摘要:

AbstractWe have investigated the possibility that the complex patterns of fluorescence associated with spermatids of the ground squirrel labeled with 7‐nitro‐benz‐2‐oxa‐1,3‐diazole‐phallacidin (NBD‐phallacidin) are due to the presence of filamentous actin within the spermatids themselves rather than to actin in attached Sertoli cell ectoplasmic specializations, as previously reported (J. Cell Biol.,100:814–825). Enzymatic treatments (trypsin, DNAase 1) freed Sertoli cell ectoplasmic specializations from spermatids and resulted in a loss, from the spermatids, of the complex fluorescence patterns, suggesting that the latter were generated by labeled actin in ectoplasmic specializations. Moreover, ectoplasmic specializations that were detached enzymatically from spermatids demonstrated the same fluorescence patterns as those emitted from spermatids in the intact or mechanically fragmented seminiferous epithelium. Most spermatids, however, do display a weak and diffuse pattern of fluorescence that changes during spermatogenesis and that is localized between the acrosomal cap and nucleus. S‐1 decoration confirmed this subacrosomal localization and further demonstrated that the actin in adjacent Sertoli cell ectoplasmic specializations is arranged in a unipolar fashion. We conclude that the complex patterns of actin fluorescence associated with mechanically isolated spermatids are a superimposition of both Sertoli cell and germ cell actin; however, the latter is either poorly detected or not detected at all when Sertoli cell ectoplasmic specializations ove

ISSN:0003-276X    

DOI:10.1002/ar.1092150402

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

年代:1986

数据来源: WILEY

摘要:

AbstractOvaries from normal mature rats, rats injected with testosterone propionate (TP), and from aged rats were removed, and large antral follicles examined by quantitative cytochemical techniques in order to analyze possible enzymatic defects that relate to follicular steroidogenesis. The ovaries from the TP‐injected and the aged rats were polycystic. Lipid deposition was analyzed in frozen sections stained with Sudan black. A microdensitometer was used to measure Δ5‐3β ‐hydroxysteroid dehydrogenase (3βOHD) activity and G‐6‐PD type IH generation in the theca, and in peripheral region, antral region, and corona radiata of large antral follicles. 3βOHD is the enzyme that converts pregnenolone to progesterone. Type IH generation is related to the conversion of androstenedione to estradiol. Lipid droplet deposition was comparable in the three types of follicles. Compared to that in normal preovulatory follicles, 3βOHD activity was similar in identical regions of large antral follicles in TP‐injected rats, but less in the theca and peripheral region of the membrana granulosa of the aged rat. G‐6‐PD type IH generation was less in the peripheral region of large antral follicles of both TP‐injected and aged rats than in preovulatory follicles. Type IH generation was also less in the theca of TP‐injected rats than in the theca of normal rats. This study provides evidence that in spite of their normal appearance, large antral follicles in polycystic ovaries are not physiologically sound. Furthermore, the enzymatic disturbance appears to be different in different typ

ISSN:0003-276X    

DOI:10.1002/ar.1092150403

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe pattern and distribution of intrahepatic lymph vessels were examined by light and electron microscopy in rat livers fixed by perfusion through the portal vein. Lymph vessels were found in the connective tissue of the larger portal canals, where they coursed in close association with branches of the hepatic artery. The smallest portal canals contained no lymphatics. Of the portal canals that lacked a lymphatic, over 50% also lacked an arterial component. Direct connections between the lymphatic lumen and the spaces of Disse or Mall were not observed but lymphatics were found close to Mall's space, separated by only a sparse connective tissue space containing a few collagen fibrils. Lymphatics were neither seen within the parenchyma, nor associated with intercalated (sublobular) veins. Cross‐sectional area (223.2 ± 48.7 μm2SEM), maximum diameter (20.5 ± 2.0 μm), volume density (0.00098 ± 0.00046 μm3/μm3) and profile density (1.8 ± 0.3 lymphatics per 1 mm2) of hepatic lymph vessels were determined by stereological measurement by a computer‐based image analyzer. These data were used to estimate the rate of lymph formation in the liver. It was concluded that (1) initial lymphatics probably originate in the portal canals; (2) the concept that fluid in the space of Disse can be regarded as the principal source of fluid‐forming hepatic lymph is questioned, since initial lymphatics appear to be separated from the space of Disse by hepatocytes and the space of Mall; and (3) the rate of lymph formation in the liver of the rat is approximately 0.06–0.08 μl/min/cm2of lymph

ISSN:0003-276X    

DOI:10.1002/ar.1092150404

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

年代:1986

数据来源: WILEY

摘要:

AbstractThyroids from rat fetuses of different ages (from day 14 to day 19 of gestation) were transplanted to organ culture for 2 days, with or without added thyroid‐stimulating hormone (TSH) in the medium. Thyroid tissue from 14‐day fetuses that initially consisted of irregularly arranged cell cords did not form follicles when cultured in the presence or absence of TSH. Thyroids from 15‐ and 16‐day fetuses initially consisted of epithelial cell masses. When cultured in the presence or absence of TSH they formed follicles, and a majority stored small amounts of colloid. In thyroid transplants from 17‐day fetuses, the response to TSH appeared as a significant increase in the follicular diameter and cell height. Thereafter, in all transplants cultured in the presence of TSH, both the follicular diameter and the cell height were markedly greater than in the transplants cultured in the absence of added TSH. These results suggest that the initial formation of thyroid follicles is independent of TSH and that, once developed, follicles become able to respo

ISSN:0003-276X    

DOI:10.1002/ar.1092150405

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

年代:1986

数据来源: WILEY

摘要:

AbstractPituitary cells from adult male rats subjected to chronic (6 and 10 weeks) medial hypothalamic ablation (MHA) were analyzed by unit gravity sedimentation to assess distribution of size and density of lactotrophs, and for subsequent in vitro prolactin (PRL) release in primary culture. Tinctorial staining (Herlant's tetrachrome) showed that initial preparations of cells from MHA rats were small and relatively undifferentiated. MHA cells did not sediment as far into the gradient as did cells from intact control pituitaries. Intracellular PRL content was lower in all gradient fractions of MHA cells. At 6 weeks after surgery, peak recovery of PRL was also in the upper portions of the gradient. In the 10‐weeks group, however, peak PRL recovery from MHA cells was in a population that sedimented further, but more restrictedly, in comparison with control cells. At both postsurgical intervals, the majority of tinctorially or immunocytochemically identified lactotrophs from lesioned rats were lower in the gradient, indicating enlarged and denser cells. Relative numbers of lactotrophs (per pituitary) were increased 10 weeks after MHA. In vitro PRL release, over a maximum of 21 days culture, was comparable for cells from MHA rats and intact controls, according to daily per cell secretion rates and “production index” (hormone released/initial hormone content). By comparison, luteinizing hormone (LH) release was suppressed in culture compared to intact controls, and LH was recovered from gradient fractions of smaller cells. The results indicate that chronic removal of hypothalamic influence results in gradual prolactin cell hypertrophy and decreased hormone retention and in relative increase in numbers. Since PRL release in vitro proceeded at a normal rate, the primary effect of such a lesion appears to be increased hormone turnover. The data also emphasize the autonomous capacity of lactotrophs, relative to other pituitary cell types, to adjust cellular mechanisms in order to continue secretory function in the absence of hypothalamic infl

ISSN:0003-276X    

DOI:10.1002/ar.1092150406

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

年代:1986

数据来源: WILEY

摘要:

AbstractWhen the lateral olfactory tract (LOT) of the golden hamster,Meso cricetus auratus, is transected in the first week of postnatal life, axons can grow back past the lesion and achieve functional reinnervation of caudal projection regions. In contrast, when the tract is sectioned after postnatal day 7 (P7), axons do not reinnervate regions caudal to the cut. The experiments reported here investigated whether regenerative failure after tract section in pups older than P7 is accompanied by developmental changes in the astrocytic response. LOT transections were performed at P3 and P9 and the glial reaction was observed at survival times ranging from 12 hr to 2 weeks. Immunocytochemistry with glial fibrillary acidic protein (GFAP) was employed for histological visualization of astrocytic reactivity.Staining for GFAP immunoreactivity showed an appreciable glial reaction after tract section at both P3 and P9, but the extent of astrocytic hypertrophy and proliferation of glial processes was considerably greater and more extensive after tract section at P9. Radial glial cells were observed 2 weeks after LOT transection at P3 but were absent after lesions made at P9.The results from this study suggest that the developmental loss of regenerative capacity after LOT transection may be related to maturational changes in the glial response. In particular, the presence of radial glial elements after P3 lesions could serve to establish a more favorable microenvironment for axonal elongation.

ISSN:0003-276X    

DOI:10.1002/ar.1092150407

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

年代:1986

数据来源: WILEY

摘要:

AbstractSpecific antibodies raised against a 28‐kilodalton chick intestinal calcium‐binding protein (calbindin‐D28k) were used to localize the protein immuno‐cytochemically in the developing rabbit kidney. Kidneys taken from rabbits between the 13th embryonic and 17th postnatal day were examined. Calbindin‐D28kwas observed in the mesonephric duct and the ureteral bud on the 13th embryonic day. During subsequent involution of the mesonephros, the ampullae of the metanephric ureteral buds contained calbindin‐D28k. The protein was gradually lost from the ureters and the deep interstitial collecting ducts. Calbindin‐D28kwas never present in the renal vesicles derived from the nephrogenic blastema, but it was present in the connecting tubule segments during formation of the arcades. The last finding supports the belief that the connecting tubule is derived from the

ISSN:0003-276X    

DOI:10.1002/ar.1092150408

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

年代:1986

数据来源: WILEY

摘要:

AbstractForty Fischer strain inbred albino rats, evenly divided by sex, were obtained at 9 days of age. The animals were weaned at 21 days and randomly divided into the four experimental groups. Two variations on dietary consistency,hardandsoftdiet, as well as two variations on cage environment,normalandno biting surfaces, constituted the experimental groupings. The experimental period consisted of 16 weeks during which the animals were raised under the designated conditions. At the end of the experimental period the animals were killed with carbon dioxide, and the entire mandible, and both femurs, were dissected free. Weight and volumetric analysis were carried out in a standard fashion on the cleaned specimens. Area and linear measurements were performed and analyzed with a specially designed computer program. The results showed that there was sexual dimorphism in the Fischer rat both with respect to body weight and the weight, volume, area, and linear measurements of the mandible. The effects of dietary consistency had a greater influence on mandibular ramus size and form than did those caused by alteration in cage environment. The posterior region of the mandible, in association with the heavy muscles of mastication, was affected more by dietary consistency than was the anterior region. The entire region of the mandibular ramus acted as an area of adaptation and growth. The findings of this study indicate that dietary consistency has a small but significant effect on mandibular size in specific measurements. The cage environment used in this experiment did not limit function to the extent necessary to see measurable changes in mandibular measurements.

ISSN:0003-276X    

DOI:10.1002/ar.1092150409

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

年代:1986

数据来源: WILEY

摘要:

AbstractDexamethasone is an important regulator of cellular proliferation and differentiation, but paradoxical effects have been noted in a variety of culture systems. The purpose of this study was to determine whether dexamethasone induces proliferation and differentiation of osteogenic precursor cells. Periosteal explants from embryonic chicks were grown in culture for 3 or 4 days, treated continuously with dexamethasone or ethanol vehicle, and then either pulse‐labeled with3H‐thymidine at 3 days or labeled for 24 hr between day 3 and day 4. Histochemical and autoradiographic procedures were used to assess the proliferation and differentiation of osteogenic cells. At 3 days, the area of bone, the percentage of alkaline phosphatase‐positive cells, the percentage of3H‐thymidine‐labeled cells, and the percentage of cells labeled with both markers were significantly higher in dexamethasone‐treated cultures. Between day 3 and day 4 no significant changes in these parameters were observed in the dexamethasone‐treated cultures. In comparison, control cultures exhibited significant increases in the percentage of3H‐thymi‐dine‐labeled cells after 24 hr of continuous labeling. The data show that dexamethasone induces a burst of proliferation in a cohort of cells that undergo differentiation. Once these cells have divided, further proliferation within the culture is limited. Finally, it is apparent that the timing of experiments may be critical in determining whether dexamethasone will inhibit or stim

ISSN:0003-276X    

DOI:10.1002/ar.1092150410

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe attraction of primordial germ cells (PGCs) by the gonadal anlage (germinal ridge; GR) in vitro has been demonstrated in the chick. PGCs were isolated from circulating blood of stage 13 embryos (Hamburger and Hamilton, 1951), placed between the GR and other embryonic tissues (neural tube, heart, allantois, liver) as controls separated by a distance of 170 μm on collagen‐coated substrate, and cultured with modified medium 199 (Kuwana and Fujimoto, Anat. Rec., 209:337–343, 1984) containing 10% fetal calf serum (pH 7.3). The behavior of PGCs was observed for 3 hr by 16‐mm time‐lapse microcinematography.PGCs showed directional movement toward GR. Also, there was a stronger attractive effect on the PGCs by GR from stage 13 embryos than by GR from later stage embryos. These results suggest that PGCs are attracted by some factor emitted

ISSN:0003-276X    

DOI:10.1002/ar.1092150411

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

年代:1986

数据来源: WILEY