadening of the Golgi saccules occurred as the result of ethionine treatment, the relative localization of thiamine pyrophosphatase (TPPase) activity in the Golgi saccules, and acid phosphatase activity (AcPase) in GERL, remained unchanged. Shortly after ethionine treatment was stopped, a dramatic redistribution of enzyme activities was noted. Within the first 24 hours of recovery, the Golgi apparatus began to enlarge, and the content of secretory granules increased. By day 3 of recovery, cisternae morphologically identifiable as GERL and forming secretory granules possessed TPPase activity, while AcPase activity was virtually undetectable. After seven days of recovery, the Golgi apparatus and GERL appeared both morphologically and cytochemically normal. The enzyme modulation observed during recovery may be correlated with increased secretory granule production. Furthermore, the presence of TPPase activity in GERL and forming secretory granules lends support to the suggestion that GERL may be derived from the trans Golgi saccule.     

LYSOSOMAL PACKAGING IN DIFFERENTIATING AND DEGENERATING ANURAN LATERAL MOTOR COLUMN NEURONS

The role of the Golgi apparatus and the Golgi-endoplasmic reticulum-lysosome complex (GERL) in the genesis of lysosomes was examined in differentiating and degenerating motor neurons of anuran larvae. Acid phosphatase, aryl sulfatase, and thiolacetic acid esterase were utilized as marker enzymes for the lysosomal system, while nucleoside diphosphatase and thiamine pyrophosphatase labeled the inner saccule(s) of the Golgi apparatus. Reduced osmium tetroxide was routinely deposited in the outer Golgi saccule regardless of the state of neuronal maturation. In all young neurons, the disposition of acid hydrolase reaction product paralleled the formation of GERL, with no lytic activity in the Golgi apparatus per se. Hypertrophy of the Golgi apparatus and GERL was observed in the early phases of degeneration, and both organelles apparently exhibit extensive hydrolytic activity. Dense bodies, autophagic vacuoles, and primary lysosomes were found arising from GERL, while the Golgi apparatus may produce primary lysosomal granules during regression. On the other hand, in differentiating neurons, hydrolytic activity was restricted to GERL and an occasional dense body and autophagic vacuole. These studies illustrate a parallelism between the development of GERL and genesis of primary and secondary lysosomes during neuronal cytodifferentiation, and implicate GERL and possibly the Golgi apparatus in lysosomal packaging in degenerating neurons.     

Different aspects of membrane differentiation at the inner side (GERL) of the Golgi apparatus in rabbit luteal cells

Synopsis After luteinization, during the growth phase, rabbit luteal cells showed a well-developed Golgi apparatus, which was clearly reduced at the end of pseudo-pregnancy. During this whole period, acid phosphatase was demonstrated in the saccules (g) of the Golgi stack and in the innermost Golgi element (G₂), which may be part of GERL. Between both acid phosphatase-positive compartments, a negative or slightly positive element (G₁) was present paralleling the saccules of the Golgi stack. This element was composed of cisternal (G₁ c) and perforated portions (G₁ p) and directly bordered the thiamine pyrophosphatase-positive saccules of the Golgi stack (g₁–g₂). Arylsulphatase activity was present in two saccules in the middle of the stack (g₃–g₄) and in the innermost Golgi element (G₂). In the acid phosphatase and arylsulphatase reactions the limiting membrane of the lysosomes was more reactive than the matrix. After phosphotungstic acid staining at a low pH, the inner elements of the Golgi apparatus (G₁ and G₂) and the border of the lysosomes were heavily contrasted. The lysosomal matrix and the other Golgi stack saccules were either almost unstained or displayed a clearly lower contrast.It is concluded that the cytochemical difference between Golgi (g) and GERL (G) membranes is most probably the result of a specific process of membrane differentiation, which takes place at G₁. There is also evidence that the lysosomal matrix hydrolases may be formed in the saccules of the Golgi stack. The strongly phosphotungstic acid-positive inner elements are, although more extended, comparable in large part with the GERL elements as described in neurons (Novikoffet al., 1971).     

Intracellular localization of basement membrane precursors in the endodermal cells of the rat parietal yolk sac. III. Immunostaining for laminin and its precursors

Reichert's membrane and the endodermal cells of the parietal yolk sac were examined for the presence of laminin antigenicity using anti-laminin antibodies and the peroxidase-antiperoxidase sequence. Immunostaining was observed through the full width of Reichert's membrane and within endodermal cells. In these cells immunostaining was observed in rough endoplasmic reticulum (rER) cisternae and Golgi apparatus. The Golgi staining could occur in any saccule, but predominated in components interpreted as the last saccule of the stack, the GERL element, and associated prosecretory granules. The secretory granules found in the ectoplasm were also immunostained. Finally, multivesicular bodies showed some staining. The immunostaining of Reichert's membrane indicates the presence of laminin itself, while that of rER cisternae and the Golgi apparatus is attributed to laminin precursors. Presumably the biosynthesis of laminin occurs along the usual protein pathway, that is, from rER through Golgi saccules and the GERL element to secretory granules, which release their content into Reichert's membrane. The laminin immunostaining of Reichert's membrane and endodermal cells is similar to that of type IV collagen. It is, therefore, likely that the two substances are processed and secreted simultaneously.     

Lectin-labeled membrane is transferred to the Golgi complex in mouse pituitary cells in vivo

Labeling of the Golgi complex with the lectin conjugate wheat germ agglutinin-horseradish peroxidase (WGA-HRP), which binds to cell surface membrane and enters cells by adsorptive endocytosis, was analyzed in secretory cells of the anterior, intermediate, and posterior lobes of mouse pituitary gland in vivo. WGA-HRP was administered intravenously or by ventriculo-cisternal perfusion to control and salt-stressed mice; post-injection survival times were 30 min-24 hr. Peroxidase reaction product was identified within the extracellular clefts of anterior and posterior pituitary lobes through 24 hr but was absent in intermediate lobe. Endocytic vesicles, spherical endosomes, tubules, dense and multivesicular bodies, the trans-most saccule of the Golgi complex, and dense-core secretory granules attached or unattached to the trans Golgi saccule were peroxidase-positive in the different types of anterior pituitary cells and in perikarya of supraoptico-neurohypophyseal neurons; endoplasmic reticulum and the cis and intermediate Golgi saccules in the same cell types were consistently devoid of peroxidase reaction product. Dense-core secretory granules derived from cis and intermediate Golgi saccules in salt-stressed supraoptic perikarya likewise failed to exhibit peroxidase reaction product. The results suggest that in secretory cells of anterior and posterior pituitary lobes, WGA-HRP, initially internalized with cell surface membrane, is eventually conveyed to the trans-most Golgi saccule, in which the lectin conjugate and associated membrane are packaged in dense-core secretory granules for export and potential exocytosis of the tracer. Endoplasmic reticulum and the cis and intermediate Golgi saccules appear not to be involved in the endocytic/exocytic pathways of pituitary cells exposed to WGA-HRP.     

Synthesis and secretion of the enamel matrix precursor by the kitten secretory ameloblast

Secretory ameloblasts in kitten molar tooth germs were examined with an electron microscope to analyze the synthesis and secretion processes of the enamel matrix precursor. The contents of the secretion granule were identified as fine granular material, which observed in both the rough endoplasmic reticulum and the Golgi cisterns, accumulated in the dilated margins of the innermost Golgi cistern and formed condensing vacuoles. The same kind of condensing vacuoles was also produced from the GERL cisterns. During the secretion granule maturation processes in the Golgi region, the contents accumulated densely and the granules grew smaller. In addition, granule-limiting membranes acquired fine, bristle coats. The mature secretion granules then migrated, along microtubules, into the surfaces of the Tomes processes and finally released their contents by a process of exocytosis at the type 1 face which faces the enamel growth region.     

ELABORATION OF THE MATRIX GLYCOPROTEIN OF ENAMEL BY THE SECRETORY AMELOBLASTS OF THE RAT INCISOR AS REVEALED BY RADIOAUTOGRAPHY AFTER GALACTOSE-3H INJECTION

The elaboration of enamel matrix glycoprotein was investigated in secretory ameloblasts of incisor teeth in 30–40-g rats. To this end, the distribution of glycoprotein was examined histochemically by the use of phosphotungstic acid at low pH, while the formation of glycoprotein was traced radioautographically in animals sacrificed 2.5–30 min after galactose-³H injection. Histochemically, the presence of glycoprotein is observed in ameloblasts as well as in the enamel matrix; in ameloblasts glycoprotein occurs within the Golgi apparatus in amounts increasing from the outer to the inner face of the stacks of saccules, and is concentrated in condensing vacuoles and secretory granules; in the enamel matrix, glycoprotein is observed within linear subunits. Radioautographs at 2.5 min after injection demonstrate the uptake of galactose-³H label by Golgi saccules, indicating that galactose-³H is incorporated into glycoprotein within this organelle. After 5–10 min, the label collects in the condensing vacuoles and secretory granules of the Golgi region. By 20–30 min, the label appears in the secretory granules of the apical (Tomes') processes, as well as in the enamel matrix (next to the distal end of the apical processes, and at the tips of matrix prongs). In conclusion, galactose contributes to the formation of glycoprotein within the Golgi apparatus. The innermost saccules then distribute the completed glycoprotein to condensing vacuoles, which later evolve into secretory granules. These granules rapidly migrate to the apical processes, where they discharge their glycoprotein content to the developing enamel.     

Acetyl coenzyme A: alpha-glucosaminide N-acetyltransferase. Evidence for a transmembrane acetylation mechanism

The lysosomal membrane enzyme acetyl-CoA: alpha-glucosaminide N-acetyltransferase catalyzes the transfer of an acetyl group from acetyl-CoA to terminal alpha-linked glucosamine residues of heparan sulfate. The reaction mechanism was examined using highly purified lysosomal membranes from rat liver. The reaction was followed by measuring the acetylation of a monosaccharide acetyl acceptor, glucosamine. The enzyme reaction was optimal above pH 5.5, and a 2-3-fold stimulation of activity was observed when the membranes were assayed in the presence of 0.1% taurodeoxycholate. Double reciprocal analysis and product inhibition studies indicated that the enzyme works by a Di-Iso Ping Pong Bi Bi mechanism. Further evidence to support this mechanism was provided by characterization of the enzyme half-reactions. Membranes incubated with acetyl-CoA and [3H]CoA were found to produce acetyl-[3H]CoA. This exchange was optimal at pH values above 7.0. Treating membranes with [3H] acetyl-CoA resulted in the formation of an acetyl-enzyme intermediate. The acetyl group could then be transferred to glucosamine, forming [3H]N-acetylglucosamine. The transfer of the acetyl group from the enzyme to glucosamine was optimal between pH 4 and 5. The results suggest that acetyl-CoA does not cross the lysosomal membrane. Instead, the enzyme is acetylated on the cytoplasmic side of the lysosome and the acetyl group is then transferred to the inside where it is used to acetylate heparan sulfate.     

Intracellular localization of basement membrane precursors in the endodermal cells of the rat parietal yolk sac. I. Ultrastructure and phosphatase activity of endodermal cells

The parietal layer of the rat yolk sac includes a 5 microliter thick sheet known as Reichert's membrane that exhibits properties of basement membranes. Its inner side is lined by a single layer of loosely distributed cells referred to as endodermal cells. Both Reichert's membrane and endodermal cells were examined at 13-14 days' gestation with emphasis on the ultrastructure of the Golgi apparatus, the identification of its component parts by specific phosphatase activities, and its possible role in the cells' secretory process. Reichert's membrane is composed of a series of stacked layers similar to basal laminae and composed of a network of fibrils with a diameter of 2-8 nm along which dots are located at irregular intervals. The endodermal cells contain the usual organelles, including interconnected rough endoplasmic reticulum (rER) cisternae and a prominent Golgi apparatus. With the help of phosphatase reactions, the stacks of Golgi saccules were divided into a) "phosphatase-free" saccules, the first ones on the cis or forming side, b) one or two "intermediate" saccules in the middle of the stacks, containing nicotinamide adenine dinucleotide phosphatase activity, c) one or two "last" saccules rich in thiamine pyrophosphatase activity on the trans or mature side, and d) continuing beyond the trans side, the GERL element displaying acid phosphatase activity. The latter is associated with profiles equally rich in acid phosphatase and tentatively considered to be prosecretory granules. Finally, the ectoplasm adjacent to Reichert's membrane displays large, acid phosphatase-containing structures tentatively considered to be secretory granules. Thus, the extensive rER network, the well-compartmentalized Golgi apparatus, and the presence of structures which may be prosecretory and secretory granules indicate that the endodermal cells are well-equipped for the secretion of the components of Reichert's membrane.     

A cytochemical study of the Golgi apparatus of the spermatid during spermiogenesis in the rat

The reactivity of the various components of the Golgi apparatus of rat spermatids for three phosphatase activities (nicotinamide adenine dinucleotide phosphatase, NADPase; thiamine pyrophosphatase, TPPase; cytidine monophosphatase, CMPase) and the incorporation of 3H-fucose by the spermatids was analyzed at the 19 steps of spermiogenesis, i.e., during and after this organelle elaborated the glycoprotein-rich acrosomic system. During steps 1-3, the Golgi apparatus produced, in addition to the proacrosomic granules, multivesicular bodies that became associated with the chromatoid body. NADPase was located within the four of five intermediate saccules of Golgi stacks, and TPPase was found in the last one or two saccules on the trans aspect of the stacks from steps 1 to 17 of spermiogenesis. CMPase was located within the thick saccular GERL elements found in the trans region of the Golgi apparatus from steps 1 to 7 of spermiogenesis, but the CMPase-positive GERL disappeared from the Golgi apparatus after its detachment from the acrosomic system at step 8. Th acrosomic system itself was reactive from CMPase and TPPase but was negative for NADPase, while the multivesicular bodies were CMPase and NADPase positive but unreactive for TPPase. Tritiated-fucose was readily incorporated within the Golgi apparatus of steps 1-17 spermatids; in steps 1-7 it was subsequently incorporated within the acrosomic system and multivesicular bodies. These various data indicated (1) that the Golgi apparatus of spermatids, although it loses its CMPase-positive GERL element in step 8, retains evidence of functional capacity until it degenerates in step 17; (2) that in early spermatids the various saccular components of the Golgi are specialized with respect to enzymatic activities; and (3) that each Golgi region may contribute in a coordinated fashion to the formation of the acrosomic system and multivesicular bodies.     

内质网及其标志酶在离体培养脊髓神经元中的发育变化

In an attempt to elucidate the relationship between synapse formation and cell development, the morphology and cytochemistry of the endoplasmic reticulum and its enzymic marker, glucose-6-phosphatase (G-6-Pase), in cultured mouse spinal neurons were investigated ultrastructurally. It was found that in the early period of the development, neurons were characterized by scarceness of organelles; only a few of granular or agranular endoplasmic reticulum and mitochondria were seen. The endoplasmic reticulum and nuclear envelope were packed specifically with G-6-Pase resection product but the product was weak. After a period of culture, most of the neurons had well-developed endoplasmic reticulum, Golgi apparatus, mitochondria and microtubules, etc. The Golgi apparatus was relatively large, having some cisternae associated with vesicles. Either concave of convex face of the saccules was labeled by thiamine pyrophosphatase (TPPase) specifically. GERL, labeled by cytidine monophosphatase (CMPase), was also seen close to the inner or outer face of some Golgi apparatus. The endoplasmic reticulum at this stage was distributed throughout the cytoplasm, including that in dendrites; its enzyme marker (G-6-Pase) localized consistently within the lumen of all endoplasmic reticulum, nuclear space and subsurface cisternae, and frequently in the concave saccules of the Golgi apparatus. After a long-term culture, some neurons became "aged". The endoplasmic reticulum cisternae enlarged and G-6-Pase reaction reduced. Along with the neuronal development, especially maturation of the endoplasmic reticulum and its enzymic marker, synapse formation was begun at the neuropile area. The axo-dendritic synapses always occurred between the axonal terminals and dendrites where the endoplasmic reticulum had showed positive G-6-Pase reactions. Considering the fact, it suggests that the appearance and change of these specific enzymes may be related to the maturation of the neurons in vitro, and also related to the synapse formation between neurons.