Intestinal villi and crypts density maximizing nutrient absorption

Claude Loverdo; Cl\'ement De Loubens; D\'acil I. Y\'anez Mart\'in; Martin Garic; Rohan Vernekar; St\'ephane Tanguy

REVIEW 3 major objections 5 minor 49 references

Intestinal villi and crypts density maximizing nutrient absorption

T0 review · 3 major / 5 minor · reviewed 2026-08-06 · deepseek-v4-flash

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Pith's one-line read The paper claims a single villus/crypt spacing maximizes nutrient absorption per gut length, that the optimum is nearly nutrient-independent, and that real animal guts sit inside the predicted zone.

desk verdict A careful analytic model of optimal villi/crypt spacing with a testable prediction; the species data need a factor-of-two fix and a more measured evolutionary claim. read the letter →

arxiv 2507.03472 v2 pith:25CINZ43 submitted 2025-07-04 q-bio.TO physics.bio-ph

Martin Garic , Rohan Vernekar , Dácil I. Yánez Martín , Stéphane Tanguy , Clément de Loubens , Claude Loverdo This is my paper · ORCID

classification q-bio.TOphysics.bio-ph

keywords intestinalvillicryptsnutrientabsorptiondiffusion-limitedtransportoptimaldensityLaplaceequationgutmorphologyevolutionaryselection

verification ladder T0 review T1 audit T2 compute T3 formal

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

Conventional wisdom holds that villi and crypts boost absorption by adding surface area, so denser should be better. This paper argues the opposite trade-off is real: packing these structures too closely leaves too little room for nutrients to diffuse in, so per unit of gut length there is a single spacing that maximizes uptake. The authors solve the steady-state diffusion equation with semi-absorbing walls in three idealized geometries (leaf-like villi, finger-like villi, and colonic crypts) and find that the optimal gap width barely depends on which nutrient is being absorbed. Measured villus and crypt geometries from mice, rats, humans, pigs, chickens, pheasants, and horses all fall inside the predicted region for at least 95% of maximal absorption. If the claim holds, gut microstructure is a quantitatively predictable optimum shaped by natural selection for nutrient uptake, and deviations from it come with a calculable absorption cost.

What carries the argument

The engine of the argument is the steady-state diffusion equation $\nabla^2 C = 0$ with a Robin boundary condition $D(\hat{n}\cdot\nabla C) + kC = 0$ on the absorbing walls, where $k$ is the surface absorptivity and $D$ the diffusion coefficient. The paper solves this analytically in three geometries — 2D rectangular wells for leaf-like villi, axisymmetric cylinders on a triangular lattice (hexagons approximated by equal-area circles) for finger-like villi, and cylindrical wells for crypts — using separation of variables with Fourier series and Bessel functions. All results collapse onto two dimensionless parameters: $\xi = R/h$, the gap half-width or crypt radius rescaled by structure height, and $\Theta = D/(kh)$, the rescaled inverse surface absorptivity. The central object is the dimensionless flux per unit of gut length $\tilde{j}$, which balances added absorbing surface against reduced diffusive penetration; the optimum spacing is the solution of $\partial \tilde{j}/\partial \xi = 0$, located numerically, and its weakness in $\Theta$ is what makes one geometry serve many nutrients.

What would settle it

Measure the absorption flux per unit of gut length in an experimental or simulated gut while sweeping villus density across the predicted optimum, keeping nutrient and flow conditions fixed. The model predicts a single-peaked curve with its maximum at a rescaled gap width of order 0.01–0.1 for villi, and a peak that barely shifts when the nutrient's absorptivity $k$ changes across orders of magnitude. A monotone rise with density, or a peak that moves strongly with nutrient type, would refute the central claim; so would a systematic deviation toward denser packing in species with vigorous villus contractions that mix the intervillous space.

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Extended reading notes

Core claim

On its own terms, the paper claims that for any fixed structure width $\tilde{e}$ and nutrient absorption parameter $\Theta$ there is exactly one rescaled gap width $\xi = R/h$ maximizing the steady absorption flux per unit of gut length, and that this optimum varies only weakly with $\Theta$ across the physiological range ($\Theta$ between 1 and 100). Because of that weakness, a geometry optimal for one nutrient is close to optimal for any other nutrient. The paper further claims that physiological measurements of villi and crypts from eight animal datasets lie within the predicted 95%-of-maximum region, with crypts correctly predicted to be much wider relative to their depth than the spaces between villi. The authors conclude that villus and crypt density has been evolutionarily selected to maximize absorption efficiency, and note that the flatness of the optimum means measurement artifacts in fixed tissues are unlikely to push real geometries far from the optimal range.

Load-bearing premise

The entire calculation assumes nutrients reach the gaps between villi and the inside of crypts by diffusion alone, with a well-mixed lumen above and stationary structures; if convection, villus contractions, or mucus pumping carries nutrients into those spaces, the predicted optimal density shifts and the match with animal data could be coincidence.

Editorial extensions

If this is right

Villus and crypt spacing becomes a quantitative prediction: given a structure's height and width, the model fixes the gap that maximizes absorption per unit of gut length, so the same calculation extends to species, gut regions, and developmental stages beyond the paper's dataset.
Because the optimal spacing barely changes across the physiological range of $\Theta$, one gut geometry can serve many nutrients at once — glucose, amino acids, and poorly absorbed sugars do not each demand their own villus packing.
Diseases that distort villus geometry, including villous atrophy in celiac disease, should reduce absorption partly by moving the gut away from the optimal spacing; the model supplies a quantitative baseline for how much uptake a given morphological change costs.
The model explains why crypts and villi look different: the predicted optimal radius-to-depth ratio for crypts is much larger, matching the observation that colonic crypts are wide relative to their depth while intervillous gaps are narrow.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

Because the 95%-of-maximum region is wide, the agreement with species data is a permissive test; a stricter check of the same theory would compare the full distribution of measured geometries across many species against the predicted optimal curve, or test whether spacing varies along a single gut where absorption demands differ.
If villus contractions do produce pumping flows, as the cited motility literature suggests, the true optimum would likely sit at a denser packing than the pure-diffusion prediction; species with strong villus motility are therefore a natural place to look for systematic deviations from the model's curve.
Treating villus height as fixed by external constraints, the model optimizes only spacing; adding a cost for building taller structures and optimizing height together with spacing would turn the paper's one-dimensional optimum curve into a joint prediction for how villus height and density co-vary across species.

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Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Desk Editor's Note

read the letter

First, this is a genuinely useful paper. The authors solve the diffusion equation with Robin boundary conditions in three geometries—leaf-like villi, finger-like villi, crypts—and compute the spacing that maximizes absorption flux per unit gut length. The leaf-like case reproduces Winne's earlier result, a good sanity check; the finger-like and crypt calculations are new. The strongest new biological idea is that the optimal spacing depends only weakly on the nutrient's absorptivity, so one geometry serves many nutrients.

The empirical section is the weakest part. Table 1 gives crypt ξ values computed from crypt diameter while the model defines ξ as radius/h; 0.24 and 0.17 should be 0.12 and 0.086. That shifts both crypt points in Figure 4 by a factor of two and should be fixed. The data points also lack error bars, which makes the visual agreement with the 95% optimal band hard to assess. The evolutionary-selection conclusion is stated more strongly than nine scattered measurements can support.

The deeper caveat is the diffusion-only, static-villi assumption. The authors honestly concede that villous contractions create flow and pumping, and may invalidate the diffusion approximation for villi. The stress-test note estimates Péclet numbers of order 0.1–10 in intervillous gaps, so advection is not negligible. This is a legitimate concern, not fatal: the optimum lies at small ξ, and the absorption landscape is flat, so moderate convection would not destroy the qualitative prediction. But if convection enhances uptake, the villi data's agreement with the diffusion-only band could be coincidental. The authors should either defend the unstirred-water-layer assumption more quantitatively or limit the empirical validation to crypts.

The math is careful, the exposition is clear, and the literature is handled fairly. This is a solid contribution to gut physiology and biophysics, useful for people working on absorption or drug delivery. It deserves a serious referee.

Recommendation: engage. The crypt ξ error is mechanical, the evolutionary wording can be tempered, and the convection caveat needs a response, but the core model—an analytically derived optimal density for villi and crypts—is a real contribution that should be in the literature after revision.

Referee Report

3 major / 5 minor

Summary. The manuscript studies diffusion-limited nutrient absorption between intestinal villi and within colonic crypts. For three idealized geometries (leaf-like villi, finger-like villi, and crypts), the authors solve the steady-state Laplace equation with Robin boundary conditions analytically, derive the absorption flux per unit gut length, and show numerically that an optimal inter-structure spacing ξ=R/h exists. They argue that the optimum depends weakly on the nutrient-dependent parameter Θ=D/(kh), and they compare the predicted optimal range against morphometric measurements from nine species, concluding that most physiological geometries fall within the 95% optimal-absorption region and may reflect evolutionary selection. The paper also discusses limitations, including the pure-diffusion approximation and tissue fixation effects.

Significance. If the result holds, the paper offers a parameter-free, first-principles prediction for villus/crypt spacing and a quantitative resolution of the surface-area/diffusion-hindrance trade-off. The analytic derivations are transparent, the reduction to the known leaf-like case is a useful check, and the model uses no fitted parameters; the species data are external and were not used to shape the prediction, making the comparison a genuine out-of-sample test. The main weaknesses are a factor-of-two error in the reported crypt ξ values, an untested robustness of the pure-diffusion assumption against convection in the intervillous space, and inconsistent geometric definitions in the finger-like and crypt models. These issues do not necessarily invalidate the central idea, but they must be fixed or clarified before the evolutionary claim can be accepted.

major comments (3)

[Table 1 and Figure 4] In Table 1, the crypt ξ values are computed as diameter/h (0.24 for human, 0.17 for mouse), but the model defines ξ = R/h with R the crypt radius (Sections 2.3 and 2.4). Using radius/h gives 0.12 and 0.086. Because the crypt data points in Figure 4 are plotted at twice their correct ξ values, the statement that "Most physiological geometries fall within the predicted region" must be re-evaluated with corrected values, and the figure and conclusions about crypt agreement should be updated.
[Sections 1 and 4] The assumption of purely diffusive transport in the intervillous space is load-bearing because 7 of the 9 data points in Figure 4 are villi. The authors themselves concede in the Conclusion that villous contractions "will create flow and pumping between them [17,45,46], and the purely diffusive approximation between villi may fail." A rough Peclet-number estimate for glucose in a 20–100 µm gap with contraction-induced velocities of 1–100 µm/s gives Pe = U R/D ≈ 0.1–10, i.e., advection can be comparable to or larger than diffusion. Please provide a quantitative estimate of Pe in the physiological range and either show that the optimal ξ is insensitive to weak advection or restrict the empirical/evolutionary claim to crypts.
[Sections 2.2, 2.3 and SI B/D] The geometric description of the triangular lattice is inconsistent. The text states that the shortest distance between the sides of two villi is 2R′ and that the hexagons have side length R′+e/2. For a triangular lattice with villus radius e/2, the center-to-center spacing is 2R′+e, and the Voronoi hexagon side length should be (2R′+e)/√3, not R′+e/2. The same issue applies to the crypt model (spacing e, radius R, hexagon side length R+e/2 in eq. 19). Since the per-structure area enters the denominator of eqs. (16) and (19), the optimum curves in Figure 4 may shift. In addition, the conversion in SI D relates R1, R2, e, and R in a way that is not compatible with the lattice geometry as written, and this affects the ξ and e~ values of the finger-like villi data in Table 1. Please clarify the definitions and recompute the affected quantities.

minor comments (5)

[Figure 4] The figure omits error bars even though Table 1 reports uncertainties for each measurement; please add error bars or state explicitly why they are not shown.
[Section 3] The claim that "Most physiological geometries fall within the predicted region for 95% of the maximal absorption" is made without specifying how the 95% region was computed (e.g., for each geometry separately, and over which range of Θ). Please provide the criterion.
[Throughout] There are several typographical errors: "Phaesant Jejunum" in Figure 4, "Th will create flow" in Section 4, "jejenum" in Table 2, and "flu" in the caption of SI Figure S9.
[Section 2.1] Equation (11) says "Where kc0e is the flux on the villi tip"; in the 2D geometry this is the flux on the villus tips per unit depth, and the wording should be clarified.
[SI Section E] The physiological range of Θ is estimated as 1–100 using glucose and mannitol as examples, but the comparison in Figure 4 uses Θ=10; a sentence explaining which nutrient's Θ is representative for the species data would improve the presentation.

Circularity Check

0 steps flagged · score 0.0 of 10

No significant circularity: the optimum is computed from a first-principles diffusion model with literature parameters, and the species data are an external, out-of-sample benchmark.

full rationale

The derivation chain is self-contained. The paper solves the steady diffusion equation (Eq. 1) with Robin boundary conditions (Eq. 3) in three geometries, obtains analytical concentration and flux expressions (Eqs. 7, 10, 13, 17), and defines the flux per unit gut length (Eqs. 12, 16, 19). The optimum is found by solving ∂J/∂ξ = 0 (Eq. 20), with no parameter fitted to the species data. Physiological parameters enter only through Θ = D/(kh), estimated from literature values (D ≈ 6·10⁻¹⁰ m²/s, k between 5·10⁻⁹ and 10⁻⁵ m/s, h from published villus heights), and the species data in Table 1 are gathered from published images and tables, appearing only after the optimum was computed. The agreement in Figure 4 is therefore a genuine out-of-sample comparison. The crypt ξ values in Table 1 appear to use crypt diameter rather than radius (human: 120/500 = 0.24 instead of 60/500 = 0.12), and the breadth of the 95% region plus the diffusion-only assumption are model-validity and data-quality concerns, not circular reductions. The only self-citations (Refs. 17, 45) are invoked in the Conclusion to acknowledge that villous contractions may create flow and that the diffusion-only approximation may fail; this is a limitation, not a load-bearing justification of the result.

Assumptions & free parameters 1 free parameters · 7 assumptions · 0 invented entities

Central claim rests on seven stated modeling assumptions, no data-fitted parameters, and no invented entities. The only free input is the literature-based range for Θ (1 to 100), which anchors the claim that the optimum is weakly Θ-dependent. The diffusion-only and static-structure assumptions are load-bearing and are acknowledged by the authors as limitations.

free parameters (1)

Physiological range for Θ = D/(kh) = 1 to 100
Estimated in SI Section E from glucose (k≈1e-5 m/s) and mannitol (k≈5e-9 m/s) permeabilities. The range is used to claim the optimal ξ is weakly Θ-dependent and to set Θ=10 in Figure 4. It is a literature-based modeling input, not fitted to villi geometry data.

assumptions (7)

standard math Steady-state Laplace equation describes nutrient transport.
Section 1, equations 1-3; assumes Fickian diffusion and steady state because diffusion time (~833 s for glucose) is shorter than gut transit.
domain assumption Lumen is well mixed with fixed concentration c0 at the top of villi and crypt mouths.
Section 1, equation 2 and text: 'we consider that mixing is efficient in the lumen, and thus the luminal concentration is fixed at a concentration c0'.
domain assumption Transport between villi and within crypts is purely diffusive.
Section 1 and conclusion: 'we explore a limiting case in which only diffusion occurs between villi and crypts, neglecting any convective contribution'; the authors note villus contractions and luminal flow could add convection.
domain assumption Epithelial walls absorb nutrients with a constant permeability k (Robin boundary condition).
Equation 3; k values taken from literature for glucose and mannitol in SI Section E; active transport and concentration-dependent uptake are not modeled.
domain assumption Villi are static; there is no motion-induced flow.
Section 1: 'we assume that the villi are not moving relative to each other'; conclusion acknowledges this may fail for villi with contractions.
domain assumption Optimization can be restricted to the spacing ξ = R/h at fixed height h and width e~.
Section 2.1: 'We assume h is set by other constraints such as resources needed to build longer villi', and e~ has a physiological minimum for blood and lymph circulation.
ad hoc to paper Hexagonal arrangements in the finger-like and crypt geometries are approximated as circles conserving surface area.
Section 2.2 and SI Section B/D; the authors note this approximation may be less adequate at high villi density.

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Pith. "Pith review of Intestinal villi and crypts density maximizing nutrient absorption." pith.science (2026). https://pith.science/paper/25CINZ43

@misc{pith2026250703472,
  author       = {Pith},
  title        = {Pith review of: Intestinal villi and crypts density maximizing nutrient absorption},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/25CINZ43}},
  note         = {Machine review of arXiv:2507.03472}
}

read the original abstract

The villi and crypts of the gastrointestinal tract increase the effective surface area of the intestinal mucosa, potentially enhancing nutrient absorption. It is commonly assumed that this is their primary function, and that a higher villi density necessarily leads to improved absorption. However, when villi are packed too closely together, diffusion can be hindered, potentially offsetting this benefit. In this work, we investigate the relationship between the density of these structures and the overall efficiency of absorption. In three different simplified geometries, approximating crypts, leaf-like villi, and finger-like villi we calculate analytically the concentration profile and the absorption flux, assuming that there is only diffusion between these structures while the lumen is well mixed. When plotting the absorption flux per unit of gut length as a function of the structures' density, we observe that there is a density maximizing absorption. We study numerically this optimum. It depends weakly on the absorption properties of the given nutrient, so that a geometry optimal for one nutrient is close to optimum for another nutrient. Physiological data from various animal species align with this predicted optimal range and potentially reflect evolutionary selection for efficient nutrient uptake, supporting the model's validity.

Figures

Figures reproduced from arXiv: 2507.03472 by the authors.

**Figure 2.** Contour plot of the rescaled nutrient concentration within an in [PITH_FULL_IMAGE:figures/full_fig_p006_2.png] view at source ↗

**Figure 3.** Leaf-like villi log flux density per unit of gut length [PITH_FULL_IMAGE:figures/full_fig_p007_3.png] view at source ↗

Figures from the paper (1 more)

**Figure 4.** Figure 4: Plot of the rescaled intervillous width maximizing absorption per unit [PITH_FULL_IMAGE:figures/full_fig_p010_4.png]

Discussion (0). Continue with ORCID to comment.

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Works this paper leans on

49 extracted references · 49 canonical work pages

[1]

K. K. Reed and R. Wickham. Review of the Gastrointestinal Tract: From Macro to Micro.Seminars in Oncology Nursing. Gastrointestinal Malig- nancies, 25(1):3–14, February 2009

work page 2009
[2]

V. E. Henderson. The mechanism of intestinal peristalsis.American Jour- nal of Physiology-Legacy Content, 86(1):82–98, August 1928. Publisher: American Physiological Society

work page 1928
[3]

R. G. Lentle and C. de Loubens. A review of mixing and propulsion of chyme in the small intestine: fresh insights from new methods. en.J Comp Physiol B, 185(4):369–387, May 2015

work page 2015
[4]

E. H. Eltantaway, G. Khalaf, and G. G. Hamam. Effect of experimentally induced chronic pancreatitis on the structure of hepatocytes and the duo- denal villi in adult male albino rats. en-US.Egyptian Journal of Histology, 38(1):1, March 2015

work page 2015
[5]

W. A. Hilton. The morphology and development of intestinal folds and Villi in vertibrates. en.American Journal of Anatomy, 1(4):459–505, 1902

work page 1902
[6]

K. D. Walton, D. Mishkind, M. R. Riddle, C. J. Tabin, and D. L. Gumucio. Blueprint for an intestinal villus: Species-specific assembly required. en. WIREs Developmental Biology, 7(4):e317, 2018

work page 2018
[7]

M. N i. The contribution of the large intestine to energy supplies in man. The American Journal of Clinical Nutrition, 39(2):338–342, Febru- ary 1984

work page 1984
[8]

S. P. Prieto, C. L. Reed, H. M. James, K. P. Quinn, and T. J. Mul- doon. Differences in colonic crypt morphology of spontaneous and colitis- associated murine models via second harmonic generation imaging to quantify colon cancer development.BMC cancer, 19:1–11, 2019

work page 2019

Show all 49 references

[9]

H. F. Helander. Morphological studies on the development of the rat colonic mucosa.Cells Tissues Organs, 85(2):153–176, 1973

1973
[10]

K. D. Walton, A. M. Freddo, S. Wang, and D. L. Gumucio. Generation of intestinal surface: an absorbing tale.Development, 143(13):2261–2272, July 2016

2016
[11]

H. F. Helander and L. Fändriks. Surface area of the digestive tract – revisited. Scandinavian Journal of Gastroenterology, 49(6):681–689, June 2014

2014
[12]

Vertzoni, P

M. Vertzoni, P. Augustijns, M. Grimm, M. Koziolek, G. Lemmens, N. Parrott, C. Pentafragka, C. Reppas, J. Rubbens, J. Van Den Abeele, et al. Impact of regional differences along the gastrointestinal tract of healthy adults on oral drug absorption: an ungap review. European jour...

2019
[13]

Strocchi and M

A. Strocchi and M. D. Levitt. Role of villous surface area in absorption science versus religion. en.Digest Dis Sci, 38(3):385–387, March 1993

1993
[14]

A. E. Shyer, T. Tallinen, N. L. Nerurkar, Z. Wei, E. S. Gil, D. L. Kaplan, C. J. Tabin, and L Mahadevan. Villification: how the gut gets its villi. Science, 342(6155):212–218, 2013. 34

2013
[15]

Lentle, P

R. Lentle, P. Janssen, C DeLoubens, Y. Lim, C Hulls, and P Chambers. Mucosal microfolds augment mixing at the wall of the distal ileum of the brushtail possum.Neurogastroenterology & Motility, 25(11):881–e700, 2013

2013
[16]

Y. Lim, C. de Loubens, R. Love, R. Lentle, and P. Janssen. Flow and mixing by small intestine villi.Food & function, 6(6):1787–1795, 2015

2015
[17]

Vernekar, F

R. Vernekar, F. Ahmad, M. Garic, D. I. Y. Martín, C. Loverdo, S. Tanguy, and C. de Loubens. Hydrodynamics in a villi-patterned channel due to pendular-wave activity.arXiv preprint arXiv:2503.08852, 2025

2025
[18]

Wang and J

Y. Wang and J. G. Brasseur. Three-dimensional mechanisms of macro-to- micro-scale transport and absorption enhancement by gut villi motions. Physical Review E, 95(6):062412, 2017

2017
[19]

R. G. Lentle and P. W. M. Janssen. Flow, Mixing and Absorption at the Mucosa. en. In R. G. Lentle and P. W. Janssen, editors,The Physical Processes of Digestion, pages 221–274. Springer, New York, NY, 2011

2011
[20]

F. A. Wilson and J. M. Dietschy. The intestinal unstirred layer: Its surface area and effect on active transport kinetics.Biochimica et Biophysica Acta (BBA) - Biomembranes, 363(1):112–126, August 1974

1974
[21]

K. W. Smithson, D. B. Millar, L. R. Jacobs, and G. M. Gray. Intestinal Diffusion Barrier: Unstirred Water Layer or Membrane Surface Mucous Coat? Science, 214(4526):1241–1244, December 1981. Publisher: Ameri- can Association for the Advancement of Science

1981
[22]

M. E. Johansson, D. Ambort, T. Pelaseyed, A. Schütte, J. K. Gustafsson, A. Ermund, D. B. Subramani, J. M. Holmén-Larsson, K. A. Thomsson, J. H. Bergström, et al. Composition and functional role of the mucus layers in the intestine.Cellular and molecular life sciences, 68:3635–...

2011
[23]

Strugala, A

V. Strugala, A. Allen, P. W. Dettmar, and J. P. Pearson. Colonic mucin: methods of measuring mucus thickness.Proceedings of the Nutrition So- ciety, 62(1):237–243, 2003

2003
[24]

D.Winne.Effectofvillosityanddistensionontheabsorptiveandsecretory flux in the small intestine.Journal of theoretical biology, 139(2):155–186, 1989

1989
[25]

R. E. Oliver, A. F. Jones, and M. Rowland. What surface of the intestinal epithelium is effectively available to permeating drugs?Journal of phar- maceutical sciences, 87(5):634–639, 1998

1998
[26]

Fagerholm and H

U. Fagerholm and H. Lennernäs. Experimental estimation of the effective unstirred water layer thickness in the human jejunum, and its importance in oral drug absorption. European Journal of Pharmaceutical Sciences, 3(3-5):247–253, 1995. Publisher: Elsevier Science

1995
[27]

Swidsinski, V

A. Swidsinski, V. Loening-Baucke, F. Theissig, H. Engelhardt, S. Beng- mark, S. Koch, H. Lochs, and Y. Dörffel. Comparative study of the intesti- nal mucus barrier in normal and inflamed colon. en.Gut, 56(3):343–350, March 2007. Publisher: BMJ Publishing Group Section: Colonic...

2007
[28]

A. N. Bashkatov, E. A. Genina, Y. P. Sinichkin, V. I. Kochubey, N. A. Lakodina, and V. V. Tuchin. Glucose and mannitol diffusion in human dura mater.Biophysical journal, 85(5):3310–3318, 2003

2003
[29]

B Ma, R Von Wasielewski, W Lindenmaier, and K. Dittmar. Immmuno- histochemical study of the blood and lymphatic vasculature and the in- nervation of mouse gut and gut-associated lymphoid tissue.Anatomia, histologia, embryologia, 36(1):62–74, 2007

2007
[30]

C. J. Watson, C. J. Hoare, D. R. Garrod, G. L. Carlson, and G. Warhurst. Interferon-γ selectively increases epithelial permeability to large molecules by activating different populations of paracellular pores.Journal of cell science, 118(22):5221–5230, 2005

2005
[31]

Sugano, N

K. Sugano, N. Takata, M. Machida, K. Saitoh, and K. Terada. Prediction of passive intestinal absorption using bio-mimetic artificial membrane per- meation assay and the paracellular pathway model.International journal of pharmaceutics, 241(2):241–251, 2002

2002
[32]

Sugano, Y

K. Sugano, Y. Nabuchi, M. Machida, and Y. Aso. Prediction of human in- testinal permeability using artificial membrane permeability.International journal of pharmaceutics, 257(1-2):245–251, 2003

2003
[33]

Lennernaäs

H. Lennernaäs. Human intestinal permeability.Journal of pharmaceutical sciences, 87(4):403–410, 1998

1998
[34]

M. N. Marsh and J. A. Swift. A study of the small intestinal mucosa us- ing the scanning electron microscope. en.Gut, 10(11):940–949, November 1969

1969
[35]

Seyyedin and M

S. Seyyedin and M. N. Nazem. Histomorphometric study of the effect of methionine on small intestine parameters in rat: an applied histologic study. en.Folia Morphologica, 76(4):620–629, 2017. Number: 4

2017
[36]

Fujimiya, T

M. Fujimiya, T. Maeda, and H. Kimura. Serotonin-containing epithelial cells in rat duodenum. I. Quantitative morphometric study of the distri- bution density. en.Histochemistry, 95(3):217–224, May 1991

1991
[37]

Abbas, T

B. Abbas, T. L. Hayes, D. J. Wilson, and K. E. Carr. Internal structure of the intestinal villus: morphological and morphometric observations at different levels of the mouse villus. eng.J Anat, 162:263–273, February 1989

1989
[38]

T. H. Skrzypek, W. Kazimierczak, H. Skrzypek, J. L. Valverde Piedra, M. M. Godlewski, and R. Zabielski. Mechanisms involved in the devel- opment of the small intestine mucosal layer in postnatal piglets. eng.J Physiol Pharmacol, 69(1):127–138, February 2018

2018
[39]

Goodarzi, M

N. Goodarzi, M. Akbari Bazm, S. Poladi, F. Rashidi, B. Mahmoudi, and M. M. A. Abumandour. Histology of the small intestine in the common pheasant (): A scanning electron microscopy, histochemical, immunohisto- chemical, and stereological study. en.Microscopy Research and Techn...

2021
[40]

M. C. Roberts and F. W. G. Hill. The Mucosa of the Small Intestine of the Horse: A Microscopical Study of Specimens Obtained through a Small Intestinal Fistula. en.Equine Veterinary Journal, 6(2):74–80, 1974. 36

1974
[41]

Samanya and K.-e

M. Samanya and K.-e. Yamauchi. Histological alterations of intestinal villi inchickensfeddried Bacillus subtilisvar.natto.Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology,133(1):95–104, September 2002

2002
[42]

X. Qi, Y. Pan, Z. Hu, W. Kang, J. E. Willis, K. Olowe, M. V. Sivak Jr, and A. M. Rollins. Automated quantification of colonic crypt morphology using integrated microscopy and optical coherence tomography.Journal of biomedical optics, 13(5):054055–054055, 2008

2008
[43]

A. E. Farkas, C. Gerner-Smidt, L. Lili, A. Nusrat, and C. T. Capaldo. Cryosectioningmethodformicrodissectionofmurinecolonicmucosa. Jour- nal of visualized experiments: JoVE, (101):53112, 2015

2015
[44]

Influence of distension on absorption and vil- lousstructureinratjejunum

G Holzheimer and D Winne. Influence of distension on absorption and vil- lousstructureinratjejunum. American Journal of Physiology-Gastrointestinal and Liver Physiology, 256(1):G188–G197, 1989

1989
[45]

Puthumana Melepattu and C

M. Puthumana Melepattu and C. de Loubens. Steady streaming flow in- duced by active biological microstructures; application to small intestine villi. Physics of Fluids, 34(6), 2022

2022
[46]

Y. Wang, J. G. Brasseur, G. G. Banco, A. G. Webb, A. C. Ailiani, and T. Neuberger. A multiscale lattice boltzmann model of macro-to micro-scale transport, with applications to gut function.Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineerin...

1921
[47]

Shalimar, P

D. Shalimar, P. Das, V. Sreenivas, S. D. Gupta, S. K. Panda, and G. K. Makharia. Mechanism of villous atrophy in celiac disease: role of apop- tosis and epithelial regeneration. Archives of Pathology and Laboratory Medicine, 137(9):1262–1269, 2013

2013
[48]

C. A. Schneider, W. S. Rasband, and K. W. Eliceiri. Nih image to imagej: 25 years of image analysis.Nature methods, 9(7):671–675, 2012

2012
[49]

Fiori, C

G. Fiori, C. Spada, P. Soru, G. E. Tontini, I. Bravi, B. M. Cesana, P. Cesaro, G. Manes, A. Orsatti, A. Prada, et al. Pharmacokinetics of oral mannitol for bowel preparation for colonoscopy.Clinical and Translational Science, 15(10):2448–2457, 2022. 37

2022

Pith tools

Reviewed August 6, 2026 · model on record in the stance chip above.

[1] [1]

K. K. Reed and R. Wickham. Review of the Gastrointestinal Tract: From Macro to Micro.Seminars in Oncology Nursing. Gastrointestinal Malig- nancies, 25(1):3–14, February 2009

work page 2009

[2] [2]

V. E. Henderson. The mechanism of intestinal peristalsis.American Jour- nal of Physiology-Legacy Content, 86(1):82–98, August 1928. Publisher: American Physiological Society

work page 1928

[3] [3]

R. G. Lentle and C. de Loubens. A review of mixing and propulsion of chyme in the small intestine: fresh insights from new methods. en.J Comp Physiol B, 185(4):369–387, May 2015

work page 2015

[4] [4]

E. H. Eltantaway, G. Khalaf, and G. G. Hamam. Effect of experimentally induced chronic pancreatitis on the structure of hepatocytes and the duo- denal villi in adult male albino rats. en-US.Egyptian Journal of Histology, 38(1):1, March 2015

work page 2015

[5] [5]

W. A. Hilton. The morphology and development of intestinal folds and Villi in vertibrates. en.American Journal of Anatomy, 1(4):459–505, 1902

work page 1902

[6] [6]

K. D. Walton, D. Mishkind, M. R. Riddle, C. J. Tabin, and D. L. Gumucio. Blueprint for an intestinal villus: Species-specific assembly required. en. WIREs Developmental Biology, 7(4):e317, 2018

work page 2018

[7] [7]

M. N i. The contribution of the large intestine to energy supplies in man. The American Journal of Clinical Nutrition, 39(2):338–342, Febru- ary 1984

work page 1984

[8] [8]

S. P. Prieto, C. L. Reed, H. M. James, K. P. Quinn, and T. J. Mul- doon. Differences in colonic crypt morphology of spontaneous and colitis- associated murine models via second harmonic generation imaging to quantify colon cancer development.BMC cancer, 19:1–11, 2019

work page 2019