The fine structure of the chinchilla placenta.

The structure of the placental labyrinth, interlobular or "coarse" syncytium, visceral (splanchnopleuric) yolk sac, giant cells and subplacenta of the chinchilla was studied with the electron microscope. The fine structure of the interhemal membrane of the placental labyrinth was found to be hemomonochorial, consisting of a single layer of syncytial trophoblast. In this respect, the placental labyrinth was similar to that of another caviomorph rodent, the guinea pig. The labyrinthine trophoblast had pinocytotic vesicles as well as larger vaculoes and multivesicular bodies. The interlobular syncytium contained granular endoplasmic reticulum, and in one case from early in gestation there were intracisternal granules in the ER. The visceral endodermal cells of the inverted yolk sac placenta had a well-developed system of apical vesicles and tubules as well as larger cytoplasmic vacuoles. Their appearance was similar to that of endodermal cells found in other rodents which are known to absorb proteins and other substances from the uterine lumen. Towards term the giant cells were often vacuolated and contained large deposits of glycogen as well as lipid droplets. The syncytial trophoblast of the subplacenta contained numerous moderately electron-dense granules which may be secretory in function; cytotrophoblastic cells lacked these granules. The subplacental syncytium often surrounded spaces or lacunae which contained an electron-dense granular material.     

Intrauterine growth retardation in experimental diabetes: possible role of the placenta

Fetal growth disorders are common in pregnancy complicated by diabetes. Whereas macrosomia often occurs in infants of diabetic women, growth retardation is almost a rule in spontaneous and experimental diabetes in animals. However, it is not clear when during development growth inhibition starts and how placental pathology might affect fetal growth in maternal diabetes. In this study pregnant Wistar rats were injected (ip) with a single dose of 50 mg/kg of streptozotocin (STZ) on gestation day (GD) 2 and a blood glucose level of 200 mg/dl or more determined 24 hrs later indicated diabetes. The controls were non-treated, buffer treated or, following confirmation of diabetes, injected with a single dose of 2--6 IU of insulin (Novo Ultralente) once daily. Fetuses and placentae were collected from GD 14--20. Intrauterine growth retardation (IUGR) in STZ group was significant as early as GD 15 and persisted to GD 20. Insulin produced a significant recovery in fetal weight gain. The placentas of STZ-treated group were significantly heavier than those of the control groups. The reduction in cord length of the STZ group became apparent on GD 16 and remained so to term. The placenta of GD 14 STZ group had a thicker decidua basalis and dilated maternal sinusoids. By GD 16, the decidua basalis contained glycogen-containing decidual cells and scattered glycogen cells confirmed by Best's carmine with or without diastase. The glycogen cells of the basal zone were more abundant, and had degenerated in some sites leaving behind cysts with eosinophilic mass. The giant cells had proliferated enormously. The labyrinthine zone appeared spongy with persistent fetal mesenchyme, peri-vascular fibrosis, and enhanced placental barrier. The trophoblasts of the labyrinths also contained traces of glycogen unlike the controls. By GD 18, the decidua basalis of the STZ group was thinner than that of the controls and contained necrotic giant cells and lymphocytic aggregations. In the basal zone, the giant cells had proliferated further; more glycogen cells had degenerated. Perivascular fibrosis was still extensive in the labyrinthine zone. Bloodless maternal sinusoids, extensive vacuolization, degeneration of glycogen islands and formation of cysts characterized the labyrinthine zone. These changes varied in intensity from one area to another in the same placenta and between placentas of the same and of different litters. The development of the upper and lower jaws, elevation and fusion of palatal shelves, reduction of physiological umbilical hernia, descent of the testes, fusion of the urethral folds and separation of digits of the paws were significantly delayed in the STZ group. The consistent association of placental pathology with fetal growth retardation is suggestive of an alteration in placental function possibly contributing to IUGR in STZ-induced diabetes in rats.     

Glycogen-containing cells in the maternal and embryonic portions of the placenta in the rat and the common vole Microtus subarvalis

Differentiation sequences and further transfiguration of glycogen-rich cells during placenta development were investigated for the rat and field vole Microtus subarvalis (11-20 day gestation). The presence of glycogen is a characteristic feature of decidual cells located in the region of lateral sinusoids, as well as of metrial gland cells, secondary giant trophoblast cells and trophoblast cells in the connective zone of placenta. Glycogen-containing metrial gland cells and trophoblast cells of connective zone of placenta are found to underlie the layer of tertiary giant trophoblast cells that cover the wall of the central arteria. Thus, both maternal and embryo-derived glycogen-containing cells always accompany the tertiary giant trophoblast cells that penetrate deeply into the maternal part of placenta but do not contain glycogen. In the field vole placenta the cells of peripheral trophoblast subpopulation of the connective zone of placenta attaching to the decidua basalis are stained by PAS-reaction more intensely than deeply situated ones. These data, as well as other phenomena revealed here, show that maternal and trophoblastic cells attaching to each other in placenta contain, as a rule glycogen. Glycogen cells in rat placenta and trophoblast cells of peripheral subpopulation of connective zone of placenta are similar in many respects. In this connection, a possible protective role of glycogen-containing cells, that probably favour the co-existence of maternal and embryo-derived cells in placenta, is discussed.     

Endopolyploid and proliferating trophoblast cells express different patterns of intracellular cytokeratin and glycogen localization in the rat placenta

The presence of keratin intermediate filaments is a characteristic of trophoblast differentiation. Meantime, their intracellular localization in the functionally different subtypes of placental trophoblast is poorly investigated in rodent, whereas their placentae are being broadly investigated in recent years as a model of the feto-maternal interaction. The purpose was to study the intracellular distribution of cytokeratin filaments in correlation with glycogen deposits, both being important constituents of the trophoblast cells in rat placenta. Different rat trophoblast cell populations exhibited different patterns of cytokeratin immunolocalization. The most intensive immunostaining was observed in the highly endopolyploid SGTCs (secondary giant trophoblast cells) at the border with decidua basalis. The most prominent cytokeratin-positive threads were found at the periphery of cytoplasm and in the extensive system of cytoplasmic sprouts by which the SGTC connect each other. Similar cytokeratin intensity and distribution was detected in the TSC (trabecular spongiotrophoblast cells) of the junctional zone of placenta that line the lacunae with the maternal blood. Clusters of highly proliferative pre-glycogen as well as glycogen cells showed some weaker cytokeratin signals mostly in the perinuclear and peripheral zones of cytoplasm. At the 11.5th to the 13.5th day of gestation, the interstitial and endovascular invasive endopolyploid TGTCs (tertiary giant trophoblast cells) prove the intensive cytokeratin staining throughout the cytoplasm and its sprouts. Meantime, the TGTCs were glycogen negative. By contrast, glycogen was heavily accumulated in the glycogen cells that belong both to the junctional zone of placenta and the cuff of the central arterial channel underlying the monolayer of endovascularly invading TGTCs. Thus, the TGTCs that are first to penetrate into the depth of the uterine wall do not contain glycogen but are accompanied by the glycogen-rich cells. The SGTC also contained the prominent deposits of glycogen at the periphery of cytoplasm and in the cytoplasmic sprouts. At the 16th day of gestation, an extensive interstitial invasion of the cytokeratin-positive glycogen trophoblast cells from the junctional zone was observed. The patterns of cytokeratin and glycogen intracellular localization are specific for each subtype of the rat trophoblast; that is, most probably, accounted for by the functional diversity of different trophoblast populations, i.e. patterns of invasion/phagocytosis and their involvement in a barrier at the feto-maternal interface.     

Ultrastructural features of the nucleus and cytoplasm of rat trophoblast cells of the connective zone of the placenta and labyrinth

Ultrastructural organization of the rat trophoblast cells in the connective zone of placenta and labyrinth was investigated on the 12-14th days of gestation. A clear distinction was revealed in the cytoplasm ultrastructure of two cell subpopulations within the connective zone of placenta, i.e. glycogen and trophospongium cells. The former display a well defined network of long thin channels of granular endoplasmic reticulum situated mainly around the glycogen clusters. On the contrary, the latter are rich in the smooth endoplasmic reticulum but lacking glycogen accumulation. Differences in the nucleolar ultrastructure in these two cell subpopulations are not very considerable. A characteristic feature of glycogen cells is the presence of numerous round or oval small-fibrillar nucleolus-like bodies with the diameter of granules 20 nm. The trophoblast cells of the labyrinth are heavily laden with polysomes, which sometimes attach to short channels of the granular endoplasmic reticulum. Not often there occur short profiles of the agranular endoplasmic reticulum. Nucleolus-like bodies are found in all the cell types examined. This means that the nucleolus-like bodies may arise not only on the lampbrush chromosomes in the oocytes or polytene chromosomes, but also in the somatic cells which are capable of dividing mitotically.     

Plasmodium berghei: histology, immunocytochemistry, and ultrastructure of the placenta in rodent malaria

The pathological changes associated with malarial infection in pregnancy were studied in rats and mice infected with Plasmodium berghei at different stages of gestation. Histopathological and ultrastructural studies of infected placentae near term in both species revealed disruption of architecture with gross thickening and necrosis of cells in the labyrinthine zone and fibrosis of the trilaminar trophoblast separating the maternal and fetal circulations. In the mouse, the extent of histopathological alterations in infected placentae ranged from the presence of immature erythrocytes in the fetal circulation in low grade maternal infection, to the marked deposition of fibrinoid material on the trilaminar trophoblast and inflammatory masses in severely infected placentae. In the rat, histopathological aberrations in the placentae were marked by placental stroma edema, fibrosis, and cellular infiltration. Immunohistological studies of cryostat sections of placentae from infected animals showed more parasites and pigment in infected mouse placentae than in the corresponding rat organ, but in both species parasites and pigment were largely confined to the maternal blood spaces and were only occasionally found in necrotic areas of trophoblast. No clear differences were observed between infected and control placentae in terms of the amount of IgG, IgM, or IgA which were each present in various amounts. These observations and the rarity of congenital malaria in the animals indicate that the placenta constitutes a major barrier to infection of the fetus. However, the pathological aberrations in the infected placentae may impose a biochemical stress upon the fetus which may account for the low birthweight, the increased frequency of abortion, and the greatly increased maternal and fetal death rates observed in malaria.     

Ultrastructural and cytochemical aspects of the basophilic cells in the hepatopancreas ofAplysia depilans(Mollusca, Opisthobranchia)

The basophilic cells ofAplysia depilanshave a pyramidal shape and a large nucleus usually located near the center or in the basal half of the cell. The nucleus possesses several clumps of condensed chromatin and a prominent nucleolus. The great profusion of rough endoplasmic reticulum cisterns in a major feature of these cells. Secretion granules are accumulated in the apical zone, and arylsulphatase was detected in some of them. In some basophilic cells a very substantial part of the cell volume was occupied by clear vacuoles, some of them reaching 9 mum. However, in other cells only a few vacuoles were observed. Probably the cells with just a few vacuoles are still young, and after a progressive accumulation, the vacuoles become abundant in old cells. The presence of a dark nucleus in the cells with a large number of vacuoles suggests that they are in a final stage of their life. Arylsulphatase was detected in the vacuoles and also in small secondary lysosomes containing substances in digestion. Bundles of tubules with 50 nm in diameter were found within some cisterns of rough endoplasmic reticulum. A cell fraction enriched in mannitol oxidase, extracted from the hepatopancreas of a terrestrial slug, consisted in very similar tubular structures. Using a histochemical method, mannitol oxidase was detected in the basophilic cells ofA. depilans, and it may be associated with the tubular structures of the endoplasmic reticulum. This is the first report of mannitol oxidase in opisthobranch molluscs. Almost spherical peroxisomes with a small nucleoid were abundant in these cells. The nucleoids presented a rectangular section, but a crystalline structure was not evident. The peroxisomes were stained after the cytochemical detection of catalase activity.     

Hormone-induced differentiation of agranular endoplasmic reticulum in the interstitial cells of the mouse testis

Summary The administration of chorionic gonadotrophin to prepuberal mice results in precocious maturation of the testicular interstitial cells. The cytoplasm of the nine-day-old cells is characterized by abundant lipid droplets, large numbers of glycogen particles and mitochondria. By contrast, the membranous organelles are poorly developed.Human chorionic gonadotrophin brings about mobilization of lipid droplets and glycogen particles, and differentiation of large areas of agranular endoplasmic reticulum.The present observations are in agreement with the reports that human chorionic gonadotrophin increases the secretion of testosterone and that the agranular endoplasmic reticulum is the site of storage of steroid and of the enzymes involved in the biosynthesis of androgens.     

Fine Structure of the Fat Body and its Bacteroids in Blattella germanica (Blattodea)

The abdominal fat body of the cockroach Blattella germanica contains three characteristic cell types—trophocytes, bacteriocytes and urate cells—which have been investigated by electron microscopy. The trophocytes are rich in lipid droplets of different sizes; glycogen, rough endoplasmic reticulum and mitochondria are also abundant. In females immediately after eclosion, the trophocytes contain a greater number of lipid droplets, some of which have different electron density; glycogen and cytoplasmic organelles are clearly reduced. The bacteriocytes hold rod-like and spherical bacteroids, which are encapsulated by a vacuolar membrane; they show a thin cytoplasmic membrane and an evident cell wall surrounded by a membrane-like outer envelope. The bacteroids appear to be dividing either by transverse partition or by budding. The urate cells, adjacent to the bacteriocytes, are characterized by complex urate vacuoles delimited by a double layer-structure.     

Juvenile hormone-controlled vitellogenin synthesis in Locusta migratoria fat body: Cytological development

Cytological development in the fat body of adult female Locusta migratoria, related to vitellogenin synthesis, has been studied by light and electron microscopy. In the newly-emerged adult, the cells are filled with lipid droplets, which indent the nucleus, and with fields of glycogen, while ribosomes and endoplasmic reticulum are scarce. Correlated with the onset of vitellogenin synthesis, about day 8 of adult life, the nucleus enlarges, lipid droplets and glycogen decrease, and rough endoplasmic reticulum and Golgi complexes become the most abundant organelles. These changes reflect a conversion of the principal role of the fat body from nutrient storage to the synthesis and secretion of protein. They are prevented by allatectomy, and restored by subsequent treatment with the juvenile hormone analogue, ZR-515. Late in the first gonotrophic cycle, about day 20, dense bodies, vesicle-containing bodies and lysosomes are seen, indicating recycling of cellular materials. Five days after ZR-515 treatment, when protein synthesis has declined, the rough endoplasmic reticulum appears in arrays adjacent to lipid droplets, possibly awaiting reactivation. By the use of ferritin-labelled antivitellin immunoglobulin, vitellogenin has been localized intracellularly in the RER saccules and Golgi vesicles, and extracellularly in channels between the folded plasma membranes, showing sites of accumulation and secretion of this protein.     

EFFECTS OF ARGININE DEPRIVATION, ULTRAVIOLET RADIATION, AND X-RADIATION ON CULTURED KB CELLS : A Cytochemical and Ultrastructural Study

Cultured KB cells (derived from a human oral carcinoma) grown in monolayers were injured by one of three agents: starvation by arginine deprivation or treatment with high doses of either ultraviolet radiation or x-radiation. The different agents produced changes in nucleolar structure and varying accumulations of triglyceride and glycogen. All three agents produced an increase in number and size of lysosomes. These were studied in acid phosphatase preparations, viewed by both light and electron microscopy, and, occasionally, in vital dye, esterase, and aryl sulfatase preparations. Ultrastructurally, alterations in lysosomes suggested that "residual bodies" developed in a variety of ways, i.e., from the endoplasmic reticulum, multivesicular bodies, or autophagic vacuoles. Following all three agents the endoplasmic reticulum assumed the form of "rough" or "smooth" whorls, and, after two of the agents, arginine deprivation or ultraviolet radiation, it acquired cytochemically demonstrable acid phosphatase activity. Near connections between the endoplasmic reticulum and lysosomes raise the possibility that in KB cells, at least when injured, the endoplasmic reticulum is involved in the formation of lysosomes and the transport of acid phosphatase to them.     

Glycogen metabolism in the placenta of streptozotocin diabetic rats.

Administration of STZ prior to mating, induced significant impairment in glycogen metabolism in term rat placentae. Glycogen retention was observed in the treated placentae, while glycogen synthetase activity was reduced. The glycogenolytic pathway seemed to proceed mainly through amyloglucosidase enzyme whose activity increased threefold. Glucose-6-phosphatase showed a moderate activation, mainly in the labyrinth zone, while phosphorylase was slightly inhibited. These changes were accompanied by a decrease in placental insulin levels. The possible defensive role played by the placenta in cases of maternal hyperglycemia was postulated.     

Placentation in the degu (Octodon degus): analogies with extrasubplacental trophoblast and human extravillous trophoblast

This study examined the placentation in the degu, the origin of the extrasubplacental trophoblast (EST) (extravillous trophoblast in human), and the activity of Na+/K+ ATPase in the placental barrier during different gestational ages, as part of a wider effort to understand the reproductive biology of this species. Fifteen degus at the first stage of gestation, midgestation and at term of pregnancy were studied. At day 27 of gestation, the subplacenta is formed under the wall of the central excavation. Simultaneously, the outermost trophoblast of the ectoplacental cone differentiated into secondary trophoblast giant cells that lie on the outside of the placenta, forming an interface with the maternal cells in the decidua. These giant cells immunostained positive for cytokeratin (CK) and placental lactogen (hPL) until term. During this period, the EST merged from the subplacenta to the decidua and immunostained negative for CK, but at term, immunostained for CK and hPL in the maternal vessels. The vascular mesenchyme of the central excavation invaded the chorioallantoic placenta during this period, forming two fetal lobules of labyrinthine-fine syncytium, the zone of the placental barrier. The activity of Na+/K+ ATPase in the placental barrier was constant during the gestational period. The residual syncytium at the periphery of the placental disc and between the lobules was not invaded by fetal mesenchyme and formed the marginal and interlobular labyrinthine syncytium that immunostained first for CK, and later for hPL, as in the labyrinthine fine syncytium. The presence of intracytoplasmic electron-dense material in the interlobular labyrinthine syncytium suggested a secretory process in these cells that are bathed in maternal blood. Placentas obtained from vaginal births presented a large, single lobe, absence of the subplacenta, and a reduced interlobular labyrinthine syncytium. At day 27, the inverted visceral yolk sac is observed and its columnar epithelium immunostained for CK and hPL. This suggests that the yolk sac is an early secretory organ. The epithelium of the parietal yolk sac covers the placenta. The origin of the EST in the degu placenta and its migration to maternal vessels allows us to present this animal model for the study of pregnancy pathologies related to alterations in the migration of the extravillous trophoblast.     

Fine structure of the transitional zone of the rat seminiferous tubule

An electron microscopic study was made on the structure of the testicular transitional zone (TZ) in the adult rat. The TZ proper consists of modified Sertoli cellss, with only a few spermatogonia and macrophages, surrounding distally a very narrow lumen. The TZ Sertoli cells have nuclei with a somewhat coarser matrix and more peripheral heterochromatin than Sertoli cell nuclei of the nearby seminiferous tubules, and the electron density of the cytoplasm varies from cell to cell. Smooth endoplasmic reticulum is abundant, but usually there are also scattered ribosomal rosettes and an occasional profile of rough endoplasmic reticulum. Microtubules are very numerous in the columnar portion of the cell, and laminar structures seemingly joining the cell surfaces are sometimes seen. Lipid droplets and lysosmal structures are frequent cellular components in proximal TZ Sertoli cells. Empty intracellular vacuoles are abundant, sometimes arranged around areas of smooth endoplasmic reticulum. Occasionally, membrane-limited fine granules and vacuoles are seen within Sertoli cells and also in the TZ lumen, suggesting a possible secretory activity by these cells. The apical processes of the Sertoli cells form large vacuolar structures, and in the basal parts of the epithelium vacuoles with capillary-like appearance are frequently seen. Phagocytosis of germinal cells by the Sertoli cells occurs in the proximal region of the TZ. Round waste bodies in contact with the Sertoli cell apices protruding into the tubulus rectus, are also common. The tunica propria of the TZ is thickened and somewhat wrinkled, and in the proximal region the myoid cell layer loses its continuity and is replaced by fibroblasts. The epithelium of the tubulus rectus adjacent to the TZ consists of several overlapping epithelial cells. The typical junctional complexes between TZ Sertoli cells appear to be impermeable to the lanthanum tracer.     

Placentation in the degu (Octodon degus): Analogies with extrasubplacental trophoblast and human extravillous trophoblast

This study examined the placentation in the degu, the origin of the extrasubplacental trophoblast (EST) (extravillous trophoblast in human), and the activity of Na⁺/K⁺ ATPase in the placental barrier during different gestational ages, as part of a wider effort to understand the reproductive biology of this species. Fifteen degus at the first stage of gestation, midgestation and at term of pregnancy were studied. At day 27 of gestation, the subplacenta is formed under the wall of the central excavation. Simultaneously, the outermost trophoblast of the ectoplacental cone differentiated into secondary trophoblast giant cells that lie on the outside of the placenta, forming an interface with the maternal cells in the decidua. These giant cells immunostained positive for cytokeratin (CK) and placental lactogen (hPL) until term. During this period, the EST merged from the subplacenta to the decidua and immunostained negative for CK, but at term, immunostained for CK and hPL in the maternal vessels. The vascular mesenchyme of the central excavation invaded the chorioallantoic placenta during this period, forming two fetal lobules of labyrinthine-fine syncytium, the zone of the placental barrier. The activity of Na⁺/K⁺ ATPase in the placental barrier was constant during the gestational period. The residual syncytium at the periphery of the placental disc and between the lobules was not invaded by fetal mesenchyme and formed the marginal and interlobular labyrinthine syncytium that immunostained first for CK, and later for hPL, as in the labyrinthine fine syncytium. The presence of intracytoplasmic electron-dense material in the interlobular labyrinthine syncytium suggested a secretory process in these cells that are bathed in maternal blood. Placentas obtained from vaginal births presented a large, single lobe, absence of the subplacenta, and a reduced interlobular labyrinthine syncytium. At day 27, the inverted visceral yolk sac is observed and its columnar epithelium immunostained for CK and hPL. This suggests that the yolk sac is an early secretory organ. The epithelium of the parietal yolk sac covers the placenta. The origin of the EST in the degu placenta and its migration to maternal vessels allows us to present this animal model for the study of pregnancy pathologies related to alterations in the migration of the extravillous trophoblast.     

Trophoblast glycogen cells differentiate early in the mouse ectoplacental cone: putative role during placentation

The role of differentiated trophoblast glycogen cells (GCs) in the ectoplacental cone (EPC) has not been elucidated yet. Recently, GC progenitors have been shown to be present from embryonic day 7.5 (E7.5), but glycogen is found in GC only from E10.5. Herein, we investigated the origin, localization and characterization of mouse GCs in EPC and their relationship with blood cells and trophoblast giant cells (TGCs) during placentation. Implantation sites (E5.5–E12.5) were processed for histological studies, histochemical detection (glycogen) and immunohistochemical staining (Ki67). Three-dimensional reconstruction of the EPC was obtained from suitably oriented embryos at E7.5. Our findings evidence that GCs are present and assembled in clusters from E6.5 to E12.5, and that they exhibit the classic vacuolated appearance and contain PAS-positive glycogen, which is amylase-sensitive and acetylation-resistant. In fact, only GCs were stained after acetylation, confirming unequivocally their presence in tissues. At E6.5, GCs showed numerous mitoses and vacuoles with scattered glycogen particles. At E7.5, GCs showed low numbers of mitoses and abundant vacuoles full of glycogen. During E7.5–E8.5, GCs were in close proximity to TGCs, and cells were intercalated by thin maternal blood spaces; placental GCs lost maternal blood contact during E9.5–E12.5. Our results indicate that GCs are originated and proliferate in the upper portion in the midregion of EPC at E6.5, and that at E7.5–E8.5 they show consistent glycogen deposits, which are likely metabolized to glucose. This compound may be directly transferred to circulating maternal blood, and used as a source of energy by GCs and TGCs during placentation.     

Ultrastructural localization of phosphatases in the testes of the domestic fowl: Acid phosphatase and thiamine pyrophosphatase

Summary ACPase and TPPase activity has been examined in the germinal epithelium of the testes in the domestic fowl. ACPase activity in spermatogonia and spermatocytes was confined to the Golgi complex. In spermatids ACPase activity was seen in the endoplasmic reticulum and nuclear envelope in the phase I and especially in the phase II (the elongating phase). This activity gradually decreased during the next phase III, and had disappeared in the final phase IV. The membrane body showed ACPase reaction in the small peripheral vacuoles and cisternal structures surrounding large central vacuoles. ACPase was also present in vesicles surrounding the developing tail. Late spermatids showed an abundance of autophagic vacuoles which had a complex array of ACPase positive delimiting membranes. In Sertoli cells ACPase activity was predominant in the lysosomes. TPPase activity was seen in the cisternae of the Golgi complex in spermatogonia and spermatocytes. In spermatids activity was present in the endoplasmic reticulum during the phase II, but it is lost in later stages. The smaller vacuoles and cisternal structures in the membrane body also showed reaction products. According to the present results it is thought likely that the smaller vacuoles and cisternal structures of the membrane body are of endoplasmic reticulum origin. The autophagic vacuoles in spermatids and the lysosomes of Sertoli cells are considered responsible for the degradation of residual bodies cast off by spermatids.     

Crohn’s disease of the colon: ultrastructural changes in submuscular interstitial cells of Cajal

Interstitial cells of Cajal (ICC) at the submuscular border of the human colon (ICC-SMP) are the proposed pacemaker cells of the musculature. In patients with Crohn’s disease (CD) of the colon, ICC-SMP showed characteristic cytological changes from controls. The changes comprised secondary lysosomes in connection with lipid droplets and cytoplasmic vacuoles or multiple empty, confluent and often outbulging vacuoles merging with cisterns of granular endoplasmic reticulum and clusters of glycogen granules. These changes were most pronounced in patients with macroscopical mucosal inflammation but were also demonstrable in uninvolved colonic segments. Relationships of ICC to other cells were undisturbed. The changes were selective to ICC-SMP, as glial cells, muscle cells and fibroblast-like cells at the submuscular border showed no cytological alterations compared with controls. Varicosities of the submuscular plexus were often empty and dilated. Fibroblast-like cells selectively encased macrophages and mast cells. The cytological changes in ICC-SMP in CD are thus similar to changes seen in ulcerative colitis and may be of pathophysiological significance with regard to the motility and sensory disturbances seen in patients with CD.     

The fine structure of ventral prostatic secretory epithelial cells in older rats

Summary The ventral prostatic secretory epithelial cells in older rats were studied by light and electron microscopy. The cells vary in height in different parts of the same organ, and ultrastructurally they show the presence of a developed secretory apparatus such as well-developed Golgi body and abundant rough endoplasmic reticulum. They also show signs of a depressed secretory activity, involving occasional emiocytosis of apical secretory vacuoles and a paucity of condensing vacuoles in the Golgi region and above it. Further, they are characterized by the frequent occurrence of supra and paranuclear pleomorphic lysosomes.