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.     

Cytochemical localization of nicotinamide adenine dinucleotide phosphatase (NADPase) in bovine Leydig cells

The ultrastructural localization of nicotinamide adenine dinucleotide phosphatase (NADPase) in bovine Leydig cells has been studied and compared with the pattern of thiamine pyrophosphatase (TPPase) and acid phosphatase distribution in these cells. Using beta-nicotinamide adenine dinucleotide phosphate (beta-NADP+) as substrate, a marked staining is observed in the intermediate Golgi saccules with some focal extension to the trans aspect. Cisternae on the cis side and associated vesicles yielded only slightly positive reactions. The pattern of NADPase localization is clearly different from that of TPPase which consistently stains only the trans Golgi elements. The specificity of NADPase for its substrate, beta-NADP+, was clearly demonstrated by using substrates modified in either the nicotinamide region e.g. alpha-nicotinamide adenine dinucleotide phosphate (alpha-NADP+), beta-thionicotinamide adenine dinucleotide phosphate (Thio-NADP+), in the attachment site of the monoester phosphate group to the molecule (e.g. 2' monophospho-adenosine 5'-diphosphoribose (ATP-ribose) or adenosine-5-monophosphate (5'AMP). With these substrates only weak or negative reactions were obtained in the Golgi apparatus of the bovine Leydig cell.     

Ultrastructural localization of CMPase, TPPase, and NADPase activity in neurons, satellite cells, and Schwann cells in frog dorsal root ganglia

Sections of bullfrog dorsal root ganglia were analyzed for cytidine monophosphatase (CMPase), thiamine pyrophosphatase (TPPase), and nicotinamide adenine dinucleotide phosphatase (NADPase) activity, and the distributions of these enzymatic activities were compared with those traditionally found in other cell types (e.g., CMPase: Golgi trans-sacculotubular network; TPPase: trans-Golgi saccule(s); NADPase: intermediate Golgi saccules). In the present study, CMPase activity in neurons was localized mainly to the Golgi trans-sacculotubular network and lysosomes, but sometimes also occurred at the ends of the trans and most distal intermediate Golgi saccules. A similar distribution was found in satellite and Schwann cells. TPPase activity in neurons occurred not only in the trans-Golgi saccule but also in the trans-sacculotubular network, lysosomes, and scattered tubular elements. In satellite and Schwann cells, activity was found in both the trans saccule and trans-sacculotubular network, and substantial activity often appeared in the more distal of the intermediate saccules. NADPase activity in neurons was usually absent from the intermediate Golgi saccules and was confined to the trans-sacculotubular network and lysosomes; however, activity was sometimes also found in the intermediate and/or trans-Golgi saccules. In satellite and Schwann cells, activity appeared consistently in both the trans-sacculotubular network and intermediate saccules, as well as in lysosomes. These distributions, especially in the case of TPPase and NADPase, differ substantially from the most frequently reported localizations of the above enzymes, indicating that the Golgi complex may exhibit considerable plasticity of structure and function in different cell types.     

Cytochemical localization of thiamine pyrophosphatase and nicotinamide adenine dinucleotide phosphatase activities in rat epiphyseal chondrocytes

Two phosphatase activities, which have been reported to be associated with the Golgi apparatus in several cellular types, have been cytochemically demonstrated in rat epiphyseal cartilage. This was the case for thiamine pyrophosphatase (TPPase) which was detected in Golgi trans face cisternae and also in nascent or immature secretory granules of chondrocytes. beta-Nicotinamide adenine dinucleotide phosphatase (beta-NADPase), on the other hand, was localized mainly in the endoplasmic reticulum region of both proliferative and hypertrophic chondrocytes. Most of the beta-NADPase reaction was shown to be associated with the cytoplasmic side of the rough endoplasmic reticulum membranes and also partially dispersed throughout the cytosol background. We suggest that beta NADPase in chondrocytes could be an enzyme with different properties from that described in other secretory cells.     

Superficial cell differentiation during embryonic and postnatal development of mouse urothelium

After drastic urothelial destruction around birth and around postnatal day 6, mouse urothelial renewal starts each time de novo. The differentiation of superficial cells during urothelial restoration was followed for the first time from embryonic day 15 to postnatal day 6 by the detection of differentiation markers: cytokeratins, uroplakins and apical membrane specialization. The differentiation markers of short-lived superficial cells were studied before and after urothelial destruction. Three distinctive types of superficial cells, typical for certain developmental period, were characterised: cells at low differentiation stage with microvilli and cilia, expressing CK7 and CK18, detected on embryonic day 15; cells at advanced differentiation stage with star-like arrangement of prominent membrane ridges, expressing CK7 and CK20, present between the two urothelial destruction events; highly differentiated cells with typically jagged apical surface, expressing CK7 and CK20, found twice during development. This cell type appears for the first time on embryonic day 18 as the terminal stage of embryonic differentiation. It was found again on postnatal day 6 as an initial stage of differentiation, leading toward terminally differentiated cells of the adult urothelium. Our work proves that apical membrane specialization is the most valuable differentiation marker of superficial cells.     

Schistosoma mansoni: cytochemistry and morphology of the gastrodermal Golgi Apparatus

The gastrodermal Golgi apparatus of adult Schistosoma mansoni displays two distinct morphologies. In one type, there is an identifiable cis (forming) face where vesicles from the endoplasmic reticulum fuse to form the cisternae. A morphological change occurs in the cisternae as the trans (emitting) face is approached with the cisternae becoming progressively flattened. The cisternae at the emitting face produce a membrane-bound secretory granule with moderately electron-dense contents and a vacuolar structure that may be analogous to a condensing vacuole as reported in several vertebrate secretory cells. In a second type, vesicles possessing a thicker membrane than those of the transfer vesicles are observed at the emitting face. They are not observed when the secretory granules are present. Several cytochemical markers were used to aid in studying the polarity of the Golgi apparatus. Enzymes studied were thiamine pyrophosphatase (TPPase) (EC 3.6.1.1), nucleoside diphosphatase (NDPase) (EC 3.6.1.6) using uridine diphosphate as a substrate, and nicotinamide adenine dinucleotide phosphatase (NADPase) (EC 3.1.3.2). Reaction products from all enzyme markers were observed in the cisternae and, to some extent, in the transfer vesicles. At times, NADPase and TPPase reaction products were observed in all cisternae and in the transfer vesicles of the Golgi. When this distribution was evident, the latter vesicles were observed in clusters occasionally fusing with lipid-like globules dispersed throughout the gastrodermis. Heterogeneity in cisternae was observed when NDPase, TPPase, and osmium reduction techniques were used. NDPase activity was limited to the middle cisternae while reduced osmium was observed in the outer two cisternae and in some transfer vesicles. TPPase reaction product was also observed in the secretory granules and in the condensing vacuoles. It is hypothesized that a functional bipolarity may be demonstrated by the Golgi. Under certain stress conditions, the forming face of the Golgi may package lysosomal enzymes while the emitting region of the Golgi appears to be responsible for the packaging of the secretory granules. The fusion of transfer vesicles and, at times, secretory granules with lipid-like globules is postulated to represent a mechanism by which enzymes may be transported to the lumen of the cecum.     

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.     

Ultrastructural distribution of NADPase within the Golgi apparatus and lysosomes of mammalian cells

Cytochemical studies with over 40 different mammalian cell types have indicated that NADPase activity is associated with the Golgi apparatus and/or lysosomes of all cells. In the majority of cases, NADPase is restricted to saccular elements comprising the medial region of the Golgi stack and an occasional lysosome. There is often weak NADPase activity in other Golgi compartments such as the trans Golgi saccules and/or elements of the trans Golgi network. In some cells, however, strong NADPase activity is found within these latter compartments, either exclusively in trans Golgi saccules or elements of the trans Golgi network, or in combination with medial Golgi saccules and each other including (1) medial Golgi saccules + trans Golgi saccules, (2) medial Golgi saccules + trans Golgi saccules + trans Golgi network, or (3) trans Golgi saccules + trans Golgi network. In some rare cases, no NADPase activity is detectable in either Golgi saccules or elements of the trans Golgi network, but it is observed in an occasional lysosome or throughout the lysosomal system of these cells. It is unclear at present if these variations in the distribution of NADPase across the Golgi apparatus, and between the Golgi apparatus and lysosomal system, are due to differences in targeting mechanisms or to the existence of "bottlenecks" in the natural flow of NADPase along the biosynthetic pathway toward lysosomes. While no clear pattern in the association of strong NADPase activity with lysosomes was apparent relative to the ultrastructural distribution of NADPase activity in Golgi saccules or elements of the trans Golgi network, the results of this investigation suggested that cells having NADPase localized predominantly toward the trans aspect of the Golgi apparatus (in trans Golgi saccules or elements of the trans Golgi network or both) have few NADPase-positive lysosomes. The only exception is hepatocytes which were classified as predominantly trans but had noticeable NADPase activity within medial Golgi saccules and elements of the trans Golgi network as well, and highly reactive lysosomes. Other cells showing highly reactive lysosomes including (1) Kupffer cells of liver and those forming the proximal convoluted tubules of the kidney, both of which also had strong NADPase activity within medial and trans Golgi saccules and elements of the trans Golgi network, (2) Leydig cells of the testis and interstitial cells of the ovary, which also showed strong NADPase activity within medial Golgi saccules, and (3) macrophages from lung, spleen and testis, and Sertoli cells from the testis all of which showed no Golgi associated NADPase activity.(ABSTRACT TRUNCATED AT 400 WORDS)     

The localization of thiamine pyrophosphatase activity in Meckel's cartilage cells during endochondral ossification

The cytochemical distribution of thiamine pyrophosphatase (TPPase) activity in Meckel's cartilage cells of the mouse embryo has been studied during the endochondral ossification. All the cartilage cells contain reaction product within the Golgi apparatus. In immature chondrocytes, at the reserve cell zone, TPPase activity is restricted to several inner cisternae of independent Golgi apparatus. In mature cells at the proliferative cell zone, several Golgi complexes form a Golgi network connecting with each other by the TPPase positive tubular stalks. Golgi cisternae, condensing vacuoles and vesicles also contain reaction product. In the hypertrophic chondrocytes located in the calcifying zone, their disorganized Golgi apparatus still retain reaction product. Some chondrocytes, even those located within calcified or opened lacunae, exhibit intact structures and normal cytochemical enzyme distribution. These data indicate the possibility that some chondrocytes may survive and contribute the formation of mandible.     

Effects of brefeldin A on the Golgi apparatus, the nuclear envelope, and the endoplasmic reticulum in a green alga,Scenedesmus acutus

Summary The effects of brefeldin A (BFA) on the structure of the Golgi apparatus, the nuclear envelope, and the endoplasmic reticulum (ER), and on the thiamine pyrophosphatase (TPPase) activity in these organelles were examined in a green alga,Scenedesmus acutus, to obtain evidence for the existence of a retrograde transport from the Golgi apparatus to the ER via the nuclear envelope. InScenedesmus, Golgi bodies are situated close to the nuclear envelope throughout the cell cycle and receive the transition vesicles not directly from the ER, but from the nuclear envelope. BFA induced the disassembly of Golgi bodies and an increase in the ER cisternae at the trans-side of decomposed Golgi bodies in interphase cells and multinuclear cells before septum formation. The accumulated ER cisternae connected to the nuclear envelope at one part. TPPase activity was detected in all cisternae of Golgi bodies, but not in the nuclear envelope or the ER in nontreated cells. On the contrary, in BFA-treated cells, TPPase activity was detected in the nuclear envelope and the ER in addition to the decomposed Golgi bodies. When septum-forming cells were treated with BFA, the disassembly of Golgi bodies was less than that in interphase cells, and TPPase activity was detected in the Golgi cisternae but not in the nuclear envelope or the ER. These results suggest mat BFA blocks the anterograde transport from the nuclear envelope to the Golgi bodies but does not block the retrograde transport from the Golgi bodies to the nuclear envelope in interphase and multinuclear cells.Abbreviations BFA brefeldin A - ER endoplasmic reticulum - TPPase thiamine pyrophosphatase     

Ultrastructural localization of acid phosphatase and thiamine pyrophosphatase activities and of phosphotungstic staining at low pH in the placental labyrinth of the cat]

The localizations of acid phosphatase (ACPase) and thiamine pyrophosphatase (TPPase) activities were studied in the placental labyrinth of the cat during the last days of gestation. ACPase activities were observed essentially in the syncytiotrophoblast and in the "interstitial inert substance" (S.I.I.) that separates maternal from foetal tissues. Reaction product was localized in lysosomes, multivesicular bodies, and in the network of smooth-membraned tubules which open on the cell surface of the syncytiotrophoblast facing the S.I.I. The S.I.I. exhibit a strong activity, probably of syncytiotrophoblastic origin. TPPase activities were found in the syncytiotrophoblast, rarely in the Golgi apparatus but always in the lumen of the network of smooth-membrande tubules. The S.I.I. shows a moderate activity. These TPPase positive tubules being frequently observed very close to the Golgi cisternae, it is proposed that they arise from the Golgi complex and convey phosphatases to the S.I.I. After phosphotungstic acid staining at low pH, luminal surface coat of maternal endothelium is always strongly and continuously visualized, while the plasma membrane of the syncytiotrophoblast facing the S.I.I. is never stained. Staining is intense in the lumen of tubules, and continuous with the stain of the S.I.I. ACPase activity of the S.I.I. could be implicated in enzymatic degradation of maternal molecules during their transfer from maternal to foetal blood. The S.I.I. may correspond to the immunological buffer zone at the interface between maternal and foetal tissues.     

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.     

The occurrence of the Golgi apparatus in mouse oocytes. Demonstration of thiamine pyrophosphatase activity

Location of thiamine pyrophosphatase activity as a marker of the Golgi apparatus was studied ultracytochemically in mouse oocytes with germinal vesicle (OGV), oocytes at metaphase I (OMI) and oocytes at metaphase II (OMII), and further in cells of the respective cumulus oophorus serving as comparative objects. TPPase activity in cumulus oophorus cells and in OGV was found exclusively in the Golgi apparatus. In OMI the reaction product of TPPase activity was observed in isolated smooth vesicles, and in only one case in structures identifiable as the Golgi apparatus. In OMII the occurrence of TPPase activity was also recorded in isolated smooth vesicles in cortical cytoplasm and further, exceptionally, in smooth concentrically arranged vesicles or tubules. The TPPase activity was not present in vesicular complexes. The results have shown that after the resumption of meiosis the occurrence of the reaction product of TPPase activity drops abruptly due to the reduction of the Golgi apparatus. Changes affecting the Golgi apparatus after the resumption of meiosis are related to the loss of the nucleus after the germinal vesicle breakdown.     

Epithelial-mesenchymal interactions in prostatic development. I. morphological observations of prostatic induction by urogenital sinus mesenchyme in epithelium of the adult rodent urinary bladder

Tissue recombinants of embryonic urogenital sinus mesenchyme (UGM) and epithelium of the urinary bladder (urothelium, BLE) of adult rats and mice were grown for 3-30 d in male syngeneic hosts. Short-term in vivo growth indicated that prostatic morphogenesis is initiated as focal outgrowths from the basal aspect of the adult urothelium. The solid epithelial buds elongate, branch, and subsequently canalize, forming prostatic acini. After 30 d of growth in the male hosts, prostatic acini exhibit secretory activity. The marked changes in urothelial morphology induced by the UGM are accompanied by the expression of fine- structural features indicative of secretory function (rough endoplasmic reticulum, Golgi apparatus, and secretory granules). During this process, urothelial cells express prostatic histochemical markers (alkaline phosphatase, nonspecific esterase, glycosaminoglycans) and prostate-specific antigens. The expression within BLE of prostatic characteristics is associated with the loss of urothelial characteristics. These data indicate that adult urothelial cells retain a responsiveness to embryonic mesenchymal inductors. Furthermore, mesenchyme-induced changes in urothelial cytodifferentiation appear to be coupled to changes in functional activity.     

Tridimensional structure of the Golgi apparatus in type A ganglion cells of the rat

The three-dimensional structure of the whole Golgi apparatus and of its components in type A ganglion cells was examined in thin and thick sections by low- and high-voltage electron microscopy. At low magnification, in 10-micron-thick sections of osmicated cells, the Golgi apparatus formed a broad, continuous perinuclear network. At higher magnification and in thinner sections of cells impregnated with uranyl acetate-lead-copper citrate or postfixed in K-ferrocyanide-reduced osmium, the Golgi apparatus appeared as a heterogeneous structure in which saccular regions characterized by stacks of saccules alternated with intersaccular regions made up of branching membranous tubules which bridged the saccules of adjacent stacks. The saccular regions consisted of the following superimposed elements: a cis-osmiophilic element made up of anastomosing tubules; two or three saccules negative for the phosphatases tested (i.e., nicotinamide adenine dinucleotide phosphatase = NADPase, thiamine pyrophosphatase = TPPase, and cytidine monophosphatase = CMPase); two saccules showing TPPase activity; and one to three trans-sacculotubular elements showing a "peeling-off" configuration, one of which showed CMPase activity. The saccules (phosphatase-negative) on the cis-side of the Golgi stacks showed, in addition to small circular pores, larger perforations in register. The cavities thus formed in the stacks of saccules, called "wells," always associated with small 80-nm vesicles, had a pan shape with the mouth directed toward the cis-face and the bottom closed by a TPPase-positive saccule. In face views of the saccules, the smallest of these perforations showed either a crescent shape, due to the presence of a bud on one side of the perforation, or a circular shape with a single small 80-nm vesicle in the center which was occasionally attached to the saccule by a filiform stalk. Such smaller cavities were considered as the precursors of the larger perforations and eventually of the wells. The small 80-nm vesicles seen in the small cavities or in the wells appeared to form in situ and possibly migrate toward the cisternae of endoplasmic reticulum seen proximal to the cis-face of the stack of saccules. Small 80-nm vesicles were also numerous in the intersaccular regions, along the lateral- and trans-aspects of the Golgi stacks, while larger, 150-to 300-nm vesicles, coated and uncoated, were seen only on the trans-face of the Golgi stacks in proximity to the trans-sacculotubular elements which appear to "peel off" from the Golgi stacks.     

The localization of thiamine pyrophosphatase activity in Meckel's cartilage cells during endochondral ossification

Summary The cytochemical distribution of thiamine pyrophosphatase (TPPase) activity in Meckel's cartilage cells of the mouse embryo has been studied during the endochondral ossification. All the cartilage cells contain reaction product within the Golgi apparatus. In immature chondrocytes, at the reserve cell zone, TPPase activity is restricted to several inner cisternae of independent Golgi apparatus. In mature cells at the proliferative cell zone, several Golgi complexes form a Golgi network connecting with each other by the TPPase positive tubular stalks. Golgi cisternae, condensing vacuoles and vesicles also contain reaction product. In the hypertrophic chondrocytes located in the calcifying zone, their disorganized Golgi apparatus still retain reaction product. Some chondrocytes, even those located within calcified or opened lacunae, exhibit intact structures and normal cytochemical enzyme distribution. These data indicate the possibility that some chondrocytes may survive and contribute the formation of mandible.     

Thiamine pyrophosphatase cytochemistry in rat endometrium during the oestrous cycle

The functional morphology of the Golgi apparatus was studied in various types of cells in the rat endometrium during the oestrous cycle. A cerium-based enzyme-cytochemical method was used for the ultrastructural visualization of the activity of thiamine pyrophosphatase (TPPase). The cerium-based method was evidently superior to the classical lead technique, which was used for comparison. TPPase activity in luminal and glandular epithelial cells displayed cyclical modulation and redistribution. It was restricted to only one or two narrow trans lamellae during dioestrus but extended during proestrus and oestrus into nearly all trans-to-cis lamellae of the well-compartmentated Golgi apparatus. A homogeneous staining reaction, which was particularly intense during the latter two phases and only partly due to unspecific alkaline phosphatase, was confined to the apical and basolateral plasma membranes of luminal epithelial cells. In the stromal fibroblasts, only one short Golgi saccule was positive at dioestrus, whereas three or more trans Golgi lamellae were filled with reaction product during oestradiol-dominated oestrus. TPPase activity was furthermore observed in the lysosomes in epithelial cells, stromal fibroblasts, capillary endothelial cells and pericytes. The present findings of cyclic changes in TPPase activity in epithelial cells and stromal fibroblasts provide the first evidence of cyclic modulation and redistribution of this enzyme in the endometrium.     

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.     

Formation of secretion granules in the Golgi apparatus of pancreatic acinar cells of the rat

The three-dimensional structure of the Golgi apparatus and its components has been analyzed in sections of pancreatic acinar cells by using stereopairs of electron microscope photographs. Pancreatic tissue fixed in glutaraldehyde was postfixed in reduced osmium, and the sections were stained with lead citrate. Tissues were also treated to demonstrate phosphatase activity (i.e., nicotinamide adenine dinucleotide phosphatase, NADPase; thiamine pyrophosphatase, TPPase; cytidine monophosphatase, CMPase). The following stacked components were observed along the branching, anastomotic, continuous, ribbonlike Golgi apparatus. 1) On the cis-face of the Golgi stack there was a tubular membranous network known to be osmiophilic and referred to as the cis-osmiophilic tubular network or cis-element. 2) A first, poorly fenestrated saccule, unreactive for the phosphatases tested, was slightly distended in places and contained a fluffy granulofilamentous material. 3) The subjacent three or four saccules, reactive for NADPase and/or TPPase, showed dilated portions containing a granulofilamentous secretory material similar to that filling the rest of the saccule. They also showed nondilated portions perforated with large fenestrations, some of which were in register and formed wells containing 80-nm vesicles. The dilated portions of these saccules were present at random along the length of the saccules and were not located exclusively at their edges. 4) The remaining one or two elements of the stack, CMPase positive, showed dilated spheroidal portions or prosecretory granules containing a homogeneous secretory material and flattened fenestrated regions free of secretory material and having the appearance of networks of narrow membranous tubules. 5) Lastly on the trans-aspect of the stack there were detached prosecretory granules reactive for CMPase and surrounded by a corona of small vesicles, and smooth-surfaced spherical CMPase-negative granules having a denser content that were identified as fully formed secretion granules; there were also occasional free trans-tubular networks strongly reactive for CMPase that appeared to undergo fragmentation and numerous small vesicles free from acid-phosphatase activity. These various images were interpreted as indicating that prosecretory granules formed in relation to two or three fenestrated saccules on the trans-side of the stack. Such granules, following their detachment from the trans-face of the stack, their separation from trans-tubular networks, and condensation of their content, yielded mature secretion granules.     

THE DISTINCT STEPS OF CELL DETACHMENT DURING DEVELOPMENT OF MOUSE UROEPITHELIAL CELLS IN THE BLADDER

In developing mouse urinary bladder the urothelial cells respond to urine accumulation by cell detachment, i.e. desquamation. To elucidate the steps of urothelial cell detachment during embryonic development and first urine accumulation in bladder lumen, superficial and intermediate cell layers were investigated. Different electron microscopic and cytochemical methods have been used. It was possible to distinguish between an early and late events on the basis of morphology. At the beginning cell detachment involves interruption of tight junctions between neighbouring superficial cells and the formation of numerous endocytotic vesicles. Endocytotic and cup-shaped vesicles then fuse and form large parallel rows of vacuoles and multivesicular bodies in desquamating superficial cells and in the neighbouring superficial and intermediate cells. These observations clearly demonstrate the existence of specific steps during the detachment of embryonic uroepithelial cells. Apoptosis accompanies cell desquamation. Only predetermined superficial bridge cells die in an apoptotic manner.