Bibliothek

Notizen: Abstract Five cases of giant inflammatory polyps associated with idiopathic inflammatory bowel disease are reported. Polyps produced intestinal obstruction in three cases; consequently, surgery was performed. In a further two cases, intestinal bleeding was improved by endoscopic polypectomy. Electron microscopy showed fibroblasts, myofibroblasts, mast cells, lymphocytes, collagen fibers, capillaries, and venules. Remnants of the original mucosal epithelial cells, smooth muscle cells, and hypertrophic autonomous nerve plexuses were noted. Nerve fibers were interwoven with the matrix of the polyps. Mast cells were closely linked with vessels, nerves, and collagen fibers. They may have an important role in the excessive granulation, angiogenesis, and fibrotic process in giant inflammatory polyps.

Notizen: Summary The functionally important lining cells of the synovium (types A and B synoviocytes) are the subjects of much study but have presented problems with their characterization and microscopical identification, particularly at the light level. Type A (macrophage-like) synoviocytes, however are more easily localized than the type B (fibroblast-like) variety because of the greater availability of antimacrophage antisera. We describe, using light and electron microscopy, a monoclonal antibody which in the synovial intimal layer is specific for type B synoviocytes.

Notizen: Summary A series of 29 cellular schwannomas is described in terms of their clinical presentation and course, light and electron-microscopic appearance, immunohistochemical properties and cytogenetics. The study indicates that cellular schwannoma can be defined as a subtype of classical schwannoma, characterized by spindle cells forming a compact fascicular, sometimes fibrosarcoma-like growth pattern, a low mitotic activity, a generally moderate nuclear and cellular polymorphism and a high degree of Schwann cell differentiation as seen by electron microscopy and immunohistochemistry. The tumour is characteristically located close to the vertebral column, in the mediastinum or retroperitoneum and has a benign course. Occasionally bone destruction and neurological symptoms develop. The clinical appearance together with the high cellularity, fascicular pattern and mitotic activity had led to the erroneous diagnosis of a soft tissue sarcoma in a few cases, and cellular schwannoma may thus be considered to be a pseudosarcoma. Immunohistochemically, cellular schwannomas appear to deviate from classical schwannomas and malignant peripheral nerve sheath tumours by their expression of glial fibrillary acidic protein. The chromosome analysis revealed a normal diploid stemline karyotype, with a variety of abnormal clones, including one with monosomy 22.

Notizen: Summary We report the second case of a malignant paraganglioma of the stomach in a 56-year-old female patient. However, our case is the first investigated by immunohistochemistry and electron-microscopy. The tumour was characterized immunohistochemically by the presence of neurofilament protein, glial fibrillary acidic protein, S-100 protein, neuron-specific enolase, chromogranin A, ACTH, leu-enkephalin and vasoactive intestinal polypeptide, and ultrastructurally by demonstration of neurosecretory granules and paranuclear intermediate filament whorls. Despite massive metastatic spread in the abdominal cavity, the patient is still alive 4 years after initial diagnosis.

Notizen: Summary Glomerular lesions in hereditary nephrotic mice (ICGN strain) were investigated by electron microscopy. The glomeruli of unaffected animals, which appeared normal by light microscopy, had developed an ultrastructural change in the glomerular capillary basement membrane (GCBM). There was a partial thickening of the GCBM with bilaminar splitting of the lamina densa and an electron-dense fibrillar material exhibiting cross-striations. In affected animals, light microscopy revealed a marked thickening of GCBM and an increase of mesangial matrix without cellular proliferaton. By electron microscopy, multilaminar splitting of the lamina densa in the thickened GCBMs and fusion of the epithelial foot processes were observed. In some severely affected animals, immune complex deposition was found in GCBM, but little if any was observed in other animals. In the end, the glomeruli were globally sclerosed. Our findings suggest that initial structural abnormalities in GCBM may play an important role in the onset and development of the disease, though subsequent events such as immune complex deposition would modify the disease.

Notizen: Summary Cyclosporin A (CsA) is a potent immunosuppressant with a selective activity on T-helper lymphocytes. However, CsA also exerts biological effects on non-lymphoid cells (fibroblasts, endothelial and epithelial cells). CsA can inhibit in vivo and in vitro DNA synthesis of epidermal keratinocytes (EK) and induces in vivo morphological alterations of kidney epithelial cells. In the present study we investigated the in vivo effects of a short-term CsA treatment (50 mg/kg per day) on DNA synthesis (evaluated through 5-bromo-2′-deoxyuridine incorporation) and on the histological features of normal human skin xenografted (NHSX) on to congenitally athymic nude mice. When compared with control NHSX, CsA induced a statistically significant inhibition of DNA synthesis of NHSX EK. At the light- and electron-microscopic level, apart from a decrease in the thickness of the viable epidermis of NHSX (statistically non-significant), no noticeable differences between treated and control NHSX could be detected. EK, Langerhans cells and melanocytes appeared morphologically unaffected by CsA and no signs of acute toxicity (giant mitochondria, vacuolization, microcalcifications) were seen. These results suggest that CsA exerts a subtle effect on human EK; indeed, despite an unequivocal antiproliferative activity, no significant histological changes related to the acute CsA toxicity seem to be induced on the various epidermal cell types.

Notizen: Summary Current classifications of salivary gland tumors separate mucoepidermoid carcinoma from other neoplasms on the basis of a number of histological features, in particular the lack of participation of neoplastic myoepithelial cells. However, ultrastructural examination of low- and intermediate-grade mucoepidermoid carcinomas and pleomorphic adenomas reveals many common organizational and cellular features. Of prime importance is the relationship of intermediate cells to the luminal cells in mucoepidermoid carcinomas, which is remarkably similar to that seen between modified myoepithelial cells and luminal cells in pleomorphic adenomas. The results suggest that intermediate cells of mucoepidermoid carcinoma are the counterpart of the modified myoepithelial cells of pleomorphic adenoma. The generally accepted hypothesis that the former tumor develops from an excretory duct reserve cell, while the latter originates from an intercalated duct stem cell does not seem to be valid; pleomorphic adenoma and mucoepidermoid carcinoma appear to be closely related morphologically.

Notizen: Summary The very heterogeneous population of glomeruli in rats with lithium-induced chronic nephropathy which includes small glomeruli without connection to a proximal tubule (atubular glomeruli) and large hypertropic glomeruli with connection to a normal proximal tubule, was studied at the ultrastructural level, using stereological methods. After 8 weeks of lithium treatment followed by 8 weeks without lithium the hypertrophic glomeruli showed no changes in their relative ultrastructural composition, including normal mesangium, basement membrane-like material and peripheral basement membrane. The absolute quantities of each component were, however, increased due to the increased volume of the glomeruli. The atubular glomeruli had increased volume fractions of mesangium, peripheral basement membrane, basement membrane-like material and epithelium, whereas the absolute quantities were decreased due to the decreased volume. The thickness of the basement membrane was within normal limits in the group of hypertrophic glomeruli but increased by 31% above controls in the group of atubular glomeruli. Both groups of glomeruli in lithium-treated animals showed normal mean foot process width, but with a slightly abnormal distribution. The atubular glomeruli showed a disproportionate large decrease in peripheral filtration surface and capillary length, compared with the reduction in glomerular volume, whereas the hypertrophic glomeruli showed changes in proportion with the increased volume.

Notizen: Summary Density and pattern of nerve fibers with neuropeptide Y-like immunoreactivity (NPY-LI) and substance P-like immunoreactivity (SP-LI) in the rat dura mater encephali were investigated by light and electron microscopy using whole-mount preparations. NPY-LI fibers are observed throughout the encephalic dura mater. A remarkable net of NPY-LI nerve fibers is located in the walls of the sagittal and transverse sinuses. Beyond that NPY-LI network, distinct NPY-LI nerve fibers or plexus occur in the rostral falx, parietal dura mater of the olfactory bulb, supratentorial dura mater, parietal dura mater of the cerebellum, tentorium cerebelli and the ventral dura mater. Electron microscopic studies reveal that NPY-LI is exclusively located in unmyelinated axons of small and large nerve fiber bundles, with or without a perineural sheath. Immunopositive C-fibers are predominantly associated with the vascular bed. SP-LI nerve fibers have a moderate and more uniform distribution in the encephalic dura mater. A distinct plexus of SP-LI fibers follows the branches of the middle meningeal artery and the adjacent dura mater. SP-LI fibers are most prominent in the parietal dura mater of the cerebellum. Fine beaded SP-LI fibers, arising from larger SP-LI fiber bundles, are observed in close association to the capillary bed. SP-LI axons are all unmyelinated. They are found in larger nerve fiber bundles with a perineural sheath or in Schwann cells lacking any perineural sheath. The function of NPY-LI and SP-LI nerve fibers in the rat dura mater is discussed in relation to their topography, density and termination.

Notizen: Summary Morphological changes are shown in the muscle biopsy specimens of an 8-year-old girl who suffered from a triosephosphate isomerase (TPI) deficiency, resulting in a chronic, nonspherocytic, hemolytic anemia, mental retardation and neuromuscular impairment. The newly introduced enzyme histochemical reaction for TPI demonstrated a total lack of histochemically detectable enzyme activity, whereas biochemical analysis of muscle tissue revealed less than 10% of the normal enzyme activity. Electron microscopy showed a degenerative myopathy with an increase in the amount of intracellular glycogen. Additionally, mitochondrial changes within the muscle fibers were observed to be similar to those in mitochondrial myopathies. The disturbed balance between glycerinaldehyde phosphate and dihydroxy-acetone phosphate, due to the deficiency of the TPI enzyme, is interpreted as the biochemical background of an impaired electron transport across the mitochondrial membrane, resulting in the coexistence of an impaired glycolytic pathway and an impaired mitochondrial metabolism of muscle cells.

Notizen: Summary Seven muscle biopsies from patients with the clinical characteristics of Marinesco-Sjögren syndrome (MSS) revealed myopathic changes of two types; muscle fiber necrosis followed by regeneration and focal myofibrillar degeneration inducing autophagocytosis with rimmed vacuole formation. In two young patients, massive muscle fiber necrosis with phagocytic invasion was the predominant feature and autophagic phenomenon was minimal, resembling the findings in progressive muscular dystrophy. Myofibrillar degeneration with autophagic phenomenon was prominent in five adult patients. The coexistence of these two degenerative processes and the secondarily induced reactive changes of muscle fiber hypertrophy, interstitial fibrosis, occasional ragged-red fibers and type 1 fiber predominance, are responsible for the wide spectrum of muscle pathology in MSS. The dense double-membrane structure surrounding myonuclei, previously reported as being specific to MSS, was present in only one biopsy.

Notizen: Summary We have developed a functional vegetative model by an 18-min clamping of the ascending aorta combined with a bypass formation between the aorta to right atrium and the aorta to femoral vein. Complete global brain ischemia (CGBI) induced for 18 min with this model provided the following distinct advantages: cardiopulmonary functions were well preserved during postischemic recirculation, and all dogs survived without serious extracerebral complications. Neuronal damage in vegetative dog induced by an 18-min CGBI was studied by light and electron microscopy. The Purkinje cells and the hippocampal CA1 pyramidal cells showing clumping of nuclear chromatin and slightly increased stainability were observed after CGBI without recirculation. All these neurons showed transient increased stainability with microvacuolation 15 min after recirculation. Over 50% of these neurons showed virtually normal features 1 h after recirculation. Damage to these neurons progressed again slowly up to 6 h after recirculation. However, all these neurons had disintegrated 2–3 days after recirculation. A decrease in synaptic vesicles was observed in many presynaptic terminals in the molecular layers of the cerebellum after CGBI without recirculation. These changes in the presynaptic terminals progressed 15 min after recirculation. These results indicated that the damage to the Purkinje cells and the CA1 pyramidal cells induced by CGBI consisted of two phases, and that the change in the early phase was reversible. We speculate that the damage to the Purkinje cells in the early stage is related to the decrease of the synaptic vesicles in the presynaptic terminals.

Notizen: Summary The pathways and mechanisms by which edematous fluid accumulation in the extracellular space (ECS) clears from brain are poorly understood. The objective of this study was to explore, using immunocytochemical technique, the fate of a proteinaceous fluid added to the brain ECS and to study the clearance pathways. The protein movement of this edema fluid was investigated using the direct infusion model on rats. Rat albumin (20 μl) was slowly infused into the caudate-putamen of anesthetized adult rats and the spread and clearance of the edema was followed in various brain regions using immunocytochemical and conventional light and electron microscopy at 0, 1, 2, 3, 4, 6, and 8 days post-infusion. Our studies showed that protein-rich edema fluid cleared slowly from the brain, with 8 days required for the infusion albumin to exit completely from the brain parenchyma. Immediately following infusion, the albumin was distributed in the ECS of the white matter and the overlying deep cortical layers related to the infusion site. During the next 24 h, more of the infused albumin traveled through the ECS to the cortical surface where the albumin passed through the glia limitans to reach the subarachnoid front. Additionally, at 48 h post-infusion, that albumin, which had migrated to the ventricular wall, cleared from the ECS of the subependymal white matter and the ependymal clefts to reach the ventricular cerebrospinal fluid (CSF). In edematous regions, the perivascular spaces of venules and veins were filled with reaction product. Continuity of this perivascular reaction product existed from the deep edematous area to the temporobasal subarachnoid space from where the reaction product gradually disappeared from the parenchyma. From these studies we infer that during the late state of the resolution process the edema front moves toward both the ventricle and the cortical surface to reach the CSF. Thus, among the potential routes for edema clearance, the pathways leading to CSF clearance of fluid predominated. During this clearance process, neither neurons, glia nor the vascular endothelium showed any endocytotic response to the infused albumin throughout the 8-day course. We conclude from these observations that the CSF pathway is the major route of protein-rich edema clearance, when such clearance is not complicated by any concomitant CNS perturbation.

Notizen: Summary The ultrastructure of corticotrophs in the pituitary of golden hamsters was studied by immunocytochemistry. Corticotrophs were classified into three types according to the different size of the secretory granules. Type A and B cells were oval or polygonal in shape containing small (158±38 nm) and medium-sized (250±53 nm) secretory granules, respectively. Type C cells were usually pyramidal or irregular in shape, and contained large secretory granules (380±78 nm). The cytoplasmic organelles of type B and C cells were fairly well developed. In all types of corticotrophs, the secretory granules varied in electron density, and were either arranged in a single row along the cell membrane, or concentrated in the vascular pole of the cytoplasm. Many of the corticotrophs sent processes to encircle neighboring somatotrophs. In the female, the proportions of type A and B cells were higher then those in the male, whereas that of the type C cells was lower. All three types of corticotrophs were observed in the early postnatal stage. The population of type A cells decreased with the advancement of postnatal development, with a concomitant increase of that of the type C cells. Thus, type A cells might represent the immature type of corticotrophs which would evolve to become the type C cells. One to 2 weeks after adrenalectomy, the number of type C cells was drastically increased. This was accompanied by their prominent changes in ultrastructure as in the type B cells. The cytoplasm became hypertrophic with extensive dilated cisternae of rough endoplasmic reticulum. The large Golgi apparatus displayed profiles seemingly involved in the formation of secretory granules. The number of type A cells was moderately decreased, and they showed little morphological alteration. Since type B and C corticotrophs exhibited a remarkable response to adrenalectomy, it is concluded that they represent the active state of corticotrophs.

Notizen: Summary Central neurocytoma has been characterised by its intraventricular localisation, predominant occurrence in young adults, oligodendroglioma-like histology, benign course and ultrastructural evidence for neuronal differentiation. Eleven intraventricular central neurocytomas were studied histopathologically, employing cell type-specific immunocytochemical markers and electron microscopic analysis. In the past, these lesions have caused diagnostic problems since central neurocytomas share basic histopathological features with other periventricular neoplasms. Accordingly, several tumours of this series had previously been classified as ependymomas of the foramen of Monro or oligodendrogliomas. Although generally regarded as benign lesions, two central neurocytomas of this series showed histopathological evidence of anaplasia, with focal necrosis, mitotic activity and vascular proliferation. All central neurocytomas exhibited immunoreactivity for neuronspecific enolase and synaptophysin, indicating consistent neuronal differentiation. Three tumours were studied by electron microscopy and contained synaptic vesicles, neuritic processes and neurosecretory granules. In addition, one tumour contained ganglioid cells and this was associated with focal immunoreactivity for neurofilament protein, suggesting that some central neurocytomas may, at least focally, continue to differentiate towards the formation of mature neurons. Two of the tumours expressed glial fibrillary acidic protein in a considerable percentage of neoplastic cells which demonstrates a capacity for bipotential, i.e. glial and neuronal differentiation. We conclude that the central neurocytoma can be reliably diagnosed using antibodies to neuron-specific enolase and synaptophysin, and that histogenetically, this neoplasm is derived from a neuroectodermal precursor cell capable of both, neuronal and glial differentiation. The hypothesis is proposed that the central neurocytoma originates from the subependymal plate of the lateral ventricles, an embryonal matrix cell layer which postnatally maintains a limited proliferative potential.

Notizen: Summary A case is reported of a 9-year-old boy with a cerebral polar spongioblastoma. This neoplasm, first described by Russell and Cairns in 1947, is morphologically a distinct entity characterized by bipolar tumor cells with palisading nuclei. In the case under study immunoreactivity for neuron-specific enolase was found and ultrastructural features of developing neuronal elements were present. A neuro-endocrine nature was suggested by de Chadarévian et al. (1984) in a morphologically similar case. These findings are in contrast with the longheld view that the polar spongioblastoma is cytogenetically related to the embryonal radial glial cells.

Notizen: Summary We have consistently observed tubulovesicular structures in brain tissues during the terminal stages of naturally occurring and experimentally induced spongiform encephalopathies, irrespective of the host species and virus strain. In NIH Swiss mice inoculated intracerebrally or intraocularly with the Fujisaki strain of Creutzfeldt-Jakob disease (CJD) virus, tubulovesicular structures, measuring 20–50 nm in diameter, were particularly prominent in dilated, pre-and postsynaptic neuronal processes, occasionally being mixed with synaptic vesicles. These structures appeared 13 weeks following intracerebral inoculation, 5 weeks before the onset of clinical signs, when spongiform changes were also detected. The number and density of tubulovesicular structures increased steadily during the course of clinical disease, and were particularly abundant in mice 47 to 51 weeks after intraocular inoculation. In hamsters infected with the 263 K strain of scrapie virus, these structures were initially detected 3 weeks following intracerebral inoculation and increased dramatically at 10 weeks postinoculation. The appearance of tubulovesicular structures before the onset of overt disease in mice inoculated with CJD virus by either the intracerebral or intraocular route, and before the appearance of other neuropathological changes in hamsters infected with scrapie virus, indicate that they represent either a part or aggregate of the infectious virus or a pathological product of the infection.

Notizen: Summary To study the pathomechanism of demyelination in canine distemper (CD), dog brain cell cultures were infected with virulent A75/17-CD virus (CDV) and examined ultrastructurally. Special attention was paid to the oligodendrocytes, which were specifically immunolabelled. In addition, cerebroside sulfotransferase (CST), an enzyme specific for oligodendrocyte activity was assayed during the course of the infection. Infection and maturation as well as CDV-induced changes were found in astrocytes and brain macrophages. Infection of oligodendrocytes was rarely seen, although CST activity of the culture markedly decreased and vacuolar degeneration of these cells occurred, resulting in their complete disappearance. We concluded that the degeneration of oligodendrocytes and demyelination is not due to direct virus-oligodendrocyte interaction, but due to CDV-induced events in other glial cells.

Notizen: Summary An unusual cerebral tumor is reported in a 14-year-old boy. On light and electron microscopy, the constituent cells were very complex; the majority of the neoplastic cells were primitive neuroectodermal cells dispersed in myxomatous or fibrous stroma. Neoplastic neuronal cells and hypertrophic astrocytes were also observed in these areas. The neuronal cells showed a continuous spectrum of differentiation from very primitive to mature ganglion cells. Furthermore, the tumor contained a highly cellular discrete area consisting of neuroblasts and their precursor cells. From these findings, a diagnosis of composite ganglioneuroblastoma was made.

Notizen: Summary A case is reported of a boy, 3 years of age, with a large medulloepithelioma in the left cerebral hemisphere. Medulloepitheliomas are rare tumors of the primitive medullar epithelium. Histological, immunohistochemical and electron microscopical findings are presented. We discuss previously reported cases, the ontogeny of this type of tumor and the relation to the socalled primitive neuro-ectodermal tumors (PNET).

Notizen: Summary An autopsy case of hereditary peroneal muscular atrophy (PMA) with rigidity and static tremor is presented. The patient developed slowly progressive distal muscular atrophy of the legs at the age of 15 years. By the age of 52 years, PMA became marked associated with pes cavus, and tremor and rigidity of the extremities were noted. Motor and sensory conduction velocities gradually depressed and lost near the end of his life. At autopsy, the major neuropathological abnormalities involved the peripheral nervous systems, and were characterized by axonal atrophy and loss of myelinated fibres. These changes involved both the proximal and distal nerves, being more severely affected in the distal. The pathological changes in other regions of the nervous systems were mainly confined to the spinal cord, dorsal ganglia and spinal nerve roots, and pigmented neurons in the brain stem. Morphometrically, the total fascicular area was much smaller than in control, but the total number of myelinated fibers greatly outnumbered that of control 75 200 to 48 200 at the proximal sciatic nerve and then gradually decreased towards the periphery; however, even in the distal sural nerve, the total number of myelinated fibers exceeded that of control (6820 to 5469). Thus, the density of myelinated fibers were much higher, being 1.5 to 2 times greater, than in control. Its abrupt decline at the distal nerve might account for neurogenic atrophy of the distal musculature. Unmyelinated fibers were slightly increased in density and not atrophic. This case is unique in its clinicopathology and does not belong to any subtypes of PMA including “neuronal plus”.

Notizen: Summary We describe postmortem findings in a patient with human T lymphotropic virus type I (HTLV-I)-as-sociated myelopathy (HAM). The patient developed the disease 8 years after blood transfusion and showed good response to corticosteroid treatment but died of cardiac failure. Histologically, chronic, mild meningoence-phalomyelitis was noted predominantly involving the bilateral lateral and anterior columns of the middle to lower thoracic segments. The spinal cord lesions showed obvious loss of myelinated nerve fibers and fibrillary gliosis with minimal inflammatory cell infiltration. Electron microscopy of the lesion revealed disintegration of the myelin sheaths, regular separation of the minor dense line of the myelin sheaths, and completely demyelinated axons. In addition, remyelinated fibers with thin central myelin sheaths and disproportionately large axons were seen frequently. These findings indicate that primary demyelination and remyelination by oligodendrocytes occur in the spinal cord lesions of HAM.

Notizen: Summary Day-6 rabbit blastocysts were cultured in Ham's F10 medium supplemented with polyvinylpyrrolidone as a macromolecular component, for 4 to 12 h. The integrity of the blastocyst cells was demonstrated by electron microscopy. Expansion and biosynthesis of proteins and of DNA were studied after culturing in the presence of 35S-methionine and 3H-thymidine. Polyvinylpyrrolidone did not interfere with the subsequent protein analysis, which was performed by two dimensional gel electrophoresis followed by silver staining and fluorography. More than 600 labelled proteins were found in the blastocyst tissue, many of them were also present in the blastocyst fluid and in the blastocyst coverings. Several proteins seemed to be produced for incorporation into the blastocyst coverings; others, only detected in the culture medium, might have been synthesized for secretion into the environment.

Notizen: Summary The present study described the labelling of amoeboid microglial cells in the postnatal rat brain with OX-42, an antibody that recognizes type 3 complement receptors CR3 in mononuclear phagocytes. Of the diverse morphological forms of amoeboid microglia present in the corpus callosum in early postnatal (2–5 days) rats, cells with a round regular outline, or showing short stout processes, were the most intensely stained. When traced from the main cell colony into the borderline zone with the cortex, the immunoreactivity of amoeboid microglia that assumed a ramified form was drastically reduced. Examination of materials from the late postnatal (8–12 days) age group showed that the majority of the OX-42 positive cells in the corpus callosum became oval, elongated and ramified. Immunoelectron microscopy confirmed the above observations, and also showed that the immunoreactivity in the round amoeboid microglia was localized in their plasma membrane, surface projections and invaginations, as well as in some of the subsurface vacuoles. The immunoreactivity was reduced in the oval cells, and diminished in the elongated or ramified form. It is proposed that the presence of CR3 membrane receptors in amoeboid microglial cells is related to their active role in endocytosis. These, however, diminish with the growth of the brain.

Notizen: Summary The astroglial cells have been studied in the lizard spinal cord by means of metallic impregnations, immunohistochemical (glial fibrillary acidic protein) and ultrastructural methods. Three astroglial cell types have been immunohistochemically identified: ependymocytes, radial astrocytes and astrocytes. Transitional forms have also been observed. Scarce immunopositive ependymocytes were located in the dorsal and ventral regions of the ependyma. The radial astrocytic somata were located around the ependymal layer and their processes reached the subpial glia limitans. Typical astrocytes were the most abundant astroglial cell type; astrocytes located in the ventral horn showed a greater development than those of the dorsal horn. In the white matter, the astrocytes were large and their processes formed part of the subpial glia limitans; on some occasions, astrocytic cell bodies also formed part of this subpial limitans. Transitional elements between astrocytes and radial astrocytes were observed in both grey and white matter. The perivascular and subpial glia limitans were continuous and showed a strong immunoreactivity. The comparative analysis of our results in the lizard spinal cord with those in other vertebrate groups leads us to conclude that reptiles could represent the key group in the phylogenetic evolution of the astroglial cells in vertebrates.

Notizen: Summary A new kind of diffuse palmoplantar keratoderma with autosomal recessive inheritance and without associated symptoms was described in Norrbotten, Sweden by Gamborg Nielsen in 1985. Clinically, it ranges between the less severe dominant Unna-Thost type and the more severe recessive Meleda type, as it is milder than the latter. Skin biopsies of five patients from three different families with this new palmoplantar keratoderma, as well as five obligatory heterozygotes from one family, were investigated ultrastructurally in order to characterize this new entity and to differentiate it from the Meleda type. Several features are common to both autosomal recessive palmoplantar keratoses. They show a broadened granular layer, a transit region consisting of cells with a marginal envelope, and considerable hyperkeratosis. Morphologically, this transformation delay is less pronounced in the Gamborg Nielsen type than in the classical Meleda type. As is typical for ridged skin, both types of palmoplantar keratoses possess composite keratohyaline granules. In contrast to the normal appearance of keratohyaline granules in the Meleda type, the Gamborg Nielsen type also shows qualitative deviations of keratohyaline granules with different degrees of spongiosity and electron density and sometimes with a granular border. It seems that abnormal keratohyaline proteins are synthesized that behave differently. The sudden transformation of a granular into a horny cell is physiologically regulated by different enzymes. A delay in this process may be caused by a mutation that reduces or alters the enzymes concerned. We assume the palmoplantar keratoderma of the Gamborg Nielsen type to be a variant of the heterogeneous group of the Meleda type of palmoplantar keratoderma with autosomal recessive inheritance.

Notizen: Summary The cultured hair cells from 4-day-old C3H mice were studied by electron microscopy. The hair roots isolated from the skin by collagenase digestion were dispersed into a cell suspension by treatment with a mixture of trypsin and ethylenediaminetetraacetate. The cells were cultured in MCDB-153 (a medium containing seven growth factors) for 1, 3, 6 or 13 days. The number of cultured cells on day 3 was twice that on day 1, and stayed at the same level until day 13. By electron microscopy, some of the cells cultured for 1 day were seen to be undifferentiated and others already showed differentiation into various hair structures. Such differentiated cells disappeared on day 3 and most of the cells cultured for 3 days were undifferentiated. Cells cultured for 6 days were differentiated showing inner root sheath cell, hair cortical cell and medulla cell structures. The characteristics of these cultured cells corresponded well to those of in vivo cells of the hair tissues from the back skin of 7-day-old C3H mice. On day 13 degeneration occurred in the cultured cells. In none of these cultures were mesenchymal cells, such as fibroblasts, found. The present electron microscopic study reveals that immature cells obtained from mouse hair tissues proliferate in vitro and differentiate into several subpopulations corresponding to those of in vivo cell layers of hair tissues. The present culture technique may be useful for studies of hair cell growth and differentiation.

Notizen: Summary Human eccrine sweat glands were embedded in Lowicryl K4M. Cytokeratin proteins and blood group H antigen were localized by applying a postembedding immunogold method using a monoclonal antikeratin antibody and the lectin Ulex europaeus I. The antikeratin antibody labeled intermediate filaments in the secretory coil and dermal duct. Within dark secretory cells bundles of filaments criss-crossing the cell were labeled. Within the luminal cells of the dermal duct filaments arranged parallel to the cell surface and lying in the apex of the cell were labeled, too. The association of keratin filaments with desmosomes was visualized demonstrating their subcellular connection with other cell organelles. The desmosomes themselves remained unlabeled. The lectin Ulex europaeus I is a blood group H specific lectin and binds to α-l-fucosyl-containing glycoproteins. Dark cells of the secretory coil reacted with the lectin. Here the secretory granules, the lateral cell membranes, and the microvilli membranes were labeled. The endoplasmatic reticulum, the Golgi complex, and transport vesicles were not labeled, although the glycoprotein synthesis is considered to be located in the Golgi complex. Thus, either the number of α-l-fucose molecules in the Golgi is too low to be detected by the technique employed or the determinant of blood group H antigen is released after the secretory granules and transport vesicles leave the Golgi complex.

Notizen: Summary Up to now, bicomponent keratohyalin has only been described for rat epithelium and human intraepidermal sweat ducts and fetal nail organ cells. In normal human interductal epidermis, the keratohyalin appears homogeneous, osmiophilic and stellate in shape. Under pathological conditions, bicomponent keratohyalin has been observed in different palmoplantar keratoses and has therefore been thought to be associated with abnormal keratosis. We studied the keratinization process in normal human plantar epidermis, in which keratohyalin was found to exhibit several morphological differences as compared to that seen in non-ridged skin. The most striking feature was seen in upper granular cells, where the keratohyalin granules consisted of two components of differing electron density. The electron-dense component formed the main part of the composite granule and was found in the cytoplasm of lower and upper granular cells. The less-electron-dense component was attached to the main component and appeared in the cytoplasm of upper granular cells, forming the convex contact zone. No intranuclear osmiophilic inclusions were present. The respective electron densities of the two keratohyalin components of ridged skin were obviously different to that of the bicomponent keratohyalin granules seen in the epidermal sweat-duct cells of the same specimen. These findings indicate the presence of at least two different types of keratohyalin proteins in normal human ridged skin. They can be distinguished at the electron-microscope level and differ from the keratohyalin of human non-ridged skin as well as from bicomponent keratohyalin granules derived from human epidermal sweat-duct cells or from rat epithelium.

Notizen: Summary The pathogenesis of a rare form of the ichthyotic diseases, ichthyosis hystrix Curth-Macklin, was investigated by immunohistochemistry and electron microscopy. Monoclonal antibodies (Mabs) against keratins expressed in normal basal cells (PKK2 and KA1), Mabs against keratins only present in normal fetal skin (PKK1), and Mabs against keratins 1, 2, 10, and 11 (KA5 and K8.60) were used. The Mabs reacting with normal basal cells showed an increased reaction with many cell layers. The Mab PKK1 distinctly reacted with the basal cell layer, suggesting an expression of fetal keratins. Electron microscopic study of both normal-looking and involved skin revealed the keratinization disorder characterized by tonofilament shells, perinuclear vacuoles, and binuclear keratinocytes. The results suggest that there is no prematurity of keratinization, but rather a pathological expression of specific keratin genes leading to expression of fetal keratins in this form of ichthyosis hystrix.

Notizen: Summary The ultrastructural, light microscopical and immunological features of twelve cases of acute childhood leukemia are described. Nine cases were unclassifiable by light microscopy, morphology and cytochemistry, and three were difficult to classify because of a low percentage of Sudan-Black B positive blasts. By means of electron microscopy (including peroxidase cytochemistry), two main groups were seen: 1. Acute myeloid leukemia, in which could be distinguished a) a more differentiated myeloid leukemia, b) a leukemia with megakaryoblastic involvement and c) a minimally differentiated acute myeloid leukemia with granules present and 2. lymphoblastic leukemia. One case could not be classified. The first group included two possible cases of a hybrid leukemia with CD19 or CD10 positivity as well as ultrastructural peroxidase activity. We conclude that electron microscopy aids to further classification of minimally differentiated and hybrid acute leukemias.

Notizen: Summary A correlative light and electron microscopic investigation was undertaken to determine the morphology and distribution of catecholamine (CA)-containing axon terminals in the hypoglossal nucleus (XII) of the rat. This was accomplished immunocytochemically with antibody to tyrosine hydroxylase (TH). The major findings in this study were the following: 1) Immunoreactive profiles were found throughout XII and included unmyelinated axons, varicosities, axon terminals and dendrites; 2) Nonsynaptic immunoreactive profiles (preterminal axons, varicosities) were more frequently observed (55.2%) than synaptic profiles (43.5%); 3) CA-containing axon terminals ending on dendrites were more numerous (71.8%) than those synapsing on somata (25.4%) or nonlabeled axon terminals (2.7%); 4) The morphology of labeled axon terminals was variable. Axodendritic terminals typically contained numerous small, round agranular vesicles, a few large dense-core vesicles and were associated with either a symmetric or no synaptic specialization, axosomatic terminals were often associated with a presynaptic membrane thickening or a symmetric synaptic specialization and contained small, round and a few elliptical-shaped vesicles, while axoaxonic synapses formed asymmetric postsynaptic specializations; and 5) CA-positive dendritic processes were identified in XII. These findings confirm the CA innervation of XII, and suggest a complex, multifunctional role for CA in controlling oro-lingual motor behavior.

Notizen: Abstract Over a 22-year period, eith patients affected with severe systemic or polyarticular juvenile chronic arthritis (JCA) developed systemic amyloidosis with nephrotic syndrome. They were treated with chlorambucil over 5–192 months (mean=44 months). With treatment, an abrupt decrease in the severity of JCA was observed in six patients but two patients were chlorambucil resistant. After a mean follow-up period of 10 years from onset of renal symptoms, one chlorambucil-resistant patient died of end-stage renal failure; two patients have a persistent nephrotic syndrome; and five patients are free from proteinaria, of whom one has developed hypertension. A good correlation was observed between the response of the rheumatic disease to chlorambucil treatment and the clinical course of renal symptoms. Fourteen renal biopsies were performed in these eight patients. In all, amyloid deposits were of the AA type, which persisted on repeat biopsies. In addition, 15%–60% of glomeruli had become globally sclerotic by the second or third biopsies. At the ultrastructural level, modifications in the structure of amyloid deposits and reparative changes of the glomeruli, characterized by partial restoration of glomerular architecture, were observed in three patients with a favourable clinical course.

Notizen: Abstract Inborn errors involving the oxidative metabolism of fatty acids may present clinically with a Reye syndrome-like picture. This case report of a patient with medium-chain acyl CoA dehydrogenase (MCAD) deficiency illustrates that electron microscopy may help to differentiate this disorder from Reye syndrome even if a liver biopsy is performed in a patient who recovered from an acute metabolic decompensation. Together with this case, a review of the few reports in the literature of pathological findings in MCAD deficiency is given. Changes uncharacteristic for Reye syndrome are a largedroplet steatosis and the presence of distinctive mitochondrial abnormalities on electron microscopy. The detection of an electron dense mitochondrial matrix and a widened space of inner mitochondrial membranes rules out Reye syndrome and is suggestive of a disorder of mitochondrial fatty acid oxidation.

Notizen: Summary The nerve fibres of the corpus callosum were studied by electron microscopy in five elderly patients with progressive subcortical vascular encephalopathy (PSVE) and compared with those in six age-matched controls. The number of nerve fibres per unit area of the corpus callosum was decreased in PSVE by 18–26%. The loss of nerve fibres in the corpus callosum can play a role in inducing the cognitive deficit of PSVE, on the basis of the loss of nerve fibres in the cerebral hemispheres.

Notizen: Summary In Alzheimer-type dementia brains, numerous “amyloid-rich primitive plaques (PPs)” were observed with β-protein immunostaining and periodicacid methenamine (PAM) staining. These amyloid-rich primitive plaques were accompanied by various degrees of small argyrophilic rod-like, granular or filamentous structures. Routine and modified-PAM electron microscopy revealed many bundles and flecks consisting of amyloid fibrils scattered widely throughout the plaques. Degenerate neurites, astrocytic processes and bundles of glial fibres also participated in the formation of the plaques. The similarities and differences between these amyloid-rich primitive plaques and diffuse plaques are described.

Notizen: Summary A case of a primary intracerebral sarcoma is described in a 5-year-old girl. Histology and immunohistochemistry excluded the diagnosis of a leiomyosarcoma, a malignant haemangiopericytoma or a fibrosarcoma; electron-microscopical findings indicated that the origin of the sarcoma was in the pia mater.

Notizen: Summary This study was designed to examine the vascular system of human xenotransplanted tumors on nude mice with different complementary morphometrical and morphological methods. The vascular system shows a chaotic arrangement. There is an extreme heterogeneity in the vascular distribution and density. Large avascular regions could be identified in several non-necrotic tumors. There was no clear difference in the vascular density between the center and the periphery of the tumors, nor was there any zonal correlation for the distribution of the necrosis. With three-dimensional corrosion casts it could be demonstrated that clusters of vessels were directly beneath areas almost free of vessels. In the center, vessels often form a sinusoidal system with numerous blind ends without clearly discernible endothelial cells. Numerous irregular tumor-cell-lined sinusoids are visible next to endothelial-lined vessels with transmission electron microscopy. With scanning electron microscopy it could be demonstrated that large-calibre endotheliazed vessels were found in the direct vicinity or in the center of non-viable zones. Even large-calibre vessels have a capillary wall structure. Sometimes, a basement membrane cannot be observed at all or only incompletely. There are numerous indications of vascular discontinuities and leaks with a widespread intercellular occurrence of blood cells.

Notizen: Summary The accumulation of mast cells in the testicular interstitium of neonatally estrogen-treated rats was studied from 15 to 90 days of age. The maturation of these cells was assessed by ultrastructural analysis and their histochemical properties were examined with the sequential alcian blue-safranin staining method. The first identifiable mast cells appeared in the testis at 17–20 days of age, as immature cells with proliferative capacity. The density of mast cells increased up to 45 days of age, showing a slight decrease from 45 to 90 days of age. Before 45 days of age, most mast cells showed alcian blue-stained granules, whereas at 45 days of age, most cells presented a mixture of alcian blue and safranin-stained granules. From this age onward, most cells were stained with safranin. These maturational changes were well-correlated with their ultrastructural features. Mast cells presented few and heterogeneous immature granules up to 45 days of age, and many uniform electron-dense granules at 90 days of age. These results indicate that the testicular interstitium of neonatally estrogen-treated rats provides an adventageous environment for the recruitment, proliferation and maturation of connective tissue mast cells.

Notizen: Summary Keratin filaments of epithelial- and taste-bud cells in the circumvallate papillae of adult and developing mice were studied by immunocytochemistry using monoclonal antikeratin antibodies (PKK2 and PKK3) and by conventional electron microscopy. Elongated cells (type-I,-II, and-III cells) of the taste buds were stained by PKK3 antibody, which reacts with 45-kdalton keratin, whereas basal cells of the taste buds and surrounding epithelial cells showed negative staining with PKK3. Such PKK3-reactive cells occurred at 0 day after birth, when taste-buds first appeared in the dorsal surface epithelium of the papillae. Thus 45-kdalton keratin seems to be an excellent immunocytochemical marker for identifying taste-bud cells. Epithelial cells in all layers of the trench wall and basal layer cells of the dorsal surface contained densely aggregated bundles of keratin filaments that reacted with PKK2 antibody, but not with PKK3. In contrast, taste-bud cells and spinous and granular layer cells of the dorsal surface possessed loose aggregated bundles of filaments that reacted with PKK3, but not with PKK2. These results suggest that the aggregation and distribution pattern of keratin filaments may reflect differences in the keratin subtypes that comprise these filaments.

Notizen: Summary The effect of vitamin A-deficiency on jejunal Paneth cells in rats was investigated. Crystalloid particles were observed in secretion granules of Paneth cells from 6 out of 8 rats with vitamin A-deficiency. The particles were similar to those found in Paneth cells under other experimental conditions. Using an immuno-electron-microscopic technique we demonstrated a clear lysozyme immunoreactivity of these particles. In 2 vitamin A-deficient rats tubular structures have been detected in addition to the crystalloid particles. Crystalloid particles or tubular structures were not detectable in a control group of 8 vitamin A-supplemented rats. The morphological alterations of Paneth cells may be correlated to an impaired local immunity of the intestine during vitamin A-deficiency.

Notizen: Summary The ultrastructure of peroxisomes in the proximal nephron tubules of bovine kidney cortex was studied using ultrathin-sectioning, diaminobenzidine cytochemistry for the visualization of catalase, and by freeze-fracture. Peroxisomes in this nephron segment are up to 1.5 μm in diameter and exhibit a peculiar angular shape, which is probably related to the occurrence of multiple straight plate-like inclusions (marginal plates) in the matrix of peroxisomes; they lie directly underneath the peroxisomal membranes. The peroxisomal membrane in such regions follows the outline of the marginal plate. The peculiar shape of peroxisomes allows their unequivocal identification in freeze-fracture preparations. Peroxisomal membranes are recognized by their flat, often rectangular appearance. Intramembrane particles are much more numerous on P-fracture faces than on E-fracture faces. A crystalline lattice-structure with a periodicity of approximately 10 nm can be observed on the flat rectangular areas of E-fracture faces. This lattice structure is intensified after prolonged freeze-etching. Intramembranous particles seem to be superimposed over this pattern. The crystalline pattern on the E-fracture faces of peroxisomal membranes is probably not a membrane structure but it reveals the structure of the membrane-associated marginal plates. A cast of the marginal-plate surface may be generated by a collapse of the peroxisomal membrane half onto the immediately underlying matrix inclusion.

Notizen: Summary Certain populations of arginine vasopressin (AVP) neurons in the magnocellular paraventricular nucleus became immunoreactive for neuropeptide Y (NPY) when rats were treated with colchicine or monosodium glutamate (MSG). The co-storage of these peptides was examined by empooying a post-embedding electron-microscopic immunohistochemistry technique using goldlabeled antibodies to the two peptides. In colchicinetreated rats, the neuronal perikarya contained numerous secretory granules showing co-storage of the two peptides. The cells of the MSG-treated rats were characterized by having well-developed Golgi bodies with the granular structures also co-storing the two peptides, although the secretory granules in the perikarya were rather fewer than in the colchicine-treated rats. It is concluded that the destruction of the arcuate nucleus by MSG-treatment may potentiate the synthesis of NPY in AVP neurons, the synthesis of which is latent in intact animals.

Notizen: Summary Ultrastructural and cytochemical features of embryo development during anther and free microspore culture inBrassica napus have been followed from the late uninucleate microspore stage through the first embryonic division. On transfer to culture, the microspore cytoplasm possesses a large vacuole, often containing electron opaque aggregates, and a peripheral nucleus. Mitochondria, endoplasmic reticulum and starch-free plastids are distributed throughout the cytoplasm. The conditions of culture induce a number of major changes in the cytoplasmic organisation of the microspore. First, the central vacuole becomes fragmented allowing the nucleus to assume a central position within the cell. Secondly, starch synthesis commences in the plastids which, in turn, are seen to occupy a domain investing the nucleus. Thirdly, the cell develops a thick fibrillar wall, situated immediately adjacent to the intine of the immature pollen wall. Finally, the microspores develop large cytoplasmic aggregates of globular material. The nature of this substance remains unknown, but it remains present until the young embryos have reached the 30 cell stage. The first division of cultured microspores destined to become embryos is generally symmetrical, in contrast to the asymmetric division seen in normal development in vivo. Consideration is given to the differences observed between embryos developing from anthers and free microspores in culture.

Notizen: Summary Localization of acid phosphatase in mammary glands of lactating rats was studied by both biochemical and cytochemical methods. Cytochemically, acid phosphatase activity was detected by using lead citrate as the capture agent for the inorganic phosphate released from p-nitrophenyl phosphate. The activity was predominantly localized in the lumina of the endomembrane system and in the milk that had been secreted into the alveolar lumen. Biochemically, acid phosphatase was present in all the subcellular fractions with higher activities in the membrane-associated fractions. The localization of tartrate-resistant acid phosphatases within the endomembrane system of fully lactating rat mammary tissue suggests a possible role for these enzymes in milk secretory processes.

Notizen: Summary The primary leaf, epicotyl, and root cells ofVigna sinensis seedlings grown continuously in a 0.08% colchicine solution, become microtubule-free and polyploid. In meristematic root cells a tubulin transformation is detected 1–3 h after the treatment had begun. Tubulin strands are organized at the positions of the pre-existing microtubules. Frequently, the strands converge on or are organized in the cortical cytoplasmic zone where in normal cells the preprophase microtubule band (PMB) is assembled. In meristematic root cells subjected to a 6–12 h colchicine treatment, the tubulin strands become perinuclear, entering the cortical cytoplasm at regions close to the nucleus. One day after the onset of the treatment, tubulin generally forms a continuous reticulum of interconnected strands in all the organs examined. In most cells this reticulum surrounds the nucleus partly or totally or lies close to it, exhibiting variable configurations in different cells. After prolonged treatments, the organization of the tubulin reticulum changes further. Now this consists of crystal-like structures interconnected by thin strands. On thin sections of fixed tissue the tubulin strands consist of paracrystalline material. The distribution of this material in the affected cells coincides with that of tubulin reticulum visualized by immunofluorescence. In transverse planes each strand exhibits circular subunits arranged close to one another in a hexagonal pattern but in longitudinal ones variable images were observed. The paracrystalline material persists in root cells subjected to an 8-day continuous colchicine treatment. The immunolabeled strands seem to be composed of tubulin-colchicine complexes and not pure tubulin.

Notizen: Summary The purpose of the present study was to clarify morphological differences in lipofuscin or so-called age pigments observed in the spiral ganglion cells of both young and adult rat groups and to characterize the size and structure of ceroid pigment granules generated in vitamin-E-deficient rats. The results showed different patterns of lipofuscin distribution in the two groups. The adult rat group had large aggregated lipoid, dark pigment granules of irregular shape in the cytoplasm. In contrast, the young group had small numbers of small, dense homogeneous granules, suggesting higher Schwann cell phagocytic activity. The ceroid pigments apparently included numerous vesicles and droplets of more variable density and size than the lipofuscin pigments appearing in the non-treated older animals. Both lipofuscin and ceroid pigments developing in such non-dividing cells are produced as a result of peroxidation reactions, so that the more they accumulate in the cytoplasm the more likely cell function deteriorates. The present study has shown that lipofuscin/ceroid granules are generated in the spiral ganglions under either endogenous (aging) or exogenous (vitamin E deficiency) conditions.

Notizen: Summary The ultrastructural distribution of hyaluronate in the nasal mucosa of Wistar rats, especially in secretory cells, was examined by hyaluronidase-gold labeling using electron microscopy. The main secretor of hyaluronate in the nasal mucosa was found to be the goblet cells and not the nasal glands.

Notizen: Summary The localization of sialic acid (N-acetyl- and N-glyconylneuraminic acid) in the organ of Corti of the mongolian gerbil was examined with electron microscopy by postembedding labeling using Limax flavus agglutinin and feutin-gold. Gold labeling was observed on the fibrous structure of the tectorial membrane, the basilar membrane and the spiral limbus. The labeling was also observed on the cuticular plate of the hair cells, the head and cone of the pillar cells and the head plate of Deiters' cells and other supporting cells. Collagen or cytoskeletal glycoproteins are suggested to be the source of the sialic acid in these structures.

Notizen: Summary The mesothelial cells of Reissner's membrane in guinea pigs were found to be connected by junctional complexes. No cell discontinuities or gaps were observed by scanning or transmission electron microscopy. These results are not in accordance with previous studies. They were achieved by in vivo vascular perfusion fixation, handling of cochleae in protective specimen carriers, thiocarbohydrazide treatment and continuous dehydration. Findings in the present study indicate that the interepithelial space between the epithelial and mesothelial cell layers constitutes a specific compartment which must be considered when examining solute transport over Reissner's membrane.

Notizen: During postnatal development of the pigeon, a large portion of the skeleton becomes pneumatized, displacing the hemopoietic bone marrow. The consequences of pneumatization on distribution and quantity of bone marrow as well as the availability of other sites for hemopoiesis have been investigated. Hemopoietic marrow of differently aged pigeons divided into five groups from 1 week posthatching (p.h.) up to 6 months p.h. was labeled with Fe-59 and examined by serial whole-body sections. Autoradiography and morphometry as well as scintillation counts of single bones and organs were also carried out. No sign of a reactivation of embryonic sites of erythropoiesis was found. Bone marrow weight and its proportion of whole-body weight increased during the first 4 weeks p.h. from 0.54% to 2.44% and decreased in the following months to about 1.0%. The developing bone marrow showed a progressive distribution during the first months of life, eventually being distributed proportionally over the entire skeleton, except for the skull. At the age of 6 months p.h. bone marrow had been displaced, its volume decreasing in correlation to increasing pneumaticity and conversion to fatty marrow. This generates the characteristic pattern of bone marrow distribution in adult pigeons, which shows hemopoietic bone marrow in ulna, radius, femur, tibiotarsus, scapula, furcula, and the caudal vertebrae.

Notizen: Artificially incubated fertile eggs from wild alligators have a significantly better hatch rate than those of captive, pen-reared alligators, possibly due to differences in the morphology of the eggshells. We compared the morphology of eggshells of wild alligators to those of captive alligators living in semi-natural environmental pens. Lengths and widths of eggs were measured and volume was determined, assuming an ellipsoid shape. Eggs were also evaluated for the quality of the eggshell (the presence or absence of rough deposits). Pieces of shell were cut from unincubated eggs and from eggs incubated for 55 days (just before hatching) and examined by scanning electron microscopy. Open pores on the outer surface of the shells were counted and thickness of the pieces was measured from micrographs. Results indicated that the number of pores on eggshells was lowest in eggs of captive alligators with early embryonic death. The number of pores was intermediate in eggs with early embryonic death from wild alligators, and the number of pores was highest in eggs with full-term embryos from wild or captive alligators. It is suggested that decreased porosity of eggshells may be associated with early embryonic death, is more prevalent in captive animals, and may, therefore, be related to poor hatch rate among penreared alligators.

Notizen: Adult hornets (Vespa orientalis; Hymenoptera, Vespinae) build the brood combs out of organic or mineral matter. The cement that serves to glue the building material together is secreted in their saliva, the latter hardening within seconds to form fibers or plates. This saliva-derived spittle overlies and unites the building particles laminally and vertically. The hornet larvae spin a cocoon within the brood cells, which is largely fastened to and supported by the cell walls and is composed of a network of silk fibers and interlinking flat surfaces. On the outside of the cocoon fibers are spherical button-like structures that are very rich in phosphorus. The chemical composition of the adult salivary cement and the larval cocoon fibers is similar: both contain the elements P, Mg, S, Cl, K, and Ca. The possible biological significance of these findings is discussed.Among social insects belonging to the Hymenoptera, there are three main groups that build a multitude of cells, namely, the paper wasps (Polistinae), the other social wasps or hornets (Vespinae), and the social bees (Apinae). The constructed cells serve mainly for rearing the brood, but in many instances (particularly among various Apinae) they also serve for storing honey and pollen. For building material, Apinae rely primarily on beeswax (a product secreted by the bee itself to which various amounts of plant resins are added). On the other hand, wasps (Polistinae and Vespinae) build mainly from matter collected in the nearby environment, be it organic matter such as tree bark, mineral matter, or a combination of the two.Much information has accumulated on comb and cell building among these insect groups (e.g., Wheeler, '23; Van der Vecht, '57, '65; Lindauer, '61; Michener, '61; Kemper and Döhring, '67; Wilson, '71; Guiglia, '72; Spradbery, '73; Edwards, '80; Brian, '83; Schremmer et al., '85). Species of Polistinae and Vespinae are prevalent in forest areas in Southeast Asia and in central and South America or in the temperate regions in both the northern and southern hemispheres, and they mainly use vegetable matter to build their combs. In contrast, species prevalent in the Mediterranean region, which is dry and relatively unvegetated during the wasp and hornet active season, rely more on nearby mineral than on plant matter. Comb building in the Oriental hornet is well known (Darchen, '64; Ishay et al., '67; Schaudinischky and Ishay, '68; Ishay, '73, '75a, b, '76; Ishay and Sadeh, '75, '76; Ishay and Perna, '79; Ishay et al., '82). Recently Ganor et al. ('86) described the cell wall in the V. orientalis comb, showing it to be composed of mineral particles collected near the subterranean nest, in contrast to the comb of two European species (V. crabro and Vespula) (Paravespula) germanica, which is built primarily of organic matter. Regardless of whether the building material is mineral or organic, the hornets utilize particles of sand or other minerals or pieces of wood wrapped and melded together by saliva. However, nothing is known about the cement or mortar used to glue together these “bricks.” The present investigation was initiated to increase our knowledge of this cementing substance.Combs of V. orientalis were collected from fields in the Tel-Aviv district in 1987 during the active season, which extends over most of the summer months. Because the combs are easily damaged, care was taken to remove them intact from the natural nest. Once removed, the combs were cleared of the existing brood (eggs, larvae, or pupae) and then stored carefully in dry glass vessels until examined. For the present study, combs were collected only from nests in Khamra soil, which is common in the Tel-Aviv district and along the coastal area of Israel. To investigate the morphology of the cement material in the comb, strips of comb wall as well as segments of the pupal silk dome were removed from each comb and prepared for examination. The comb wall strips were cut to a size of 3 × 6 mm and fastened to the stub of a scanning electron microscope (SEM). The silk pieces were processed in two ways: (1)strips of 3 × 4 mm were fastened onto a stub with the convex (outer surface) facing up or (2) with the concave (interior) side upward.Silk strips were boiled for 2 hours in distilled water to remove all impurities, such as foreign matter adhering to the silk secreted by the larvae. Examination of these silk fibres was carried out in the three ways: (1)SEM micrography of the exterior (white portion) of the silk dome; (2) micrography of the interior; (3) micrography of both exterior and interior aspects after boiling for 2 hours in distilled water to remove water-suspended foreign materials that may have clung to the silk dome in the course of ordinary nest activity.The chemical composition of selected specimens was investigated by x-ray analysis. They were done on JEOL 840 Scanning Electron Microscope (SEM) equipped with Link 10,000 Energy-Dispersive System (EDS). (With the EDS System, the spectrometer separates the elements according to energy rather than wavelength). Quantitative analysis was by ZAF4 program. Five strips of comb cell wall were examined from a randomly selected comb, each comb from a different nest. Micrographs were taken of isolated silk samples from each of the examined combs.

Notizen: Dissections were performed to document buccal anatomy in three species of the pulmonate genus Helisoma Swainson, 1840. The 28 muscles which are responsible for radular feeding in these animals are organized in three concentric and integrated envelopes. The deepest of these includes muscles which manipulate the radula about the odontophoral cartilage. Elements of the middle envelope direct movements of the cartilage within the buccal cavity, and muscles of the outer envelope control movements of the buccal mass within the cephalic haemocoel. Motion analysis by videomicrography showed that muscles of the middle and outer envelopes contribute to the action of radular feeding by acting as antagonists to other muscles and to hydrostatic elements of the buccal apparatus. Observations of radular dentition showed that although each of the three species examined has a unique radula, especially with regard to the specific details of tooth shape, all resemble a radula characteristic of the Planorbidae with regard to other, more general, aspects of ribbon architecture.

Notizen: Crocodilians and birds are the extant representatives of a monophyletic taxon known as archosaurs. Their limbs are highly derived in terms of reduction in number of skeletal elements in both the carpus and the tarsus. It is necessary to have a detailed description of crocodilian limb ontogeny to address the evolutionary issue dealing with the origin and organization of the avian limb. In this paper, we present an analysis of the early development of the crocodilian limb skeleton. Contrasting with earlier observations, we redefine the number and composition of carpal, tarsal, and phalangeal elements. This ontogenetic information is then used to introduce a revision of the homologies of the skeletal elements in the crocodilian limb. Some invariances are pointed out in the developmental organization of tetrapod limbs and this evidence serves to readdress several issues concerning the evolution of the avian limb. We present further embryological data in support of the hypothesis that digits 2-3-4 are the components of the wing skeleton in birds. In general, our comparative survey indicates that the elements that appear late in ontogeny are the ones lost in phylogeny. By comparing turtle (primitive) limb development with crocodilian and bird development, we propose a hypothesis in which the derived skeletal patterns found in crocodilians and birds have originated by a heterochronic process of paedomorphosis.

Notizen: A unique pathway that utilizes endoplasmic reticulum (ER) networks is proposed for screening pigment granule formation in the retina of adult Eumesosoma roeweri. Smooth endoplasmic reticulum (SER) functions to transport pigment particles to the formative site. Each site is composed of concentric, interconnected rings of SER that are filled with dense-cored, spherical pigment particles. Formation of the screening pigment granule begins by the release of particles from the innermost rings of carrier SER. Continued release followed by fusion and condensation of the pigment particles results in the formation of a mature pigment granule.

Notizen: Light and scanning electron microscopy of vascular replicas from the facultative air-breathing fish Heteropneustes fossilis show modifications in the macrocirculation of the respiratory organs and systemic circulation, whereas, gill microcirculation is similar to that found in typical water-breathing fish. Three and sometimes four ventral aortae arise directly from the bulbus. The most ventral vessel supplies the first pair of arches. Dorsal to this another aorta supplies the second gill arches, and a third, dorsal to, and larger than the other two, supplies the third and fourth arches and the air sacs. Occasionally a small vessel that may be the remnant of a primitive aortic arch arises from the first ventral aorta and proceeds directly to the mandibular region without perfusing gill tissue. The air sac is perfused by a large-diameter extension of the afferent branchial artery of the fourth gill arch and its circulation is in parallel with the gill arches. Blood drains from the air sac into the fourth arch epibranchial artery. A number of arteries also provide direct communication between the efferent air sac artery and the dorsal aorta. All four gill arches are well developed and contain respiratory (lamellar) and nonrespiratory (interlamellar and nutrient) networks common to gills of water-breathing fish. Air sac lamellae are reduced in size. The outer 30% of the air sac lamellar sinusoids are organized into thoroughfare channels; the remaining vasculature, normally embedded in the air sac parenchyma, is discontinuous. A gill-type interlamellar vasculature is lacking in the air sac circulation. Despite the elaborate development of the ventral aortae, there is little other anatomical evidence to suggest that gill and air sac outflow are separated and that dorsal aortic oxygen tensions are maintained when the gills are in a hypoxic environment. Physiological adjustments to hypoxic water conditions probably include temporal regulation of gill and air sac perfusion to be effective, if indeed they are so.

Notizen: The antennae of adult Damalinia ovis, the sheep louse, were studied using light and scanning electron microscopy. Sensory structures are located on all three antennal segments with the predominant sensilla type being tactile. Nine different types of sensilla are described on the basis of external appearance. One of the sensilla, designated a “pit organ” because of its unusual shape, has not been described previously. A pair of these sensilla are present on each antenna, and their function is unknown. A group of 11 sensilla on the tip of each antenna contains olfactory and chemosensory pegs, and a possible thermohygroreceptor. The antennae are sexually dimorphic, the male having more tactile sensilla, two well-developed terminal hooks, and a different cuticular architecture on the posterior surface of antennal segment 1.

Notizen: The formation of the unpaired structure ventral to the basibranchial region, the so-called urohyal, differs within osteichthyans. A cartilaginous preformed, unpaired “urohyal” is present in sarcopterygians. A three-tendon ossification is present in Polypterus. An “urohyal” or urohyal is absent in both Amia and Lepisosteus. The urohyal formed as an unpaired ossification of the tendon of the sternohyoideus muscle is a feature of teleosts. A new structure, the parurohyal, arises as a double ossification of the tendon of the sternohyoideus muscle in siluroids; during ontogeny an anterodorsal crest or cup-like structure derives from the anterior basibranchial region and the tendon bone; therefore, the parurohyal is compound in origin. Judging from their formation and their distribution within osteichthyans the cartilaginous preformed “urohyal” and the teleostean urohyal are nonhomologous, whereas the urohyal and parurohyal are homologous. The urohyal is connected by ligaments with the ventral hypohyals in most teleosts, whereas it articulates with the ventral hypohyals in teleosts such as Anguilla and Chanos. The parurohyal is a synapomorphy of siluroids. The parurohyal in siluroids is articulated with both ventral and dorsal hypohyals, and with the basibranchial region in catfishes such as diplomystids and ictalurids, whereas it articulates only with the ventral hypohyals in other catfishes such as trichomycterines. The passage of the hypobranchial artery through the hypobranchial foramen of the parurohyal is a unique feature of siluroids, like the absence of the basihyal bone.An ossified dorsal hypohyal appears late in ontogeny in Amia, as do tooth plates related to the medial side of the hyoid arch and branchiostegal rays in Amia, and tooth plates on the hyoid arch and branchiostegal rays in Elops (unique features within extant teleosts). Two ossified hypohyals, a synapomorphy of teleosts, are present early in ontogeny.There is intraspecific variation in the onset of ossification of the bones of the head, but the sequence of ossification between bones in a defined structural system is conserved (e.g., branchiostegal rays ossify first, then bones of the hyoid arch).

Notizen: The vas deferens of Ambystoma macrodactylum is composed of a peritoneal epithelium, connective tissue layer with fibroblasts, circular smooth muscle, capillaries, cells containing lipid, and a luminal epithelium composed of a single layer of cuboidal cells covered by a net of interconnected ciliated squamous cells. The cuboidal cells have abundant rough endoplasmic reticulum, mitochondria, and PAS + secretory vesicles. Squamous cells of breeding males consistently have tufts of ∼100 cilia located at one end of the long axis of each cell. These cilia may help distribute secretory products. The squamous cells, absent in post-breeding males, are apparently sloughed into the lumen. Lipid vesicles are present throughout the cytoplasm of the cuboidal and squamous epithelial cells and are also in some cells of the connective tissue layer. These vesicles increase dramatically in number during the first 4 weeks after breeding and may serve as an energy pool for the next breeding season. Enzyme-histochemical tests for testosterone synthesis were negative. In addition to the accumulation of lipid and the loss of squamous cells in the vas deferens, after breeding PAS + vesicle production is terminated. These alterations appear to represent energy conservation strategies employed by the sperm-depleted vas deferens.

Notizen: The concept of parallel muscle combinations, in which spindle density is significantly higher in small muscles compared to their larger counterparts in large-small muscle combinations acting across a joint, is supported by the results of this study regardless of the joint. Analysis of the canine data as well as previously published guinea pig forelimb and human pelvic limb data revealed no significant difference in spindle density between antigravity and non-antigravity muscles. Furthermore, a gradual increase in spindle density from proximal to distal on the limb was not found, although spindle density was significantly higher in the intrinsic manus or pes muscles compared to more proximal limb muscles in all three species. The significant differences in spindle densities in parallel muscle combinations and in manus/pes versus proximal muscles are discussed relative to their possible role in the control of locomotion.

Notizen: The choanocyte chambers of eight different haplosclerid sponge species have been investigated with regard to their histological structure, their relation to the mesohyl, and their arrangement between the canal systems. Two fundamentally different organizational types occur in the investigated sponge species. In Haliclona rosea, H. oculata, H. elegans, H. simulans, H. rava, H. fistulosa, and Acervochalina limbata the choanocytes are separated from the mesohylar tissue, being more or less covered over the outer surface by pinacocytes belonging to the incurrent canal walls. In Haliclona indistincta, on the other hand, the choanocytes are, as in most other Demospongiae, in contact with the mesohyl at their outer surfaces. This indicates that the present order Haplosclerida is polyphyletic and contains sponges of a presumably poecilosclerid origin.

Notizen: The three-dimensional structures of the carotid labyrinth in five species of anurans representing four families (Rana nigromaculata, Rana catesbeiana, Bufo japonicus, Hyla arborea, and Xenopus laevis), and three species of caudates representing three families (Cynops pyrrhogaster, Hynobius nebulosus, Ambystoma mexicanum) were compared using vascular corrosion castings and scanning electron microscopy (SEM). Anuran carotid labyrinths are spherical in shape and are classified into two groups according to the origin of the external and internal carotid arteries. One group, which included Rana, Hyla, and Bufo, is characterized by the presence of a vascular ring at the proximal end and some vascular routes at the distal end of the labyrinth. The external and internal carotid arteries originate from these structures. The other group, which includes only Xenopus, is characterized by the external carotid artery opening directly from the central chamber or the common carotid artery, and by the internal carotid artery originating from within the vascular maze. The vascular maze is most complex in Xenopus, less so in Rana and Bufo, and simplest in Hyla. The carotid labyrinths in Cynops and Hynobius are oblong in shape. The fundamental organization in salamanders is similar to that in anurans. The vascular maze, however, is much simpler than in Hyla. There is no specialized swelling in Ambystoma mexicanum. The present findings suggest that most amphibian carotid labyrinths have the appropriate architecture for controlling vascular tone.

Notizen: The vomeronasal sensory epithelium of a crotaline snake, Trimeresurus flavoviridis, was shown to consist of a superficial supporting cell layer and an underlying sensory cell layer composed of columns of sensory cells. The supporting cell layer consists of both supporting cells and dendrites of the underlying sensory neurons. The apical regions of sensory cell dendrites contain numerous microtubules, many elongated mitochondria, centrioles, and electron-dense bodies. The dendrites terminate as dendritic knobs from which microvilli project into the vomeronasal lumen. Smooth vesicles are abundant in the dendritic terminals and their vicinity. Supporting cells also bear microvilli, and these cells contain large electron-opaque granules and dense vesicles near their free surfaces. Cytoplasmic extensions of the supporting cells form a meshwork which separates dendrxites from each other in the vicinity of the luminal surface. The meshwork becomes obliterated in the infranuclear region of each supporting cell. Bipolar-shaped sensory cells with lightly stained round nuclei contain the characteristic cell organelles of neurons and are thought to be sensory neurons. These cells are especially characterized by well-developed lamellae of rough endoplasmic reticulum and extensive arrays of smooth endoplasmic reticulum. The perikarya of cells located in the apical region of the cell columns tend to contain larger amounts of smooth endoplasmic reticulum and lipofuscin granules than the perikarya of cells located in lower regions. Undifferentiated cells are found in the basal region of the columns. Satellite cells form the framework of the columns and are also found among neuronal elements.

Notizen: The protandric hermaphrodite Ophryotrocha puerilis possesses one pair of eyes. They are located in the peristomium. Each light-sensitive organ consists of one sensory cell and one to two supporting cell(s) embedded in a cup-shaped reflector. The sensory-supporting cell complex is enveloped by a basal lamina. This lamina is supposed to be identical with the neural lamella. Thus the eyes proper have to be regarded as protrusions from the brain, while epidermal cells seem to differentiate to crystalline cells (reflector) and are deposited onto the sensory complex.The reflector is built up by several cup-shaped cells (juveniles, 4-5; adults, 10-12). Each of these cells comprises a multilayer of parallel-oriented, membrane-bound crystalline platelets which are thought to be guanine. The sensory cell is of the inverted rhabdomere type. Submicrovillar cisternae, typical for most polychaete eyes, are lacking. The first and always present supporting cell entirely envelops the sensory cell, thus forming the extracellular space around the rhabdomere. It does not contain any pigment granules. Often but not always a second supporting cell has been observed surrounding the sensory cell and first supporting cell. It is interpreted as a glial cell.In the sensory cell beneath the rhabdomere, pino- and phagocytosis can be observed and secondary lysosomes are found in high densities. Preliminary results seem to demonstrate that there is no distinct diurnal cycle of receptoral membrane recycling. In comparison with the ocelli of Dinophilidae, which have been interpreted as a dorvilleid-related family, morphological differences and their application to phylogenetic considerations are discussed.

Notizen: The appearance pattern of pharyngeal tooth germs was investigated in the larval Japanese dace, Tribolodon hakonensis, which has a bilaterally asymmetrical dentition. Teeth develop in a series of replacement waves beginning with the initial central tooth (Ce) and continuing with teeth of anterior (An) and posterior (Po) positions relative to the initial one. Identified by wave number (n) and tooth position (r), according to the formula n-1[r], tooth germs appeared in the order of tooth 0[Ce0], 1[Po1], 1[Anl], 2[Ce0], 2[An2], 3[Po1], 3[An1], 4[Ce0], 4[An2], 5[Po1], 5[An1], 5[An3], 6[Ce0], 6[An2] during the larval period. Dentition on the right side, however, lacks the first tooth at position An2 (tooth 2[An2]) and teeth at position An3. Tooth germs on the first, second, and third replacement waves appeared simultaneously on the arches of both sides. During following waves, tooth germs on the left side appeared later than those on the right. Delay of tooth germ appearance On the left side is interpreted as an inhibitory influence of existing tooth germs in accordance with Osborn's (Proc. R. Soc. Lond. Ser. B 179:261--289, '71) theory. The delay of tooth germ appearance on the left arch is most pronounced on the seventh replacement wave. Teeth of the right major row in adults of this species are replaced more frequently than those of the left major row, apparently in correlation with the absence of the first larval tooth at position An2 and teeth at position An3. It is hypothesized that cyprinids evolved the minor rows and specialized teeth of their adult dentition as apomorphic characteristics by the process of neoteny.

Notizen: Development of the internal structures of the caudal region (muscles, bones, cartilages, nerves, and blood vessels) of the Da/Da mutant medaka and of wild-type +/+ fish was compared. Muscles and nerves were immunochemically stained by using an antibody to troponin T and antibodies to neurofilament proteins, respectively. Bones and cartilages were stained with alizarin red and alcian blue. In stages 31-32 of the Da/Da embryo, the rudiments of epurals 1, 2, and 3 differentiated dorsally opposite the sites of the ventral rudiments of the parhypural, the lower hypural plate, and the upper hypural plate, respectively. In the +/+ embryo, the rudiments of epurals 1 and 2 differentiated in the later developmental stages (after stage 34), but the rudiment of epural 3 did not differentiate. In the Da/Da embryo, the deep dorsal flexor passed dorsalwards and ended at the rudiment of epural 2, whereas the muscle passed ventralwards and ended at the rudiment of the upper hypural plate in the +/+ embryo. In the Da/Da fry, the epichordal region of the caudal fin fold grew and the notochord extended straight into the tail without bending, while in the + /+ fry, the epichordal region did not grow and the notochord turned dorsalwards within the tail. In the Da/Da fry, extra skeletal rudiments and musculature differentiated in the epichordal region of the caudal fin, whereas these supernumerary structures did not develop in the +/+ fry. The pattern of the epichordal skeleton and musculature in the caudal region of the adult Da/Da fish was an almost mirror-image duplication of the hypochordal structures. These observations suggest that the characteristic expansion of the dorsal fin and epichordal lobe in the caudal region of the adult Da/Da fish is due to a process of ventralization, whereby the dorsal skeleton, musculature, and fin fold are stimulated to differentiate in a pattern like that which is restricted to the anal fin and hypochordal lobe of the wild type.

Notizen: Tongue musculature in 24 genera of snakes was examined histologically. In all snakes, the tongue is composed of a few main groups of muscles. The M. hyoglossus is a paired bundle in the center of the tongue. The posterior regions of the tongue possess musculature that surrounds these bundles and is responsible for protrusion. Anterior tongue regions contain hyoglossal bundles, dorsal longitudinal muscle bundles and vertical and transverse bundles, which are perpendicular to the long axis of the tongue. The interaction of the longitudinal with the vertical and horizontal muscles is responsible for bending during tongue flicking. Despite general similarities, distinct patterns of intrinsic tongue musculature characterize each infraorder of snakes. The Henophidia are primitive; the Scolecophidia and Caenophidia are each distinguished by derived characters. These derived characters support hypotheses that these latter taxa are each monophyletic. Cylindrophis (Anilioidea) is in some characters intermediate between Booidea and Colubroidea. The condition in the Booidea resembles the lizard condition; however, no synapomorphies of tongue musculature confirm a relationship with any specific lizard family. Although the pattern of colubroids appears to be the most biomechanically specialized, as yet no behavioral or performance feature has been identified to distinguish them from other snakes.

Notizen: Wall and internal organelles of the encysting salt marsh heterotrich ciliate Fabrea salina were examined by bright field and Nomarski interference contrast microscopy and by transmission and scanning electron microscopy. A mucoid sheath believed to be derived from bacteria covers the ectocyst. The possible bacterial origin of this sheath has been demonstrated experimentally by its removal and reappearence after 24 hours. Control ectocyst maintained in sterile seawater did not replace the sheath. The ectocyst has a crinkled appearance. The endocyst is composed of two layers. The inner endocyst material is continuous with that of the plug located at one end of the cyst. The two membranes are separated from one another by an interwall space filled with fibrous material. The cytoplasm, covered by an outer double membrane pellicle, contains mucocysts, pigment granules, microtubules, non-ciliated kinetosomes, Golgi complexes, ribosome-studded endoplasmic reticulum, and mitochondria. The endoplasm contains numerous autophagosomes, mitochondria, and food reserve materials. The macronucleus is centrally located in the cytoplasm of the encysting organism.

Notizen: Analysis of lateral and dorsoventral radiographic films shows that ingestion, transport, and mastication in Pedetes capensis (Rodentia) are cyclic and their movement patterns are essentially similar for the three food types offered. During the ingestion cycle, closing of the mouth is accompanied by a backward translation of the condyles, so that movement is predominantly orthal. During the opening stage, the extent of the anterior condylar translation is smaller. As a result the mandibular incisors move ventrally and posteriorly. During the ingestion cycles, food is transported to the back of the tongue, with the transverse rugae and the folds of the upper lip playing important roles.Springhares show a bilateral masticatory pattern; food is chewed on both sides simultaneously. During chewing, the condyles lie in their most forward position at maximum opening of the mouth. The mouth is closed by rotation of the lower jaw around the temporomandibular joint coupled with posterior condylar translation. At the beginning of the slow-closing stage, the upward rotation of the mandible slows and the jaw slowly shifts forward. During the grinding stage, the mandible is shifted forward with both toothrows in occlusion. During the opening stage, the jaw returns to its starting position.Comparison of kinematic and anatomical data on rodent mastication suggests that some dental characteristics form the most important factors regulating the masticatory pattern and consequently allow reasonably reliable prediction of rodent masticatory patterns.

Notizen: Avian embryos can be completely paralyzed by injection of neuromuscular-blocking agents. We used a single injection of decamethonium iodide to paralyze embryos at 7, 8, or 10 days of incubation and analyzed the growth of individual bones (clavicle, mandible, ulna, femur, tibia, humerus) and of individual muscles that act upon some of those bones (clavicular and sternal heads of m. pectoralis, and mm. biceps brachii, depressor mandibulae, pseudotemporalis, and adductor externus). Growth of the bones is not equally affected by paralysis. Only 27% of clavicular growth (by mass) but 77% of mandibular growth occurred in paralyzed embryos, whereas the four long bones exhibited 52-63% of their normal growth. Analysis of muscle weight, fiber length and physiological cross-sectional area (weight/fiber length) indicate that there was greater reduction of the muscles acting on the limbs than of those acting on the mandible, i.e., diminished growth of the skeleton is correlated with reduced muscular activity. Specific retardation of clavicular growth is due to fusion of sternal rudiments and collapse of the thorax, as well as virtual absence of the musculature that normally attaches to the clavicle. We discuss these results in the light of intrinsic and extrinsic factors governing growth of tne embryonic skeleton. Paralysis reduces skeletal growth by reducing both the movements taking place in ovo, and the loads imposed on the bones by muscle contraction, changes that represent alterations in the mechanical environment of the skeleton.

Notizen: This study using light and electron microscopy indicates that the saccus vasculosus is distinguishable in 9-mm embryos and grows continuously throughout embryonic development to the adult stage. In the saccus vasculosus, epithelial mitoses are observed in all stages studied. Phases of centriologenesis, ciliogenesis, and globule formation have been characterized in developing coronet cells. During the phase of centriologenesis, new centrioles appear in association with pre-existing centrioles and not on deuterosomes. After ciliogenesis, each cilium differentiates to a globule almost at the same time as the other cilia of the coronet cell. The inner membrane system of the globules seems to derive from the ciliary plasma membrane. This membrane system often produces membrane whorls during the development. The different phases of coronet cell development have been found in the same individual and in all the stages studied except the 9-mm embryo. Cerebrospinal fluid-contacting neurons are observed in the saccus epithelium from the 12-mm embryos on and are distinguishable from coronet cells in their early formative stages. The three cell types of the saccus vasculosus increase continuously in number during development. Nerve processes are found in the saccus vasculosus of embryos, whereas differentiated synapses appear later in the fry. The significance of continued coronet cell formation is discussed in relation to a putative coronet cell and/or a globule renewal cycle in the adult.

Notizen: Changes of architecture of adult rat gastrocnemius medialis muscle (GM) due to growth were studied in relation to length-force characteristics. Myofilament lengths were unchanged, indicating constant sarcomere length-force characteristics. Number of sarcomeres within fibers was unchanged as a consequence of growth, allowing persistence of differences between proximal and distal fibers in all age groups. Distal fiber length at muscle optimum length was shorter for the 14- than for the 10- and 16-week age groups despite a lack of difference of number of sarcomeres. This is indicative of a shift of optimum fiber length with respect to muscle length to lengths higher than optimum length. Some evidence for the occurrence of distribution of fiber optimum lengths with respect to muscle optimum length was found in other age groups as well, albeit of a smaller magnitude. Muscle and aponeurosis length increased substantially with growth. Functional effects of increased aponeurosis lengths were increased contributions to muscle length changes by the aponeurosis, allowing smaller fiber contributions in older animals. Fiber angle increased approximately 5° with growth. Despite the differences of architecture indicated above, muscle length range between optimum length and active slack length was constant. This was probably caused by widening of this length range in the youngest age group by variations of architecture within the muscle. It is concluded that adaptation of aspects of muscle architecture is an important mechanism for adult muscle growth in rat GM. Of these aspects regulation of muscle length seems a dominant factor.

Notizen: A light and electron microscopic study of the skin of domestic chickens, seagulls, and antarctic penguins revealed abundant extracellular dermal lipid and intracellular epidermal lipid. Dermal lipid appeared ultrastructurally as extracellular droplets varying from less than 1 μm to more than 25 μm in diameter. The droplets were often irregularly contoured, sometimes round, and of relatively low electron density. Processes of fibrocytes were often seen in contact with extracellular lipid droplets. Sometimes a portion of such a droplet was missing, and this missing part appeared to have been “digested away” by the cell process. In places where cells or cell processes are in contact with fat droplets, there are sometimes extracellular membranous whorls or fragments which have been associated with the presence of fatty acids. Occasionally (in the comb) free fat particles were seen in intimate contact with extravasated erythrocytes. Fat droplets were seen in the lumen of small dermal blood and lymph vessels. We suggest that the dermal extracellular lipid originates in the adipocyte layer and following hydrolysis the free fatty acids diffuse into the epidermis. Here they become the raw material for forming the abundant neutral lipid contained in many of the epidermal cells of both birds and dolphins. The heretofore unreported presence and apparently normal utilization of abundant extracellular lipid in birds, as well as the presence of relatively large droplets of neutral lipid in dermal vessels, pose questions which require a thorough reappraisal of present concepts of the ways in which fat is distributed and utilized in the body.

Notizen: Development of neurons in the area triangularis of Gallotia galloti was investigated in Golgi-impregnated brain tissue. Four major neuronal types present in adults were found to originate from two migratory neuroblast types, which were followed from embryonic stage S.32. One type has a thick main medial process, whereas the second type has a long main lateral process. As they migrate toward the periphery of the nucleus, morphological characteristics of maturation appear, including growth cones, filopodia, and outgrowth of axons. Neuroblasts with a main lateral process differentiate into two immature neuronal types, bipolars and pyramidals, observed at S.33 and thereafter. The neuroblasts with a main medial process undergo some somatic translocation through a transitory tangential shaft. Then they develop into monopolar immature forms with a long varicose medial, process, appearing from S.36. onward. Immature bipolar neurons do not experience great changes in their dendritic arborization during development to the adult stage, but pyramidals and monopolars undergo a rapid development of the dendritic tree after S.36. By S.38 archetypes of adult neuronal forms are established. Hairlike appendages first appear on neurons at S.36 They decrease suddenly in S.38 and then proliferate in S.39 when spines first appear. Around the time of hatching, the hairlike appendages begin to disappear and spines become established. Reduction of spines occurs after hatching and continues to the adult stage. Possible influences of several external factors on neuronal maturation are discussed.

Notizen: The female reproductive system of Sphaerodema rusticum consists of a pair of ovaries, two lateral oviducts, a median common oviduct, and a median spermatheca. Accessory glands are absent. Each ovary has five free ovarioles branching from the oviduct. Each ovariole consists of a terminal filament, germarium, vitellarium, brown mass, and an exceptionally long pedicel. The terminal filament consists of a central core, interstitial cells, and an outer sheath. In the germarium, which consists of trophic and prefollicular regions, the trophic region or nurse cell chamber is divided into four histologically differentiated zones, distinguished as zones I-IV. Nutritive cords, originating from the posterior end of the trophic core in zone IV extend centrally and join the developing oocytes in the prefollicular chamber and the vitellarium. The compact prefollicular tissue at the base of the trophic core gives rise to prefollicular cells which, after encircling the young oocytes, become modified into follicular epithelial cells, the interfollicular plug, and epithelial plug. The young oocytes descend into the vitellarium and gradually develop into mature oocytes. A compound corpus luteum is observed simultaneously in all the ovarioles of both ovaries after ovulation. Below the epithelial plug there is an accumulation of material, the “brown mass,” which develops cyclically in correlation with the ovulation cycle. Each pedicel stores five mature chorionated eggs ready for oviposition. The epithelium of the anterior region of the pedicel secretes a PAS-positive material. General morphology and histology of the subdivisions of the ovarioles are described.

Notizen: The feeding mechanisms of two labrid fishes (Cheilinus chlorurus and C. diagrammus: Labridae: Perciformes) are modeled using four-bar linkage theory from mechanical engineering. The actions of the feeding mechanisms are simulated by a computer program that uses morphometric data to calculate the geometry of mechanism structure. The predictions of three different four-bar linkages regarding the kinematics of feeding are compared to the movements observed through hign speed (200 fps) cinematography. A previously unidentified four-bar chain was found to be an accurate model of the mechanism by which upper jaw protrusion, maxillary rotation, and gape increase occur in Cheilinus. This mechanism involves the anterior jaws including the mandible, maxilla, premaxilla, palatine, and suspensorium. The accuracy of two previously described four-bar linkages was also tested by comparison of model predictions and film results. The opercular linkage proposed by Anker ('74) as a mechanism of jaw depression via opercular levation was found to be a poor predictor of feeding movements. This four-bar chain involves the opercle, suspensorium, interopercle, and mandible. Muller ('87) proposed a mechanism of hyoid depression involving cranial elevation due to epaxial muscle contraction as input motion The links in this mechanism include the neurocranium and hyomandibula, hyoid, sternohyoideus muscle, and pectoral girdle. This model was an accurate predictor of hyoid depression in Cheilinus when simultaneous cranial elevation and sternohyoideus contraction were simulated. Quantitative kinematic models involve simplifying assumptions when applied to complex musculoskeletal systems, but such models have a wide range of applications to vertebrate functional morphology.

Notizen: The morphology of both the main nasal cavity and the vomeronasal organ differs among species representing six families of caecilians. The main nasal cavity is either divided or undivided. The vomeronasal organ differs in position (mediolateral, lateral), size (large vomeronasal organ in the aquatic species), and shape (mediolateral extension, vomeronasal organ with a lateral rostral projection). The great amount of respiratory epithelium of the main nasal cavity, the large vomeronasal organ, and its extensive innervation in typhlonectids may reflect both phylogeny and habitat adaptation, for these taxa are secondarily aquatic or semiaquatic and have several concomitant morphological and physiological modifications. The vomeronasal organ is associated with the caecilian tentacle as the tentacular ducts open into it. This association is further evidence for the involvement of the caecilian tentacle in vomeronasal chemoperception and may represent the mechanism by which these animals smell though the main nasal cavity is closed during burrowing or swimming. Labelings of primary olfactory and vomeronasal projections by means of horseradish peroxidase reaction reveal that the pattern of vomeronasal projections is similar in Ichthyophis kohtaoensis, Dermophis mexicanus, and Typhlonectes natans, even though T. natans possess stronger vomeronasal projections relative to olfactory projections than I. kohtaoensis and D. mexicanus. However, there are differences with respect to the patterns of olfactory projections. The olfactory projection of I. kohtaoensis is characterized by many displaced glomeruli. T. natans has the smallest olfactory projection. The nervus terminalis is associated with the olfactory system as shown by selective labelings of olfactory projections.Six characters potentially useful for phylogenetic analysis emerge from this study of comparative morphology. The characters were subjected to analysis using PAUP to see (1) if any resolution occurred and (2) if any groups were distinguished, whether they corresponded to phylogenetic arrangements based on other morphological characters. The characters are too few to produce nested dichotomous sets for all cases, but they do support the two typhlonectid genera examined and Dermophis and Gymnopis as sister taxa discrete from other groups, and they show that species within genera cluster together.

Notizen: A kidney from the budgerigar (budgie, parakeet; Melopsittacus undulatus) is composed of cortical reptilian-type nephrons (without loops of Henle) and mammalian-type nephrons (with loops) grouped together in medullary cones. The loop of the mammalian-type nephrons has a descending segment composed of thin and highly interdigitated cells. These thin limb cells have few mitochondria (15% of cell volume), undetectable Na+, K+-ATPase activity, and virtually no basolateral surface amplification. Prior to the hairpin turn, the descending limb thickens, but the cells continue to lack basolateral amplification. Cells just prior to and within the hairpin turn resemble cells of the entire ascending limb. These cells are thick (there is no thin ascending segment in the avian loop), with extensive infoldings of the basolateral membrane surrounding numerous mitochondria (45% of cell volume). The area of basolateral membrane is 25 times that of the apical membrane. The basolateral membrane (but not the apical membrane) is enriched in Na+, K+-ATPase activity. The structure of the avian mammalian-type nephron (as epitomized by the budgie nephron) and the fact that NaCl accounts for over 90% of the osmotic activity of avian urine leads to the conclusion that the countercurrent multiplier of the avian kidney functions by active NaCl transport from the entire ascending limb. No explanation is offered for the transport specializations found in the thick descending segment of the loop, just prior to the hairpin turn.

Notizen: The cells-of-origin and the mode and site of termination of the interhemispheric connections passing through the anterior and posterior pallial commissures in the telencephalon of two lizards (Podarcis hispanica and Gallotia stehlinii) were investigated by studying the anterograde and retrograde transport of unilaterally injected horseradish peroxidase. The commissural projections arise mainly from pyramidal cells in the medial, dorsomedial, and dorsal cortices (medial subfield). Additionally some non-pyramidal neurons in the medial and dorsal cortices contribute to the commissural system. Medial cortex neurons project to the contralateral anterior septum through the anterior pallial commissure. The dorsomedial cortex projects contralaterally via the anterior pallial commissure to the dorsolateral septum and to the medial, dorsomedial, and dorsal cortices. The projection to the medial cortex terminates in two bands at the inner and outer border, respectively, of the cell layer; the projection to the dorsomedial and dorsal cortex ends in a zone in layer 1 which previously has been described to be Timm-negative, and in a diffuse band in the inner half of layer 3. The medial subfield of the dorsal cortex projects through the anterior pallial commissure to the dorsomedial and dorsal cortices with a similar pattern of termination to that found for the dorsomedial cortex. The posterior pallial commissure contains only the projections from the ventral cortex to its contralateral counterpart and to the ventral part of the caudal medial cortex. The similarities found between this commissural system and the mammalian hippocampal interhemispheric connections are discussed.

Notizen: The distribution of structural and secretory glycoconjugates in the gastric region of metamorphosing Xenopus laevis was studied by the avidin-biotinperoxidase (ABC) histochemical staining method using seven lectins (concanavalin A, Con A; Dolichos biflorus agglutinin, DBA; peanut agglutinin, PNA; Ricinus communis agglutinin I, RCA-I; soybean agglutinin, SBA; Ulex europeus agglutinin I, UEA-I; and wheat germ agglutinin, WGA). Throughout the larval period to stage 60, the epithelium consisting of surface cells and gland cells was stained in various patterns with all lectins examined, whereas the thin layer of connective tissue was positive only for RCA.-I. At the beginning of metamorphic climax, the connective tissue became stained with Con A, SBA, and WGA, and its staining pattern varied with different lectins. The region just beneath the surface cells was strongly stained only with RCA-I. With the progression of development, both the epithelium and the connective tissue gradually changed their staining patterns. The surface cells, the gland cells, and the connective tissue conspicuously changed their staining patterns, respectively, for Con A and WGA; for Con A, PNA, RCA-I, SBA, and WGA; and for Con A, RCA -I, and WGA. At the completion of metamorphosis (stage 66), mucous neck cells became clearly idpntifiable in the epithelium, and their cytoplasm was strongly stained with DBA, PNA, RCA-I, and SBA. These results indicate that lectin histochemistry can provide good criteria for distinguishing among three epithelial cell types, namely, surface cells, gland cells, and mucous neck cells, and between adult and larval cells of each type.

Notizen: Ultrastructural features of the ovotestes, spermatogenesis, and the mature sperm are described for three galeommatid bivalves, Divariscintilla yoyo, Divariscintilla troglodytes, and Scintilla sp., from stomatopod burrows in eastern Florida. All three species yielded similar results except with respect to mature sperm dimensions. The ovotestis contains three types of somatic cells within the testicular portion: flattened myoepithelial cells defining the outer acinal wall; underlying pleomorphic follicle cells containing abundant glycogen deposits; and scattered, amoeboid cells containing lysosomal-like inclusions which are closely associated with developing sperm. Early spermatogenesis is typical of that reported from other bivalves. In contrast, the late stages of spermiogenesis involve the migration and gradual rotation of the acrosomal vesicle, resulting in a mature acrosome tilted about 70° from the long axis of the cell. The mature sperm possesses an elongated, slightly curved nucleus; a subterminal, concave acrosome with a nipple-like central projection; five spherical mitochondria and two centnoles in the middlepiece; and a long flagellum. The rotational asymmetry and the presence of perimitochondrial glycogen deposits in these sperm are unusual in the Bivalvia and may be associated with fertilization specializations and larval brooding common among galeommatoideans.

Notizen: Polychaetes normally possess one pair of nuchal organs at the posterior edge of the prostomium or peristomium. They have been regarded as chemosensory organs. The nuchal organs of four marine polychaete species with different habits were investigated by electron microscopy.Although the shapes of nuchal organs can vary greatly from simple ciliary bands (Scolelepis squamata, Spionidae) to retractile tongue-like, piston- or finger-shaped forms (Eteone longa, Anaitides mucosa, Phyllodocidae; Heteromastus filiformis, Capitellidae), the structural components, including the ciliated supporting cells, sensory cells, and nuchal epidermal cells, are essentially similar. The differences basically concern 1) the position of the sensory cells with relation to the ciliated supporting cells, 2) the location and structure of the nuchal nerve, and 3) the structure of the nuchal cuticle.The diverging nature of this modified cuticle is described and discussed in detail. Comparisons are made with the fine structure of nuchal organs of other polychaete species. Similarities of cellular components of nuchal organs are found not only in the four species studied here but also in all nuchal organs investigated so far. This is hypothesized to be due to the fact that the polychaete stem species already possessed nuchal organs with the respective cell types. Differences in the number and distribution of cellular components and in the overall shape of nuchal organs are thought to have evolved in correlation with the equipment of other cephalic appendages and with different habits and modes of nutrition.

Notizen: The buccal glands of adults of the Southern Hemisphere lamprey Geotria australis consist of a pair of small, bean-shaped, hollow sacs, embedded within the basilaris muscle in the region below the eyes and to either side of the piston cartilage. Each gland, which is lined by a simple columnar epithelium and surrounded by an incomplete layer of skeletal muscle, discharges its contents into the oral cavity via a long, narrow duct. In downstream migrating young adults, the epithelial cells are low columnar, intermediate in electron density, and contain dark-staining inclusions and numerous lipid-like droplets. After saltwater acclimation, the epithelial cells become taller and the numbers of dark-staining inclusions increase whereas those of lipid-like droplets decline. By the end of the marine phase, the epithelium is more folded and now also contains dark and light cells. The ultrastructure of the epithelium shows the characteristics of both apocrine and merocrine secretion. Although intra-epithelial nerve endings were not observed, axons and occasional neurons are present in the lamina propria. Since the skeletal muscle capsule is also well innervated and contains neurons, a local feed-back mechanism may regulate the release of buccal gland fluid by monitoring the luminal pressure. Contractions of the skeletal muscle capsule and movements of the basilaris muscle during feeding would presumably assist the movement of secretion along the duct. The secretion possesses anticoagulating and haemolytic properties.

Notizen: The early development of Pedetontus unimaculatus from maturation to germ rudiment formation has been described by light and electron microscopy. Newly laid eggs of P. unimaculatus are in the metaphase of the first maturation division, and two successive maturation divisions produce two polar bodies. Nuclear divisions up to the eighth or ninth are accompanied by cytoplasmic divisions, and are holoblastic. Each resulting blastomere contains a single nucleus. Most cleavages are radial, but a few are tangential resulting in the formation of primary yolk nuclei. After the eighth or ninth nuclear division, cytoplasmic divisions are restricted to the egg periphery, and these later cleavages are superficial. Boundaries of blastomeres gradually disappear. Nuclei, which settle in the peripheral cytoplasm, proliferate and differentiate into blastoderm cells, and they also give rise to secondary yolk nuclei. A posterior circular region of blastoderm thickens and concentrates to form a germ rudiment 50-100 μm in diameter. During the formation of a germ rudiment the serosal cuticle begins to form.A similar pattern of cleavage was observed in other species of the Machilidae belonging to four genera in two subfamilies (Machilinae, genus Haslundichilis; Petrobiinae, genera Pedetontus, Pedetontinus, Petrobiellus). The cleavage pattern of the machilids closely resembles that found in the myriapod groups, the Symphyla, Diplopoda, ana Pauropoda, as well as in the apterygote Collembola, but it differs from the purely superficial cleavage pattern characteristic of the apterygote Thysanura sensu stricto (Zygentoma) and the Pterygota.It is concluded 1) that the pattern of early total cleavage changing later to superficial cleavage is a plesiomorphic character for the Antennata, and 2) that the purely superficial pattern is an apomorphic character within the Hexapoda.

Notizen: The digestive gland (midgut gland, hepatopancreas) of the American lobster, Homarus americanus (Decapoda: Nephropidae), is permeated with terminal arterioles of the hepatic artery. Fixed phagocytes associated with the terminal hepatic arterioles removed two types of non-biogenic, foreign particles (carbon particles and latex beads) that were injected into the blood. These cells play an important role in the cell-mediated immunity of lobsters.

Notizen: The digestive gland (midgut gland, hepatopancreas) of the American lobster, Homarus americanus (Decapoda: Nephropidae), is supplied with blood by the hepatic artery. Numerous branches, ending in terminal hepatic arterioles, permeate the organ and discharge blood into the hemal sinuses. Histological and ultrastructural studies show the arterioles to be elongate tubes that lie in the hemal spaces, interspersed among the digestive tubules of the digestive gland. The terminal hepatic arterioles comprise three distinct populations of cells: endothelial cells form the wall of the blood vessel; hemocytes circulate through the lumen of the vessel; and fixed phagocytes are attached to the outer surface of the endothelium. In addition, extracellular membranes form an endothelial intima that lines the lumen and a perforated membrane that covers the outer surface of the arteriole.

Notizen: mAb WE3 recognizes an antigen that is developmentally regulated in the wound epithelium of regenerating newt limbs. The antigen is precociously expressed when pieces of WE3-negative wound epithelium axe grafted subcutaneously (Tassava et al.: Recent Trends in Regeneration Research. New York: Plenum Publishing Co., pp. 37-49, 1989). In the present study, we investigated whether the WE3 antigen is expressed in epidermis of subcutaneous grafts of skin. Small pieces of limb skin were grafted into small tunnels in the lower jaw, limb, and tail, oriented either the same as (epidermis facing out) or opposite to (epidermis facing in) the orientation of the host skin. In most cases, the epithelium migrated from the graft along the wounded surface of the tunnel, closed onto itself, and formed a multilayered “emigrant” epithelium. Infrequently, the migrating epithelium combined with the wound epithelium of the insertion wound. In no case did the epithelium migrate over the cut edge of the grafted dermis. Reactivity to mAb WE3 was first seen at 4 days after grafting, when the migrating epithelium had almost closed over onto itself. By 6 days and thereafter, the entire emigrant epithelium was reactive to mAb WE3. While initially restricted to the emigrant epithelium, at 10 days after grafting and thereafter, reactivity was also seen in the epidermis that remained in contact with the dermis. Expression of the WE3 antigen was not influenced by the orientation of the graft nor by the graft site. The results show that, compared to amputated limbs, the epithelium originating from these grafts precociously expresses the WE3 antigen. Also, epidermis of grafted skin is capable of expressing the WE3 antigen.

Notizen: Endocrine cells and brush cells at the bronchiolo-alveolar junctions of the lung of neonatal hamsters were studied by transmission electron microscopy. On both sides of the junctions (bronchiolar and alveolar), clusters of endocrine cells occur as neuroepithelial bodies (NEB). A few solitary endocrine cells are also present at the alveolar sides of the junctions. Some endocrine cells reach from the basement membrane to the air space but the area of apical cell membrane exposed to the airway is small as the cells are largely covered by Clara cells in the bronchioles and by thin attenuations of alveolar type 1 cells in the alveoli. Some Clara cells around NEB contain cytoplasmic lamellar bodies, similar to those characteristically associated with alveolar type 2 cells. A few brush cells are also seen at both sides of the junctions. Long wide microvilli with filamentous cores extend from the apices of the brush cells. Endoplasmic reticulum and Golgi apparatus are moderately developed. Well-developed bundles of intermediate filaments course throughout the cytoplasm of some of the brush cells. The functions of endocrine cells and brush cells are unknown. However, the presence of these cells at the bronchiolo-alveolar junctions of neonatal hamster lungs suggests a role in regulation of respiratory function.

Notizen: Anolis carolinensis has two aggressive displays involving movements of the hyoid apparatus: erection of the throat and extension of the dewlap. Erection of the throat is an enlargement of the gular region and dewlap extension consists of a vertical erection of the gular flap. Cinefluoroscopy and high speed cinematography show that the dewlap is extended in three phases: 1) protraction of the entire hyoid apparatus; 2) forward pivoting movement of the ceratobranchials II; and 3) retraction of the ceratobranchials II and the entire hyoid apparatus. The cartilaginous elements of the hyoid apparatus are variably mineralized. The entoglossal process and the hypohyals are the most calcified elements. The mineralized portion of the hyoid body, to which the other elements articulate, presents a complex pattern. The calcification of entoglossal process and the hypohyals stop just where they are fused with the hyoid body. The hyoid body presents four mineralized masses, two central corresponding to the base of the ceratobranchials II and two lateral being the head of the ossified ceratobranchials I. The lateral masses articulate on the central masses by a synovial joint. Morphologically, the ceratobranchials II form the hyoid body and become separated at the mid length of the synovial articulation of the ceratobranchials I and the hyoid body. The calcified matrix of the ceratobranchials II gradually changes from a large calcified mass (within the hyoid body) to a semicircle, opened ventrally, which permits their bending during dewlap extension. The highly mineralized posterior tip of the entoglossal process and the hyoid body serve as a pivot to pivoting forward movement of the ceratobranchials II producing at the change of the pattern of mineralization. Forward movement of the ceratobranchials II is produced by electrical stimulation of the M. branchio hyoideus. The opposition of the throat skin to the movement of the ceratobranchials II produces the bending of those longest elements. Electrical stimulation of the hyoid muscles confirms the key role of M. branchiohyoideus during dewlap extension. Simultaneous contractions of all the hyoid and extrinsic tongue (retractor and protractor) muscles with the M. branchiohyoideus during dewlap extension may be a possible motor pattern for dewlap extension in Anolis lizards.

Notizen: The ovotestis of Arion hortensis was investigated by electron microscopy, using serial ultrathin sections and freeze-fracture. Desmosome-like junctions between Sertoli-Sertoli and Sertoli-germ cells (spermatogonia, spermatocytes, spermatids, and spermatids just prior to spermiation) were studied. Desmosome-like junctions were circular when viewed en face and 90--180 nm in diameter. The intercellular space at the junctional site was 15-25 nm in width. An intermediate dense line was absent.Freeze-fracture replicas showed that these junctions formed groups, with one to ten junctions within each group. Groups of junctions were scattered over the Sertoli cell surface. The most prominent feature of this junction was an electron-dense plaque on the cytoplasmic face of the plasmalemma. We describe variation in the development of the electron-dense plaque on the germ cell side at different stages in the development of the germ cell. In the spermatogonium and spermatocyte stages, desmosome-like junctions had equally developed electron-dense plaques. The plaques are pronounced in junctions between Sertoli cells and spermatocytes/spermatids and less developed in relation to late spermatids where nuclear condensation is complete, and appear to be lost at spermiation. Finger-like processes arise from the Sertoli cell as desmosome-like junctions are lost at spermiation.Hypertonic fixative solutions containing dextrose were applied to the ovotestis resulting in cell shrinkage. The intercellular space between Sertoli cells and germ cells was increased except where the desmosome-like junctions were present. We suggest that desmosome-like junctions provide strong adhesive sites between Sertoli and germ cells.

Notizen: The ultrastructural studies have shown three types of motor endings in the macaque intrafusal fibers: (1) unindented axon terminals with smooth or shallowly folded postsynaptic membrane; (2) indented terminals with few postsynaptic folds; and (3) indented terminals with heavily folded postsynaptic membrane. The terminals on bag 1 and chain fibers were generally more indented than those on the bag 2 fibers. Deeply indented terminals with highly folded postsynaptic membranes were noticed on the bag 1 and chain endings in spindles from lumbrical but not the biceps muscle. In the individual intrafusal fibers from the biceps and lumbrical spindles, the degree of indentation did not correlate with the extent of postsynaptic folding (P〉.01). Endings on bag 1 and chain fibers in the lumbrical spindles showed a positive correlation between indentation of terminals and their distance from the primary sensory endings (P〈.01), whereas the lumbrical bag 2 endings and the biceps intrafusal endings did not (P〉.01). The shape of the intrafusal motor endings thus is independent of their location but dependent on the type of intrafusal fibers.

Notizen: Sockeye salmon were transferred rapidly from freshwater to seawater and the changes in gill morphology, in particular the distribution and sizes of chloride and mucous cells on the afferent filamental surface examined. Salmon that successfully adapted to seawater were compared with salmon that did not adapt to seawater and died as a consequence of osmoregulatory failure. The number of mucus cells (density), determined from scanning electron microscopy, increased significantly after seawater challenge. A greater increase in mucus cell density occurred in the salmon that failed to adapt to seawater. Light microscopy of transverse sections of gills detected no difference in mucus cell numbers after seawater challenge. It is proposed that mucus cells that lie just beneath the gill epithelium are activated in response to the seawater challenge, and migrate and open onto the epithelium. Freshwater-adapted salmon that had low densities of chloride cells prior to the seawater challenge failed to adapt, whereas salmon that had high densities of chloride cells adapted successfully to seawater. In the latter, the density of chloride cells on the afferent surface decreased after 30 days in seawater. The apical surface of the chloride cells of freshwater-adapted sockeye were either smooth or covered with microvilli. A greater proportion of microvilli-covered chloride cells occurred in the freshwater-adapted salmon that subsequently adapted to seawater.