Onset of nutrient consumption during early life stage digestive system development of two tuna species (Thunnus orientalis and Thunnus albacares).

To specify the timing of exogenous nutrient consumption in the larvae of two commercially important tuna species, the Pacific bluefin tuna (PBF) Thunnus orientalis and the yellowfin tuna (YFT) Thunnus albacares, the gene expressions of peptide transporter 1 (PEPT1) were examined. The mRNA expressions of PEPT1 first occurred at 2 days post hatching (dph) in PBF larvae and 3 dph for the YFT, and PEPT1 was found to only be expressed in the intestinal tract. The histological changes of the digestive tract of the YFT larvae were observed and compared to PBF larvae from a previous study. The intestines were developed at the hatching day for both species. It was found that the developmental timing of internal organs differed between the species, with the YFT showing an approximately one-day delay. The major organs such as liver, pancreas and gall bladder that excrete digestive enzymes appeared at 1 dph for PBF and 2 dph for YFT. The development of external morphological features was similar to organ development timings, with mouth-opening and first feeding starting at 2 dph for PBF, and 3 dph for YFT. Growth during the first month is rapid and variable for both species, ranging from 1.06 to 1.56 mm/d. Our findings provide new information about the early onset of feeding and larval development for the two species which would contribute to future aquaculture.

Ontogeny and development of the gastrointestinal system in Indian walking catfish (Clarias magur) during its early development.

Ontogeny of the digestive tract and its accessory organs and their further development in the Indian walking catfish (Clarias magur) were examined in larvae, starting from the day of hatching until 35 days post-hatching (dph) reared at 28-29 °C. Many organs at their primordial stage were seen on the day of hatching. These include opened oral cavity with monolayered epithelial lining and very few newly emerging taste buds and goblet cells, primordial pharyngeal teeth on slightly stratified epithelia of the pharyngeal plate, stomach anlage with some degree of the mucosal fold, and a few newly forming gastric glands embedded under its mucosa, primordial anterior and posterior intestine with the smooth mucosal surface, anal opening, and primordial liver and pancreas. At 1 dph, the stomach appeared to be bilobed with the first evidence of food particle in it, and the intestine had some initial folding. On the day of hatching, goblet cells appeared in all lengths of the gut, but not densely, except in the stomach; on it, they appeared at 2 dph. Pancreatic zymogen granules also appeared on this day. Supranuclear vesicles first appeared on 4-5 dph (7.9 ± 0.5-8.6 ± 0.8 mm TL), and they continue to exist until 35 dph. The developmental sequence in this fish confirmed it as an altricial species with some major histomorphological events after the onset of feeding; these include-the appearance of fully developed-pharyngeal teeth at 4 dph and onwards, pyloric sphincter, anterior to posterior intestinal sphincter at 6 dph, and the continuous development of buccopharyngeal cavity and stomach in their shape, size, and functionality until the completion of metamorphosis. Overall, the information on gastrointestinal development in the early life stage of C. magur will be useful for understanding its larval digestive physiology, and this, in turn, will help in designing effective larval feed for growth and survival.

Evaluation of hydrolytic enzyme activities from digestive fluids of Anthonomus grandis (Coleoptera: Curculionidae).

The cotton boll weevil, Anthonomus grandis, is a major pest of cotton crops in South America. In this work, partial biochemical characterizations of (hemi) cellulases and pectinases activities in the digestive system (head- and gut- extracts) of A. grandis were evaluated. Gut extract section from third instar larvae exhibited endoglucanase, xylanase, ß-glucosidase, and pectinase activities. The endoglucanase and xylanase activities were localized in the foregut, whereas ß-glucosidase activity was mainly detected in the hindgut. In addition, no difference in pectinase activity was observed across the gut sections. Thus, A. grandis digestive system is a potentially interesting reservoir for further lignocellulolytic enzymes research.

Structural and ultrastructural description of larval development in Zungaro jahu.

The Zungaro jahu is an important large catfish of the order Siluriformes that is in danger of extinction due to habitat destruction. Studies on its biology are scarce and the majority relates only to nutrition or parasitology. In order to provide greater information on its morphology and aid husbandry and larviculture studies, the aim of this study was to characterize larval development in Z. jahu from hatching to total yolk absorption. Samples were collected at pre-established times, processed, stained, and analyzed under stereomicroscopy, light microscopy, and scanning electron microscopy. Total yolk absorption was observed by 60 hours post-hatching (hph) at 28.75 ± 0.59°C. The newly hatched larvae showed slightly pigmented body, the outline of the digestive tract, evident eyes, and the first swimming movements. Mouth opening took place at 12 hph and the connection between the oral cavity and the rudimentary intestine was observed at 24 hph. Were analyzed the main larval organs and systems: digestive organs, heart, gill arches, sensory system, thyroid, kidney, and swim bladder. As the larvae grew, these organs became more mature and functional. The development of the sensory and feeding structures was observed at the start of larval development, and thus before depletion of endogenous energy reserves, the strategy for this species is to increase its chances of survival in the environment.

Histomorphological changes in digestive tract of golden mahseer (Tor putitora) during different developmental stages.

Histomorphological changes in digestive tract of golden mahseer (Tor putitora) were examined in larvae [starting from hatching to 45 days post-hatching (dph)], fry, fingerling, and adult. Digestive tract appeared during hatching, on the dorsal side of yolk sac, as a straight tube with a narrow lumen. Mouth opening and appearance of liver and pancreas were observed at 2 dph, and subsequently anal opening, appearance of goblet cells in esophagus, and posterior intestine were evident at 3 dph. The remodeling of oral cavity in terms of epithelial stratification, appearance of taste buds, and goblet cells were observed in a window of 4-5 dph. Intestinal folding was found to be initiated at 8 dph. From 12 to 45 dph, thickening of oral and esophageal mucosal/extramucosal layers, increase in intestinal folding, increases in the density of goblet cells in entire gut were observed. Within the same time window, other histological changes such as disappearance of vacuoles in liver, and abundance of zymogen granules in pancreas were also observed. Supranuclear vesicles in mid-to-posterior intestine were found to be prominent from first feeding to 45 dph; however, this phenomenon was no longer evident in fry and fingerling. Overall, the increase in intestinal folding and complexity of extramucosal layer were found to be continuous from the first appearance to adult, and this inferred the fact that the nutritional physiology, in terms of digestion and assimilation, progressively changes throughout the life stages of golden mahseer. Findings of this study will, therefore, help in preparing diets for different life stages of this fish, and in addition, the present information widens the understanding of digestive physiology of golden mahseer.

Digestive enzymatic activity during ontogenetic development in zebrafish (Danio rerio).

Despite the growing importance of zebrafish (Danio rerio) as an experimental model in biomedical research, some aspect of physiological and related morphological age dependent changes in digestive system during larval development are still unknown. In this paper, a biochemical and morphological study of the digestive tract of zebrafish was undertaken to record the functional changes occurring in this species during its ontogenetic development, particularly from 24 hr to 47 days post fertilization (dpf). Endo- and exo-proteases, as well as α-amylase enzymes, were quantified in zebrafish larvae before first feeding (7 dpf). The most morphologically significant events during the ontogenesis of the gut occurred between 3 dpf (mouth opening) and 7 dpf (end of exocrine pancreas differentiation). The presence of a wide range of digestive enzymes, already active at earlier zebrafish larval stages, closely related with the omnivorous diet of this species. Increasing enzyme activities were found with increasing age, probably in relation with intestinal mucosa folding and consequent absorption surface increase. J. Exp. Zool. (Mol. Dev. Evol.) 324B: 699-706, 2015. © 2015 Wiley Periodicals, Inc.

Development of seahorse (Hippocampus reidi, Ginsburg 1933): histological and histochemical study.

Biological aspects and global demand for aquarium promote seahorses as new species with high potential for commercial purposes; however, the low newborn survival rate represents the main bottleneck of seahorses farming. In this study, the organogenesis of the Hippocampus reidi was analysed from release until the 30th day after birth, using histological and histochemical approaches. To study the stages of their early life, 360 individuals were killed, sectioned, and stained with haematoxylin and eosin, periodic acid-Schiff, and Sudan Black B techniques. At birth, mouth and anus were open, the swim bladder inflated, and the visual system highly developed. Among the results, it was emphasized the presence of the yolk sac until the 2nd day after birth, the loops of the intestine to accommodate its elongation, and the ability of the larvae to absorb lipids in the anterior and posterior tract of the intestine. A short time (7/8 days) between reabsorption of yolk sac and formation of gonads was registered, with primordial follicles visible from the 10th day after birth. For the first time, organogenesis in H. reidi was described in detail; seahorses underwent a marked metamorphosis, and the indirect development observed in this species lead up to reconsider the term "juvenile" used for H. reidi during this period.

Organogenesis during budding and lophophoral morphology of Hislopia malayensis Annandale, 1916 (Bryozoa, Ctenostomata).

BACKGROUND: Bryozoans represent a large lophotrochozoan phylum with controversially discussed phylogenetic position and in group relationships. Developmental processes during the budding of bryozoans are in need for revision. Just recently a study on a phylactolaemate bryozoan gave a comprehensive basis for further comparisons among bryozoans. The aim of this study is to gain more insight into developmental patterns during polypide formation in the budding process of bryozoans. Particular focus is laid upon the lophophore, also its condition in adults. For this purpose we studied organogenesis during budding and lophophoral morphology of the ctenostome bryozoan Hislopia malayensis. RESULTS: Polypide buds develop on the frontal side of the developing cystid as proliferation of the epidermal and peritoneal layer. Early buds develop a lumen bordered by the inner budding layer resulting in the shape of a two-layered sac or vesicle. The hind- and midgut anlagen are first to develop as outpocketing of the prospective anal area. These grow towards the prospective mouth area where a comparatively small invagination marks the formation of the foregut. In between the prospective mouth and anus the ganglion develops as an invagination protruding in between the developing gut loop. Lophophore development starts with two lateral ridges which form tentacles very early. At the lophophoral base, intertentacular pits, previously unknown for ctenostomes, develop. The ganglion develops a circum-oral nerve ring from which the tentacle nerves branch off in adult zooids. Tentacles are innervated by medio-frontal nerves arising directly from the nerve ring, and medio-frontal and abfrontal nerves which originate both from an intertentacular fork. CONCLUSIONS: We are able to show distinct similarities among bryozoans in the formation of the different organ systems: a two-layered vesicle-like early bud, the ganglion forming as an invagination of the epidermal layer in between the prospective mouth and anal area, the digestive tract mainly forming as an outpocketing of the prospective anal area, and the lophophore forming from two lateral anlagen that first fuse on the oral and afterwards on the anal side. Future studies will concentrate on cyclostome budding to complement our knowledge on developmental patterns of bryozoans.

Development of foregut and proboscis in the buccinid neogastropod Nassarius mendicus: evolutionary opportunity exploited by a developmental module.

This article extends previous descriptions of foregut development and metamorphosis in neogastropods by providing data on the buccinid Nassarius mendicus, a species with a feeding larva. Histological sections showed that, like many other gastropods, the postmetamorphic buccal cavity and radular sac of N. mendicus differentiate during the larval stage from a ventral outpocketing of the distal larval esophagus. However, in N. mendicus the outpocketing also gives rise to the entire anterior esophagus and valve of Leiblein, suggesting that both these structures may be evolutionary derivatives of the gastropod buccal cavity. Scanning electron microscopy and three-dimensional reconstructions of section profiles revealed that the distal larval esophagus and larval mouth are completely destroyed at metamorphosis. The postmetamorphic mouth is formed as a new orifice. Furthermore, epithelia covering the proboscis and proboscis sac arise from preexisting epidermal epithelium of the larval head, an interpretation that contradicts an earlier suggestion on the origin of these epithelial elements in neogastropods with a feeding larval stage. These results, when compared to foregut development in other gastropods, lead me to propose that the gastropod buccal cavity and buccal mass is a developmental module. Canalized development of this module may have been important to the "evolvability" of the complex gastropod foregut, because it allowed a silent developmental novelty to arise (secondary formation of the postmetamorphic mouth) without disrupting development of the whole module. Nevertheless, this silent novelty might have subsequently facilitated dramatic evolutionary change by allowing the elaborate foregut structure of predatory, postmetamorphic neogastropods to arise in late stage larvae without compromising larval feeding.

New tetrachromic VOF stain (Type III-G.S) for normal and pathological fish tissues.

A new VOF Type III-G.S stain was applied to histological sections of different organs and tissues of healthy and pathological larvae, juvenile and adult fish species (Solea senegalensis; Sparus aurata; Diplodus sargo; Pagrus auriga; Argyrosomus regius and Halobatrachus didactylus). In comparison to the original Gutiérrez VOF stain, more acid dyes of contrasting colours and polychromatic/metachromatic properties were incorporated as essential constituents of the tetrachromic VOF stain. This facilitates the selective staining of different basic tissues and improves the morphological analysis of histochemical approaches of the cell components. The VOF Type III -6.5 stain is composed of a mixture of several dyes of varying size and molecular weight (Orange G

Expression of neuropsin in the keratinizing epithelial tissue-immunohistochemical analysis of wild-type and nude mice.

Neuropsin is a trypsin-type serine protease that was first cloned from the mouse brain as a factor related to neural plasticity. Subsequent in situ hybridization histochemical analysis indicated a broad localization of its mRNA throughout the whole body, although the details remain obscure. In this study, we showed that neuropsin immunoreactivity is localized in the keratinized stratified epithelia of the mouse epidermis, hair, tongue, palate, nasal cavity, pharynges, esophagus, and forestomach. In the skin and mucous membranes, neuropsin immunoreactivity was found in the stratum spinosum and the stratum granulosum. The immunoreactivity in the former sublayer was mainly present in the cytoplasm, but that in the latter sublayer was exclusively present in the intercellular space or on the outer surface of the cell membrane and thus exhibited a lamellar-like peripheral distribution. During development, the appearance of neuropsin immunoreactivity in the various epithelia was found at embryonic days 14.5-15.5, prior to formation of the stratum corneum. More extensive expression of neuropsin immunoreactivity was found in the nude mouse skin and mucous membranes than in wild-type mice. Because the nude mouse is characterized by genetic impairment of keratinization, such abnormal neuropsin expression might be caused or affected by this impairment. Therefore, neuropsin, an extracellular serine protease, is suggested to be involved in keratinization in the stratified epithelia.

Fiber and the development of gastrointestinal function.

Dietary lipid represents a major calorie source for the developing infant, yet dietary lipid absorption is relatively inefficient by adult standard. Recent studies are presented, indicating that the developmentally related improvement in lipid absorption observed in the preterm and fullterm infant relate to the maintenance of an intact intraluminal phase and completion of the enterohepatic circulation for bile salts. Critical issues including the absorption of nonpolar vitamins, iron, and the type of dietary lipid are discussed. The possible influence of the introduction of dietary fiber to the food of the developing infant is examined, and areas for future investigation are discussed.

Larval and metamorphic development of the foregut and proboscis in the caenogastropod Marsenina (Lamellaria) stearnsii.

The specialized, postmetamorphic feeding structures of predatory caenogastropods evolved by changes to an ancestral caenogastropod developmental program that generated a planktotrophic larval stage followed by a herbivorous postmetamorphic stage. As part of a program of comparative studies aimed at reconstructing these developmental changes, I studied the development of the postmetamorphic feeding system of Marsenina stearnsii using histological sections for light microscopy and scanning and transmission electron microscopy. The feeding system of this species has two very different designs during ontogeny. The larval system uses ciliary effectors to capture and ingest microalgae, whereas the juvenile/adult system includes a proboscis, jaws, and radular apparatus for predation on ascidian zooids. The postmetamorphic foregut begins to develop during the early larval phase, but the anlagen does not interfere with larval feeding because it develops as an increasingly elaborate outpocketing from the ventral wall of the larval esophagus. At metamorphosis, an opening is created in the anterior tip of the prospective, postmetamorphic buccal cavity and the margins of this opening anneal with the metamorphically remodeled lips of the larval mouth. This process exposes the jaws, which differentiate within the buccal cavity prior to metamorphosis. As a working hypothesis, I suggest that rupture of the buccal cavity to the outside at metamorphosis was selected as a mechanism to allow precocious development of jaws in species where jaws enhanced feeding performance by young juveniles. The larval esophagus of M. stearnsii appears to be completely destroyed at metamorphosis. Larval esophageal cells have distinctive apical characteristics (cilia, blebbed microvilli, stacks of lamellae within the glycocalyx) and no cells having this signature persist through metamorphosis. Development of the proboscis and proboscis sac, which begins prior to metamorphosis, conforms to previous descriptions of pleurembolic proboscis development, although an acrembolic proboscis has been ascribed to members of the Lamellaroidea.

Organogenesis in the budding process of the freshwater bryozoan Cristatella mucedo Cuvier, 1798 (Bryozoa, Phylactolaemata).

The phylogenetic position of bryozoans has been disputed for decades, and molecular phylogenetic analyzes have not unequivocally clarified their position within the Bilateria. As probably the most basal bryozoans, Phylactolaemata is the most promising taxon for large-scale phylogenetic comparisons. These comparisons require extending the morphological and developmental data by investigating different phylactolaemate species to identify basal characters and resolve in-group phylogeny. Accordingly, we analyzed the bud development and the organogenesis of the freshwater bryozoan Cristatella mucedo, with special focus on the formation of the digestive tract and differentiation of the coelomic compartments. Most parts of the digestive tract are formed as an outpocketing at the future anal side growing towards the mouth area. The ganglion is formed by an invagination between the anlagen of the mouth and anus. The lophophoral arms develop as paired lateral protrusions into the lumen of the bud and are temporarily connected by a median, thin bridge. All coelomic compartments are confluent during their development and also in the adult. The epistome coelom develops by fusion of two peritoneal infolds between the gut loop and overgrows the ganglion medially. The coelomic ring canal on the oral side develops by two lateral ingrowths and supplies the oral tentacles. On the forked canal, supplying the innermost row of tentacles above the epistome, a bladder-shaped swelling, probably with excretory function, is present in some adults. It remains difficult to draw comparisons to other phyla because only few studies have dealt with budding of potentially related taxa in more detail. Nonetheless, our results show that comparative organogenesis can contribute to phylactolaemate systematics and, when more data are available, possibly to that of other bryozoan classes and bilaterian phyla.

Histological and ultrastructural characterization of the alimentary system of solifuges (Arachnida, Solifugae).

Solifuges are voracious and fast predators. Once having captured a prey item, mostly small arthropods or even small vertebrates, they start feeding on their prey by constant chewing movements with their huge chelicerae. At the same time, they squeeze out the soft tissue that passes the anterior lattice-like part of the mouthparts. The digestion of the food takes place in the midgut, which is anatomically highly complex. It consists of the midgut tube from which numerous prosomal and opisthosomal diverticula and tubular lateral branches arise. The dimorphic epithelium of the midgut tube and the diverticula is constituted of digestive and secretory cells. The digestive cells are characterized by an apical tubulus system and contain nutritional vacuoles, lipids, spherites, and glycogen. Secretory cells contain a huge amount of rough endoplasmic reticulum and secretory vacuoles. The lateral branches are ultrastructurally similar to Malpighian tubules and are likely involved in excretion. In contrast to the midgut, the epithelium of the hindgut consists of only one type of cell overlain by a thin cuticle. Digested residuals are stored in the hindgut until defecation.

[Changes in the digestibility of constituents of the diet in the rabbit]. / Variations de la digestibilité des constituants de la ration chez le lapin.

Fiber digestibility of two diets (the first based on alfalfa dried, the second based on beet-pulp dried) with the same level of crude fiber and crude protein was measured on rabbits of 6, 7, 11, 13 and 17 weeks old. The age has no significative effect on digestibility (dry matter, organic matter, crude fiber) of the two experimental diets. The quantity of cellulose and hemicellulose digested was greater in rabbits on the pulp diet. Independantly of the diet hemicellulose is more digestible than cellulose. Expediency of use other analytical test than crude fiber in the nutritional requirements of rabbits is discussed.

Sonic hedgehog signaling pathway in vertebrate epithelial appendage morphogenesis: perspectives in development and evolution.

Vertebrate epithelial appendages are elaborate topological transformations of flat epithelia into complex organs that either protrude out of external (integument) and internal (oral cavity, gut) epithelia, or invaginate into the surrounding mesenchyme. Although they have specific structures and diverse functions, most epithelial appendages share similar developmental stages, including induction, morphogenesis, differentiation and cycling. The roles of the SHH pathway are analyzed in exemplary organs including feather, hair, tooth, tongue papilla, lung and foregut. SHH is not essential for induction and differentiation, but is involved heavily in morphogenetic processes including cell proliferation (size regulation), branching morphogenesis, mesenchymal condensation, fate determination (segmentation), polarizing activities and so on. Through differential activation of these processes by SHH in a spatiotemporal-specific fashion, organs of different shape and size are laid down. During evolution, new links of developmental pathways may occur and novel forms of epithelial appendages may emerge, upon which evolutionary selections can act. Sites of major variations have progressed from the body plan to the limb plan to the epithelial appendage plan. With its powerful morphogenetic activities, the SHH pathway would likely continue to play a major role in the evolution of novel epithelial appendages.

Morphological alterations in the peripheral and central nervous systems of mice lacking glial cell line-derived neurotrophic factor (GDNF): immunohistochemical studies.

Glial cell line-derived neurotrophic factor (GDNF) is a member of the TGF-beta superfamily of growth factors with neurotrophic activity on midbrain dopaminergic neurons and on developing and mature motoneurons of the brainstem and spinal cord. To investigate the extent of GDNF dependency of central and peripheral nervous structures during development, we have performed an immunohistochemical analysis of sections from the whole head including brain, peripheral ganglia, developing teeth and tongue, as well as intestines, in mutant mice lacking a part of the third exon that encodes the GDNF protein. As described previously, these null-mutated mice lack most of the enteric nerve plexus and are subject to agenesis or severe dysgenesis of the kidneys. In the present communication, we examined the development of vibrissae and incisor and molar teeth, as well as the innervation of these structures, and found no differences between null-mutated and control mice. A decrease in the immunohistochemical labeling intensity with tyrosine hydroxylase was observed in the superior cervical ganglion (SCG), as well as in the pontine nucleus locus coeruleus, and the sympathetic innervation of blood vessels and glands in the head was significantly decreased. None of the brain nuclei studied exhibited any significant decreases in the total number of neurons, but the packing density of neurons in the nucleus locus coeruleus was decreased. These data indicate that GDNF might be one neurotrophic factor that contributes to the development of central and peripheral noradrenergic neurons.

Effects of oral IGF-I or IGF-II on digestive organ growth in newborn piglets.

To study whether colostrum-borne growth factors are responsible for the rapid GI tissue growth in naturally suckled newborn animals, newborn unsuckled piglets were bottle-fed for 24 h with infant milk formula with or without addition of 2 micrograms/ml of recombinant human insulin-like growth factor-I (IGF-I) or insulin-like growth factor-II (IGF-II), a level which approximated that of porcine colostrum. The animals were then sacrificed for measurements of their digestive organ weights and contents of protein, RNA and DNA in the organs. The treatment with IGF-I or IGF-II failed to show any significant effect on the weight of the esophagus, stomach, small intestine, large intestine, mandibular glands, kidneys and the spleen, and had no effects on the contents of protein, RNA and DNA in the small intestinal mucosa, the liver and the spleen. However, piglets fed with infant formula containing IGF-I (n = 7) or IGF-II (n = 7) had a heavier pancreas (p < 0.05) compared to formula-fed controls (n = 7). The DNA content in the stomach and the pancreas were greater in animals treated with IGF-I or IGF-II than in controls. Using a cell labelling technique it was shown that both IGF-I and IGF-II stimulated cell proliferation in the small intestinal crypts. The results indicate that the substantial GI tissue growth reported in newborn animals is unlikely due to colostrum-borne IGF-I or IGF-II alone. On the other hand the study does suggest that oral IGF-I and IGF-II are capable of stimulating cell proliferation in the GI tract.

Biorecognition of HPMA copolymer-lectin conjugates as an indicator of differentiation of cell-surface glycoproteins in development, maturation, and diseases of human and rodent gastrointestinal tissues.

Lectins are proteins that bind glycoproteins; binding patterns are altered with changes in glycoprotein expression accompanying maturation or disease. Binding of two lectins, wheat germ agglutinin (WGA) and peanut agglutinin (PNA), in human and rodent colon were previously examined. Normal tissue showed intense WGA binding; PNA binding was minimal. Diseased tissues showed increased PNA binding. We hypothesized that N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer-lectin-drug conjugates could deliver therapeutic agents to diseased tissues by targeting colonic glycoproteins. We examined biorecognition of free and HPMA copolymer-conjugated WGA and PNA and anti-Thomsen-Friedenreich (TF) antigen antibody binding in normal neonatal, adult, and diseased rodent tissues, human specimens of inflammation, and Barrett's esophagus. Neonatal WGA binding was comparable to the adult, with additional luminal columnar cell binding. PNA binding was more prevalent; luminal columnar cell binding existed during the first 2.5 weeks of life. WGA binding was strong in both normal and diseased adult tissues; a slight decrease was noted in disease. PNA binding was minimal in normal tissues; increases were seen in disease. Anti-TF antigen antibody studies showed that PNA did not bind to the antigen. The results suggest that HPMA copolymer-lectin-drug conjugates may provide site-specific treatment of conditions such as colitis and Barrett's esophagus.