RADIOAUTOGRAPHIC VISUALIZATION OF THE INCORPORATION OF GALACTOSE-3H AND MANNOSE-3H BY RAT THYROIDS IN VITRO IN RELATION TO THE STAGES OF THYROGLOBULIN SYNTHESIS

Rat thyroid lobes incubated with mannose-³H, galactose-³H, or leucine-³H, were studied by radioautography. With leucine-³H and mannose-³H, the grain reaction observed in the light microscope is distributed diffusely over the cells at 5 min, with no reaction over the colloid. Later, the grains are concentrated towards the apex, and colloid reactions begin to appear by 2 hr. With galactose-³H, the reaction at 5 min is again restricted to the cells but it consists of clumped grains next to the nucleus. Soon after, grains are concentrated at the cell apex and colloid reactions appear in some follicles as early as 30 min. Puromycin almost totally inhibits incorporation of leucine-³H and mannose-³H, but has no detectable effect on galactose-³H incorporation during the 1st hr. Quantitation of electron microscope radioautographs shows that mannose-³H label localizes initially in the rough endoplasmic reticulum, and by 1–2 hr much of this reaction is transferred to the Golgi apparatus. At 3 hr and subsequently, significant reactions are present over apical vesicles and colloid, while the Golgi reaction declines. Label associated with galactose-³H localizes initially in the Golgi apparatus and rapidly transfers to the apical vesicles, and then to the colloid. These findings indicate that mannose incorporation into thyroglobulin precursors occurs within the rough endoplasmic reticulum; these precursors then migrate to the Golgi apparatus, where galactose incorporation takes place. The glycoprotein thus formed migrates via the apical vesicles to the colloid.     

EVIDENCE FOR THE PARTICIPATION OF THE GOLGI APPARATUS IN THE INTRACELLULAR TRANSPORT OF NASCENT ALBUMIN IN THE LIVER CELL

A comparative biochemical and radioautographic in vivo study was performed to identify the site of synthesis and route of migration of albumin in the parenchymal liver cell after labeling with leucine-¹⁴C or leucine-³H via the portal vein. Free cytoplasmic ribosomes, membrane-bound ribosomes, rough- and smooth-surfaced microsomes, and Golgi membranes were isolated. The purity of the Golgi fraction was examined morphologically and biochemically. After administration of leucine-¹⁴C, labeled albumin was extracted, and the sequence of transport was followed from one fraction to the other. Approximately 2 min after the intravenous injection, bound ribosomes displayed a maximal rate of leucine-¹⁴C incorporation into albumin. 4 min later, a peak was reached for rough microsomes. Corresponding maximal activities for smooth microsomes were recorded at 15 min, and for the Golgi apparatus at ~20 min. The relative amount of albumin, calculated on a membrane protein basis, was higher in the Golgi fraction than in the microsomes. By radioautography the silver grains were preferentially localized over the rough-surfaced endoplasmic reticulum at the 5 min interval. Apparent activity in the Golgi zone was noted 9 min after the injection; at 15 and 20 min, the majority of the grains were found in this location. Many of the grains associated with the Golgi apparatus were located over Golgi vacuoles containing 300–800 A electron-opaque bodies. It is concluded that albumin is synthesized on bound ribosomes, subsequently is transferred to the cavities of rough-surfaced endoplasmic reticulum, and then undergoes migration to the smooth-surfaced endoplasmic reticulum and the Golgi apparatus. In the latter organelle, albumin can be expected to be segregated together with very low density lipoprotein in vacuoles known to move toward the sinusoidal portion of the cell and release their content to the blood.     

A BIOCHEMICAL AND RADIOAUTOGRAPHIC ANALYSIS OF PROTEIN SECRETION BY THYROID LOBES INCUBATED IN VITRO

In this study we analyzed several aspects of protein secretion by thyroid follicular cells. The study was carried out on intact thyroid lobes obtained from newborn rats and incubated in vitro. The fate of leucine-³H incorporated into protein within follicular cells of untreated and thyrotropic hormone (TSH)-treated lobes was traced by quantitative electron microscope radioautography. Our findings indicate that protein synthesized by the rough-surfaced endoplasmic reticulum during a pulse exposure to leucine-³H is released relatively slowly by this organelle. Approximately 1 hr after onset of the pulse, a peak of radioactive protein appears in the Golgi region. The significance of this peak is not clear. Newly synthesized secretory protein passes through the apex of follicular cells without being concentrated or temporarily stored there in the form of large secretory droplets. Passage probably takes place via small vesicles which are intermingled among diverse small vesicles at the apex of the cells as well as in the Golgi region. Exposure of the lobes to TSH in the incubation medium for 45 or 90 min does not stimulate incorporation of leucine-³H into protein. Acute stimulation with TSH does, however, modify the movement of secretory protein within the exocrine secretory apparatus of the follicular cell. It accelerates the arrival of the protein at the apex of follicular cells, and it accelerates the release of the protein into the follicular lumen.     

Morphology and ultrastructure of the adult ovarian cycle in Mithracidae (Crustacea,Decapoda, Brachyura,Majoidea)

The ultrastructure of the ovary during development and yolk production is poorly known in Brachyura and Majoidea in particular. Here, we describe the histology, histochemistry and ultrastructure of the adult ovarian cycle in four Mithracidae species from three different genera: Mithrax hispidus, Mithrax tortugae, Mithraculus forceps and Omalacantha bicornuta. All species showed a similar pattern of ovarian development and vitellogenesis. Macroscopically, we detected three stages of ovarian development: rudimentary (RUD), developing (DE) and mature (MAT); however, in histological and ultrastructural analyses, we identified four stages of development. The oocytes of the RUD stage, during endogenous vitellogenesis, have basophilic cytoplasm filled with dilated rough endoplasmic reticulum. The reticulum lumen showed many granular to electron-dense materials among the different stages of development. The Golgi complexes were only observed in the RUD stage and are responsible for releasing vesicles that merge to the endogenous or immature yolk vesicles. At the early DE stage, the oolemma showed many coated and endocytic vesicles at the cortex. The endocytic vesicles merge with the endogenous yolk to form the exogenous or mature yolk vesicles, always surrounded by a membrane, characterizing exogenous vitellogenesis. The exogenous yolk vesicles comprise glycoproteins, showing only neutral polysaccharides. At the late DE stage, endocytosis still occurs, but the amount of endogenous yolk decreases while the exogenous yolk increases. The late DE stage is characterized by the beginning of chorion production among the microvilli. The MAT stage is similar to the late DE, but the endogenous yolk is restricted to a few cytoplasmic areas, the ooplasma is filled with exogenous yolk, and the oolemma has very few coated vesicles. In the MAT stage, the chorion is fully formed and shows two electron-dense layers. The ovarian development of the species studied has many similarities with the very little known Majoidea in terms of the composition, arrangement and increment of the yolk vesicles during oocyte maturation. The main differences are in the vitellogenesis process, where immature yolk formation occurs without the direct participation of the mitochondria but with the participation of the rough endoplasmic reticulum in the endogenous phase.     

Fine Structure of the Ovarian Development in the Orb-web Spider, Nephila clavata

ABSTRACT Fine structural changes of the ovary and cellular composition of oocyte with respect to ovarian development in the orb-web spider, Nephila clavata were examined by scanning and transmission electron microscopy. Unlike the other arthropods, the ovary of this spider has only two kinds of cells-follicle cells and oocytes. During the ovarian maturation, each oocyte bulges into the body cavity and attaches to surface of the elongated ovarian epithelium through its peculiar short stalk attachments. In the cytoplasm of the developing oocyte two main types of yolk granules, electron-dense proteid yolk and electron-lucent lipid yolk granules, are compactly aggregated with numerous glycogen particles. The cytoplasm of the developing oocyte contains a lot of ribosomes, poorly developed rough endoplasmic reticulum, mitochondria and lipid droplets. These cell organelles, however, gradually degenerate by the later stage of vitellogenesis. During the active vitellogenesis stage, the proteid yolk is very rapidly formed and the oocyte increases in size. However, the micropinocytosis invagination or pinocytotic vesicles can scarcely be recognized, although the microvilli can be found in some space between the oocyte and ovarian epithelium. During the vitellogenesis, the lipid droplets in the cytoplasm of oocytes increase in number, and become abundant in the peripheral cytoplasm close to the stalks. On completion of the yolk formation the vitelline membrane, which is composed of an inner homogeneous electron-lucent component and an outer layer of electron-dense component is formed around the oocyte.     

PRODUCTION OF MEMBRANE WHORLS IN RAT LIVER BY SOME INHIBITORS OF PROTEIN SYNTHESIS

Inhibitors of protein synthesis capable of differential effects on nascent peptide synthesis on membrane-bound and free polyribosomes were employed to investigate the structure and function of cellular membranes of liver. The formation of membranous whorls in the cytoplasm and distension of nuclear membranes were induced by inhibitors of protein synthesis (i.e., cycloheximide and emetine) which predominantly interfere with nascent peptide synthesis on membrane-bound polyribosomes in situ. Other inhibitors of protein synthesis such as puromycin and fusidic acid, which inhibit nascent peptide synthesis on both free and membrane-bound polyribosomes, and chloramphenicol, which inhibits mitochondrial protein synthesis, did not induce these alterations. Cycloheximide, puromycin, and chloramphenicol produce some common cellular lesions as reflected by similar alterations in morphology, such as swelling of mitochondria, degranulation of rough endoplasmic reticulum, and aggregation of free ribosomes. The process of whorl formation in the cytoplasm, the incorporation of [³H]leucine and of [³H]choline into endoplasmic reticulum and the total NADPH-cytochrome c reductase activity of the endoplasmic reticulum were determined. During maximum formation of membranous whorls, [³H]leucine incorporation into cytoplasmic membranes was inhibited, while [³H]choline incorporation into these structures was increased; maximum inhibition of protein synthesis and stimulation of choline incorporation into endoplasmic reticulum, however, preceded whorl formation. Cycloheximide decreased the activity of NADPH-cytochrome c reductase of rough endoplasmic reticulum, but increased NADPH-cytochrome c reductase activity of smooth endoplasmic reticulum. In addition, cycloheximide decreased the content of hemoprotein in both the microsomal and mitochondrial fractions of rat liver, and the activities of mixed function oxidase and of oxidative phosphorylation were impaired to different degrees. Succinate-stimulated microsomal oxidation was also inhibited. The possible mechanisms involved in the formation of membranous whorls, as well as their functions, are discussed.     

Oogenesls in the terrestrial hermit crab,coenobita clypeatus (decapoda,anomura): II. Vitellogenesis

Oocytes from the land hermit crab, Coenobita clypeatus, in various stages of vitellogenesis were examined by light and electron microscopy. Early vitellogenic oocytes are characterized by accumulations of discrete vesicles of endoplasmic reticulum in the perinuclear cytoplasm. As oocytes develop, the endoplasmic reticulum becomes abundant, and numerous Golgi complexes are seen. There is a well developed Golgi-endoplasmic reticulum interaction. Within the confines of the reticulum are discrete intracisternal granules, which can be seen coalescing into electron-dense yolk bodies. Lipid accumulation is seen throughout the cytoplasm. Coincident with the burst of intra-oocytic metabolism are oolemma modifications and micropinocytosis, which provide ultrastructural evidence for extra-oocytic yolk production. The mature oocyte contains numerous yolk and lipid vesicles of varying electron density that comprise both intra- and extra-oocytic substrates.     

HETEROGENEITY OF ROUGH-SURFACED LIVER MICROSOMAL MEMBRANES OF ADULT,PHENOBARBITAL-TREATED,AND NEWBORN RATS

Rough microsomes from the livers of adult, phenobarbital-treated, and newborn rats were subfractionated on a continuous sucrose gradient. Among the subfractions a marked heterogeneity in the distribution patterns of some enzyme activities appears. The isopycnic density of the various fractions in aqueous sucrose ranges from 1.17 to 1.25. The sedimentation coefficients (s₀) in 0.25 M sucrose lie between 0.4 x 10³ S and 1.2 x 10³ S. In adult animals, the NADH- and NADPH-cytochrome c reductase as well as the G6Pase activities are much higher in the slower sedimenting fractions than in the pellet. The increase in the level of G6Pase induced by fasting as well as the phenobarbital-induced changes are most prominent in the slowly sedimenting fractions. Three injections of phenobarbital have no effect on the specific NADPH-cytochrome c reductase activity in the pellet, but cause a significant increase of this enzyme activity in the light fractions. In the newborn animal, the NADH-ferricyanide reductase and NADPH-cytochrome c reductase activities are highest in the light fractions. On the other hand, the amount of cytochrome b ₅ is evenly distributed in all cases. Short-term incorporation of leucine-¹⁴C and glycerol-³H in vivo after phenobarbital treatment shows contrasting results, as the former is increased and the latter is decreased in the slowly sedimenting fractions. Leucine-¹⁴C incorporation into isolated, total membrane proteins is greater in both phenobarbital-treated and newborn animals than in untreated adults. The data support a multistep model for membrane biogenesis and indicate dynamic and individual behavior of the different parts of the rough-surfaced endoplasmic reticulum.     

Mechanisms of protein yolk synthesis and deposition in crustacean oocytes

Summary Electron microscope studies on the oocytes of several crustacean species demonstrate that the protein yolk arises within vesicular and lamellar forms of the rough-surfaced endoplasmic reticulum. The vesicular form of the endoplasmic reticulum may have its origin from a blebbing process of the outer layer of the nuclear envelope. Disc-shaped granules, representing precursor elements of the yolk granules, appear within the vesicular and lamellar profiles of endoplasmic reticulum. Autoradiographic results suggest that the ribosomes attached to the endoplasmic reticulum take part in the biosynthesis of yolk proteins. Numerous disc-shaped granules accumulate within the cisternae of the endoplasmic reticulum, but eventually they undergo a transformation into a finely granular yolk granule. Thus, both the origin and growth of protein yolk granules occur within membranes constituting the endoplasmic reticulum. The results provide evidence that intra-ooplasmic synthesis of yolk protein occurs in these oocytes.This investigation was supported by research grants (HD-00699; GM-09229) and a Career Development Award (GM-11,524) from the National Institutes of Health, U.S. Public Health Service.     

中华稻蝗卵子卵黄发生期超微结构研究

利用透射电镜研究了中华稻蝗Oxya chinesis卵子发生中卵黄发生期的超微结构.卯黄发生初期,滤泡上皮细胞胞质内出现大量粗面内质网及线粒体等细胞器,可能与为卵母细胞提供营养有关.卵黄发生期卵母细胞胞质内卵黄球逐渐增多,它也许有多种来源.观察到环形片层结构,并讨论了其可能功能.     

Ultrastructural studies of differentiation in the oocyte of the polyclad turbellarian,Prostheceraeus floridanus

Oocyte differentiation in the polyclad turbellarian Prostheceraeus floridanus has been examined to determine the nature of oogenesis in a primitive spiralian. The process has been divided into five stages. (1) The early oocyte: This stage is characterized by a large germinal vesicle surrounded by dense granular material associated with the nuclear pores and with mitochondria. (2) The vesicle stage: The endoplasmic reticulum is organized into sheets which often contain dense particles. Vesicles are found in clusters in the cytoplasm, some of which are revealed to be lysosomes by treatment with the Gomori acid phosphatase medium. (3) Cortical granule formation: Cortical granules are formed by the fusion of filled Golgi vasuoles which have been released from the Golgi saccules. The association between the endoplasmic reticulum and Golgi suggests that protein is synthesized in the ER and transferred to the Golgi where polysaccharides are added to form nascent cortical granules. (4) Yolk synthesis: After a large number of cortical granules are synthesized, yolk bodies appear. They originate as small membrane-bound vesicles containing flocculent material which subsequently increase in size and become more compact. Connections between the forming yolk bodies and the endoplasmic reticulum indicate that yolk synthesis occurs in the ER. (5) Mature egg: In the final stage, the cortical granules move to the periphery and yolk platelets and glycogen fill the egg. At no time is there any evidence of uptake of macromolecules at the oocyte surface. Except for occasional desmosomes between early oocytes, no membrane specialization or cell associations are seen throughout oogenesis. Each oocyte develops as an independent entity, a conclusion supported by the lack of an organized ovary.     

Cytochemistry of late ovarian chambers of Drosophila melanogaster

Summary Late ovarian chambers of Drosophila melanogaster have been examined by ultrastructural cytochemistry in an attempt to characterize some of the transformations which precede the completion of oogenesis. From stage 11 onward peroxidase activity is present in the endoplasmic reticulum of both nurse cells and oocyte, as well as in the egg-covering precursors of the columnar follicle cells. Catalase activity is restricted to the very last stages of oogenesis (stage 13–14) and appears to be located in membrane-bound organelles of the ooplasm which are continuous with the endoplasmic reticulum. Because of the presence of catalase as well as by their structural appearance, these organelles are to be identified as microperoxisomes. Catalase activity becomes cytochemically detectable in the ooplasm somehow in coincidence with the formation of glycogen. Furthermore, glycogen is first formed in intimate association with alpha-1 yolk platelets. On the basis of these findings it is suggested that glycogen synthesis occurs by a process of gluconeogenesis.     

A follicle cell contribution to the yolk spheres of moth oocytes

The incorporation of H(3)-histidine and H(3)-glucosamine by ovarian follicles of cecropia moths during incubation in female blood was followed autoradicgraphically. Labeling was most prominent in the follicle cells, the spaces between these cells, and the nascent yolk spheres in the oocyte cortex. Results of puise-chase experiments and the fact that viable follicle cells were required for normal yolk sphere labeling indicated that the endogenous component of the yolk was provided by the follicle cells via the intercellular spaces. The material was accumulated by the oocyte in the absence of blood proteins, suggesting an independent role in yolk formation.     

Studies on the ovotestis of the slug Agriolimax reticulatus (Müller)

Summary The ovarian oocytes of Agriolimax reticulatus (Müller) have been studied by light and electron microscopy and electron cytochemistry. The development of the oocyte in the ovotestis may be divided into three stages.During Stage I the oocyte cytoplasm contains mainly ribosomes and also strands of endoplasmic reticulum, scattered mitochondria and Golgi systems. The nucleus contains both a paranucleolus and an eunucleolus. By Stage II the oocyte has enlarged, especially in a plane parallel to the basement membrane. In addition to the above mentioned organelles, the cytoplasm contains lipid, glycogen and early yolk platelets. During Stage III, the oocyte continues to enlarge, but mainly in a plane perpendicular to the basement membrane. A considerable degree of cytoplasmic differentiation has also taken place. The plasma membrane of the oocyte has become specialized with the appearance of a polysaccharide-rich glycocalyx, microvilli and pinocytotic tubules. Elsewhere, much of the background cytoplasm, containing Golgi-derived, polysaccharide and acid phosphatase-rich multivesiculate bodies, lipid and glycogen, is sequestered by smooth membranes and ultimately fuses with the growing yolk platelets. The nucleus contains an amphinucleolus, characteristic of many gastropods.The findings of this study are discussed in relation to results from other studies on oogenesis.     

INTRACELLULAR TRANSPORT OF SECRETORY PROTEINS IN THE PANCREATIC EXOCRINE CELL : II. Transport to Condensing Vacuoles and Zymogen Granules

In the previous paper we described an in vitro system of guinea pig pancreatic slices whose secretory proteins can be pulse-labeled with radioactive amino acids. From kinetic experiments performed on smooth and rough microsomes isolated by gradient centrifugation from such slices, we obtained direct evidence that secretory proteins are transported from the cisternae of the rough endoplasmic reticulum to condensing vacuoles of the Golgi complex via small vesicles located in the periphery of the complex. Since condensing vacuoles ultimately become zymogen granules, it was of interest to study this phase of the secretory cycle in pulse-labeled slices. To this intent, a zymogen granule fraction was isolated by differential centrifugation from slices at the end of a 3-min pulse with leucine-¹⁴C and after varying times of incubation in chase medium. At the end of the pulse, few radioactive proteins were found in this fraction; after +17 min in chaser, its proteins were half maximally labeled; they became maximally labeled between +37 and +57 min. Parallel electron microscopic radioautography of intact cells in slices pulse labeled with leucine-³H showed, however, that zymogen granules become labeled, at the earliest, +57 min post-pulse. We assumed that the discrepancy between the two sets of results was due to the presence of rapidly labeled condensing vacuoles in the zymogen granule fraction. To test this assumption, electron microscopic radioautography was performed on sections of zymogen granule pellets isolated from slices pulse labeled with leucine-³H and subsequently incubated in chaser. The results showed that the early labeling of the zymogen granule fractions was, indeed, due to the presence of highly labeled condensing vacuoles among the components of these fractions.     

Cytodifferentiation and vitellogenesis during oogenesis in arachnida: Cytological studies on developing oocytes of a harvestman

Light and electron microscope studies were made on harvestman oocytes during the course of their origin, differentiation, and vitellogenesis. The germ cells appear to originate from the ovarian epithelium. They subsequently migrate to the outer surface of the epithelium, where they remain attached often by means of stalk cells which suspend them in the hemocoel during oogenesis. The “Balbiani bodies,” “yolk nuclei,” or “nuage” constitute a prominent feature of young, previtellogenic oocytes, and take the form of large, but variable sizes of electron-dense cytoplasmic aggregates with small fibrogranular components. The cytoplasmic aggregates fragment and disperse, and cannot be detected in vitellogenic oocytes. The young oocytes become surrounded by a vitelline envelope that appears to represent a secretory product of the oocyte. The previtellogenic oocytes are impermeable to horseradish peroxidase under both in vivo and in vitro conditions. In addition to mitochondria, dictyosomes, and abundant ribosomes, the ooplasm of the previtellogenic oocyte acquires both vesicular and lamellar forms of the rough-surfaced endoplasmic reticulum. In many areas, a dense homogeneous product appears within the cisternae of the endoplasmic reticulum and represents nascent yolk protein synthesized by the oocyte during early stages of vitellogenesis. Later in vitellogenesis, the oocyte becomes permeable to horseradish peroxidase under both in vivo and in vitro conditions. This change is associated with a massive process of micropinocytosis which is reflected in the presence of large numbers of vesicles of variable form and structure in the cortical ooplasm. Both spherical and tubular vesicles are present, as are coated and uncoated vesicles. Stages in the fusion of the vesicles with each other and with developing yolk platelets are illustrated. In the harvester oocytes, vitellogenesis is a process that involves both autosynthetic and heterosynthetic mechanisms.     

Electron microscope studies on the oocyte of the fresh-water mussel (Anodonta), with special reference to the stalk and mechanism of yolk deposition

An interesting relationship exists between the ovary and the developing oocyte in the fresh-water mussel. As the oocytes grow, they elongate and bulge into the ovarian cavity. In the early stages, the nucleus migrates from the attached region (“foot”) to the distal region of the cell. With continued growth and maturation the connection between the proximal “foot” and distal nucleated portion becomes reduced to a narrow stalk. Microtubules appear in the young oocytes as they start to elongate and become packed in the stalks of older oocytes. It is suggested that the microtubules function as supporting structures and possibly also as channels for the transfer of materials from one portion of the oocyte to the other. The fine structure of the oocyte reveals evidence that the developing yolk bodies or spheres are formed, in part at least, by the incorporation of many smaller “precursor yolk vesicles.” These appear in the region of the Golgi complex and are presumed to be derived from the Golgi saccules. The oocyte contains an unusually well developed endoplasmic reticulum whose cisternae are filled with a rather conspicuous material.     

The pig yolk sac II

Summary Since previous morphological studies have revealed abundant rough endoplasmic reticulum in the yolk sac endoderm, pig yolk sac explants from 30 day old embryos were incubated for 3–12 h with [³H]-l-leucine in order to study their protein biosynthesis. They were fractionated into a 12,000×g-pellet, 105,000×g-pellet, and supernatant. Newly synthesized proteins in these tissue fractions, and proteins discharged into the culture medium, were analysed with the aid of scintillation technique and identified by column chromatography, SDS-polyacrylamide gel electrophoresis with urea, isoelectrofocusing, and 2D-electrophoresis. Most of the radioactivity incorporated into the tissue fractions was regained from the coarse pellet and was located in the molecular weight region between 70,000 and 45,000 daltons, indicating that most of the newly synthesized proteins are membrane bound and include albumin. Albumin, an acid protein of a MW around 80,000 daltons, and many neutral and basic peptides were present in the culture medium. The yolk sac endodermal cells of the pig synthesize less proteins than those of the cat, although the pig cells display much larger amounts of endoplasmic reticulum.     

ONTOGENETIC CHANGES OF PROTEINS OF ENDOPLASMIC RETICULUM

The proteins of the smooth and rough endoplasmic reticulum from fetal, immature, and adult male rats were compared after incorporation of two radioactively labeled precursors, ¹⁴C-labeled amino acids and δ-aminolevulinic acid-³H by means of gel electrophoresis. The labeling patterns indicated that protein components present in two major electrophoretic bands underwent significant synthesis in fetal tissue while three actively incorporating protein bands were noted in adult tissue. Although the uptake of the amino acids-¹⁴C decreased for the smooth and rough elements of the endoplasmic reticulum as a whole during liver development, the qualitative patterns were not significantly different in adult and fetal livers. The over-all incorporation (disintegrations per minute per milligram protein) of the heme precursor into the smooth and rough elements also did not change with development. However, a change was noted in the distributional electrophoretic patterns with development. The estimation of molecular weight (by disc electrophoresis) and the incorporation of the heme precursor suggested the similarity of the two major protein bands to cytochrome P-450 and cytochrome b₅, components of the endoplasmic reticulum, thought to be involved in the mixed-function oxidase system. The evidence indicated that in fetal liver, at a time when the oxidase capability was low, the amino acid incorporation into these two protein groups was the same as in the adult. The incorporation of the heme moiety, however, was different, decreasing in the cytochrome b₅ region and increasing in the cytochrome P-450 region during development. These results correlate with the increase in oxidase activity associated with liver development.     

大阪鲫鱼两种卵黄蛋白免疫细胞化学的研究

以电泳提纯的卵黄脂磷蛋白和卵黄蛋白Ｌ制备兔抗两种蛋白的抗血清,采用ＰＡＰ法对性腺成熟雌性大阪鲫鱼的肝细胞和卵母细胞进行两种蛋白免疫细胞化学位研究。肝细胞的粗面内质网上有强烈的卵黄脂磷蛋白的阳性反应,特别是在线粒体的基质中也发现卵黄脂磷蛋白的阳性反应,而另外一种类似于卵黄高磷蛋白的卵黄蛋白－卵黄蛋白Ｌ在肝细胞的粗面内质网和线粒体均呈现阴性反应,提示卵黄脂磷蛋白的前体物质存在于肝细胞的粗面内质网和线粒