Conjugated linoleic acids differentially alter polyp number and diameter in the Apc(min/+) mouse model of intestinal cancer.

OBJECTIVE: Dietary conjugated linoleic acids (CLA) have had many health benefits claimed for them, including antineoplastic actions. MATERIALS AND METHODS: The effects of the predominant forms of CLA, namely the c9t11 and t10c12 isomers, or a mixture of these on polyp development, were investigated in the Apc(Min/+) mouse. CLAs have also been linked to altered rates of cell renewal and cell proliferation so this was also studied, as was a further means of increasing tissue mass, namely crypt fission. RESULTS: The stomach and small intestine were significantly heavier in the t10c12, and in the mixture-treated groups (P < 0.001). Crypt fission was increased in the middle small intestine by the t10c12 diet while colonic weight was reduced by c9t11 provision and crypts were 20% shorter. The t10c12 and the mixture significantly reduced polyp number in the proximal small intestine but they increased polyp diameter in the middle and distal small intestine, to an extent that the polyp burden was significantly increased at these sites. All CLAs significantly reduced polyp number in the colon, but the mixture significantly increased polyp diameter in the colon. CONCLUSION: Increased polyp diameter associated with t10c12 diet and especially with the mixture is a cause of concern, as this is the commercially available form. The naturally occurring isomer, c9t11 decreased colonic polyp number and did not increase diameter, suggesting that this natural isomer is the most likely to be protective.

A simple device to rapidly prepare whole mounts of murine intestine.

Many mouse models of neoplasia and pre-neoplasia require the examination of whole mounts of the gastrointestinal tract. A simple device has been produced to facilitate the rapid preparation of mouse intestines for subsequent quantification of tumours and pre-neoplastic lesions such as aberrant crypt foci. The device greatly speeds up the production of whole mounts and also provides far more consistent and better-quality preparations.

Inhibiting vascular endothelial growth factor receptor-2 signaling reduces tumor burden in the ApcMin/+ mouse model of early intestinal cancer.

The Apc(Min/+) mouse model is a clinically relevant model of early intestinal cancer. We used AZD2171, an oral, highly potent and selective vascular endothelial growth factor (VEGF) signaling inhibitor, to investigate the role of VEGF receptor-2 (VEGFR-2) signaling in adenoma development and growth in Apc(Min/+) mice. AZD2171 (5 mg/kg body wt/day) was administered once daily for 28 days to 6-week-old (early-intervention) or 10-week-old (late intervention) mice. In the early-intervention study, AZD2171 reduced the number of macroscopic polyps in the small bowel and colon. Macropolyp diameter was lower in the small bowel, but remained unchanged in the colon. In animals receiving AZD2171, microscopic evaluation of the small intestine showed a significant reduction in the number of larger lesions. In the late-intervention study, AZD2171 treatment reduced macropolyp diameter (but not number) in the small intestine. Microscopic analysis revealed that AZD2171 significantly reduced the number of larger micropolyps in the small bowel, with no large micropolyps present in the colon. AZD2171 treatment had no effect on microvessel density or localization of beta-catenin staining in adenomas or non-tumor intestinal tissue, but significantly reduced the number of cells expressing VEGFR-2 mRNA. In conclusion, the effects of AZD2171 in the small intestine of Apc(Min/+) mice are consistent with an antiangiogenic mechanism of action, limiting growth of adenomas to < or =1 mm. These data also suggest that an early step in adenoma development may depend on VEGFR-2 signaling. Together, these results indicate that VEGFR-2 signaling may play key roles in the development and progression of intestinal adenomas.

Leptin, cell proliferation and crypt fission in the gastrointestinal tract of intravenously fed rats.

Many peptides, hormones and growth factors have been implicated in the control of cell renewal in the gastrointestinal epithelium. Leptin is present in the stomach and salivary glands and leptin receptors are seen throughout the gut. Leptin can stimulate mitogen-activated protein kinase activity in vitro and short-term infusion has been reported to have a proliferative action on the colon in vivo, suggesting a biological link between obesity, physical activity and colon cancer. Food intake is one of the most important determinants of intestinal mucosal cell renewal, thus any direct effects of leptin on the gut may be hidden. This problem has been avoided experimentally by maintaining animals on total parenteral nutrition (TPN). Male Wistar rats were anaesthetized and cannulae were inserted into the jugular vein to deliver the TPN diet to which had been added 0, 0.5, 2.5, or 10 mg/kg of recombinant murine leptin. Orally fed rats were also studied. After 6 days of treatment, all animals were injected with vincristine and killed 2 h later. Tissue weight was recorded and crypt cell proliferation (arrested metaphases) and crypt fission were scored in 'microdissected' crypts. Leptin infusion led to a small decrease in body weight and in the weight of the caecum. Intestinal cell proliferation was significantly reduced by TPN when compared to the orally fed rats, but the addition of leptin had no effect on the small intestine or colon. Crypt fission was also significantly lowered in the TPN group. Fission was slightly but significantly increased in the proximal and mid-colon of the leptin-treated rats, but was decreased in the distal colon. Although leptin did not significantly alter cell proliferation, it had significant effects on the process of crypt fission in the colon, which varied according to the exact locality.

Histogenesis of human colorectal adenomas and hyperplastic polyps: the role of cell proliferation and crypt fission.

BACKGROUND: The histogenesis of human colorectal hyperplastic polyps and colorectal adenomas is poorly understood even now. METHOD: Human colorectal adenomas, hyperplastic polyps, and normal colorectal mucosae (patients with familial adenomatous polyposis and hereditary non-polyposis colorectal carcinoma were excluded) were obtained during colonoscopy and microdissected into individual crypts. Morphology, cell proliferation characteristics, and fission indices of crypts isolated from these lesions were then studied. RESULTS: Crypts isolated from colorectal adenomas and colorectal hyperplastic polyps were significantly larger (p<0.001) than crypts from normal colorectal mucosae. Crypt fission was an uncommon event in normal colonic mucosae but common in crypts isolated from adenomas and hyperplastic polyps (p<0.001). Analysis of the distribution of mitoses suggested an upward expansion of the proliferation compartment in adenomas to the surface of the crypt with no reversal of proliferating cell distribution, as has previously been described. CONCLUSIONS: Sporadic human colorectal adenomas and hyperplastic polyps grow by the process of crypt fission. Expansion of the proliferative compartment was demonstrated in crypts from adenomas, consistent with deregulation of cell cycle control.

Glicentin, an active enteroglucagon, has a significant trophic role on the small intestine but not on the colon in the rat.

BACKGROUND: Many experiments have indicated that the gut glucagons (enteroglucagons) are associated with cell proliferation in the small intestine. However, recent studies have failed to show trophic effects of glicentin (enteroglucagon) on the intestine. AIMS: To examine the effects of glicentin on intestinal proliferation in vivo in the rat. METHODS: Rats were established on total parenteral nutrition for 6 days. Four experimental groups were given daily doses of 1, 4, 20 and 80 microg/rat of glicentin via the jugular vein. Rats fed by total parenteral nutrition and rats fed chow ad libitum were used as controls. Tissues taken from the duodenum, jejunum, ileum and colon were fixed in Carnoy's fluid and microdissected to determine the metaphase arrest scores and crypt fission ratios. RESULTS: The mean metaphase arrest scores per crypt of the small intestine were significantly increased in the rats given 4, 20 and 80 microg of glicentin. These responses were dose-dependent, and were most prominent in the ileum. Crypt fission of the ileum was significantly decreased in the 20 and 80 microg glicentin groups. Glicentin had no effects on proliferation or fission in the colon. CONCLUSIONS: Glicentin is trophic to the rat small intestine, but not the colon.

Proglucagon-derived peptides in intestinal epithelial proliferation: glucagon-like peptide-2 is a major mediator of intestinal epithelial proliferation in rats.

Proglucagon-derived peptides have been implicated in the control of intestinal mucosal cell division. To investigate the actions of these peptides on intestinal cell proliferation, different doses of enteroglucagon, oxyntomodulin, glucagon-like peptide-1 (GLP-1) and glucagon-like peptide-2 (GLP-2) were tested in male Wistar rats maintained on total parenteral nutrition. Crypt cell proliferation was assessed by the analysis of arrested metaphases in microdissected crypts. Enteroglucagon and oxyntomodulin had no effect on intestinal weight or cell proliferation. GLP-1 had a slight effect on stomach and small intestinal weights and on epithelial cell proliferation in the small and large intestines. GLP-2 infusion dose-dependently increased the weights of the stomach, small intestine, colon, and cecum and increased crypt cell proliferation in the small and large intestines of parenterally fed rats. In orally fed animals, GLP-2 increased intestinal weight but had little effect on proliferation. Therefore, of the proglucagon-derived peptides, GLP-2 appears to be a major mediator of intestinal epithelial proliferation.

Gastrointestinal cell proliferation and crypt fission are separate but complementary means of increasing tissue mass following infusion of epidermal growth factor in rats.

BACKGROUND AND AIMS: Epidermal growth factor (EGF) is a potent mitogen for the gastrointestinal tract and also influences the number of new crypts formed by crypt fission. The time course of these events and possible linkage between these two complementary mechanisms is however poorly understood. We therefore examined the temporal relationship of proliferation and fission in rats treated with EGF. METHODS: Osmotic minipumps were implanted subcutaneously into male Wistar rats to infuse EGF continuously (60 microg/rat/day) for periods of 1-14 days. Proliferation and crypt branching were quantified following vincristine induced metaphase arrest and morphometric assessment of microdissected tissue. RESULTS: In the small intestine, EGF significantly increased epithelial cell proliferation and crypt and villus area after 24 hours of EGF, although maximal effects were only reached following six days of infusion. EGF also resulted in an approximate 30% reduction in crypt fission in the small bowel. In the colon, EGF caused a twofold increase in epithelial cell proliferation one day after infusion, from 15.3 (2.3) to 29.6 (3.5) metaphases per crypt (p<0.01). Maximal effects were seen in rats receiving EGF for seven days. For all time points, colonic crypt size increased in response to EGF. The amount of branching increased following one day of infusion with EGF (from 15.3 (1.9) to 32.4 (5.5)%; p<0.001) but was significantly lower (approximately 25% of control values) following longer periods of infusion. Crypt fission did not correlate with crypt area. CONCLUSION: EGF has profound effects on cell proliferation and also altered crypt fission, with its actions on crypt fission most pronounced in the colon where it first increased and then decreased fission. EGF can thus be a potent stimulus for crypt fission during short term infusion and may reduce the number of branched crypts present in a resting or quiescent stage. Growth factors can alter cell mass by two separate but linked mechanisms, namely altered cell production and crypt fission.

Starvation, leptin and epithelial cell proliferation in the gastrointestinal tract of the mouse.

BACKGROUND/AIMS: Leptin, the ob/ob gene product, is a recently discovered peptide hormone, secreted by adipocytes, which can act as a satiety factor to regulate food intake. Its levels thus will be related to the presence of food in the lumen of the gut, and food intake is one of the most potent stimuli for intestinal epithelial cell proliferation. Leptin has a variety of other actions and the aim of this study was to see if one of these was to stimulate mucosal growth. METHODS: Three groups of mice were fed ad libitum, starved for 48 h or starved for 48 h and given twice-daily intraperitoneal injections of recombinant leptin (1 microg/g). RESULTS: Starvation led to a 20% decrease in body weight and a similar decrease in the weights of the intestines. Starvation also markedly inhibited intestinal epithelial cell proliferation. Leptin had little effect on the small intestine and did not stimulate proliferation. However, in the hind gut it was associated with small but significant decreases in caecal weight, distal colon mitotic counts (p = 0.036) and in colonic crypt area (approximately 20%, p<0.001). CONCLUSION: Leptin did not stimulate intestinal cell proliferation, however it did have a paradoxical inhibitory action on the caecum and colon.

Does the response of the intestinal epithelium to keratinocyte growth factor vary according to the method of administration?

BACKGROUND: Keratinocyte growth factor (KGF) is a potent mitogen and may be of value for the treatment of conditions such as short bowel syndrome and chemotherapy-induced mucositis. However the most efficacious route and method of administration is unclear. METHODS: Rats maintained by total parenteral nutrition (TPN) were given KGF (1 mg/kg/rat/day, i.v.) infused continuously or as a once-daily injection. The same dose was also given s.c. to chow-fed rats. Changes in gut growth were assessed by measurement of wet weight, proliferation (vincristine induced metaphase arrest) and crypt branching index. Changes in gut hormone profile were also determined to examine if any trophic effects were mediated via this mechanism. RESULTS: KGF caused a 70-100% increase in wet weight of the stomach, small and large intestine of TPN-fed rats (P < 0.01) with no significant differences seen between the two methods of administration. The increase in metaphase counts was greatest in the stomach (about seven-fold P < 0.01), but was less pronounced in the distal small intestine and colon (about 50% increase). The trophic effect of KGF was much less prominent in orally-fed rats. Crypt branching index was significantly reduced by KGF in the proximal small intestine of TPN, but not orally-fed rats. Plasma gastrin, PYY, total glucagon, enteroglucagon and GLP-1 all increased by two-three-fold (all P < 0.01) in response to KGF whereas insulin levels fell by about 25% in the TPN group. CONCLUSIONS: The mitogenic action of KGF occurred predominantly in the stomach and proximal small intestine. Its efficacy was less pronounced in orally-fed animals, suggesting KGF may be of greatest benefit in conditions associated with lowered intestinal proliferation. Clinical trials of KGF can probably use single daily i.v. injections without reduction in efficacy.

The effects of glutamine on intestinal epithelial cell proliferation in parenterally fed rats.

BACKGROUND: Several papers have indicated that glutamine is a preferred fuel for the enterocyte and that it can increase intestinal epithelial cell proliferation. AIMS: To investigate the effects of glutamine on intestinal epithelial cell proliferation in the parenterally fed rat. METHODS: Five groups of six rats were fed parenterally; a group of orally fed rats was also studied. Crypt cell proliferation was studied after six days using native mitoses in microdissected crypts and bromodeoxyuridine labelling. RESULTS: No effect of treatment was seen on intestinal weight; however, the weights of the small intestine, caecum, and colon were all significantly heavier in the orally fed group than in the total parenteral nutrition groups (p<0.001). There was no effect of any of the glutamine treatments on mitotic activity in the small intestine. In the colon there was a small increase in native mitoses with glutamine (p=0.03). There was also an indication of increased proliferative activity in the first fifth of the small intestine and colon with glutamine. Little effect of glutamine on bromodeoxyuridine labelling in either site was observed, but there was a small but significant reduction in growth fraction of the colon of the glutamine treated group. The labelling distribution curve from sections and the mitotic distribution curve obtained from crypt squashes showed a good correlation. CONCLUSION: Glutamine has a small, but significant effect on mitotic activity but only in the colon. Modest effects on the distribution of labelled cells were also seen.

APC in the regulation of intestinal crypt fission.

The functional effects of APC (adenomatous polyposis coli gene) germ-line mutations on crypt fission and cell proliferation were investigated in the normal intestine of human familial adenomatous polyposis (FAP) and multiple intestinal neoplasia (MIN) mice. Compared with controls, there was a 19-fold increase in the proportion of crypts in fission in FAP colon [95 per cent confidence interval (CI): 11-32, P < 0.0001], and a 75 and 61 per cent increase in MIN colon (95 per cent CI: 1.08-2.82, P < 0.02) and small bowel, respectively (95 per cent CI: 1.31-1.99, P < 0.001). In marked contrast, no significant differences in intra-cryptal epithelial cell proliferation or mitotic distribution were seen. Furthermore, 10.9 per cent of crypts in FAP were in asymmetrical fission as opposed to only 1 per cent in controls (P = 0.001). The largest relative increases in MIN crypt fission were in the colon (proximal and distal colon:190 per cent, P = 0.02 and 83 per cent, P = 0.01), suggesting that Apc mutations exert their maximal influence site-specifically. However, sites with the highest relative increases were also those with the largest eventual tumour sizes, but not the highest polyp counts. Three-dimensional serial section reconstruction analysis corroborated that FAP adenomas enlarge by crypt fission, which was frequently both asymmetrical and atypical. It is proposed that the absence of an increase in intestinal cell division infers that APC regulates intestinal crypt differentiation, specifically through the crypt cycle. This role appears analogous to the control of axis re-duplication in embryonic development, when downstream targets of APC are over-expressed. It is concluded that in vivo, the major defect in pre-neoplastic intestine harbouring APC mutations is elevated rates of crypt fission, and that this is also the mode by which micro-adenomas enlarge.

Dietary fibre and intestinal microflora: effects on intestinal morphometry and crypt branching.

BACKGROUND: Fermentable dietary fibre has many effects on the gastrointestinal tract. One is to alter epithelial crypt cell proliferation, especially in the colon. A discrepancy between epithelial cell production rates and intestinal weights has been noted previously: crypt cell production rates only increase if bacterial fermentation occurs, but intestinal wet weight can increase in the same animals without bacterial fermentation of fibre. AIMS: To quantify intestinal cell populations in order to resolve the above paradox. METHODS: Conventional and germ-free rats were fed fibre-free or fibre supplemented diets and their intestines were quantified by morphometry. RESULTS: There was evidence of fibre associated muscle hypertrophy in the colon, but the main effect of fibre was an increase in the number of crypts per circumference and also the number of branched crypts in the proximal colon in both groups. There was also a large increase in the number of branched crypts in the mid colon of the germ-free rats (both fibre-free and fibre supplemented). Fibre had a direct (bacteria independent) effect on goblet cells in the small intestine and a direct effect on the goblet cells in the colon, which was attenuated by the presence of bacteria. There was a notable decline in the number of enteroendocrine cells in the small intestine of the germ-free animals. CONCLUSIONS: Fibre has several direct and indirect effects on the gut. In the proximal colon it can directly increase the number of crypts present. This provides a means for increasing intestinal mass in addition to intestinal crypt cell production.

Effects of keratinocyte growth factor (KGF) on gut growth and repair.

Keratinocyte growth factor (KGF) is a mitogen found throughout the gastrointestinal tract, but its role in gastrointestinal pathophysiology is unclear. The effect of recombinant KGF on gut growth and repair has been examined using a variety of in vivo models. Rats receiving total parenteral nutrition had co-infusions of KGF or control for 6 days. Changes in gut growth (wet weight and vincristine-induced metaphase arrest) were then assessed. The effects of KGF on gastric repair and acid secretion in rats were determined using an indomethacin (20 mg/kg)/restraint model and animals fitted with chronic gastric fistulae. KGF at 0.1, 1, and 3 mg/kg increased gut growth as assessed by wet weight throughout the gastrointestinal tract and increased vincristine-induced accumulation of metaphases in the stomach and small intestine but not in the colon. Plasma gastrin, peptide YY, enteroglucagon, and glucagon-like peptide-1 were all increased, whereas insulin was lowered by KGF (all P < 0.01). KGF was ineffective in reducing indomethacin-induced gastric damage but caused a reduction in basal acid secretion of about 35 and 50 per cent when administered at 0.2 or 5 mg/kg (P < 0.05). These studies support the idea that KGF is involved in the control of proliferation of the gastrointestinal tract. They do not provide evidence, however, for a role in the early reparative process invoked during short-term models of gastrointestinal injury.

Effect of retinoids on follicular cells.

It has been demonstrated that topical application of all-trans retinoic acid and other retinoids can alter the hair-growth cycle in the C3H mouse model. The anagen phase is prolonged and the telogen phase is shortened. This effect is similar to the effect of minoxidil on the hair-cycle dynamics in this animal model. The levels of cellular retinoic acid binding protein measured by radioreceptor assay in whole skin of C3H mice were higher during anagen and lower during telogen. Topical application of certain retinoids caused elevated levels of cellular retinoic acid-binding protein (cRABP) in the whole skin homogenates during both phases of the cycle. Of the retinoids tested, those most effective in altering the levels of cRABP in the skin of the mice were also capable of significantly altering the hair-cycle dynamics. There appeared to be a relationship between the ability of retinoid to increase cRABP, increase 3H-thymidine incorporation, and alter the dynamics of the hair cycle. Only cRABP-II is detectable in human cultured dermal fibroblasts and dermal papilla cells. Dermal fibroblasts showed higher amounts of cRABP-II as compared to dermal papilla cells. The difference in cRABP-II expression might explain a distinct response to RA by these two cell populations. Whether the difference in expression of cRABP-II might be of physiologic importance remains to be determined. Treatment of human dermal papilla cells in culture with retinoic acid does not appear to affect proliferation, at least at the doses tested.

Morphological analysis of in vitro human hair growth.

The histological and ultrastructural aspect of normal human hair follicles maintained ex vivo for 12 days was evaluated. Anagen hair follicles, dissected free of contaminating connective tissue, were maintained for up to 12 days in a serum-free medium. Macroscopic observations revealed continued viability for 12 days, at which time some follicles involuted in a manner morphologically similar to catagen. Increased growth of maintained follicles was measured from the abrupt ending of the connective tissue sheath (CTS), as no increase in this component was observed from initiation of culture. In general follicles maintained up to 8 days exhibited little divergence from normal in vivo morphologies including the persistence of functional hair bulb melanocytes--a marker of anagen. After this time melanin granules were present in dermal papilla cells, as occurs during impending involution in vivo. Heterotypic cell contact occurred in the middle to upper follicle between outer root sheath (ORS) keratinocytes and disorganized CTS. Herniation of some ORS cells away from the follicle and the occurrence of loose desmosomal junctions between ORS keratinocytes reflected loss of normal follicular cell interactions in upper follicles maintained after 8 days. Continued follicle growth correlated with the presence of mitotic matrix keratinocytes even at 12 days. After 12 days in culture most follicles involuted displaying apoptotic-like keratinocytes and hair bulb melanocytes and the presence of highly keratinized hair 'club' structures. While most follicles exhibited this orderly sequence of events, a few follicles involuted after 24 h with synchronous degeneration of all cells. Two follicles exhibited upregulated cortical cell differentiation at the level of the dermal papilla (DP).(ABSTRACT TRUNCATED AT 250 WORDS)

Prostaglandins and the colonic epithelium. Effects of misoprostol on crypt size, cell production, and cell migration in the dog.

Colonic epithelial cell division, cell migration, and cell transit were investigated in dogs given 300 micrograms.kg-1.day-1 of the prostaglandin E1 analogue, misoprostol, for 11 weeks. The animals were then injected with [3H]thymidine and killed at timed intervals. The distribution of labeled and mitotic cells within the crypts was determined by scoring autoradiographs. There were no significant differences in mitotic index or labeling index between the two groups. The data were pooled and converted to give crypt cell production rates of 51.1 +/- 11.1 (control) and 58.24 +/- 8.6 cells per crypt per hour (test). However, the crypt length and cell population were slightly, but significantly, greater in the misoprostol-treated group (P less than 0.01). The movement of the wave of labeled cells with time after injection was used to calculate the median cell migration rates, which were 23.50 +/- 3.03 cell positions per day (control) and 18.30 +/- 2.56 (test). Thus, misoprostol had no significant effect on either the cell migration rate or the transit rates.

Morphometry and cell proliferation in endoscopic biopsies: evaluation of a technique.

A simple method for the quantification of intestinal epithelial cell proliferation in humans was evaluated. Endoscopic biopsy specimens were stained and microdissected, and the number of mitoses per gland or crypt was determined, as was the area of these units. The technique could readily be applied to tissue from the stomach, small intestine colon, and rectum. The number of mitoses and the size of the proliferative compartments increased caudally from the stomach to the cecum in humans. There was a good correlation between area and mitoses per gland or per crypt (r = 0.89; P less than 0.001), confirming the general equivalence between proliferative rate and compartment size. The method was validated by comparing microdissection-derived data with data previously obtained as part of an autoradiography-based study in the dog. This showed that similar differences in proliferation and crypt cell mass could be obtained but in less than one sixth of the time taken to score autoradiographs. It is concluded that this method for the estimation of gastrointestinal epithelial proliferation correlates well with other well-established techniques, confers speed as well as accuracy, has an all encompassing denominator, and can thus avoid many of the problems associated with the quantification of tissue sections.

Intranuclear rodlets and associated true intranuclear bodies in normal cultured human dermal papilla cells.

The dermal papilla is believed to exert controlling influences on hair growth. This report documents, for the first time, the occurrence of intranuclear rodlets in normal cultured human dermal papilla cells. Intranuclear rodlets have been observed predominantly in normal neurons, neural neoplasms, and paraneuromas. Whereas intranuclear rodlets and complex intranuclear bodies have not been identified in dermal papilla cells in vivo, they were observed, by light microscopy and transmission electron microscopy, in primary and subsequent passaged cultures in all 10 individuals examined. Intranuclear rodlets and bodies were not found, however, in parallel cultures of scalp dermal fibroblasts from the same individuals. Rodlet ultrastructure in cultured dermal papilla cells exhibited many features in common with previous reports on rodlets in neuronal and paraneuronal cells. Features that differentiated the rodlets in this study, however, included: doublet/triplet rodlets in the same nucleus; rodlets or crystalline filament bundles within complex nuclear inclusions; close relationship with the nuclear membrane, and their frequent intimate association with intranuclear bodies; and nucleoli and fine chromatin-distinct fibrillar material. Although the function of these true intranuclear inclusions in dermal papilla cells is unknown, it is noteworthy that they were present in these highly metabolically active fibroblasts while absent in comparatively less active dermal fibroblasts, and may indeed be a marker for this fibroblast cell type.