The effect of centrifugal accelerations on the polarity of statocytes and on the graviperception of cress roots

The structural polarity of statocytes of Lepidium sativum L. is converted to a physical stratification by a root-tip-directed centrifugal acceleration. Sedimentation of amyloplasts and nucleus to the centrifugal (distal) cell pole and the lateral displacement of the distal endoplasmic reticulum (ER) complex occur after centrifugation for 20 min at an acceleration of 50 g. With higher doses (20 min, 100-2,000 g), smaller organelles become increasingly displaced. From the centrifugal to the centripetal cell pole, the following stratification is observed: 1) amyloplasts with mitochondria; 2) nucleus with mitochondria and a few dictyosomes, as well as laterally located ER; 3) dictyosomes with a few mitochondria; 4) vacuoles; and 5) lipid droplets. Within the first 7.5 min, after the roots have been returned to 1 g, the original arrangement of the amyloplasts sedimented on the underlying ER complex is reestablished in 66% of the statocytes. When roots previously centrifuged in an apical direction are exposed in a horizontal position to 1 g, the latent period of the graviresponse is increased by 7.5 min relative to the non-centrifuged controls. The kinetics of the response are identical to the controls. Roots centrifuged first in an apical direction and then for 2 h in a lateral direction (1,000 g) have statocytes with a physical stratification perpendicular to the root axis. A gravitropic curvature does not take place during the lateral centrifugation. These results support the hypothesis that the distal ER complex is necessary and sufficient for graviperception.     

AN EXAMINATION OF THE EFFECTS OF ULTRACENTRIFUGATION ON THE ORGANELLES IN LIVING ROOT TIP CELLS

Bouck, G. Benjamin. (Yale U., New Haven, Conn) An examination of the effects of ultracentrifugation on the organelles in living root tip cells. Amer. Jour. Bot. 50(10): 1046–1054. Illus. 1963.—Excised pea roots were centrifuged at 20,000 g for various periods to determine the speed and order of stratification of living plant organelles; 20,000 g for 24 hr at 6 C seems to produce the most consistent layering with least damage to the organelles or to the root as a whole. The recovery of the cells was then followed to determine how fast and in what order the organelles achieve a random redistribution. Rough endoplasmic reticulum seems slow to stratify in its ultimate position at the centrifugal pole but is among the first of the organelles to reorient after centrifugation. Proplastids, large vacuoles, and the nucleolus are slow to recover from centrifuging, but after 8 hr of recovery only the nucleolus and very large vacuoles show indications of a previous layering. Within 12 hr after removal of the root from the centrifuge, growth (in length) of the whole root could be measured.     

LYSOSOMES AND GERL IN NORMAL AND CHROMATOLYTIC NEURONS OF THE RAT GANGLION NODOSUM

The rat ganglion nodosum was used to study chromatolysis following axon section. After fixation by aldehyde perfusion, frozen sections were incubated for enzyme activities used as markers for cytoplasmic organelles as follows: acid phosphatase for lysosomes and GERL (a Golgi-related region of smooth endoplasmic reticulum from which lysosomes appear to develop) (31–33); inosine diphosphatase for endoplasmic reticulum and Golgi apparatus; thiamine pyrophosphatase for Golgi apparatus; acetycholinesterase for Nissl substance (endoplasmic reticulum); NADH-tetra-Nitro BT reductase for mitochondria. All but the mitochondrial enzyme were studied by electron microscopy as well as light microscopy. In chromatolytic perikarya there occur disruption of the rough endoplasmic reticulum in the center of the cell and segregation of the remainder to the cell periphery. Golgi apparatus, GERL, mitochondria and lysosomes accumulate in the central region of the cell. GERL is prominent in both normal and operated perikarya. Electron microscopic images suggest that its smooth endoplasmic reticulum produces a variety of lysosomes in several ways: (a) coated vesicles that separate from the reticulum; (b) dense bodies that arise from focal areas dilated with granular or membranous material; (c) "multivesicular bodies" in which vesicles and other material are sequestered; (d) autophagic vacuoles containing endoplasmic reticulum and ribosomes, presumably derived from the Nissl material, and mitochondria. The number of autophagic vacuoles increases following operation.     

A fine-structural analysis of mouse molar odontoblast maturation.

The first mandibular molars of the Swiss albino mice, 1 through 4 days of age, were fixed in glutaraldehyde or Karnovsky's fixative. The tissues were postfixed in OSO4, dehydrated and embedded in Epon. The prepolarizing, polarizing and secretory odontoblasts were described. The prepolarizing cells, located in the vicinity of the cervical loop, were mesenchymal-like in morphology. The cells of the polarizing stage possessed organelles indicative of protein synthesis. The nucleus was located proximally. Aperiodic fibers were evident in the wide basement membrane. The secretory odontoblasts were long, slender, polarized cells closely adjoining one another. Each odontoblast possessed six morphologically discernible regions: (1) an infranuclear region, limited in size and containing few cellular organelles; (2) a nuclear region, housing the oval nucleus and a few associated lamellae of rough endoplasmic reticulum as well as a limited number of mitochondria; (3) a supranuclear rough endoplasmic reticulum region, possessing an abundance of these organelles as well as some mitochondria and secretory vesicles; (4) a Golgi region, occupying the middle third of the cell, housing the elements of an extensive Golgi apparatus which was surrounded by peripherally located profiles of rough endoplasmic reticulum; additionally, this region contained smooth endoplasmic reticulum, mitochondria, numerous secretory granules and vesicles and occasional intracellular collagen fibers; (5) an apical rough endoplasmic reticulum region, containing a rough endoplasmic reticulum component that was less extensive than its supranuclear counterpart; in addition, this region was the one richest in mitochondria and contained a plethora of secretory vesicles and granules; (6) the odontoblastic process, a region mostly void of organelles, containing various secretory products, some of which appeared to be in the process of being released extracellularly into the surrounding dentin matrix.     

Ultrastructure and development of nonarticulated laticifers in seedlings ofEuphorbia maculata L.

The ultrastructure of nonarticulated laticifers in the seedlings ofEuphorbia maculata was studied at various developmental stages. The apical regions of the seedling laticifers growing intrusively contained large nuclei with mainly euchromatin and dense cytoplasm possessing various and many organelles such as rich ribosomes, several small vacuoles, giant mitochondria with dense matrices, rough endoplasmic reticulum, dictyosomes, and proplastids. This result suggested that the apical regions of laticifers were metabolically very active. Laticifers in seedlings at the first-leaf developmental stage did not contain latex particle. In seedlings at second-leaf growth stage, the laticifer cells contained numerous and elongated small vacuoles. These vacuoles appeared to arise by dilation of the endoplasmic reticulum and frequently possessed osmiophilic or electron-dense latex particles. The small vacuoles fused with the large vacuole occupying the central portion of the subapical region of laticifers, and then the latex particles were released into the large central vacuole. The latex particles varied in size and were lightly or darkly stained. Proplastids with a dense matrix and a few osmiophilic plastoglobuli were filled with an elongated starch grain and thus were transformed into amyloplasts. Latex particles were initially produced in the laticifers after seedlings had developed their second young leaves. In seedlings at forth-leaf stage, latex particles with an alveolated rim were found in the laticifers.     

A comparative study of the ultrastructure of resting and active cambium of Salix fragilis,L.

Summary Cells of the resting cambium contain vesiculate smooth endoplasmic reticulum, free ribosomes, oil droplets, and protein bodies. There are comparatively few vacuoles, and these are small. The nucleus is fairly central within the cell and is surrounded by a cluster of plastids and mitochondria. Active cambial cells and young differentiating xylem elements are highly vacuolate, contain rough endoplasmic reticulum and polyribosomes, the Golgi apparatus is active in the production of vesicles, and the distribution of organelles is a function of the vacuolation of the cell.It is suggested that the lipid droplets and protein bodies are storage materials which are required during the first stages of differentiation at the beginning of the growing period.     

The repetitive calcium waves in the fertilized ascidian egg are initiated near the vegetal pole by a cortical pacemaker.

Ascidian eggs respond to fertilization with a series of repetitive calcium waves that originate mostly from the vegetal/contraction pole region (J. E. Speksnijder, C. Sardet, and L. F. Jaffe, 1990, Dev. Biol. 142, 246-249), where the myoplasm is concentrated during the first phase of ooplasmic segregation. This suggests that the myoplasm may be involved in initiating these calcium waves. To test this possibility, the starting position of the calcium waves was determined in eggs that had the subcortical, mitochondria-rich part of the myoplasm displaced by centrifugation. Such centrifuged eggs display four cytoplasmic layers: a large centrifugal yolk zone, a narrow clear zone, a mitochondria-rich layer, and a small clear zone at the centripetal pole. Imaging of the cytosolic calcium in centrifuged eggs that were injected with the calcium-specific photoprotein aequorin reveals a series of repetitive calcium waves after fertilization. About 70% of these waves start in the vegetal/contraction pole area, which is similar to the number of waves previously found to start in this area in uncentrifuged eggs. In contrast, only about 25% of the waves start close to the displaced mitochondria-rich layer. From this result it is concluded that the main wave initiation site is not displaced by the centrifugal forces that displace the subcortical, mitochondria-rich part of the myoplasm. Moreover, the observation that the animal-vegetal polarity of cortical components such as actin filaments and the endoplasmic reticulum has been retained after centrifugation further suggests that a cortical component located in the vegetal hemisphere--most likely the endoplasmic reticulum network in the cortical region of the myoplasm--is involved in initiating the repetitive calcium waves in the fertilized ascidian egg.     

The ultrastructure of mammary explants from virgin ovariectomized goats during hormone-induced lactogenesis

The effect of insulin (I), cortisol (F) and prolactin (P) on the ultrastructural morphology of epithelial cells of cultured mammary explants from virgin ovariectomized (OV-X) goats were studied. The epithelial cells showed little structural organization and were devoid of fat droplets and secretory protein granules at zero time of culture. The cytoplasm contained few profiles of smooth and rough endoplasmic reticulum and the Golgi apparatus was rudimentary. After being cultured in Waymouth's medium without added hormones the epithelial cells were indistinguishable from epithelial cells of uncultured explants. The addition of I induced changes mainly in the appearance of nucleoli. The nucleoli were enlarged and fibrillogranular areas with light spaces were observed. The most obvious cytological changes of epithelial cells of explants cultured in the presence of I and F are translocation of the nucleus into the basal cytoplasm, increase of rough endoplasmic reticulum, an increase in the size of the Golgi apparatus, presence of one or two lipid droplets and in some cells vacuoles with protein granules were present. Mitochondria were more abundant. The epithelial cells of explants cultured in the presence of I, F and P were characterized by the polarization of organelles within the cytoplasm and by the formation and release of protein granules and small and large fat droplets. The cell nucleus was in the basal cytoplasm, the Golgi apparatus was supranuclear. The rough endoplasmic reticulum was extensively developed and formed large sacs. Golgi vacuoles contained protein granules.(ABSTRACT TRUNCATED AT 250 WORDS)     

Subcellular fractionation of actively growing protoplasts of Saccharomyces cerevisiae

Cell homogenates obtained from partially regenerated Saccharomyces cerevisiae protoplasts were fractionated by a procedure using a combination of continuous and discontinuous sucrose gradients, under experimental conditions that minimize possible artifacts due to centrifugation and resuspension. At least five different membranous organelle fractions (plasma membrane, mitochondria, rough endoplasmic reticulum, smooth endoplasmic reticulum-like structures and small-sized particulated structures) were isolated. Subcellular fractions were characterized by assaying established marker enzymes. Radioactive labelled ([U-³H]uracil) ribosomes were also used as a further characterization criterion of the rough endoplasmic reticulum. Comparative SDS-polyacrylamide gel electrophoresis of the protein constituents of the isolated membrane-bound organelles suggest that the polypeptide pattern could also be used as an additional marker for some of these structures. Finally, subcellular distribution of chitin synthase was determined using this fractionation procedure, and two partially zymogenic enzyme pools (one inside the cell associated to particles which sediments at high speed, and the second one associated to the plasma membrane) were found.     

Effects of centrifugal force and centrifugation time on the sedimentation of plant organelles

The effect of centrifugal force and length of centrifugation time on the sedimentation of plant organelles was determined for corn (Zea mays L.) root homogenates. A centrifugal force of 6000g for at least 20 minutes was necessary to pellet 90% of the mitochondrial marker (cytochrome c oxidase). This initial centrifugation step is optimal for separating mitochondria from microsomes, since cross-contamination of endoplasmic reticulum and plasma membrane vesicles with mitochondria is minimized. Centrifugal forces of 8000g or 10,000g for 20 minutes and 13,000g for 15 minutes pellet 90% of the mitochondrial marker; however, these centrifugation conditions also sediment more plasma membrane and endoplasmic reticulum.     

Relationships between membranous organelles in amoebae studied by electron microscopic cytochemical staining

Summary The intracellular location of a variety of enzymes was studied in Amoeba proteus with the use of electron microscopic cytochemical methods, in an attempt to assess the relationships between different membranous organelles. One group of enzymes, including nucleoside diphosphatases (IDPase, UDPase, GDPase, ADPase), carbamoyl phosphatase, alkaline phosphatase, and BAXD oxidase was localized mainly in the rough endoplasmic reticulum, nuclear envelope, and convex side of the Golgi apparatus. Esterase activity had a similar localization except that the Golgi apparatus was "stained" throughout most of its extent. A second group of enzymes was found in Golgi cisternae and vesicles, and in some vacuoles. This group included acid phosphatase, thiamine pyrophosphatase, and aryl sulfatase. Some enzymes previously detected in cytoplasmic membranes of other cells, including glucose-6-phosphatase, showed little or no activity in amoebae. The results suggest that there are chemical similarities and probable functional relationships between the rough endoplasmic reticulum, the nuclear envelope, and the convex side of the Golgi apparatus. On the other hand, the concave pole of the Golgi apparatus, aggregates of smooth tubules and vesicles, and the cell surface appear more closely related to one another than to the endoplasmic reticulum and the convex side of the Golgi apparatus. The cytochemical similarity between the Golgi apparatus and certain vacuoles such as food vacuoles may reflect the role of the Golgi apparatus in the formation of lysosomes. The locations of reaction products of the various enzymes in amoebae are compared with observations reported for other cell types.Supported by a research grant (VC-169) from the American Cancer SocietyThe author is indebted for technical assistance to Mrs. Sue Thompson and Mrs. Christine Folsom-Kovarik     

Ultrastructureofthe human intervertebral disc. I. Changes in notochordal cells with age

We examined nucleus pulposus notochordal cells of individuals ranging in age from the eighth week of fetal life to 32 years of age. With increasing age, notochordal cell structure changed, as did the cell-to-cell relationships and the cell-to-matrix relationships. All notochordal cells contained normal organelles, including welldeveloped endoplasmic reticulum, but, in addition, fetal notochordal cells demonstrated an unusual relationship between rough endoplasmic reticulum and mitochondria: elements of the rough endoplasmic reticulum encircled almost every mitochondrion. Fetal notochordal cells contained large amounts of glycogen, while older cells had much smaller glycogen deposits. Cytoplasmic filaments were observed in cells of all ages. The cells formed tightly packed clusters in the fetus with little, if any, extracellular matrix between individual cells. Cells separated from each other with age and by the twenty-first week of fetal life, only slender strands of cytoplasm connected them. Previous light microscopic studies described notochordal cells as ‘physaliphorus’ cells since they appeared to contain large cytoplasmic vacuoles. However, electron microscopy showed that these apparent vacuoles consist of extracellular matrix surrounded by cells or cell processes. The structure of notochordal cells and their persistence in the nucleus pulposus after fetal life suggest that they may have a significant role in the formation and maintenance of the nucleus pulposus.     

细叶黄芪叶肉原生质体发育早期几种细胞器的变化

在细叶黄芪叶肉原生质体发育早期,细胞器的变化较大。离体培养4h后,线粒体的嵴和基质物质开始增加。培养3—5天后,线粒体的数量增加5倍以上,此时可见大部分线粒体围绕细胞核分布。在培养24h后,高尔基体开始发育,它们主要分布在细胞质周边区域。多糖细胞化学染色表明,高尔基体内沉积着大量嗜银物质。培养1天后,粗面内质网开始发育。培养3天时,部分叶绿体边缘出现一些空隙结构。随着叶绿体内膜结构的消失,淀粉粒增大,叶绿体逐渐转变为造粉质体。     

ROOT APEX STRUCTURE IN EPHEDRA MONOSPERMA AND EPHEDRA CHILENSIS (EPHEDRACEAE)

The root meristem of E. monosperma and E. chilensis possesses a central group of distinctive, large cells. These cells have large nuclei with scattered heterochromatin, proplastids with no starch, small vacuoles, mitochondria, few dictyosomes and endoplasmic reticulum cisternae, and lipid deposits. Over a 24 hr labelling period, the large cells fail to incorporate ³H-thymidine, whereas cells both distal and proximal to this region do. A quiescent center which includes these large cells is present therefore. Both species have an extensive root cap, the length being contributed by mitoses in many tiers of cells distal to the quiescent center. The root cap consists of a columella and peripheral regions. Distinctive amyloplasts, an increase in the number of endoplasmic reticulum cisternae and dictyosomes, large vacuoles, and lipid deposits are characteristic of differentiated columella cells. Peripheral cells elongate, lose most of their starch, and are eventually sloughed from the root.     

Ultrastructural Changes in Maturing Sporangia of Albugo Candida

Maturation of sporangia in Albugo sp. involved considerableinternal differentiation. There was a burst of activity in sporangiasoon after their formation when the numbers of mitochondria,and the amounts of endoplasmic reticulum increased. Perinuclearvesicles and smooth surfaced cisternae differentiated into well-developedgolgi apparatus which remained secretory until completion ofmaturation. The cisternae of rough endoplasmic reticulum arrangedthemselves in parallel stacked arrays. Maturing sporangia hadautophagic vacuoles containing various cell organelles. Nucleardegeneration and mitosis proceeded simultaneously. All activitiesdeclined towards the end of sporangial maturation: Golgi dictyosomesbecame quiescent and numbers of mitochondria and amounts ofendoplasmic reticulum decreased. There was a three-fold increasein the thickness of the sporangial wall during maturation.     

Synthesis and deposition of zein in protein bodies of maize endosperm

The origin of protein bodies in maize (Zea mays L.) endosperm was investigated to determine whether they are formed as highly differentiated organelles or as protein deposits within the rough endoplasmic reticulum. Electron microscopy of developing maize endosperm cells showed that membranes surrounding protein bodies were continuous with rough endoplasmic reticulum membranes. Membranes of protein bodies and rough endoplasmic reticulum both contained cytochrome c reductase activity indicating a similarity between these membranes. Furthermore, the proportion of alcohol-soluble protein synthesized by polyribosomes isolated from protein body or rough endoplasmic reticulum membranes was similar, and the alcohol-soluble or -insoluble proteins showed identical [¹⁴C]leucine labeling. These results demonstrated that protein bodies form simply as deposits within the rough endoplasmic reticulum.

Messenger RNA that directed synthesis of only the smaller molecular weight zein subunit was separated from mRNA that synthesized both subunits by sucrose gradient centrifugation. This result demonstrated that separate but similar sized mRNAs synthesize the major zein components. In vitro translation products of purified mRNAs or polyribosomes were approximately 2,000 daltons larger than native zein proteins, suggesting that the proteins are synthesized as zein precursors. When intact rough endoplasmic reticulum was placed in the in vitro protein synthesis system, proteins corresponding in molecular weight to the native zein proteins were obtained.

     

Destructive and restorative processes of the liver in rats under intensive physical loading

The ultrastructure of rat liver cells after running exercise was investigated. When rats were trained for a month and sacrificed immediately after the last exercise it was revealed that the number of liver cells mitochondria increased, but many of them had alterations: mitochondria became swollen, had lucid matrix. There were some variations in degree of alterations between different mitochondria: a) in the same hepatocyte, b) in different hepatocytes of the same animal, that was connected with individual sensitivity of organelles on the levels of the cell and of the organ. Rough endoplasmic reticulum bore few ribosomes. Glycogen was absent. There were abundant vesicles of smooth endoplasmic reticulum, autophagic vacuoles and peroxisomes in the liver cell cytoplasm. Adaptation of rat liver to the exercise programme becomes evident by 1.5 month of exercise. Mitochondria and rough endoplasmic reticulum were numerous and of normal structure. There were many peroxisomes and glycogen granules in the cytoplasm of hepatocyte. The presence of large autophagic vacuoles in the cytoplasm of some hepatocytes were obviously connected with more rapid destruction of some organelles, than in control.     

Gravitropic bending of cress roots without contact between amyloplasts and complexes of endoplasmic reticulum

The polar arrangement of cell organelles in Lepidium root statocytes is persistently converted to a physical stratification during lateral centrifugation (the centrifugal force acts perpendicular to the root long axis) or by apically directed centrifugation combined with cytochalasin-treatment. Lateral centrifugation (10 min, 60 min at 10\g or 50\g) causes displacement of amylplasts to the centrifugal anticlinal cell wall and shifting of the endoplasmic reticulum (ER) complex to the centripetal distal cell edge. After 60 min of lateral centrifugation at 10\g or 50\g all roots show a clear gravitropic curvature. The average angle of curvature is about 40° and corresponds to that of roots stimulated gravitropically in the horizontal position at 1\g in spite of the fact that the gravistimulus is 10-or 50-fold higher. Apically directed centrifugation combined with cytochalasin B (25 g\ml^-1) or cytochalasin D (2.5 g\ml^-1) incubation yields statocytes with the amyloplasts sedimented close to the centrifugal periclinal cell wall and ER cisternae accumulated at the proximal cell pole. Gravitropic stimulation for 30 min in the horizontal position at 1\g and additional 3 h rotation on a clinostat result in gravicurvature of cytochalasin B-treated centrifuged (1 h at 50\g) roots, but because of retarded root growth the angle of curvature is lower than in control roots. Cytochalasin D-treatment during centrifugation (20 min at 50\g) does not affect either root growth or gravicurvature during 3 h horizontal exposure to 1\g relative to untreated roots. As lateral centrifugation enables only short-term contact between the amyloplasts and the distal ER complex at the onset of centrifugation and apically directed centrifugation combined with cytochalasin-treatment even exclude any contact the integrity of the distal cell pole need not necessarily be a prerequisite for graviperception in Lepidium root statocytes.Abbreviations CB cytochalasin B - CD cytochalasin D - ER endoplasmic reticulum - g gravitational acceleration     

马占相思子叶离体培养中细胞早期变化的研究

用光学和电子显微镜观察马占相思子叶在离体培养中的细胞早期变化,结果表明,未培养的子叶薄壁细胞内充满大量贮藏物质,在脱分化过程中,贮藏物质逐渐减少,细胞核体积增大,液泡蛋白体出现,质体转化为原质体,线粒体,内质网等细胞器数量增加,马脱分化启动后的细胞分裂方式进行了讨论。     

The ultrastructure of hemocytes inDactylopius confusus (Cockerell), and the role of granulocytes in the synthesis of cochineal dye

Summary The ultrastructural study of free circulating hemocytes in the adult cochineal scale,Dactylopius confusus (Cockerell), demonstrated five cell types: prohemocytes, typical granulocytes (T-granulocytes), oenocytoids, plasmatocytes, and granulocytes with modified sub-cellular structure to perform a special synthetic and secretory function, which we refer to as modified granulocytes (M-granulocytes). Prohemocytes showed undifferentiated sub-cellular structure of the basic stem cell type (i.e., high cytoplasmic density with numerous ribosomes, centrally located large nucleus with a distinct nucleolus, and poorly developed endoplasmic reticulum). The commonly observed typical granulocytes (T-granulocytes) had several smooth endoplasmic reticulum (SER) with dilated cisternae and many SER-derived membrane bounded granules of different sizes and electron density. Oenocytoids were identified by the presence of many crystals, RER-originated fine secretory granules, and an eccentric nucleus. Plasmatocytes were easily characterized by their variable shapes and irregular outline with pseudopodia-like cytoplasmic extensions, possession of an elongated lobed nucleus, multivesicular bodies, RER-derived membrane bounded, electron-dense, lysosomelike vacuoles, well-developed SER cisternae, and numerous pinocytic and SER-originated vesicles of different sizes along the peripheral region. M-granulocytes comprised the largest proportion of hemocytes in all samples observed. M-granulocytes were distinguished not only by the presence of membrane bounded granules of different sizes and electron density, but by the possession of large nuclei with distinct nucleoli, many mitochondria, and a highly developed network of rough endoplasmic reticulum (RER). M-granulocytes had abundant, rosette-shaped, RER-derived chains of fine secretory granules, which accumulated in the cytoplasm and vacuoles, and were ultimately deposited into the hemolymph by exocytosis. These fine granules gave a positive result with periodic acid-Schiff (PAS) test. Based on RER-synthesized fine secretory granules (M-granulocytes), their ultimate deposition into hemolymph, the red pigmentation of hemolymph, positive PAS histochemical test of these granules, and the high population of these hemocytes, no such cell type has been described in previous studies in insects. The sub-cellular structure of the granulocyte in this insect has been modified to perform a special synthetic and secretory function (i.e., possibly the synthesis of the red pigment found in hemolymph, which has been the source of commercially important cochineal dye).Abbreviations EM electron microscope - ER endoplasmic reticulum - LM light microscopy - MVB multivesicular body - PAS periodic acid-Schiff - RER rough endoplasmic reticulum - SER smooth endoplasmic reticulum - SG secretory granules - TEM transmission electron microscopy - UA uranyl acetate