Hindgut Research Articles

Germ cells and germ cell transplantation.

The germ cell lineage in mice is established about a week after fertilization, in a group of cells that have left the epiblast and moved to an extraembryonic site. They migrate back into the embryo, along the hind gut and into the gonads. Germ cells in male and female embryos then pursue different pathways: in the testis the germ cells cease proliferating and enter mitotic arrest, while germ cells in the ovary, like those in male embryos that remain outside the gonads, enter meiotic prophase. Studies on explanted germ cells suggest that all germ cells may enter meiosis at a certain stage of their development, unless prevented from doing so by some inhibitory influence of the testis. Germ cells during the migratory stage can be cultured, but do not enter meiosis unless embedded in somatic tissue. Addition of certain growth factors and cytokines to the culture medium allows germ cells to proliferate indefinitely in vitro: Like embryonic stem cells, these immortalized EG (embryonic germ) cells will colonize all cell lineages if introduced into a blastocyst. After birth, germ cells undergo gametogenesis; oogenesis in the female, spermatogenesis in the male. Brinster and his colleagues have shown that spermatogonial stem cells injected into a germ-cell depleted testis will repopulate the seminiferous tubules and undergo spermatogenesis, giving rise to functional spermatozoa. Stem cells from frozen testicular tissue are still capable of giving rise to spermatogenesis in a host testis. Rat testicular tissue can undergo spermatogenesis in a mouse testis, to form morphologically normal rat spermatozoa, even though the Sertoli cells that support them are of endogenous mouse origin. These findings are of fundamental importance for our understanding of spermatogenesis and the interactions between germ cells and Sertoli cells; but they also have significant practical implications, in relation to both agricultural practice and clinical treatment of infertility.

Dietary Response of Chimpanzees and Cercopithecines to Seasonal Variation in Fruit Abundance. II. Macronutrients

In a continuation of our study of dietary differentiation among frugivorous primates with simple stomachs, we present the first comparison of differences in dietary macronutrient content between chimpanzees and cercopithecine monkeys. Previously we have shown that chimpanzee and monkey diets differ markedly in plant part and species content. We now examine whether this diet diversity is reflected in markedly different dietary macronutrient levels or the different feeding strategies yield the same macronutrient levels in their diets. For each primate group we calculated the total weighted mean dietary content of 4 macronutrients: crude lipid (lipid), crude protein (CP), water-soluble carbohydrates (WSC), and total nonstructural carbohydrates (TNC). We also calculated 4 fiber fractions: neutral-detergent fiber (NDF), which includes the subfractions hemicellulose (HC), cellulose (Cs), and sulfuric acid lignin (Ls). The HC and Cs are potentially fermentable fibers and would contribute to the energy provided by plant food, depending on the hind gut fermenting capacity of the individual primate species. The chimpanzee diet contained higher levels of WSC and TNC because during times of fruit abundance the chimpanzees took special advantage of ripe fruit, while the monkeys did not. The monkey diets contained higher levels of CP because the monkeys consumed a constant amount of leaf throughout the year. All four primate species consumed diets with similar NDF levels. However, the chimpanzees also took advantage of periods of ripe fruit abundance to decrease their Ls levels and to increase their HC levels. Conversely, the monkey diets maintained constant levels of the different fiber fractions thoughout the year. Nevertheless, despite these differences, the diets of the 4 frugivores were surprisingly similar, considering the substantial differences in body size. We conclude that the chimpanzee diet is of higher quality, particularly of lower fiber content, than expected on the basis of their body size.

Effects of post-ruminal fermentation on the faecal and urinary excretion of purines

AbstractThe effect of post-ruminal fermentation on faecal output of purine bases (PB) and urinary excretion of their derivatives (PD) was studied by the infusion of yeast RNA (2·9 g/day), corn starch (100 g/day), cellulose (200 g/day) and saline solutions into the gastro-intestinal tract offour sheep (35·4 kg live weight) fitted with caecal and duodenal catheters and given 0-80 kg/day alfalfa hay. All substrates were infused into the caecum except cellulose that was infused into the proximal duodenum.The infusion of RNA did not affect either the faecal excretion of PB or the urinary excretion of allantoin or total PD, although xanthine excretion increased significantly from <0·01 to 0·12 mmol/day.Starch and cellulose infusions promoted a significant increase in the faecal excretion of diaminopimelic acid (206 and 159v.131 mg/day) and PB (4·55 and 3·62v.2·29 mmol/day) and modified the partitioning of total nitrogen losses between faeces and urine. The urinary excretion of allantoin and total PD were not affected by the caecal infusion of starch (6·60 and 22·9v.7·02 and 22·8 mmol/day) but both tended to increase with the duodenal infusion of cellulose (7·75 and 26·4 mmol/day).It is concluded that the urinary excretion ofPD is independent of either the supply of nucleic acids to the caecum or the extent of hind gut fermentation although it may be affected by variations in the flow of undigested fibre along the small intestine.

The Danforth's short tail mutation acts cell autonomously in notochord cells and ventral hindgut endoderm.

Danforth's short tail (Sd) is a semidominant mutation in mouse affecting the axial skeleton and urogenital system. The notochord is the first visibly abnormal structure in mutant embryos, and disintegrates beginning around embryonic day 9.5 along its entire length, suggesting an essential role for Sd in notochord development and maintenance. Here, we report on the fate of Sd/+ and Sd/Sd cells in chimeric embryos. Up to day 9-9.5, Sd cells contributed efficiently to the notochord of chimeric embryos. In advanced day 9.5 embryos, Sd cells were less abundant in the posterior-most region of the notochord and in the notochordal plate. During subsequent development, Sd cells were specifically lost from the notochord and replaced by wild-type cells. In Sd/+<-->+/+ chimeras, the notochord appeared histologically and functionally normal, leading to a rescue of the mutant phenotype. However, strong Sd/Sd<-->+/+ chimeras showed malformations of the axial skeleton and urogenital system. All Sd/Sd<-->+/+ chimeras with malformations of the axial skeleton also had kidney defects, whereas chimeras without vertebral column defects had highly chimeric kidneys that appeared normal, suggesting that the urogenital malformations arise secondarily to impaired posterior development caused by the degenerating notochord. Sd mutant cells also were specifically absent from the ventral portion of the hindgut, whereas they contributed efficiently to the dorsal region, implying the existence of distinct cell populations in the dorsal and ventral hindgut. Our findings demonstrate that the Sd mutation acts cell autonomously in cells of the notochord and ventral hind gut. Sd leads to the degeneration of notochord cells and the number or allocation of notochord precursors from the tail bud to the notochordal plate seems impaired, whereas notochord formation from the node appears to be unaffected.

Effect of SCFA on Intracellular pH and Intracellular pH Regulation of Guinea-Pig Caecal and Colonic Enterocytes and of HT29-19a Monolayers

The response of the intracellular pH (pH i, measured with BCECF) of the caecal and distal colonic epithelium of guinea pig and of monolayers of HT29 clone 19a cells on the addition of short-chain fatty acids (SCFA) was assessed. Addition of SCFA to the luminal side of these cells had no major effect on pH i, independent of whether the apical Na +/H + exchange or the apical K +/H + ATPase was inhibited or not. Addition of SCFA to the serosal side, on the other hand, caused a marked decrease of pH i, followed by an effective regulation back to basal values, and after removal of the acid, the cells became alkalinized. Intracellular pH is mainly regulated by mechanisms in the basolateral membrane. The basolateral Na +/H + exchanger and the Cl −/HCO 3 − exchanger were mainly responsible for pH i regulation. Inhibition studies are consistent with a NHE-1 type Na +/H + exchanger in the basolateral membranes. The apical Na +/H + exchanger of caecal enterocytes and in HT29 cells, and the apical K +/H + ATPase in the apical membrane of the distal colon have no or little influence on pH i regulation. The comparison shows that the HT29-19a cell line is an adequate model for studying pH i phenomena of hind gut epithelial cells.

Neutral-sugar determination by HPAEC-PAD to characterise polysaccharide degradation by colonic bacteria

In vitro methods are widely used to characterise dietary fibre fermentability in the human hind gut. The activity of faecal bacteria can be followed by measuring fermentation products and substrate degradation. This paper describes a method for establishing neutral-sugar profiles by HPAEC-PAD during in vitro fermentation studies. Freeze-dried fermentation residues are hydrolysed with H2SO4, and the monomers are separated on an anion-exchange column using a reverse NaOH gradient. Sulphate ions are removed from hydrolysates on-line with a special ion-exchange guard column. 2-D-deoxyribose is used as internal standard for quantification. A method for separating all neutral sugars that typically occur in dietary fibre is given. Possibilities for enhancing the resolution for other purposes are suggested. Compared to GC the described method is particularly attractive for routine analyses. Data relating to the decreasing levels of neutral sugars in fermentation residues of oat bran fractions that differ in their mixed-linked β-glucan content are given and degradation patterns of the polysaccharides present in these substrates are discussed.

Changes in the Elemental Composition of Bladder Mucus in Stone and Non-Stone forming Patients following Augmentation Cystoplasty

The incidence of bladder stones is increased by 50% following bladder augmentation(l,2). Stones require surgical removal as they are typically too large to pass. A recurrence rate of 19% has been noted(2) necessitating multiple sugical procedures. Etiology of stones in augmented bladders is due to a number of factors including foreign body reactions, metabolic abnormalities, infection and intestinal mucus. In order to determine whether the elemental composition of bladder mucus plays a role in the development of bladder calculi, energy dispersive x-ray spectrometry(EDXS) was done on the mucus from stone and non-stone forming patients. In addition, stones from the same patients were examined and analyzed and the data compared with the composition of the mucus.Eighteen patients participated in this study, 14 of whom had ileo-cystoplasties and 2 ileo-cecal augments. Two were cloacal extrophy patients where the hind gut was incorporated with the bladder halves. To avoid any foreign body reactions, metal staples were not used in any of the bladder augmentation procedures.

Interactions between germ cells and extracellular matrix glycoproteins during migration and gonad assembly in the mouse embryo.

Cells are known to bind to individual extracellular matrix glycoproteins in a complex and poorly understood way. Overall strength of adhesion is thought to be mediated by a combinatorial mechanism, involving adhesion of a cell to a variety of binding sites on the target glycoproteins. During migration in embryos, cells must alter their overall adhesiveness to the substrate to allow locomotion. The mechanism by which this is accomplished is not well understood. During early development, the cells destined to form the gametes, the primordial germ cells (PGCs), migrate from the developing hind gut to the site where the gonad will form. We have used whole-mount immunocytochemistry to study the changing distribution of three extracellular matrix glycoproteins, collagen IV, fibronectin, and laminin, during PGC migration and correlated this with quantitative assays of adhesiveness of PGCs to each of these. We show that PGCs change their strength of adhesion to each glycoprotein differentially during these stages. Furthermore, we show that PGCs interact with a discrete tract of laminin at the end of migration. Closer analysis of the adhesion of PGCs to laminin revealed that PGCs adhere particularly strongly to the E3 domain of laminin, and blocking experiments in vitro suggest that they adhere to this domain using a cell surface proteoglycan.

Activités osidasiques du tube digestif du criquet puant, Zonocerus variegatus L.

A study on the digestive carbohydrates complex was carried out in adult Zonocerus variegatus (Orthoptera: Pyrgomorphidae) to determine the status of the cyanogenetic glucose ingested by the grasshopper feeding on cassava. Two groups of adult Zonocerus were used. One group had been starved for 48 hours immediately prior to the experiment while the other had been fed continuously. After dissection, 10 to 15 portions of intestinal tracts (i.e. foreguts, caeca, midguts, hindguts) and 20 to 30 salivary glands were respectively crushed, centrifuged and dialysed for 24 hours in distilled water. The distillates obtained from different parts of the digestive system were used for determining the osidasic activities. Twenty-three substrates; i.e. 5 oligosaccharides, 10 synthetic heterosides and 8 soluble polysaccharides were selected for measuring the activities of the enzymes. Results showed that Z. variegatus has a wide range of enzymes whose activities differ according to different portions of the gut. The mid- and hind guts are the most active parts of the digestive tract but amylase activity was higher in the salivary glands. The Zonocerus variegatus osidase complex is characterised by the following proprieties: (a) high oligosaccharides activities on β-glucopyrones (maltose, saccharose) and on α-glucopyrones (cellobiose); (b)varied heteroside activities with α-glucosides and linamarase very active; (c) amylase activity very high, and hemicellulase and cellulase activities very low. In Zonocerus, starvation increases maltose hydrolyse but it does not affect other oligosaccharide activities. On the other hand, starvation reduces most of carbohydrases activities. The origin and consequences of the linamarase activity in the insect gut are also discussed.

A study of the assimilation of fluorescent pigments of microalgae Isochrysis galbana by the early larval stages of turbot and herring

The appearance of large supranuclear vacuoles in the enterocytes of 1‐ and 4‐days post‐hatch larvae of turbot and herring, respectively, revealed by the pinocytotic uptake of a fluorescent marker (FITCdextran), indicates a potential for the absorption of dissolved nutrients by the endotrophic stages of marine fish larvae. Ingestion of algal cells by turbot larvae was observed soon after hatching, but low level pinocytotic absorption of algal material was first seen during the second day. More extensive lysis of algal cells and pinocytotic absorption occurred 24 h later. Although lysis of I. galbana was shown to occur at low external osmolarities, it is unlikely that sufficiently low osmolarities present in the hind gut of turbot larvae explained the observed rupture of algae. Other mechanisms for digestion are discussed. In newly hatched herring larvae, algal cells were unable to pass beyond the constriction in the mid‐gut caused by the yolk sac. When algal cells were eventually seen to pass into the hind gut, there was no evidence of algal digestion or absorption throughout the remaining endotrophic and early exotrophic stages of herring larvae, although pinocytosis was observed to occur mid‐way through the endotrophic stage.

Level of wheat bran and saturation of lipid on fibre digestibility in the pig

The recent renewed interest in the feeding of fibrous feedstuffs to pigs has been precipitated by a number of economic and welfare issues. To reduce the costs of pig meat production, farmers have increased the use of cheaper ingredients which tend to contain a high proportion of fibre. The feeding of finely ground cereals in intensive systems has been linked with high rates of mortality resultant from gastric lesions. Adding materials rich in fibre can be beneficial in this respect through its effects on the gut environment.The addition of fibrous feeds to a diet will however have the effect of diluting the energy concentration of the diet and it is likely that counterbalancing levels of high energy materials will need to be added in order to maintain energy levels.Fibre digestion in the ruminant is known to be depressed by the addition of lipid to a diet and it may be that fermentation in the hind gut of the pig is similarly affected. Tallow, a saturated fat, and maize oil, an unsaturated oil, were used to investigate the effect of saturation of lipid on the digestibility of fibre from wheat bran. The effect of level of wheat bran on fibre digestibility was also examined.

The degradation of organic matter and crude protein of four botanically diverse feedstuffs in the foregut of ponies as measured by the mobile bag technique

There is a paucity of information on the digestion and utilisation of feeds by horses. Currently, most diets are formulated according to NRC (1989) recommendations which assume digestibility coefficients: for example, a digestibility coefficient for crude protein of 0.46 is used for animals at maintenance compared with 0.55 for lactating mares. However, if the digestibility of diets is uncertain, then use of such assumed values could result in either the under- or over-supply of nutrients. Furthermore, knowledge of the site of digestion is important. For example, only dietary protein digested and absorbed in the proximal small intestine can be efficiently utilised by the horse and the digestion of carbohydrate in the foregut (in terms of ATP yield) is more efficient than its fermentation in the hind gut. Therefore, in order to formulate diets more precisely, it is important to know a) the site at which dietary components are degraded and b) the extent of this degradation. In the present study mobile bags were used to determine the extent of organic matter disappearance (OMD) and crude protein disappearance (CPD) from four botanically diverse feedstuffs in the foregut of caecally - fistulated ponies.

De novo mutation of GDNF, ligand for the RET/GDNFR-alpha receptor complex, in Hirschsprung disease.

Hirschsprung disease (HSCR) is a common congenital abnormality characterized by absence of the enteric ganglia in the hind gut. In 10-40% of HSCR cases, mutations of the RET receptor tyrosine kinase have been found. The recent identification of a multimeric RET ligand/receptor complex suggested that mutations of genes encoding other components of this complex might also occur in HSCR. To investigate this role, we examined the gene for glial cell line-derived neurotrophic factor (GDNF), the circulating ligand of the RET receptor complex, for mutations in a panel of sporadic and familial HSCR. We identified GDNF sequence variants in 2/36 HSCR patients. The first of these was a conservative change which did not affect the GDNF protein sequence. The second variant was a de novo missense mutation in a family with no history of HSCR and without mutation of the RET gene. Thus, our data are consistent with a causative role for GDNF mutations in some HSCR cases.

Retention of furunculosis vaccine components in Atlantic salmon, Salmo salar L., following different routes of vaccine administration

AbstractThe retention of vaccine components was studied in Atlantic salmon, Salmo salar L., following different routes of vaccination against Aeromonas salmonicida. Frozen tissue was collected from the spleen, head kidney, hind gut and liver of fish that had been vaccinated by intraperitoneal injection (monovalent and trivalent vaccines), immersion and oral administration 2,6,8 and 16 weeks previously. The trivalent injection group showed the highest levels of specific antibodies and was the only group to show protection following challenge with virulent A. salmonicida. Following intraperitoneal injection, there was an initial widespread distribution of Aeromonas lipo‐polysaccharide, but by 16 weeks lipopolysaccharide was predominantly found in macrophage populations in the spleen, head kidney and abdominal granulomas. Only small amounts of lipopolysaccharide were retained in the head kidney of the immersion group and no lipopolysaccharide was retained in the oral group. Small and inconsistent amounts of A‐layer protein were present in the meianomacrophages of the head kidney of all groups. The relative prominence of A‐layer protein in the spleen of the trivalent injection group 8 weeks after vaccination was linked to the high levels of specific antibodies, and possible immune‐complex trapping and the enhancement of immunological memory.

Oily substances from gastral intersegmental glands of the antPachycondyla tridenta (Ponerinae): Lack of pheromone function in tandem running and antibiotic effects but further evidence for lubricative function

Gas chromatographic analyses of volatizable material from gaster intersegmental complex glands ofP. tridentata revealed the presence of linoleic acid, palmitic acid, methyl oleate, and several long-chain hydrocarbons as major constituents, which form an oily fluid mixture. The nest relocation communication ofP. tridentata is tandem running. Tandem following is mediated by pheromones as demonstrated by dummy experiments with isolated gasters and thoraces and with glass balls. The secretions of all gaster complex glands, as well as hind gut contents and metapleural gland secretions, were unable to evoke tandem following. Morphology and position of the glands, lack of pheromonal function, oily properties, low volatility, and lack of antibiotic effects of these secretions strongly suggest a function as lubricants for the ants' gastral segments.

クロクサアリの道しるべフェロモン

The trail pheromone of Lasius fuliginosus LATREILLE contained two kinds of chemicals: fatty acids such as n-hexanoic acid and n-heptanoic acid contained in the hind gut (HUWYLER et al., 1975), and an aliphatic alcohol. The trail-pheromone activity of the latter compound was stronger than that of the fatty acids. However, no peak corresponding to the putative trail pheromone could be detected in two different capillary columns, probably because the amount of pheromone was too small.

1019 Rectal cancer surgery-Europe leads the way

There is probably no more important issue in the field of cancer treatment at this time than the relative impact on the outcomes of the modalities in common use. The major renaissance of chemotherapy in the last decade, for example in colorectal cancer, has been based on surgical results which are markedly inferior to those which have been achieved by the best units in various part of the world. Thus the major trial by Krook and Moertel from the NCCTG, which has probably had the greatest impact on cancer treatment of any paper ever written, was based upon surgery practiced across many centres in the United States where the surgery was clearly of an unacceptable standard. Furthermore the premature discontinuation of this trial leaves many authorities with serious doubts about whether the apparent benefits of chemotherapy really represented anything more than prolongation of the tumour free interval rather than the claimed increase in the definitive number of cures. Recent interim results from the Dutch trial in the event showed no difference between treatment and control arms when the study was evaluated after three years. Whilst massive investments continue in chemotherapy trials no public cash has been injected in most countries into refinement of surgical technique and the teaching of such important techniques to specialist surgeons. The work of Hermanek in Germany suggested that whereas a maximum of 20% improvement in outcomes might be achieved by the optimal use of adjuvant therapies four times this improvement could be achieved by improvement in surgical technique. Some progress has however been made in Norway and Sweden and plans are in place for further initiatives in Holland and Finland. The author will present the interim results of surgical workshops undertaken in 13 Scandinavian cities to introduce the defined surgical technique of total mesorectal excision. This is an example of “specimen orientated surgery” where the surgeon gives the highest priority to achieving an intact untorn specimen comprising the whole of the visceral mesentery of the hind gut. This includes Denonvillier's fascia on the front and the whole specimen is as far as possible covered with areolar tissue which intervenes between the mesorectum and its external relations—prostate, vesicles, vagina, inferior hypogastric nerve plexuses, piriformis, levatoris ani, etc. In Basingstoke in England the use of this technique over 17 years has reduced local recurrence rates to 3% in “curative” anterior resections (the best group) and to an overall local recurrence rate for every person undergoing surgery of any kind of 7%. Data are also presented to show that there is a substantial improvement in the latter part of the series so that locally recurrent disease appears to be capable of being virtually elimirtated by the combination of selective pre-operative radiotherapy in a small percentage of locally advanced cases and obsessional pre-occupation with the technical achievement of good TME specimens. If these figures can be reproduced as a result of the workshops then it becomes clear that the whole range of adjuvant therapy protocols must be fundamentally reappraised and their role probably reduced to a more selective group of patients with a greater chance of benefit.

Rapid digestion and assimilation of bait by the deep-sea amphipod Eurythenes gryllus

Scavenging lysianassoid amphipods ( Eurythenes gryllus) were collected with a newly designed trap to measure digestion rates with timed exposure to bait in the Canada Basin of the Arctic Ocean (2075 m) and in the Nares (3521 m) and Sohm Abyssal (4978 m) Plains, northeast Atlantic Ocean. In feeding experiments up to 157 h long, water and organic matter content were not significantly different in anterior, central and hind gut regions of individual amphipods, showing that digestion in E. gryllus conforms to the batch reactor feeding model. Ingested bait was rapidly solubilized and water content increased from < 70% to > 90% within 69 h. Digestion rates, calculated from exponential curves fitted to decreases in gut contents for dry matter and various organic components, were very high (2.1–6.5% loss h −1) for sardines ingested during short (6–11 h) incubation periods in the Canada Basin. Mackerel ingested by amphipods trapped in the Nares and Sohm Abyssal Plains were digested at lower rates (0.4-1.0% loss h −1) in in situ experiments up to 123 h. Allometric regressions described relationships between body length and calories potentially available for assimilation from one meal by male and female instars. Rapid digestion in opportunistic scavengers like E. gryllus makes gut capacity available for additional feeding when food supply is unpredictable.

Microbial production of skatole in the hind gut of pigs given different diets and its relation to skatole deposition in backfat

AbstractThe intestinal production of skatole and its deposition in backfat was investigated in 35 uncastrated crossbred male pigs. The pigs were fed five purified non-commercial diets containing either casein or brewers yeast slurry as protein source. The yeast slurry diet was used alone or supplemented with either wheat bran (200 g/kg), sugar-beet pulp (200 g/kg), or soya oil (100 g/kg).Skatole concentrations in backfat, and in digesta in different sections of the gastro-intestinal tract were measured at slaughter (mean weight 112 kg). There were large variations in skatole concentrations in the hind gut of different animals given the same diet. Although there was some correlation between skatole in intestinal contents and deposition in adipose tissue, there were also large variations between individual animals in their response to intestinal skatole. Nevertheless, there was a clear effect of diet on both intestinal skatole production and skatole deposition in backfat. The use of casein as a protein source decreased microbial skatole production, the total amount in the gut, and the concentration in the backfat. Addition of sugar-beet pulp to the yeast slurry diet increased microbial activity in the intestine (measured as ATP content, concentration of short-chain fatty acids, and lowering of digesta pH). There was a decreased rate of skatole production during in vitro incubations of intestinal content, and less skatole in the hind gut and backfat.In vitro fermentations of freeze-dried Heal effluent inoculated with faecal bacteria, and addition of substrates to in vitro incubations of intestinal contents, demonstrated that tryptophan availability rather than microbial activity was the limiting factor for skatole production.The results show that skatole production depends on the amount of protein entering the hind gut and the proteolytic activity of the intestinal microbiota. Protein fermentation in the hind gut can be decreased either by using more readily digestible protein sources (for example casein rather than yeast slurry) which reduce the amount of protein passing through to the hind gut, or by adding an alternative energy source which is more readily metabolized by the hind gut microbiota (for example supplementation of the yeast slurry diet with sugar-beet pulp). This provides a basis for the rational design of diets which will decrease skatole concentrations in the carcass.

Rectal cancer: the surgical options.

The hypothesis is considered that the tissue block relevant to optimal cure encompasses the integral visceral mesentery of the hind gut, or mesorectum. Surgical technique can recreate the tissue planes around an intact globular specimen which must not be torn or the margin compromised. This emphasis on the "perfect tumour package" has reduced the local recurrence rates in a consecutive personal series of 333 rectal cancer operations to 4% in those operated upon for cure. If patients with metastases or residual disease at presentation are included, the figure increases to 7%. Introduction of selective pre-operative high dose radiotherapy (DXT) for locally unfavourable cancers has combined with further attention to surgical detail to achieve a 5-year follow-up period (January 1990-January 1995) without a single case of locally recurrent disease. Problems remain with healing of the ultra-low anastomosis.