摘要:

AbstractThe progress of salivary gland morphosis was followed by microscopic examination of serial histologic sections of the heads and necks of rats at age intervals from 13 daysin uteroto two days postnatally. The anlagen of the submandibular and sublingual glands appear late in the thirteenth or early in the fourteenth dayin utero, with the submandibular anlage appearing first. The parotid anlage appears last, later in the fourteenth dayin utero, and is located in the buccal wall near the angle of the mouth. The cells of the anlage proliferate to form a narrow cord (the future Stensen's duct) with a cluster of cells at its distal terminus. By 16 daysin utero, the terminal cluster has migrated to the vicinity of the developing mandibular ramus, at which point it begins to ramify. Ductal lumena begin to form at 17 daysin utero, but the ductal system is not patent until 20 daysin utero. These findings indicate that secretions of the parotid gland cannot enter the oral cavity until about two days before birth. The ductal systems of the submandibular and sublingual glands are patent at 17 daysin utero, and morphologically both glands appear to be at a more advanced developmental stage than the parotid at the time of birth.

ISSN:0003-276X    

DOI:10.1002/ar.1091680201

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

年代:1970

数据来源: WILEY

摘要:

AbstractThymidine‐H3was injected into the femoral and tibial marrow (labeled marrow) of guinea pigs while the hind limb circulation was arrested temporarily and non‐radioactive thymidine was administered systemically. Blood and lymphoid tissue radioautographs were subsequently examined for the presence of marrow‐derived labeled cells.Small lymphocytes in the labeled marrow showed a wave of labeling, maximal at two to three days. Concurrently, labeled small lymphocytes appeared in the blood and lymphoid tissues, mainly the spleen and mesenteric lymph node. Their numbers were greatest at four to five days, and declined rapidly thereafter. At first they appeared predominantly in the splenic red pulp and throughout the lymph node cortex, including the subcapsular sinus. By four to five days they were also concentrated in the splenic white pulp, including periarteriolar lymphoid sheaths, and in the lymph node medullary cords. They were detected within medullary sinuses, hilar lymphatics and thoracic duct lymph. Labeled monocytes and large lymphoid cells also appeared in the blood and lymphoid tissues, mainly in the spleen.It is concluded that bone marrow is a major source of circulating newly‐formed small lymphocytes many of which migrate rapidly into the spleen and mesenteric lym

ISSN:0003-276X    

DOI:10.1002/ar.1091680202

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

年代:1970

数据来源: WILEY

摘要:

AbstractLight and electron microscopic studies of the adrenal medulla of golden hamsters (Mesocricetus auratus) indicates that the chromaffin cells are arranged in hitherto undescribed irregular follicles surrounded by thin‐walled blood vessels. Each follicle is generally one cell thick with a lumen of variable size and shape, which contains finely granulated materials, nerve endings and chromaffin cell processes. Chromaffin cells are polarized; basal regions, containing the nuclei, about on the follicular cavity, and the apical areas are in close proximity to blood vessels. In the central portion of the organ, follicles contain only adrenaline cells while at the periphery “mixed follicles” occur which have both adrenaline and noradrenaline cell types. Occasional follicles with only noradrenaline cells are found in this area also. These findings have been compared with previous observations. The possible function of the follicular cavities has been discussed br

ISSN:0003-276X    

DOI:10.1002/ar.1091680203

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

年代:1970

数据来源: WILEY

摘要:

AbstractNuclear bodies, similar to those described in various types of cells, are frequently observed in the sympathetic neurons of the rabbit superior cervical ganglia both before and after postganglionic section. The bodies are 0.3 to 1.5 μ in diameter and either consist of spheres of finely granular material or else possess a dense outer cortex surrounding a less dense central zone which may contain small dense masses similar to chromatin and/or large (500 Å) or small (200 Å) dense granules. Many bodies of the latter type are unusual in that their central regions are filled with dense parallel filaments (50 and 100 Å in diameter). The thicker filaments are often arranged in an hexagonal array.The function of nuclear bodies is unknown although they have been implicated in protein synthesis. Counts of nuclear bodies were made in a large number of normal nerve cell nuclei and compared with those present in a similar number of neurons at various times after axon section. However no statistically significant difference in the numbers of nuclear bodies could be detected between normal and chromatolytic neurons. Thus the increased protein synthesis following axon section does not affect the number or structure of neuronal nuclear bod

ISSN:0003-276X    

DOI:10.1002/ar.1091680204

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

年代:1970

数据来源: WILEY

摘要:

AbstractThe origin of the presumptive ventricular septum (PVS) in the chick embryo was traced by radioautographic analysis of the movements of tritiated thymidine‐labeled grafts excised from medium streak (MS) to three somite (3S) stage embryos and transplanted to the primitive streak and endoderm‐mesoderm layer of similarly staged recipient embryos. The migration of the PVS was traced from the streak into the heart of the early limb bud (ELB) stage embryos by combining the pathways of at least three labeled grafts, since none of the 15 embryos reported here developed all the way from the MS to the ELB stage.At the MS stage the PVS cells are in the primitive streak approximately halfway between the anterior and posterior ends of the streak. Beginning at the late medium streak (LMS) stage, they migrate into the mesoderm of the lateral plate, anterior and lateral to the streak; during the early somite stages they are folded to the midline as part of the splanchnic mesoderm, where they form part of the atrial and ventricular myocardium at the 13S stage; they move into their definitive position at the apex of the ventricle by the ELB st

ISSN:0003-276X    

DOI:10.1002/ar.1091680205

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

年代:1970

数据来源: WILEY

摘要:

AbstractSpecializations of extracellular structures opposite hemidesmosomes at the basal surface of epithelial cells of the fetal rat urogenital sinus are described. A moderately dense band or lamella ∼ 100 Å wide forms a cap about 50 Å from the plasma membrane. The normally electron‐lucent inner zone between the plasma membrane and the basal lamina is increased in density and may be traversed by filaments or strands of material extending from the cell surface. The basal lamina is thickened and its density is increased locally opposite hemidesmosomes. The possible role of these specializations in adhesion between epithelial cells and the underlying extra‐cellular structures is con

ISSN:0003-276X    

DOI:10.1002/ar.1091680206

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

年代:1970

数据来源: WILEY

摘要:

AbstractThe brains of normal and irradiated C57BL/J6 adult female mice were studied for morphologic and biochemical differences at four and six hours after focal brain irradiation when the animals first experienced seizures and, at the terminal phase just prior to death. Focal irradiation of the brain was performed under stereotaxic conditions with microbeams delivered through a 5.0 × 9.0 mm aperture to the dorsal surface of the brain at an adsorbed surface dose of 50,000 rad.An analysis of variance did not indicate any difference in brain weight or in DNA, RNA, or protein concentration due to irradiation. There was a significant increase in 5‐HT and NE concentration, and in AChE activity in the brains of the irradiated groups. Histochemical observations failed to show differences in the localization of alkaline and acid phosphatase activity. However, localization of ATPase activity associated with the blood vessels was more diffuse in the irradiated regions of the brain. Biochemical comparisons of ATPase activity indicated that there was a change in the subcellular distribution of ATPase enzyme following irradiation. Light and electron microscopic comparisons revealed a selective damage to astrocytes and dendritic processes in irradiated regions of the cort

ISSN:0003-276X    

DOI:10.1002/ar.1091680207

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

年代:1970

数据来源: WILEY

摘要:

AbstractThe effect of triparanol, an inhibitor of cholesterol synthesis, on the phenobarbital induced proliferation of the smooth endoplasmic reticulum (SER) is reported. Hepatocytes of hamsters treated with phenobarbital alone display the expected proliferation of the SER. Those given triparanol alone do not show this phenomenon but appear similar to controls with the exception of increased numbers of dense bodies characteristic of this treatment. Hepatocytes of hamsters receiving triparanol followed by phenobarbital display a SER proliferation of approximately the same magnitude as that achieved with phenobarbital alone. The effectiveness of the triparanol blockade is documented by the administration of labeled mevalonic acid and the subsequent quantitation of the amount of labeled cholesterol and labeled desmosterol. Desmosterol is the primary end product after triparanol treatment. Greater than 95% of the labeled sterol appears as desmosterol indicating a high degree of blockade. It is concluded that newly‐synthesized cholesterol is not a prerequisite for the phenobarbital induced proliferation of the SER. Several possible explanations for these results are discusse

ISSN:0003-276X    

DOI:10.1002/ar.1091680208

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

年代:1970

数据来源: WILEY

摘要:

AbstractA correlation between ovarian steroids and ovarian abnormalities is demonstrated. The decrease in levels of ovarian estrogen and progesterone is correlated, one week later, with an increase in polyovular follicles and then in multinucleate ova. The time sequence of the onset of ovarian abnormalities, as correlated with levels of estrogens and progesterone are an indication of the possibility of hormonal control of the ovarian abnormalities.

ISSN:0003-276X    

DOI:10.1002/ar.1091680209

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

年代:1970

数据来源: WILEY

ISSN:0003-276X    

DOI:10.1002/ar.1091680210

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

年代:1970

数据来源: WILEY