Showing papers on "Crypt published in 1981"

Dose-survival characteristics of mouse jejunal crypt cells

Abstract: The survival of mouse jejunal crypt cells after multiple doses of 60 Co γ-rays has been measured with the microcolony technique. Fractionation protocols were designed with common dose fractions in regimens with different fraction numbers. An average number of 152 clonogens per crypt was estimated from the experiments. The survival curve has a broad shoulder, remaining near-exponential over the initial dose range 0 to 300 rad, with initial slope 1 D 0 = 357 rad. It is not possible to distinguish between the linear-quadratic (LQ) and two-component (TC) survival models on the basis of the results of these experiments.

Separation and use of enterocytes.

Abstract: Publisher Summary For in vitro studies, the suspensions of enterocytes offer certain advantages as compared with everted gut sacs or rings because they contain fewer cell types and their cell surfaces are better exposed to oxygen and substrates. Negative aspects are a loss of polarity and the inherent possibility of damage to plasma membranes during isolation. This chapter describes chelation-elution methods that subsequently release villous and crypt cells, or yield mixed suspensions of enterocytes from the intestinal epithelia of rats and guinea pigs. Weiser's improvement of Stern's method is used in case of rats, which allows a rapid separation of villous and crypt cells from the jejunum, ileum, or whole intestine. The attachment of cells to the basement membrane is loosened by chelation and the loosened cells are released in a villous-to-crypt gradient by repeated expansion and the contraction of the intestinal wall. The utility of such preparations and some criteria for their viability are also discussed in the chapter.

The stem‐cell zone of the small intestinal epithelium. V. Evidence for controls over orientation of boundaries between the stem‐cell zone, proliferative zone, and the maturation zone

Abstract: We studied, in mouse jejunum, the possibility that coordinate systems related to crypt axis or muscularis mucosae have an influence over the orientation of the boundaries between three crypt compartments: the stem-cell, the proliferative, and the maturation zones. Segments of jejunum, from male Swiss albino mice injected with 3H-thymidine 1 hour before death, were collected, embedded in Epon, and 1-μm-thick serial sections were prepared and radioautographed. Similar material was also obtained from an experimental preparation in which the anti-mesenteric border of a short segment of jejunum was involuted surgically, thus creating a fold similar to the plicae circulares in the human intestine. The crypts lining the sides and top of the folds were greatly tilted, relative to the muscularis mucosae 2 weeks after surgery. The angle formed between the crypt axis and the plane of the muscularis mucosae (Θ) was measured. This was related to the angle formed between the crypt axis and the 3H-thymidine-labeled leading edge (β), and that between the crypt axis and the upper boundary of the Paneth-cell distribution (α). The angle α indicates the orientation of the boundary between the stem-cell and proliferative zones, while β indicates the orientation of the boundary between the proliferative and maturation zones. We found that β remained perpendicular to the crypt axis for all degrees of crypt tilt (Θ). In contrast, α did not remain perpendicular to the crypt axis over all degrees of crypt tilt. When crypts were tilted by more than 30°, α reoriented and was found to be parallel to the plane of the muscularis mucosae. However, in crypts tilted less than 30°, α remained perpendicular to the crypt axis. We concluded that there are probably two coordinate systems that provide information to the crypt epithelium. The first is a coordinate system related to crypt axis that influences the orientation of the boundary between the proliferative and maturation zones and the second is related to muscularis mucosae an influences the orientation of the boundary between the stem-cell and proliferative zones. The latter has a threshold of about 30°, which probably represents the range of peristalsis-induced crypt tilt.

Kinetic analysis of epithelial cell migration in the mouse descending colon.

Abstract: The kinetics of epithelial cell replacement in the descending colon of the mouse were studied using cell counts and other measurements in mice given a single injection of 3H-thymidine at 10:00 a.m. Cell migration occurs from the base of the crypts in the direction of the colonic lumen. The mean turnover time of epithelial cells as measured after the single injection of 3H-thymidine has been estimated at 4.85 days. Since this figure is in agreement with published data based on continuous infusion of the labeled precursor, it is concluded that the time selected for the analysis provides an index of proliferation which is representative of the mean proliferative activity of the epithelium. If each side of a crypt cut along its axis is referred to as a “crypt column,” the mean number of cells per crypt column has been found to be 32.9; after a one-hour pulse labeling starting at 10:00 a.m., the mean number of labeled cells per column was 2.8; and the overall labeling index of the epithelium, 8.6%. The frequency of labeled cells in each cell position along the crypt column varies according to a Poisson distribution with a peak close to position 3. Presumably then, cell proliferation is taking place in a random manner and is, therefore, asynchronous, despite evidence to the contrary in the literature. The kinetic analysis supports the view that cell migration occurs along the crypt column in the direction of the colonic lumen at a velocity averaging 0.28 cell position per hour, or 4.48 μm per hour. The results support the view that vacuolated-columnar, mucous, and caveolated cells migrate jointly; whereas entero-endocrine cells migrate separately from these cell lines, except during the initial stages of the migration.

Comparative virulence of different bovine rotavirus isolates.

Abstract: Intestinal loops, ligated in colostrum-deprived calves were used to compare the virulence of four isolates of bovine rotavirus. Histopathological studies were carried out on infected and control loops and measurements of villous length, crypt depth, villus:crypt ratio and crypt mitotic index were recorded. Pathological changes associated with the rotaviruses included villous atrophy, flattening of absorptive epithelium and reduced villus:crypt ratios. The changes were confined to infected intestinal loops in which the presence of virus was demonstrated by specific immunofluorescence. Consistent differences in the measured histopathological changes suggested differences in virulence among the rotavirus isolates tested. The least virulent rotavirus isolate had a polypeptide electrophoretic pattern that differed from the other three more virulent isolates.

Description and basic cell kinetics of the murine pericryptal fibroblast sheath.

Abstract: The size of the pericryptal fibroblast sheath (PCFS) population was determined by scoring serial sections. There are 38 and 124 PCFS cells per murine small intestinal and colonic crypt, respectively. The cells of the PCFS are slightly weighted towards the lower two-thirds of the crypt in their distribution. The ratio of epithelial cells to PCFS cells is approximately 6.5:1. The in vivo cell kinetics were analysed under control and stressed (fasted-refed) conditions. The control labelling index increases from 8.9% in the small intestine and 7.0% in the colon to peaks 49% and 113% respectively above these values 24 hours after 3HTdR administration. Labelling is observed at all crypt levels equally, and no evidence of vertical migration of labelled PCFS cells was found. Colonic epithelial and PCFS cells show a similar pattern of response to feeding after a fast of 72 hours with respect to time, but a different distribution of response in terms of crypt position.

The surface topography of the colonic crypt in rabbit and monkey.

Abstract: Scanning electron microscopy (SEM) was used to investigate the epithelial topography of the surface and crypt in rabbit and monkey colon. Crypt openings in monkey colon are arranged in a hexagonal pattern, in sharp contrast to rabbit colon where they are randomly arrayed and frequently hidden by epithelial folds. Crypt lumens were exposed by freezing ethanol-dehydrated tissue in liquid nitrogen and fracturing the tissue with a razor blade. The resulting overview of crypt-cell luminal surfaces showed that as columnar cells mature and migrate up the crypt and onto the colonic surface, their microvilli become progressively more abundant. Goblet cells were readily identified in the cross-fractured crypt epithelium; their luminal surfaces are characterized by short, sparse microvilli. The changing appearance of the luminal surface of goblet cells was visualized by SEM during the exocytosis of single mucous granules from unstimulated crypt goblet cells, and during the compound exocytosis of multiple granules in response to acetylcholine.

A Band of Alkaline Phosphatase Activity in the Crypts of Mouse Duodenal Epithelium

Abstract: Isolated mouse duodenal epithelium, in the form of structurally intact crypt-villus units, was used to study the distribution of alkaline phosphatase with histochemistry. The tissue was incubated on ice in the medium of Hugon and Borgers (J Histochem Cytochem 14:629, 1966), with constant stirring to ensure uniform reaction. Continuous activity was observed frm the crypt mouth to the villus tip. A single band of alkaline phosphatase activity, 2-03 cell in height, was observed in the mid-crypt region in about 80% of crypts studied. Control studies (no substrate control, no lead control, pH control, inhibitor control, inactivated enzyme control, no enzyme control, and stimulator indeed due to alkaline phosphatase. The narrow band of activity in the crypt was also observed in vibratome sections of nonfrozen tissue. When isolated epithelium was subjected to a freeze-thaw cycle and then incubated in Hugon's medium, reaction product was observed continuously from the mid-crypt region to the villus tip. This pattern was similar to that observed with frozen sections. We conclude that alkaline phosphatase is present in an active form in epithelial cells in the region of the band. In epithelial cells above the band, e.e., in the upper crypt, alkaline phosphatase is present in an inactive form which may be activated by a freeze-thaw cycle.

The effects of the carcinogen, 1,2‐dimethylhydrazine, on turnover 3H‐thymidine labeled cells from mucosal glands of mouse colon

Abstract: 1,2-dimethylhydrazine (DMH), administered weekly to mice for 20 weeks, induces tumors in the distal segment of colon. Tumors are preceded by enlargement of the mucosal glands resulting from increases in the number of total cells and 3H-thymidine labeled cells/crypt. Cells located in the crypt base normally undergo 2–3 divisions as they migrate toward the lumen, and they become post-mitotic in the upper crypt. It is not known if cells in these eniarged crypts have rates of turnover similar to cells in normal crypts. Groups of w/s female mice were treated with DMH (20 mg/kg body wt) for 3,8, or 16 weeks; controls were given 0.001 M EDTA. After treatment, the animals were injected with 3H-thymidine and killed one hour or 1,2,4,7 or 17 days later. Autoradiographs were prepared from sections of distal colon. The total cells/crypt column in 30 crypts/animals were counted. Crypts were divided into 10 equal segments based on the crypt length and the labeled cells/segment were counted. The relative number of labeled cells and the distribution of these cells within crypts were similar in DMH-treated and control animals after one hour. However, as the cells migrated toward the lumen, the number of labeled cells doubled after 2 days and tripled after 4 days in DMH-treated animals but only doubled during the 4 days in controls. This difference was caused by retention of an increased number of dividing cells in the lower 4 segments of the crypts and suggests an increase in those cells that divide twice. In addition, increased numbers of labeled cells were retained in the upper 3 segments of DMH-treated animals after 4 days. These findings indicate that the crypt cells of DMH-treated animals are generally more immature than those of controls and this immaturity contributes to the enlargement of mucosal glands during carcinogenesis.

Scanning electron microscopy, autolysis, and irradiation as techniques for studying small intestinal morphology.

Abstract: SUMMARY Examination of autolysed control mouse small intestine using scanning electron microscopy has revealed details of the connective tissue components of the mucosa. The cores of the villi are seen collapsed across the intervillous basin. Crypts of Lieberkuhn are seen as tubular channels stretching down from the intervillous basin. Sometimes the crypts are split in two by a connective tissue septum. The mouths of the crypts of Lieberkuhn are, in general, arranged in double rows between the single rows of villi. The ratio of number of crypts to numbers of villi was calculated as 5.01:1. This is close to the figure of 4.53:1, as quoted by Smith & Jarvis (1980) who used differential interference contrast microscopy to investigate the crypt to villus ratio. After radiation, the severe drop in the number of crypt mouths can be clearly seen by the combination of autolysis and scanning electron microscopy: the rows of crypt mouths between the villi have been lost, and many crypt mouths have been occluded by stromal tissue. The arrangement of the crypt mouths and the observation of mucosal abnormalities after irradiation have led to the postulation that cells leaving the crypt mouths move in a spiral manner towards and then up the villous surface: this postulated movement might imply an asymmetry in some properties of enterocytes. The use of scanning electron microscopy in conjugation with autolysis and irradiation has thus forced a critical re-examination of the relationships between crypts and villi.

Squalene and Sterol Synthesis in Isolated Small-Intestinal Cells of the Rat

Abstract: To compare the synthesis rate of cholesterol in different cells of the small intestine, isolated villous and crypt cells were incubated with a mixture of 14C-acetate and 3H-mevalonate in the presence of unlabeled carriers. The synthesis rate of squalene (includes the portion converted to sterols) from acetate was tenfold higher in the crypt than villous cells. The synthesis rate of squalene from mevalonate and the cyclization rate of squalene (the portion found in sterols) were about twofold higher in crypt than in villous cells. The conversion of acetate to squalene was correlated with that to fatty acids in the crypt cells only (r = 0.823), and the ratio of the two synthesis rates (squalene/fatty acids) was threefold higher in crypt than in villous cells. Despite the significant differences in the synthesis rates of squalene and sterols the concentrations of squalene and methyl sterols were similar in the two cell types. The cholesterol content was, however, consistently higher in villous than in crypt ...

Alterations in gastrointestinal steady-state kinetics associated with the growth of experimental tumours.

Abstract: Changes in the growth kinetics of the intestinal epithelium were observed in mice bearing the Lewis lung carcinoma and the T1699 mammary adenocarcinoma and in rats bearing the H-4-II-E2 hepatoma. Proliferative activity in the jejunal tissue was markedly depressed with increasing tumour burden. Simultaneously, a significant reduction in total crypt cellularity occurred, followed by a reduction in villus height. While the total number of proliferative cells per crypt decreased, the relative proliferative compartment within the shrinking crypt increased. The rate of mucosal DNA synthesis remained constant during the initial cytokinetic changes, falling only after proliferative activity of the intestine was reduced to less than 50% of control levels. No general correlation could be drawn from the three tumour models studied between the level of gastrointestinal proliferation and tumour size, tumour growth rate or loss of weight by the tumour-bearing animals. However, intestinal proliferation was reduced by 50% when the tumour burden for each of the three tumours reached 6--8% of the host animal weight.

Effect of Leukemia and Methotrexate on Digestive Enzymes in the Jejunum of Mice

Abstract: A leukemic mouse model was employed to elucidate the separate effect of leukemia and cytotoxic drugs on the jejunal mucosa and its associated digestive enzymes. The mitotic activity, depth of the crypt and villus-crypt quotient were not significantly changed in leukemic mice in comparison to normal mice. The mitotic activity and the depth of the crypt 48 h after 20 mg methotrexate (MTX)/kg were significantly reduced (p

Modification of the intestinal postirradiation proliferative response by intraabdominal H-4-II-E2 tumors.

Abstract: Intraperitoneal injection of H-4-II-E/sub 2/ tumor cells gave rise to a number of individually growing intraabdominal tumors concentrated at sites of high abdominal vascularization. During tumor growth, both tumor and intestinal crypt cell proliferative activity were progressively depressed. A linear reduction of (/sup 3/H)TdR incorporation occurred in individual tumors independent of tumor size, suggesting that total tumor burden determines the proliferative status of individual tumors. Cytokinetic jejunal crypt analyses indicated that both a reduction in crypt cellularity and an abbreviated cell cycle transit time were noted during the depression of proliferative activity in the jejunum. In tumor-bearing rats the migration rate of cells from the jejunal crypt through the villus was reduced in response to a reduction in total cell production in the crypt. The life span of the epithelial cell in both tumor-bearing and normal rats was similar due to a reduction in villus cellularity in the tumor-bearing animals. Following abdominal irradiation of the tumor, the magnitude, but not the time course of hyperproliferative intestinal recovery, was influenced by the tumor mass. For nontumor-bearing animals, maximal hyperproliferation (>200% of control) occurred 96 hr postradiation. With increasing tumor burden the compensatory proliferative response to radiation was progressively reduced.