摘要:

AbstractThe neonatal pig colon has several unique structural and developmental features. At birth it has a variable population of epithelial cells which in their arrangement on villus‐like protrusions and in their capability for protein uptake into large preformed supranuclear vacuoles closely resemble neonatal ileal cells. Such villus‐like protrusions and vacuolated cells are not present in the 2‐day‐old piglet. On the first day after birth absorptive epithelial cells which lack supranuclear vacuoles transiently accumulate a large number of lipid droplets, each separated from the cytoplasm only by a proteolipid interface. None of the much smaller lipid droplets bounded by a unit membrane of the smooth endoplasmic reticulum and characteristic of normal small intestinal fat uptake were ever seen in these cells. Very few of the large lipid drops remain on the second day after birth.This initial capacity of the colon for protein and lipid uptake never reappears.The pattern of colonic amino acid transport also changes markedly in the first four days of independent life and this may be correlated with the observation that the absorptive cells at birth have microvilli which are twice the length of those on similar cells at and after two days old. These morphological results are discussed in terms of implied functional changes in the neonatal

ISSN:0002-9106    

DOI:10.1002/aja.1001520302

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe distribution and behavior of anionic sites on the micro‐villous surface of rat jejunal absorptive cells were studied using the multivalent ligand polycationic ferritin (PCF) as a visual probe. Segments were incubated in PCF either before or after glutaraldehyde fixation. The results indicated that the anionic sites can be divided into three groups based on their interaction with PCF: (1) Some sites along the length of the microvilli are accessible for binding PCF in living, unfixed cells. These sites are capable of translational mobility at the membrane surface and can be induced to cluster into discrete patches by PCF. Under appropriate conditions, they may be taken into the cell by endocytosis. Their redistribution is prevented by prefixation, and slowed by incubation at temperatures of 0°C or below. (2) Some sites along the length of the microvilli are inaccessible to PCF without prior fixation. These sites may provide uniform coverage or may be preferentially localized to the distal microvillus. (3) Some sites restricted to the microvillous tips are accessible to PCF without fixation, but are apparently immobile. Their high density on some tips forms a distinctive cap of ferritin particles. More anionic sites were found on the microvilli of the more mature cells of the upper villus. In addition, independent variation was observed in the number of sites in each of the three groups among neighboring cells, irrespective of villous position, suggestive of variations in the turnover of these sit

ISSN:0002-9106    

DOI:10.1002/aja.1001520303

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

年代:1978

数据来源: WILEY

摘要:

AbstractTo determine the rate of follicular development in long‐term hypophysectomized (H) hamsters, single IP injections of3H‐thymidine were given six days afterHand autoradiographs were prepared from animals killed on days 6–15. Only follicles in stages 1 (2–3 layers of granulosa cells), 2 (4–5 layers) and 3 (6–7 layers) were present and there were fewer follicles than in intact, cyclic hamsters. The entire population of follicles in stages 1 and 2 was replaced every five to six days in hypophysectomized hamsters, whereas in cyclic hamsters, complete turnover takes eight days (Chiras and Greenwald, '77).Other groups ofHhamsters were treated on days 4–6 with either estradiol benzoate (EB — 10 μg), progesterone (P — 1 mg) or EB and P and then given3H‐thymidine at 0900 hours of day 6 and killed one hour later. Steroid treatment affected early stages of follicular development: EB stimulated growth of these follicles; P alone had little effect; given with EB, P acted as an antagonist.OtherHhamsters were treated with FSH (100 μg), LH (10 μg), FSH + LH, PMS (30 IU) or saline vehicle at 0900 hours six days post‐hypophysectomy. They were injected with3H‐thymidine at 2100 hours on day 6 and killed one hour later. LH‐ and saline‐treated animals had approximately the same number of follicles; however, there were no stage‐3 follicles in the LH‐treated group and the percentage of labelled follicles in stages 1 and 2 was significantly lower after LH treatment. FSH enhanced follicular development and thymidine uptake. Twice as many stage‐3 follicles were seen in FSH‐treated animals as controls; stage‐4 follicles (>8 layers of granulosa cells) were also encountered after FSH treatment. Labelling Index (LI) and Intensity (L. Int.) for the FSH‐treated group were the highest of all treatments. LH antagonized some of the effects of FSH. PMS resulted in follicular growth similar to that achieved by FSH; however, PMS markedly depressed LI and L. Int., which was probably due to the LH‐like component of PMS. These results demonstrate that the gonadotropins affect the development of small follicles. FSH stimulates growth; LH depresses follicular growth when administered alone and antagonizes some of the effects of FSH.Hamsters pretreated with EB or P on days 4–6 and then given a single, subcutaneous (SC) injection of FSH at 0900 hours on day 6, were treated with3H‐thymidine at 2100 hours on day 6 to assess the interaction of steroids and FSH. EB pretreatment caused the development of stage‐5 follicles (early antral follicles) but did not increase thymidine uptake (measured by LI and L. Int.) in the small follicles above that attained by FSH alone. P pretreatment diminished thymidine uptake in small follicles, but did not reduce their number.These results demonstrate that in the hamster the population of small follicles, i.e., the often misnamed “pituitary‐independent” follicles, can be influenced quanti

ISSN:0002-9106    

DOI:10.1002/aja.1001520304

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

年代:1978

数据来源: WILEY

摘要:

AbstractQuantitative electron microscopic analysis of the supragranular zone of the dentate gyrus molecular layer has shown that the number, volume fraction and surface area of dendritic shaft profiles are significantly decreased in senescent rats, relative to young adults. These modifications of dendritic morphology, which are not associated with age‐related changes in dimensions of the molecular layer or in numbers of granule cells, may result from a decrease in the number and/or length of dendrites. In either case, the decreases in the number, volume fraction and surface area of dendritic shaft profiles found in the dentate gyrus of senescent rats signify an age‐related atrophy of dendrites. Comparison of changes in the number and volume fraction of dendritic shaft profiles has demonstrated that age‐related dendritic atrophy involves predominantly smaller dendritic bra

ISSN:0002-9106    

DOI:10.1002/aja.1001520305

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

年代:1978

数据来源: WILEY

摘要:

AbstractOsteopetrosis in theiarat is known to be due to reduced bone resorption and the absence of ruffled borders in osteoclasts. The disease can be cured by the temporary parabiotic union with, or by transfusion of spleen, thymus, or liver cells from, normal littermates. This investigation was pursued in an attempt to determine the cellular basis of this cure by testing the relative effectiveness of populations of mononuclear cells — lymphocytes, monocytes, and tissue macrophages, from spleen and thymus of normal rats — in curing the disease, compared with cell suspensions of the entire organs. The mononuclear fractions were separated from cell suspensions of spleen or thymus by an adaptation of the Ficoll‐Hypaque density‐gradient‐centrifugation procedure. The mononuclear isolates were evaluated by conventional histological procedures and non‐specific esterase histochemistry and found to contain approximately 97% lymphocytes and 3% monocytes from the spleen and 99% lymphocytes and less than 1% monocytes from the thymus.The results of these transplantations were evaluated radiographically and histologically three weeks after treatment. No difference in the rate of skeletal cure was observed in theiarats that received cells from either whole spleen or thymus, or the mononuclear isolate from these organs. Osteoclasts from theiaanimals cured by the transplantation of the mononuclear isolate were examined by electron microscopy and found to have ruffled borders.We conclude that the mononuclear cells isolated from either the spleen or thymus of normal littermates have positive effects on osteoclasts and bone resorption in theiarat, either indirectly, by elaboration of some local factor that affects the mutant osteoclasts, or directly by transformation into

ISSN:0002-9106    

DOI:10.1002/aja.1001520306

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

年代:1978

数据来源: WILEY

摘要:

AbstractLight and electron microscopic examinations of developing Mullerian vaginae were performed on untreated and neonatally estrogenized mice 1 to 12 days old. Vaginae of 1‐day‐old mice have an undifferentiated, pseudostratified columnar epithelium which slowly differentiates in untreated mice into an apparently mucus‐secreting epithelium. By day 12 the rough endoplasmic reticulum (RER), Golgi, and secretion granules are poorly developed features of the apical epithelial cells. In contrast, the stromal cells develop prominent RER and Golgi zones which in part are involved in the synthesis and secretion of collagen, which accumulates in the intercellular spaces.The effect of estradiol on developing vaginal epithelium is observed after 24 hours of exposure as an increase in RER and the Golgi. Estradiol (E) accelerates the differentiation of mucus‐secreting apical epithelial cells, whose apices become filled with secretory granules, and also promotes the formation of a cornifying epithelium from the underlying basal cells. This latter process is associated with an increase in cellular proliferation, an increase in the occurrence of desmosomes and associated tonofilaments, and the development of extensive interdigitation of plasma membranes.In untreated and E‐treated mice, the vaginal epithelium is separated from the stroma by a continuous, intact basal lamina. Transport of basal laminar material appears to occur via the processes of endo‐ and/or exocytosis in adjacent epithelial and st

ISSN:0002-9106    

DOI:10.1002/aja.1001520307

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

年代:1978

数据来源: WILEY

摘要:

AbstractA quantitative comparison of isolated lymphocytes prepared for SEM by the critical‐point drying (CPD) and freeze drying (FD) methods revealed that the mean cellular diameter dropped from 7.9 μm after fixation to a final diameter of 6.9 μm after FD, and to 5.7 μm after CPD. In addition to their larger sizes, FD lymphocytes were immediately distinguishable by their more complex surfaces, featuring wider microvilli which often emanated from ridges on the cell surface and branched extensively near their bases. The mean width of microvilli was 0.22 μm after FD and 0.12 μm after CPD. The number of microvilli per cell was essentially the same by the two methods. In view of these findings, a critical comparison of the CPD and FD methods using the particular cells or tissue to be investigated is an essential prelude to a rigorous SEM

ISSN:0002-9106    

DOI:10.1002/aja.1001520308

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

年代:1978

数据来源: WILEY

摘要:

AbstractCopulation forced the mucous cells of rat bulbo‐urethral (Cowper's) glands to accelerate their secretion. Determination of macromolecularly‐bound hexose as a measure for the mucous contents of the glands and light and electron microscopic observations showed that the glands lost their mucus within four hours after the start of copulation. Secretion of the mucous granules occurred in an exocytotic fashion. This led to the formation of extensive secretory canaliculi extending to the cell bases. Successive mutual coalescing of the mucous granules formed intracellular secretion channels running from the secretory cell surfaces deeply into the cells.The vast reduction of cellular volume by loss of the numerous secretory granules and the sudden addition of large amounts of granule membrane to the cell membrane caused a considerable enlargement of the cell surface. The superfluous cell membrane was stored temporarily in tufts of long microvilli. The appearance of endocytotic structures and lysosomes was interpreted as indicative of internalization and breakdown of cell membrane. Between four and six hours after copulation cytoplasmic volume and size of RER and Golgi complex increased considerably, concurrently with increasing glycoprotein synthesis (Geuze and Slot, '76). During repopulation of the cells with mucous granules, luminal vesicles appeared close to the cell membrane between exocytotic pits. We suggest that the luminal vesicles originate by pinching off from microvilli and apical rims of cytoplasm overlying the mucous granules. Refilling of the glands was slow and took more than one w

ISSN:0002-9106    

DOI:10.1002/aja.1001520309

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe purpose of this paper is to describe in detail the shoulder myology of the La Plata River Dolphin,Pontoporia blainvillei, and to review the literature on cetacean shoulder myology. Three fetal and one adult animal were used for the collection of morphological information.Pontoporiais less specialized in its shoulder anatomy that most delphinid cetaceans, and shares several characteristics with some mysticetes. The omohyoid and anterior serratus anterior muscles are found in bothPontoporiaand the mysticeteBalaenoptera, but are absent in most delphinids. The pectoralis abdominalis and three rhomboideus divisions are found inPontoporiaandKogia, but in only a few delphinid species described in the literature. It is suggested that these characteristics are associated with a generalized use of the forelimb inPontoporia.

ISSN:0002-9106    

DOI:10.1002/aja.1001520310

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

年代:1978

数据来源: WILEY

摘要:

AbstractDispersion of cisternae of rough endoplasmic reticulum (RER) in aging rats has been determined quantitatively for mitral cells of the olfactory bulb and Purkinje cells of the cerebellum using a recently published morphometric technique (Cruz Orive, '76). In both cell types dispersion of cisternae occurred throughout the period studied and in a linear fashion. The observed RER dispersion cannot be attributed to a decrease in the total amount of RER, since the total amount of RER was constant in Purkinje cells and increased in mitral cells during the ages studied.

ISSN:0002-9106    

DOI:10.1002/aja.1001520311

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

年代:1978

数据来源: WILEY