摘要:

The ontogeny of the mandibular joint and the middle ear region was studied in Tupaiajavanica, Microcebus murinus, Nycticebus coucang and Tarsiusbancanus. During development, a passage connection was found between the mandibular condyle and Meckel’s cartilage that is produced by the primordium of the lateral pterygoid muscle. The articular disk is formed separately, and it appears later in development. A theory is presented on the interpretation of these finding

ISSN:1422-6405    

DOI:10.1159/000146850

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

Exencephaly was induced in Wistar rat fetuses by the administration of a single dose of cyclophosphamide (15 mg/kg) in saline after neural tube closure. The neuroepithelium (NE) and the choroid plexus were studied electron-microscopically in sections taken from a few hours after treatment to day 19 of gestation. The reduction in polyribosomes and condensation of the nucleus and cytoplasm were followed by cell death and fragmentation in the NE. Such cellular debris were phagocytosed and digested by the apparently normal neuroblasts. Cell proliferation was inhibited. The progressive loss of cells and lack of neuropil arborisation resulted in the expansion of the extracellular space and reduced intercellular contacts. The internal and external limiting membranes became weak. The vascular endothelium was attenuated. There were no obvious discontinuities of endothelium, but clusters of extravascular red blood cells particularly in the vicinity of capillaries in the cavitations in the NE and in the ventricular lumen were prominent by day 15. Subsequently, the cavities in the NE frankly communicated with the ventricle internally and subcutaneous blebs externally . The choroid plexus of exencephalic embryos was more extensive than that of the age-matched controls. Hydropic vacuoles, dense bodies, distended mitochondria, clusters of vesicles in basal cytoplasm and lakes of monoparticulate glycogen progressively increased in the plexus cells. Pericapillary oedema was obvious in the core of the plexus. These observations suggest that, in addition to cell death and reduced cell proliferation, haemorrhage, oedema and enhanced cerebrospinal fluid production contribute to reopening of the closed neural tube in this model.

ISSN:1422-6405    

DOI:10.1159/000146851

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

The effects of easily chewable diets and unilateral extraction of upper molars on the masseter muscle were studied in developing mice. A liquid diet requiring no mastication suppressed the development of the masseter muscles more than a fine-grained diet, and extraction of unilateral upper molars also caused inhibition of muscle development. Moreover both unilateral extraction of upper molars and a liquid diet had an additive effect on the the suppression of the postnatal development of the masseter muscle and bilateral suppression of the development of the masseter muscle was induced following unilateral extraction of upper molars. These findings suggest that the sensory input from the sensory endings in the periodontal ligament may also play an important role in the postnatal development of the masseter muscle and that there may be some crossing pathways to convey the sensory input coming from the side of the extracted upper molars to the contralateral motor neurons via the interneuronal circuits.

ISSN:1422-6405    

DOI:10.1159/000146852

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

In a testicular biopsy of an infertile man most of the spermatids revealed a lack of the middle piece because of a malformed or untimely occurring spindle-shaped body. When during spermatid differentiation the spindle-shaped body appeared it contained the typical bundles of tubules but was often reduced in size and arranged only unilaterally to the axoneme. After the disappearance of the incomplete spindle-shaped body, the annulus did not descend, the ribs of the fibrous sheath of the principal piece were found far proximally and the mitochondrial sheath of the middle piece could not be formed. In consequence of this faulty development, the spermatozoa were immotile.

ISSN:1422-6405    

DOI:10.1159/000146853

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

By removing epidermis with EDTA and a subsequent enzymatic digestion of dermis, eccrine sweat glands of rat fingertips were exposed and examined by scanning electron microscopy (SEM). Different protocols were tested to remove as much connective tissue as possible while minimizing damage to other structures and to expose the epithelial surface of secretory tubules in order to display vascular and nervous networks. SEM observations gave detailed informations on the relationship between epithelial secretory cells and myoepithelial cells, as well as on the vascular and nervous networks which surround the glomeruli of glands.

ISSN:1422-6405    

DOI:10.1159/000146854

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

Axon collaterals emerging from the vasopressinergic neurons of the supraoptic (SON) and paraventricular (PVN) nuclei and recurving back towards their respective nuclei have been previously reported. Since such axon collaterals can play a role in the neuromodulation of SON and PVN these nuclei have been further investigated immunohistochemically under the light and electron microscope. The PAP technique, using a commercial antibody, was employed. Vasopressin-positive axon collaterals were seen to recurve towards their nuclei of origin. In the latter, vasopressinergic intrinsic neurons were also observed. Under the electron microscope, axon terminals containing vasopressin-immuno-reactive neurosecretory granules were noted. Such terminals presumably arise from the vasopressin-positive recurrent axon collaterals or from the intrinsic neurons for the purpose of neuromodulation within the SON and PVN.

ISSN:1422-6405    

DOI:10.1159/000146855

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

The ultrastructural changes of rat corticotrophs were studied with the protein-A-gold immunocytochemistry. The number of secretory granules per square micrometer of cytoplasm decreased after adrenalectomy and remained low. This change was mainly due to the decrease in the mature granules. The number of gold particles on the secretory granule was increased 3 or 7 days after adrenalectomy, reflecting the high immunoreactive adre’nocorticotro-pin content in these states as has been already reported. The number of coated pits or coated vesicles beneath the plasma membrane was not increased significantly, and exocytosis was only infrequently observed. Ultrastructural changes which suggest a secretion pathway other than the secretory granules were not observe

ISSN:1422-6405    

DOI:10.1159/000146856

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

Day-night differences in the ultrastructure of pineal neuronal elements were quantitated in the rat and the chick – two species that exhibit important differences in adrenergic control of melatonin synthesis. Area densities of small clear vesicles (40–60 nm) and small dense-cored vesicles (40–60 nm) in nerve terminals were significantly reduced during the night in the rat. In the chick, there were no day-night differences in the frequency of clear vesicles, but the number of small dense-cored vesicles tended to be greater at night. There was no effect of day-night sampling on area densities of large dense-cored vesicles (80–120 nm) in either species. These findings are consistent with biochemical evidence for day-night species differences in the adrenergic control of pineal f

ISSN:1422-6405    

DOI:10.1159/000146857

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

In this study 13- to 14-day fetal thymic lobes were implanted within the anterior eye chambers in mice either with or without a syngeneic newborn sympathetic ganglion. It was observed after 6 weeks of implantation that the thymic lobes that grew with the ganglia had fewer lymphoid cells than their counterparts which were grown without the ganglia. The cells that developed within the thymic lobes were Thy-1- and peanut agglutinin-positive. The thymic lobes that grew with sympathetic ganglia also showed the presence of adrenergic nerves, perhaps due to reinnervation of the thymic grafts from the ganglia.

ISSN:1422-6405    

DOI:10.1159/000146858

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

Explanted palates of day 12 and day 13 mouse fetuses were cultured in a chemically defined serumless medium for 48–72 h by a suspension culture technique. The palate of day 12 fetuses closed successfully within 72 h and that of day 13 fetuses within 48 h. Both macroscopically and histologically the in vitro fusion of palatal shelves simulated the palatogenetic process in vivo. This novel technique for culturing the fetal mouse palate may be of potential use for the study of palatogenesis and in developmental toxicolog

ISSN:1422-6405    

DOI:10.1159/000146859

出版商:S. Karger AG    

年代:1990

数据来源: Karger