摘要:

AbstractThe development of the atrioventricular (AV) node and bundle in the ferret heart was examined at the light microscopic level. The AV node develops from two primordia which were first observed in the posterior wall of the common atrium during the stage when the single heart tube convolutes. During septation of the heart, the AV nodal primordia eventually fuse and come to lie at the base of the interatrial septum. The right AV nodal primordium is located below the attachment of the right venous valve to the interatrial septum. The left AV nodal primordium maintains a position anterior to the prospective ostium of the coronary sinus. At 16 days of gestation, large pale cells were seen in the dorsal AV canal. By 21 days of gestation these AV canal cells have been replaced by AV bundle cells. At this time the bundle is continuous with both nodal primordia. At birth the AV bundle is continuous mainly with the component of the AV node that is derived from the right AV node primordium. The anulus fibrosus begins to undergo the greatest developmental change after the AV node and bundle attain their final position in the AV junction. However, the anulus does not completely separate the atria from the ventricles during the later stages of development nor at birth, so that accessory AV pathways are present in the newborn ferret heart. Both the AV node and the AV bundle also demonstrated continuity with the myocardial cells of the interventricular septum in the neonatal heart. During development there was no evidence that rings of specialized tissues at the junctions of the cardiac chambers give rise to any component of the cardiac conduction system.

ISSN:0002-9106    

DOI:10.1002/aja.1001540202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1979

数据来源: WILEY

摘要:

AbstractMicrofilaments (MF, 5–8 nm in diameter) are a prominent feature of the pinealocyte cytoplasm of baboons (Papio ursinus) kept under controlled lighting conditions. MF occurred as a filamentous network in these cells during the light phase of the diurnal light‐dark cycle, while a close structural association was noted between MF and the membranes of the smooth endoplasmic reticulum (SER). This association was especially evident during the dark period. Increased numbers of single synaptic ribbons (SR, vesicle‐crowned rodlets), together with large aggregations of SR, i.e., ribbon fields (RF), were seen in the pinealocyte cytoplasm of baboons killed during the dark phase. It is suggested that the vesicles of RF may arise from those of the SER and that MF may play a role in the movement of SER‐vesicles to those areas of the cytoplasm where new RF are being

ISSN:0002-9106    

DOI:10.1002/aja.1001540203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1979

数据来源: WILEY

摘要:

AbstractPilocarpine HCl, a parasympathomimetic drug, was administered to pregnant white rabbits in a daily subcutaneous injection of 5 mg/kg on days 24 through 27 of gestation. Fetuses from these animals and from salineinjected controls were obtained by caesarean section at day 28 of gestation. Light microscopic examination revealed thinner alveolar septa in the lungs of pilocarpine‐treated fetuses and, morphometrically, a significant increase in the number of mature type II cells, both per unit area and per 1,000 lung cells of any kind. Examination by electron microscopy revealed that the alveolar epithelium of pilocarpine‐treated fetuses demonstrated morphologic correlates of increased maturation. These included thinning of type I cells to form blood‐air barriers and substantial reductions in the glycogen content of both epithelial cell types. Type II cells of pilocarpine‐treated fetuses contained (as indicated by morphometric analysis) more and larger lamellar inclusion bodies, as well as more multivesicular bodies than those of controls. Biochemical determination indicated that the glycogen content of fetal lung, but not liver, was reduced significantly in the pilocarpine‐treated group. The findings of this study indicate that maternal administration of pilocarpine results in increased maturation of the fetal alveolar epithelium, thus providing a basis for the autonomic manipulation of fetal lung m

ISSN:0002-9106    

DOI:10.1002/aja.1001540204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1979

数据来源: WILEY

摘要:

AbstractThe normal postnatal development of the canine kidney was investigated utilizing qualitative and quantitative histologic methods. Kidneys were examined at 2, 4, 8, 14, 22, 70, and 200 days of age. A subcapsular nephrogenic zone was present in the kidneys until approximately eight days of age. This zone contained tissues which interacted to produce new nephrons and interstitial tissues. Several developmental stages of forming nephrons were identified in this zone. Beneath the nephrogenic zone, renal corpuscles of increasing maturity were located at successively deeper cortical levels. The total number of nephrons was estimated to be 445,000 per kidney. This number did not vary significantly during growth. The corpuscular volume per nephron increased 249% from 14 to 200 days of age. During the same period there was a 303% increase in the tubular volume per nephron. Although the developing kidney differed anatomically from the adult kidney, the individual nephrons maintained volumetric corpuscular‐tubular balance during growt

ISSN:0002-9106    

DOI:10.1002/aja.1001540205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1979

数据来源: WILEY

摘要:

AbstractHuman embryonic and fetal eyes from 4 mm to 200 mm crownrump length (26 days to 21 weeks of gestation) were studied in 0.75‐μm sections impregnated with silver and toned with gold. The layer of Chievitz was formed by an inward migration of ganglion‐cell and Müller‐cell nuclei from the outer neuroepithelium and then, after further changes in nuclear location, the layer of Chievitz was cleared of ganglion‐cell nuclei to become the definitive inner plexiform layer. Müller‐cell nuclei later populated all retinal layers in the fetus. The argyrophilic Müller‐cell cytoplasm associated with neuronal development is discussed in relation to glia‐neuron interactions, with emphasis on the particular needs

ISSN:0002-9106    

DOI:10.1002/aja.1001540206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1979

数据来源: WILEY

摘要:

AbstractStudies were undertaken to elucidate the role of the complex consisting of the trophoblast and uterine epithelial cells during decidual induction in rats. Animals with estradiol‐induced implantation after an experimental delay were used.In one experiment the ultrastructural changes of the complex were examined at 4‐hourly intervals from delay of implantation to the appearance of the Pontamine Blue Reaction, 24 hours after estradiol injection (24 h.a.e.). Transmission electron microscopy of the trophoblasts revealed signs of increased synthetic activity from 8 h.a.e. onwards, with formation of polyribosomes and glycogen‐like particles and dilation of the granular endoplasmic reticulum. The epithelial cells displayed signs of endocytosis, but no differences between blastocyst‐free and blastocyst‐containing uterine sites were noted. Occasionally, signs of membrane contacts between the trophoblast and epithelial cells were observed before 12 h.a.e., as revealed by transmission electron microscopy of uterine sites and by scanning electron microscopy of blastocyst surfaces. Later an attachment of the trophoblast onto the epithelial cells became evident. Since previous studies have shown that the stromal cells are influenced by the presence of a blastocyst about 12 h.a.e., the results are in accordance both with a humoral and with a contact‐mediated signal from the blastocyst to the endometrium.In another experiment attempts were made to ascertain whether a continuous influence of the complex upon the stroma is required for the maintenance of an ongoing decidual differentiation. Blastocysts were flushed out from the uterus 16–18 and 24–26 h.a.e. and on the following day the presence of uterine sites with a decidualizing stroma were sought for. The results suggest that the differentiating stroma is dependent upon the presence of an intact complex 16–18 h.a.e. but not 24–26 h.a.e. A continuous signal release from the complex to the stroma is therefore possible during the initial stages of th

ISSN:0002-9106    

DOI:10.1002/aja.1001540207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1979

数据来源: WILEY

摘要:

AbstractThe autonomic innervation of the rat ventral prostate was studied in an attempt to evaluate the role of innervation in the normal function of the gland. Specific histochemical methods for both catecholamines (the formaldehyde‐induced fluorescence method, FIF) and acetylcholinesterases (the Gomori‐Koelle thiocholine method) were used. The neuro‐effector contacts were studied by electron microscopy using both 3% glutaraldehyde and 3% potassium permanganate (KMnO4) as fixatives. It was found that the rat ventral prostate receives dual autonomic innervation. Adrenergic fibers, which formed the majority of the nerves, were often seen in close contact with the smooth muscle cells around both the prostatic alveoli and secretory ducts. The non‐adrenergic nerve fibers, which were fewer in number, did not form such intimate contacts with the muscle cells. No direct synapses with epithelial cells were d

ISSN:0002-9106    

DOI:10.1002/aja.1001540208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1979

数据来源: WILEY

摘要:

AbstractPyroantimonate has long been used as a cytochemical technique for the localization of cations. Although the technique was originally alleged to be specific for Na+, other cations, including Mg++, Ba++, Ca++, Zn++and polycationic amines, form pyroantimonate precipitates. In seminiferous tubules treated with antimonate‐osmium fixation, the nuclei of the Sertoli cells and germ cells contained precipitates. In regions of condensed chromatin the precipitates were dense while, in dispersed chromatin, precipitates were sparse or absent. It is postulated that the dense precipitates observed in the condensed chromatin may represent an accumulation of calcium that may facilitate chromatin condensation. The Sertoli cell nucleolar apparatus contained light precipitates in the pars amorpha, moderate precipitates in the nucleolonema, and heavy precipitates in the perinucleolar heterochromatin bodies. The nuclei of the maturation‐phase spermatids lacked any precipitates. The perinuclear ring of the acrosome‐phase spermatids contained pyroantimonate deposits. In the maturation‐phase spermatids, staining occurred in the postacrosomal dense lamina, in the subacrosomal space between the perforatorium and the inner acrosomal membrane, and in the central mass of the residual bodies. Since the postacrosomal dense lamina is the portion of the spermatozoon that initially fuses with the ovum, it is postulated that its cationic properties in some way facilitate this

ISSN:0002-9106    

DOI:10.1002/aja.1001540209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1979

数据来源: WILEY

摘要:

AbstractSurface coats can be demonstrated on human peripheral blood lymphocytes by staining with ruthenium red, alcian blue, Thorotrast, and cationized ferritin, which are similar in distribution to a 40‐ to 65‐nm layer of amorphous extracellular material recently reported on fixed, freeze‐dried lymphocytes. Several additional lines of evidence, including X‐ray micro‐analysis, suggest that the latter is not a contaminant added by freeze‐drying. Freeze‐drying may provide the means for a morphological assessment of the lymphocyte surface, including the extracellular coat, which may give additional insight into the im

ISSN:0002-9106    

DOI:10.1002/aja.1001540210

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1979

数据来源: WILEY

摘要:

AbstractBy iontophoretically introducing, first, cobalt and, subsequently, sulfide ions into the vagus nerve, it is possible to trace sensory nerves to their endings in the rat lung. Nerve fibers and terminals are found predominantly in the adventitia of the airways and blood vessels. Some nerves are found in the submucosa of the bronchi and bronchioles. Some are found in the cardiac muscle on the periphery of pulmonary veins, and a few nerves are seen to end among smooth muscles of the blood vessels and the airways. At least three types of nerve endings can be identified at the light microscopic level: (1) free nerve endings; (2) brush‐like endings; (3) knob‐like termin

ISSN:0002-9106    

DOI:10.1002/aja.1001540211

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1979

数据来源: WILEY