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PubMed1985

Ultrastructure of the articular cartilage of the mandibular condyle: aging and degeneration.

To obtain more insight into the pathogenesis of osteoarthrosis of the temporomandibular joint, we examined the ultrastructure of articular cartilage of six healthy and sixteen osteoarthrotic human mandibular condyles. Ultrastructural changes due to aging and osteoarthrosis are described and compared with the findings of other ultrastructural studies of articular cartilage of synovial joints. Aging was accompanied by some slight degenerative signs. Osteoarthrotic hyaline cartilage and fibrocartilage showed a striking similarity. The only ultrastructural difference was the presence of elastic fibers in the latter. Therefore, both seem to have the same pathogenesis. Several current statements on the pathogenesis of osteoarthrosis are discussed.

Adolescent↗
PubMed1987

Ultrastructural morphology and cellular differentiation in acinic cell carcinoma.

Acinic cell carcinomas, in some instances, contain a component of intercalated duct cells. However, the manner in which this element is integrated within the more obvious acinar cells, as well as the role neoplastic intercalated duct cells play in determining morphologic patterns in acinic cell tumors, has not been fully investigated. Ultrastructural study and immunostaining with antibodies to cytokeratins and to S-100 protein carried out in nine cases of parotid acinic cell carcinoma suggest two basic differentiation patterns. In three cases, the lesions were essentially composed of acinar cells (with variation in the number and form of secretory granules), and one of these tumors was unique in having ultrastructural evidence of differentiated myoepithelial cells. In the second group of six cases, there was light microscopic, ultrastructural, and immunohistochemical evidence of a significant component of intercalated duct cells. By means of both immunostaining (intercalated ducts were positive for keratin and S-100 protein; acinar cells were negative for both antigens) and electron microscopy, flattened-to-cuboidal intercalated duct cells were noted to enclose and, presumably, to be involved in the formation of microcystic spaces. Acinic cell carcinomas with a more solid growth pattern contained groups of intercalated duct cells positive for keratin and S-100 protein. Ultrastructurally, these cells were organized into well-formed ducts related to nests of acinar cells. Acinic cell carcinoma is another class of salivary gland tumor in which there can be an integrated proliferation of intercalated duct and acinar cells and, infrequently, of myoepithelial cells, all organized in a simulation of the intercalated duct-acinar unit of the normal salivary gland.

Carcinoma↗
PubMed1989

Microtubules, organelle transport, and steroidogenesis in cultured adrenocortical tumor cells. 2. Reversibility of taxol's inhibition of basal and ACTH-induced steroidogenesis is unaccompanied by reversibility of taxol-induced changes in cell ultrastructure.

Taxol inhibits the basal and ACTH-stimulated steroidogenesis of cultured mouse adrenocortical tumor cells, presumably by preventing the arrival of cholesterol in mitochondria. In these cells, taxol polymerizes and rearranges microtubules, disperses SER masses, disrupts the Golgi, and impedes the formation of cholesterol-containing lysosomes. However, taxol's alterations in ultrastructure appear likely to permit both a microtubule-based organelle transport proposed to bring mitochondria of unstimulated cells close to alternate sources of cholesterol--the SER and lipid droplets--and postulated ACTH-caused increases in these encounters. Conceivably, taxol may prevent the transfer of cholesterol from the SER and lipid droplets to mitochondria, once the meetings are achieved. To investigate this possibility, we determined the reversibility of taxol's ultrastructural effects and inhibition of steroidogenesis. Primary cultured adrenal tumor cells were incubated for 4 hr with and without ACTH (10 mU/ml). with taxol (50 micrograms/ml), and with ACTH and taxol 50 simultaneously. Some cultures from each set were washed with fresh medium and re-incubated for 1.5 hr. with and without ACTH. Media taken from cultures at the ends of pre- and post-washout incubations were analyzed for the presence of secreted steroids. Sample cultures were fixed for electron microscopy at the ends of both incubations. Data derived from pre-washout incubations confirmed previous reports of taxol's ultrastructural changes and inhibition of steroidogenesis. When cells recovered from taxol in the absence of ACTH, the inhibition of steroidogenesis was completely reversed. In the presence of ACTH, ex-taxol-treated cells demonstrated a "rounding up' and an increased steroid production that are characteristic responses to the hormone. However, in all cases, there was a persistence of taxol's alterations in organelle numbers and arrangements. Our findings establish that the ultrastructural effects of taxol which we recorded cannot prevent mitochondria of unstimulated and ACTH-stimulated adrenal tumor cells from gaining cholesterol. They strengthened the possibility that in pre-washout incubations, taxol allowed organelle motility to bring mitochondria adjacent to cholesterol-containing SER tubules and lipid droplets, but inhibited steroidogenesis by preventing the cholesterol transfer. Taxol might limit the availability of a protein required for the transfer, an effect not visible in our electron micrographs.

Adrenal Cortex Hormones↗
PubMed1989

Trophoblastic tumors: ultrastructural comparison of choriocarcinoma and placental-site trophoblastic tumor.

Ten trophoblastic tumors, including seven classical choriocarcinomas, two choriocarcinomas with atypical histology, and one placental-site trophoblastic tumor (PSTT), were studied to compare their fine structural features. Ultrastructurally, the classical choriocarcinomas showed well-defined cytotrophoblasts and syncytiotrophoblasts. The cytotrophoblasts were primitive epithelial cells, while the syncytiotrophoblasts were complex cells with multiple nuclei and dense cytoplasm containing dilated endoplasmic reticulum, lysosomes, vesicles, and tonofilaments. The syncytiotrophoblast cell membranes often contained numerous microvilli. In the choriocarcinomas, scattered intermediate trophoblasts showed features transitional between the cytotrophoblasts and the syncytiotrophoblasts, with moderately complex cytoplasm containing some of the organelles found in the syncytiotrophoblasts. Histologically, the atypical choriocarcinomas showed a predominance of mononucleate and binucleate cells and indistinct syncytiotrophoblasts. Ultrastructurally, these atypical tumors were composed largely of intermediate trophoblasts, yet contained scattered syncytiotrophoblasts with microvilli in compressed aggregates. The PSTT was composed primarily of intermediate trophoblasts that contained prominent paranuclear filaments not seen in the intermediate trophoblasts of the choriocarcinomas. Rare cells resembling syncytiotrophoblasts were found in the PSTT, but no cytotrophoblasts were observed. Immunoreactivity for human chorionic gonadotropin and human placental lactogen was found in the intermediate trophoblasts and syncytiotrophoblasts of both the choriocarcinomas and the PSTT, demonstrating functional homology between these tumors despite some ultrastructural differences. These results demonstrate ultrastructural features of trophoblastic cells that correlate with the morphologic diversity seen in these tumors by light microscopy. Furthermore, the comparisons suggest that the PSTT is composed of a distinct form of intermediate trophoblast that appears to reflect its origin from the extravillous trophoblast.

Choriocarcinoma↗
PubMed1990

Immunohistochemical and ultrastructural studies of twelve argentaffin and six argyrophil carcinoids of the appendix vermiformis.

Endocrine cell types in 12 argentaffin and six argyrophil carcinoids and in nonneoplastic epithelia of the appendix vermiformis were investigated histochemically, immunohistochemically, and ultrastructurally. The nonneoplastic epithelia contained serotonin (Ser), peptide YY (PYY), glicentin (Gli), neurotensin (Neu), and somatostatin (So) cells in decreasing frequency. Out of 30 nonneoplastic Ser cells examined ultrastructurally, 28 cells were EC1 cells and two were non-EC cells. Eleven of 12 argentaffin carcinoids could be immunostained with anti-Ser serum and all of those 11 were composed almost totally of Ser cells. One of the 11 contained a small number of Neu cells. Ultrastructurally, 11 argentaffin carcinoids were composed predominantly of EC1 and/or ECn cells, and one was composed primarily of non-EC cells. Out of the six argyrophil carcinoids, five were argyrophil, non-argentaffin carcinoids; three consisted almost totally of PYY cells; one consisted of 60% PYY cells, 40% So cells and a few Gli cells; and one consisted of Ser cells alone. Ultrastructurally, the first four of those tumors were composed of D1 and/or L cells and the latter tumor was composed of ECn cells. The remaining one argyrophil carcinoid contained a few Ser-positive argentaffin cells and consisted almost totally of ECn cells which were found in both parts, with and without argentaffinity. It is concluded that the appendiceal carcinoids comprise two distinct groups on the basis of the main constituting cell type: Ser-positive, argentaffin carcinoids, composed of EC cells and peptide (especially of PYY)-positive, and Ser-negative, argyrophil non-argentaffin carcinoids of D1 and/or L cells.

Adolescent↗
PubMed1983

Hormone-producing capabilities of renal cell carcinomas. Correlation with ultrastructural findings.

A retrospective study was conducted to evaluate ultrastructural aspects of hormone production by renal cell carcinomas. Fifteen renal cell carcinomas examined ultrastructurally were retrieved from the files. Six cases revealing abundant and diffusely distributed secretory granules in the neoplastic cells were found and correlated with clinical manifestations and laboratory findings. Five of these patients were hypercalcemic; the sixth patient was asymptomatic, and no abnormalities were detected in routine laboratory workup. Two additional cases showed focal aggregates of electron dense neurosecretory granules. These last 2 patients had no biochemical abnormalities and were entirely asymptomatic. The size and ultrastructural morphology of the cytoplasmic granules identified in the renal neoplasms were compared with the usual granular morphology associated with the specific hormones involved. Immunohistochemistry was used to confirm the parathormone hormone content of the granules in 7 of the 8 cases presented. The other case revealed granules with ultrastructural characteristics of prostaglandin granules.

Adenocarcinoma↗
PubMed1985

Ultrastructural study of cultured smooth muscle cells from uterine leiomyoma and myometrium under the influence of sex steroids.

Upon the hypothesis that the differentiation or development of smooth muscle cells in both myometrium and leiomyomas may be under the regulation of sex steroids, myometrial and myoma cells were cultured in the presence of sex steroids and their morphological changes were studied ultrastructurally. The cells from the explants of both leiomyoma and myometrium at the 14th day in either control or E (10(-8) M 17-beta-estradiol)-added medium showed extremely well-developed cytoplasmic organelles with few filaments located at the marginal portion of the cytoplasm. These ultrastructural features resembled those of a dedifferentiated stage of smooth muscle cells in vitro. At the 21st day, these cells showed a moderate number of cytoplasmic filaments with dense bodies. These ultrastructural features resembled those of a redifferentiated stage of smooth muscle cells in vitro. In both E- and P (10(-7) M progesterone)-added medium, the cultured smooth muscle cells from both leiomyoma and myometrium showed an increased number of myofilaments with dense bodies even at the 14th day to the 21st day of culture in comparison to the cells either in control or estrogen-added medium. Therefore, the cultured smooth muscle cells in the medium with E and P lacked their dedifferentiated phase in vitro and/or the differentiation or maintenance of their filaments might be under the influence of both estrogen and progesterone. On the observation that the cultured smooth muscle cells from both leiomyoma and myometrium showed very similar ultrastructural changes under the influence of sex steroids, it was suggested that leiomyoma may have the same progenitor cells as myometrium.

Adult↗
PubMed1996

Citrinin produces acute adverse changes in renal function and ultrastructure in pentobarbital-anesthetized dogs without concomitant reductions in [potassium]plasma.

Citrinin's nephrotoxicity was examined in pentobarbital-anesthetized dogs under conditions that minimized or avoided significant changes in a number of its actions that could indirectly and adversely affect renal function and ultrastructure, such as, (i) major acute reductions in blood pressure and renal blood flow and, (ii) emesis and diarrhea that could lead to dehydration and electrolyte imbalances, especially hypokalemia. Slow intravenous injection of 20 mumol citrinin/kg to pentobarbital-anesthetized dogs did not induce any alterations in renal tissue ultrastructure or in any of the 23 whole blood, plasma or renal function parameters that were monitored over a 6-h post-citrinin period. On the other hand, 80 mumol citrinin/kg produced significant increases in the hematocrit and in the renal excretion rates of protein and glucose; modest reductions were noted in CIN, RBF and excretion rate of inorganic phosphorus. In addition, 80 mumol citrinin/kg induced ultrastructural lesions in the cells of the S2 proximal tubular segment, the thick ascending limb, the distal convoluted tubule and the collecting ducts. The glomeruli, S1 and S3 cells of the proximal tubule and the thin descending and ascending limbs of Henle's loop were unaffected by both citrinin doses. The location and nature of the adverse ultrastructural lesions were most likely the result of the direct actions of citrinin (or a citrinin metabolite) since the effects of citrinin that could lead to indirect adverse renal effects were totally avoided or greatly minimized.

Anesthesia, Intravenous↗
PubMed1980

Early effect of estrogen on chromatin ultrastructure in endometrial nuclei.

The effect of estradiol on chromatin ultrastructure in interphase nuclei was studied in immature rat and lamb endometrium. Physiological doses of estradiol within the first hour transformed the condensed chromatin into dispersed chromatin both in vivo and in vitro. These ultrastructural modifications were specifically induced by hormones translocating the estrogen receptor to the nucleus of estrogen-responsive tissues. Conversely, the antiestrogen tamoxifen gave a hypercondensation of chromatin. The addition of actinomycin D, cordycepin or alpha-amanitin, but not of cycloheximide, prevented the effect of estradiol both on the ultrastructural change and on [3H]uridine incorporation, suggesting that chromatin decondensation was closely related to transcriptional activity. These results indicate that in endometrium, estrogen rapidly provokes a large and extended modification of chromatin ultrastructure, which suggest a general effect on chromatin function rather than a selective activation of a limited number of genes.

Animals↗
PubMed1996

Testosterone effects on the neuronal ultrastructure in the medial preoptic nucleus of male Japanese quail.

Dorsolateral neurons of the medial preoptic nucleus (POM) of male Japanese quail are sensitive to the plasma levels of testosterone: their volume and optical density in Nissl-stained sections increase in castrated birds treated with testosterone. The present study was performed on castrated male quail treated or not with Silastic implants filled with testosterone to describe the ultrastructural variations induced by testosterone in these neurons. Gonadally intact male birds were included as controls. The ultrastructure of neurons, taken from the dorsolateral portion of the POM, was dramatically affected by the endocrine manipulations. Quantitative evaluations demonstrated a significant decrease in castrated birds of the rough endoplasmic reticulum (RER), of free polyribosomes, of Golgi complexes, and of dense bodies; these changes paralleled the decrease in cell size. The cell size and the percentage of volume occupied by the intracellular organelles in castrated birds treated with testosterone were comparable to values observed in controls. These ultrastructural changes are similar to those observed in neuronal targets for other gonadal hormones, supporting the idea that testosterone stimulates the development of cytoplasmic structures involved in protein synthesis and secretion. In addition, exposure to testosterone affects the synaptic inputs to POM. These ultrastructural changes are presumably related to the physiological effects (e.g., activation of male sexual behavior) exerted by testosterone on this preoptic region.

Analysis of Variance↗
PubMed1987

Chronic ultrastructural changes in acoustic trauma: serial-section reconstruction of stereocilia and cuticular plates.

Two cochleas with permanent, noise-induced threshold shifts of 40 to 60 dB (as measured by responses of single, auditory-nerve fibers) were analyzed in detail, first at the light-microscopic level, and subsequently with transmission electron microscopy of serial sections. The light-microscopic analysis showed that there was little hair cell loss, but widespread damage to the stereocilia, especially those on the inner hair cells and first-row outer hair cells. Transmission electron microscopy revealed no pathology in any cells or organelles in the organ of Corti except for the stereocilia and their rootlets. Stereocilia tufts on first-row OHCs and IHCs were badly damaged; those on second- and third-row OHCs appeared ultrastructurally normal. Within the IHC tuft, the damage to the tall, outer row of stereocilia was often selective: the shorter rows could remain ultrastructurally normal even when the tall row was completely missing. The data suggested that most of the structures which appear normal in a careful light-microscopic analysis are also normal at the ultrastructural level. This strengthens earlier suggestions that the correlations between light-microscopic stereocilia changes and alterations in single-unit physiology are causal in nature. The most common stereocilia pathologies were fracture, attenuation or complete loss of the stereociliary rootlets, especially in the region of the cuticular plate near the endolymphatic surface of the cell. The degree and extent of these changes were well correlated with the degree and extent of stereocilia disarray. Abnormalities of the actin-filament matrix within the stereocilia were extremely rare in unfused stereocilia, however, they were common when the stereocilia were part of a fusion bundle. Fusion of stereocilia was always associated with ectopic supracuticular cytoplasm. Based on the ultrastructural observations, different sequences of structural changes preceding the generation of disarray, loss or fusion of stereocilia are suggested.

Animals↗
PubMed1988

Ultrastructure of three-dimensionally localized distal nephron segments in superficial cortex of the rat kidney.

The ultrastructure of superficial distal nephron segments was analyzed after precise localization of tubule cross sections using computer-assisted three-dimensional reconstructions. Five systems of tubules, each with three interconnected distal tubules, were reconstructed and the lengths of the post macula densa segment of the distal straight tubule (DST), the distal convoluted tubule (DCT), the connecting tubule (CNT), and the initial collecting tubule (ICT) were determined. Each cortical collecting duct (CCD) was in continuity with only one tubule in contact with the renal capsule. In three of the five reconstructions, the two nonsubcapsular tubules fused and had a common connection to the subcapsular tubule. The length, between the macula densa (MD) and the confluence, of subcapsular tubules (2.68 +/- 0.15 mm) significantly exceeded the length of tubules not in contact with the renal capsule (2.05 +/- 0.10 mm). This difference was mainly due to a longer ICT in subcapsular tubules. Subcapsular tubules always contacted the renal capsule in the early DCT and often again in the ICT. Cells in the early DCT showed more microvilli on the luminal surface and more infoldings of basolateral membranes than cells in the late DCT. The ultrastructure of intercalated cells (I cells) varied within a range of different manifestations and the ultrastructural variation of I cells was similar in all the analyzed tubule segments. Connecting tubule cells and principal cells were similar in ultrastructure in all tubule segments and cortical levels analyzed.

Animals↗
PubMed1991

Ultrastructural morphometry of human leucocytes in health and disease.

In this review, the literature on ultrastructural morphometry of each of the main types of human blood leucocytes has been considered, together with the technical and numerical procedures essential for valid analysis. Quantitative data have been reported for these cell types in health and comparisons have been made with those in disease states. In monocytes, and in macrophages developing from them, subtle ultrastructural differences have been detected and quantitated in malignant lymphoma; as the mononuclear phagocytes were not themselves neoplastic, the changes may have related to defects in host defence. Change in the ultrastructural characteristics of leukaemic monoblasts have also been reported. Lymphocytes and malignant lymphoid cells have been extensively investigated: differences between different types and subsets have been shown to be present in both normal lymphocytes and their malignant counterparts in leukemias and lymphomas. Particular attention has been paid to morphometric assessment of nuclear shape and size in these disorders and to its possible value as a diagnostic tool. Granulocytes have so far been the subject of few morphometric studies, although in hypereosinophilic syndrome, cellular changes have been defined and have thrown light on the abnormal pattern of degranulation. There have also been scattered reports on the cells of acute myelogenous leukaemia. The use of computers and sophisticated statistical packages has greatly facilitated the application of multiple comparison procedures and has permitted discriminant analysis to be carried out where appropriate. This review shows that ultrastructural morphometry of leucocytes will have an increasing application in clinical pathology.

Granulocytes↗
PubMed1995

Left ventricular hypertrophy in spontaneously hypertensive rat: effects of ACE-inhibition on myocardiocyte ultrastructure.

The aim of this study is to investigate the effects of two ACE-inhibitors with different chemical formulae, cilazapril (CLZ) and captopril (CPT), on left ventricular myocardiocytes from spontaneously hypertensive rats (SHR), characterized by ultrastructural alterations associated with left ventricular hypertrophy, and from Wistar-Kyoto (WKY) rats, considered as controls. After CLZ-treatment, not remarkable changes are observed in WKY myocardiocytes, whereas SHR ones show a considerable reduction in their original alterations in ultrastructure. After CPT-treatment, both SHR and WKY myocardiocytes are altered in ultrastructure. The morphometric investigation confirms that CPT and CLZ produce different effects. Even if the drugs induce a similar decrease in blood pressure and left ventricular mass index, CLZ unlike CPT seems to improve the ultrastructural abnormalities associated with left ventricular hypertrophy. These changes could be related to the different chemical structure of CLZ and CPT, or to a different affinity of the two drugs for the local renin-angiotensin system.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2006

Phenotype and enamel ultrastructure characteristics in patients with ENAM gene mutations g.13185-13186insAG and 8344delG.

OBJECTIVE: The main clinical manifestations of amelogenesis imperfecta (AI) include alteration in the quality and quantity of enamel. AI is associated with different mutations in four genes: enamelin (ENAM), amelogenin (AMGX), kallikrein (KLK4) and enamelysin (MMP-20). Seven different mutations have been identified in the enamelin gene (ENAM). DESIGN: In this paper, we describe the phenotype and ultrastructure of enamel observed using scanning electron microscopy (SEM) in patients with two autosomal dominant (AD) mutations in the ENAM gene: g.13185-13186insAG and g.8344delG, each in one of two unrelated families. Mutations were confirmed by sequence analysis of PCR amplified products of all 10 exons and exon/intron boundaries of the ENAM gene. RESULTS: Phenotypic diversity was observed in patients with ENAM gene mutations g.13185-13186insAG with consecutive protein alteration designated as p.P422fsX488 within family 1. In the proband, the enamel of his entire dentition was chalky white with only mild local hypoplastic alteration, while the phenotypic appearance of his father's dentition was that of local hypoplastic AI. In patients with the ENAM gene mutation g.8344delG from family 2 with consecutive protein alteration designated as p.N197fsX277, generalised hypoplastic AI was observed. CONCLUSIONS: Ultrastructural enamel changes in the patient with the autosomal dominant ENAM g.13185-13186insAG mutation, described for the first time in this study, were less pronounced compared to ultrastructural changes in patients with the autosomal dominant ENAM mutation 8344delG. Ultrastructural characteristics of the g.13185-13186insAG mutation revealed deformed prisms, an oval shape on the cross-section and wider interprism spaces, while enamel with the ENAM mutation 8344delG was laminated, but prismless.

Amelogenesis Imperfecta↗
PubMed2005

Antiproliferative and ultrastructural effects of BPQ-OH, a specific inhibitor of squalene synthase, on Leishmania amazonensis.

Parasites of the Leishmania genus require for the growth and viability the de novo synthesis of specific sterols as such as episterol and 5-dehydroepisterol because cholesterol, which is abundant in their mammalian hosts, does not fulfill the parasite sterol requirements. Squalene synthase catalyzes the first committed step in the sterol biosynthesis and has been studied as a possible target for the treatment of high cholesterol levels in humans. In this work we investigated the antiproliferative and ultrastructural effects induced by 3-(biphenyl-4-yl)-3-hydroxyquinuclidine (BPQ-OH), a specific inhibitor of squalene synthase, on promastigote and amastigote forms of Leishmania amazonensis. BPQ-OH had a potent dose-dependent growth inhibitory effect against promastigotes and amastigotes, with IC(50) values 0.85 and 0.11 microM, respectively. Ultrastructural analysis of the treated parasites revealed several changes in the morphology of promastigote forms. The main ultrastructural change was found in the plasma membrane, which showed signs of disorganization, with the concomitant formation of elaborated structures. We also observed alterations in the mitochondrion-kinetoplast complex such as mitochondrial swelling, rupture of its internal membrane and an abnormal compaction of the kinetoplast. Other alterations included the appearance of multivesicular bodies, myelin-like figures, alterations of the flagellar membrane and presence of parasites with two or more nuclei and kinetoplasts. We conclude that the BPQ-OH was a potent growth inhibitor of L. amazonensis, which led to profound changes of the parasite's ultrastructure and might be a valuable lead compound for the development of novel anti-Leishmania agents.

Animals↗
PubMed2006

Ultrastructure of preimplantation genetic diagnosis-derived human blastocysts grown in a coculture system after vitrification.

OBJECTIVE: To evaluate ultrastructural features of preimplantation genetic diagnosis (PGD) blastocysts before and after vitrification. DESIGN: Descriptive study of both vitrified and fresh hatching blastocysts. SETTING: PGD program at the Instituto Universitario, Instituto Valenciano de Infertilidad. PATIENT(S): Patients undergoing PGD donated their abnormal embryos for research (n = 26). INTERVENTION(S): Biopsied embryos were cultured in the presence of human endometrial cells until day 6. Sixteen blastocysts were vitrified. A total of 11 high-scored hatching blastocysts, 6 warmed and 5 fresh, were fixed for ultrastructure. MAIN OUTCOME MEASURE(S): The cytoskeleton structure, type of intercellular junctions, and basic intracellular organelles in trophoectoderm cells and the inner cell mass were analyzed. RESULT(S): Ten of 16 blastocysts (62%) survived the warming process. Six of these showed no signs of cell degeneration and light microscopy revealed similar ultrastructural characteristics to those of controls. However, in trophoectoderm cells from both fresh and cryopreserved blastocysts, a reduced number of tight junctions and the presence of degradation bodies were detected. CONCLUSION(S): The particular ultrastructural features observed in PGD-derived blastocysts could be related to embryo manipulation and culture conditions. Vitrification does not seem to alter blastocysts, as those that survive hatching do not display detectable cellular alterations when observed through electron microscopy.

Blastocyst↗
PubMed2004

Ultrastructural differentiation of Toxoplasma gondii schizonts (types B to E) and gamonts in the intestines of cats fed bradyzoites.

The ultrastructural characterisitics of four types of Toxoplasma gondii schizonts (types B, C, D and E) and their merozoites, microgamonts and macrogamonts were compared in cats killed at days 1, 2, 4 and 6 after feeding tissues cysts from the brains of mice. Schizonts, merozoites and gamonts contained most of the ultrastructural features characteristic of the phylum Apicomplexa. All four types of schizonts developed within enterocytes or intraepithelial lymphocytes. Occasionally, type B and C schizonts developed within enterocytes that were displaced beneath the epithelium into the lamina propria. Type D and E schizonts and gamonts developed exclusively in the epithelium. Tachyzoites occurred exclusively within the lamina propria. Type B schizonts formed merozoites by endodyogeny, whereas types C to E developed by endopolygeny. The parasitophorous vacuoles surrounding type B and C schizonts consisted of a single membrane, whereas those surrounding types D and E schizonts were comprised of two to four electron-dense membranes. The parasitophorous vacuole of type B schizonts had an extensive tubulovesicular membrane network (TMN); the TMN was reduced or absent in type C schizonts and completely absent in types D and E schizonts and gamonts. Type B merozoites were ultrastructurally similar to tachyzoites, except that they were slightly larger. Type C merozoites exhibited a positive periodic acid-Schiff reaction by light microscopy and ultrastructurally contained amylopectin granules. Rhoptries were labyrinthine in type B merozoites but were electron-dense in types C-E. The development of microgamonts, macrogamont and oocysts is also described.

Amylopectin↗