Dorsal Subcutaneous Adipose Research Articles

Adipose tissue proteomes of intrauterine growth-restricted piglets artificially reared on a high-protein neonatal formula

The eventuality that adipose tissues adapt to neonatal nutrition in a way that may program later adiposity or obesity in adulthood is receiving increasing attention in neonatology. This study assessed the immediate effects of a high-protein neonatal formula on proteome profiles of adipose tissues in newborn piglets with intrauterine growth restriction. Piglets (10th percentile) were fed milk replacers formulated to provide an adequate (AP) or a high (HP) protein supply from day 2 to the day prior weaning (day 28, n=5 per group). Adipocytes with small diameters were present in greater proportions in subcutaneous and perirenal adipose tissues from HP piglets compared with AP ones at this age. Two-dimensional gel electrophoresis analysis of adipose tissue depots revealed a total of 32 protein spots being up- or down-regulated (P<.10) for HP piglets compared with AP piglets; 18 of them were unambiguously identified by mass spectrometry. These proteins were notably related to signal transduction (annexin 2), redox status (peroxiredoxin 6, glutathione S-transferase omega 1, cyclophilin-A), carbohydrate metabolism (ribose-5-phosphate dehydrogenase, lactate dehydrogenase), amino acid metabolism (glutamate dehydrogenase 1) and cell cytoskeleton dynamics (dynactin and cofilin-1). Proteomic changes occurred mainly in dorsal subcutaneous adipose tissue, with the notable exception of annexin 1 involved in lipid metabolic process having a lower abundance in HP piglets for perirenal adipose tissue only. Together, modulation in those proteins could represent a novel starting point for elucidating catch-up fat growth observed in later life in growing animals having been fed HP formula.

Expression of TGH and its role in porcine primary adipocyte lipolysis

Triacylglycerol hydrolase (TGH) plays an important role in intracellular lipid metabolism. However, most previous studies on TGH were focused on rodent animals. Pig is considered as one of the best models for studying obesity, diabetes, and other lipid metabolism related diseases. So far, we do not know whether TGH is to play a role in lipolysis in porcine primary adipocyte through stimulation by hormones as Hormone-sensitive lipase (HSL). The objective of this study is to explore the mechanisms that regulate TGH expression in porcine adipocyte and its role in fasting-induced and Isoproterenol-stimulated lipolysis in porcine primary adipocytes. Stromal-vascular cells containing preadipocytes were isolated from cervical and dorsal subcutaneous adipose tissues of approximately 3-day-old Chinese male piglets. After confluence, the differentiation was induced by Insulin, hydrocortisone, and transferrin. The primary adipocytes were cultured in various concentration (0.1 to 200 micromol/l) Isoproterenol for 0-12 h or serum-free medium after differentiation. The glycerol release and triacylglycerol (TG) contents were detected when the cells were collected. Then, expression of TGH and HSL mRNA and their protein were determined by RT-PCR, Western Blot, and lipolytic analysis. Both TGH mRNA and protein were not detected on day 0, but as differentiation was induced, their expression displayed a great increase. The expression of TGH mRNA showed the highest level on day 4, but its protein reached the highest level on day 6 and began to fall down from day 8. The expression of TGH mRNA and proteins was increased in serum-free media, and mRNA expression was decreased while changed into complete media again. The glycerol release increased significantly when the cells were cultured with serum-free media. The lower concentration of Isoproterenol (0.1 and 1 micromol/l) did not affect the expression of TGH and HSL, but higher concentration (10, 100, and 200 micromol/l) could greatly up-regulate HSL expression but did not affect TGH level. Also, the higher concentration of Isoproterenol could increase the glycerol release and decrease TG content in dose-dependent manner. These results suggested that TGH expression is differentiation-dependent in porcine primary adipocytes and TGH plays a role in fasting-induced lipolysis not hormone-stimulated lipolysis.

Effect of dietary fat or starch supply during gestation and/or lactation on the performance of sows, piglets’ survival and on the performance of progeny after weaning

Two trials were carried out to compare the effects of fat or starch inclusion in sow’s diet on sow and litter performance. In each trial, sows were assigned to one of two treatments. In trial 1, the sows were fed diets containing either soybean oil (5%, treatment GL5) or cornstarch (11.3%, GL0) from day 35 of gestation to weaning. Daily net energy and nutrient allowance were equalised during gestation. In trial 2, the same treatments were applied only after farrowing (treatments L5 and L0, respectively). Within each trial, a batch of piglets was studied until slaughter. In trial 1, adipose cell development and total lipid content were determined on some pigs at weaning (n = 6/treatment) and at slaughter in dorsal subcutaneous adipose tissue (n = 13/group at least) and in muscle (n = 46/group at least). Piglets’ birth weight was not affected by treatment in trial 1. Survival rates at birth and after 24 h of life were higher in treatment GL5 (4.0% v. 7.5% stillborn piglets in GL0 treatment, P < 0.05; 8.7% v. 12.6% of piglets alive at 24 h of age died in treatment GL0, P = 0.06). Subsequently, overall survival rate until weaning was higher in treatment GL5 (81.4% v. 75.7% of total born piglets, P = 0.03), but litter size at weaning was not significantly affected (11.3). Litter growth rate before weaning was increased when a fat-enriched diet was provided during gestation and lactation (+140 g/day per litter; P < 0.01) and to a lower extent when provided only after farrowing (+90 g/day; P < 0.05). Energy supply through fat did not decrease the mobilisation of the sow’s body reserve and backfat thickness loss was even higher with treatment GL5 (P < 0.05). After weaning, pigs’ average daily gain, feed : gain ratio and carcass lean content were not affected by the energy source supplied before and/or after farrowing. At weaning, the number of adipose cells in the dorsal subcutaneous adipose tissue and in the Longissimus dorsi muscle was higher in the GL5 pigs. Muscle lipid content at weaning did not differ between treatments, but it was higher at slaughter, around 110 kg, in the GL5 pigs (3.46% v. 2.58%, P < 0.001).

Effects of 1,25-dihydroxyvitamin D 3 on proliferation and differentiation of porcine preadipocyte in vitro

1,25-Dihydroxyvitamin D 3, the physiologically active form of vitamin D 3, exerts its functions through a receptor-mediated mechanism and plays an important role in the cell differentiation. This study investigated the effects of 1,25-dihydroxyvitamin D 3 on the proliferation and differentiation of porcine preadipocyte. Stromal-vascular cells containing preadipocytes were prepared from dorsal subcutaneous adipose tissue of approximately 3-day-old Chinese male crossbred pigs. After confluence, the differentiation was induced by transferrin, dexamethasone and insulin for 2 days, and then subsequently cultured for 6 days. The cells were treated with 1,25-dihydroxyvitamin D 3 during the induction of differentiation (the early phase of differentiation) or throughout the differentiation period. The terminal differentiation markers, such as glycerol-3-phosphate dehydrogenase activity and lipid accumulation were measured during the process of cultures. The treatment with 1,25-dihydroxyvitamin D 3 severely affected the induction of all differentiation markers throughout the differentiation period. 1,25-Dihydroxyvitamin D 3 suppressed the expression of peroxisome proliferator-activated receptor gamma mRNA and interfered with the induction of retinoid X receptor alpha mRNA. The mRNAs of the adipogenesis-related genes, lipoprotein lipase, stearoyl-CoA desaturase, phosphoenolpyruvate carboxykinase, glycerol-3-phosphate dehydrogenase and glucose transporter 4 were reduced when 1,25-dihydroxyvitamin D 3 was added into differentiation medium. Also, 1,25-dihydroxyvitamin D 3 inhibited preadipocyte differentiation in dose-dependent manner. These results suggested that 1,25-dihydroxyvitamin D 3 inhibited porcine preadiopocyte differentiation through suppressing PPARγ and RXRα mRNA expressions and then down regulating the expression of adipogenesis-related genes.

Effect of level of linseed on fatty acid composition of muscles and adipose tissues of lambs with emphasis on trans fatty acids

The effects of linseed content in concentrates on the fatty acid (FA) composition of adipose tissues and muscles of lambs were studied in a 2 × 4 design: males (M) vs. females (F) and linseed content (0%, L0, 3%, L3, 6%, L6, 9%, L9). FA proportions were determined both on a DB-wax and on a CP-Sil column in perirenal (PR), dorsal subcutaneous (SC) adipose tissue and in longissusmus dorsi muscle (IM). No effects of linseed contents in the diet on growth performances either in male or female lambs were observed. Linseed supplementation tended to decrease the fatness score. The proportion of linolenic acid increased linearly with the linseed content in the diet, from: 0.6, 0.5, and 0.5% for L0 to 1.9, 1.6, and 1.3% for L9, in PR, SC and IM, respectively. The increase in n − 3 PUFA and in total PUFA was similar to that of linolenic acid. The n − 6: n − 3 ratio decreased from 5.7, 5.3 and 5.8 for L0 to 1.8, 1.7 and 2.7 for L9, in PR, SC and IM, respectively. There was no change in the proportion of docosahexaenoic acid with linseed supplementation. The proportions of C18:1 trans-10 and C18:1 trans-11 did not vary in PR, SC and IM with linseed supplementation. The total proportion of trans-octadecenoic acid was high in each tissue type and group of lambs. C18:1 trans-10 represented about half of the total trans-octadecenoic isomers. With an increase in linolenic acid, most cis- and trans-octadecenoic isomers also increased, but trans-10 and trans-11 isomers did not and cis-9 and cis-11 isomers decreased. With linseed supplementation there was a decrease in the Δ9 desaturase indices in SC.

Different Transcription Profiles of &amp;lt;italic&amp;gt;SOCS-3&amp;lt;/italic&amp;gt;, &amp;lt;italic&amp;gt;ob&amp;lt;/italic&amp;gt; and &amp;lt;italic&amp;gt;IGF-I&amp;lt;/italic&amp;gt; Genes and their Possible Correlations in Obese and Lean Pigs

Pig breeds have significant differences in fat deposition and muscle development ability. However, the molecular mechanism behind these differences is still unknown. In this study, the expression patterns of three candidate genes, suppressor of cytokine signaling 3 (SOCS-3), obesity (ob) and insulin-like growth factor I (IGF-I), which are involved in adipose metabolism or muscle development, were analyzed. Total RNA was extracted from dorsal subcutaneous adipose tissue and longissimus of 8-month-old Bamei and Largewhite pigs. Semiquantitative reverse transcription-polymerase chain reaction was used to determine the expression levels of the SOCS-3 and ob genes in adipose tissue, and SOCS-3 and IGF-I genes in muscle tissue. The results showed that in adipose tissue the expression level of SOCS-3 was significantly higher in Bamei (obese) pigs than that in Largewhite (lean) pigs (P<0.01). However, in muscle tissue it was significantly lower in Bamei than that in Largewhite pigs (P<0.01). Furthermore, the expression of SOCS-3 was positively correlated to that of ob in adipose tissue and that of IGF-I in muscle tissue. These findings suggest that the difference in SOCS-3 gene expression levels in adipose and muscle tissues, the relationship between SOCS-3 and ob in adipose tissue, and that between SOCS-3 and IGF-I in muscle tissue, might contribute to the different fat deposition and muscle development ability between obese and lean pigs.

Adiponectin regulates the expression of genes associated with fatty acid synthesis and oxidation in primary pig adipocytes

Adiponectin has been implicated in the regulation of glucose uptake and fatty acid synthesis in adipocytes, and in the long-term suppression of weight gain when over-expressed in rodents by adenovirus associated virus vectors. The aim of this research was to determine whether adiponectin regulates the expression of genes associated with fatty acid oxidation in porcine adipocytes. Primary adipocytes were isolated from the dorsal subcutaneous adipose tissue of pigs (male castrates, n=5). Cells were incubated in DMEM with 3% BSA, in the presence and absence of recombinant porcine adiponectin (30 ìg/mL), and were harvested at 0, 30, 60, 120, 240 and 360 minutes. Total RNA was extracted for cDNA synthesis, and the abundance of selected transcripts determined by real time PCR analysis. Adiponectin transiently increased (2–6.5 fold, P < .05) the expression of acetyl Co-A carboxylase (ACC), AMP activated kinase (AMPK), acyl Co-A oxidase (ACO) and peroxisome proliferator activated receptor-α (PPARα). After the initial increase in mRNA abundance, there was either a return to initial levels of expression (PPARα), a significant reduction (AMPK), or a cyclic pattern of expression (ACC, ACO). The abundance of the uncoupling protein-3 (UCP3) transcript was not influenced by adiponectin until the final measure at 360 minutes, at which time it was increased 3.8-fold (P < .05). Collectively, these data indicate that adiponectin acts through autocrine/paracrine signaling pathways to coordinately regulate lipid metabolism in the adipocyte, and may thus be a determinant of adipocyte size and overall lipid accumulation. Funding is USDA

Hormonal regulation of leptin and leptin receptor expression in porcine subcutaneous adipose tissue1,2

The current study was performed to examine the response of the leptin gene to hormonal stimuli in porcine adipose tissue from finishing pigs. Yorkshire gilts (approximately 150 kg BW) were used in this study. Tissue from four to six pigs was used per experiment. Dorsal subcutaneous adipose tissue samples were acquired, and adipose tissue explants (approximately 100 mg) were prepared using sterile technique. Tissue slices were transferred to 12-well tissue culture plates containing 1 mL of Media 199 with 25 mM HEPES, 0.5% BSA, pH 7.4, and various hormone supplements. Triplicate tissue slices were incubated with either basal medium or hormone-supplemented media in a tissue culture incubator at 37 degrees C with 95% air:5% CO2. Hormones included insulin (100 nM), dexamethasone (1 microM), porcine GH, 100 ng/mL), triiodothyronine (T3, 10 nM), porcine leptin (100 ng/mL), or IGF-I (250 ng/mL). Following incubation for 24 h, tissue samples from the incubations were blotted and transferred to microfuge tubes, frozen in liquid N, and stored at -80 degrees C before analysis for gene mRNA abundance by reverse-transcription PCR and subsequent quantification of transcripts by capillary electrophoresis with laser-induced fluorescence detection. Media from the incubations were collected in microfuge vials and stored at -20 degrees C before analysis for leptin content by RIA. Insulin was required to maintain tissue and mRNA integrity; therefore, insulin was included in all incubations. The combination of insulin and dexamethasone stimulated leptin secretion into the medium by 60% (P < 0.05; n = 6). Porcine GH inhibited insulin induced leptin secretion by 25% (P < 0.05; n = 6). Dexamethasone in combination with insulin produced a 22% increase in leptin mRNA abundance relative to insulin (P < 0.05; n = 4), and T3 stimulated a 28% increase in insulin-induced leptin mRNA abundance (P < 0.05; n = 4). Leptin receptor mRNA abundance was decreased by 25% with the combination of insulin and dexamethasone, relative to insulin-treated adipose tissue slices (P < 0.05; n = 4). Porcine GH decreased leptin receptor mRNA abundance by 17% (P < 0.05; n = 6). These data suggest that leptin secretion is a regulated phenomenon and that posttranslational processing may be significant. Alternatively, transport and exocytosis of leptin containing vesicles in the pig adipocyte may be quite complicated, which could account for the differences in observed mRNA abundance and protein secretion.

Developmental patterns of serum leptin levels, leptin gene expression in adipose tissue and Ob-Rb gene expression in hypothalamus of Erhualian and Large White pigs.

The present study was aimed to investigate the developmental patterns of leptin mRNA expression in dorsal subcutaneous adipose tissue and Ob-Rb mRNA expression in hypothalamus in pigs of different breeds and sexes. Erhualian gilts and boars and Large White boars were sampled at birth, 3, 20, 30, 45, 90, 120 and 180 days of age, respectively. Serum concentration of leptin was measured with RIA and single tube semi-quantitative RT-PCR was applied to determine the relative abundances of mRNA expression using 18S rRNA as an internal standard. The results showed that leptin mRNA expression in adipose tissue increased with age and displayed both sex and breed differences. In Erhualian pigs, females expressed higher leptin mRNA compared with males, and Erhualian boars showed higher abundance of leptin mRNA than Large White boars (P < 0.01). Serum leptin levels were in good agreement with adipose leptin mRNA, displaying similar sex and line differences. In contrast, expression of Ob-Rb mRNA in hypothalamus exhibited a distinctive pattern, decreased gradually after birth, and then increased till weaning. After weaning, Ob-Rb gene expression decreased gradually with age but rose gradually again from 120 to 180 days of age in Erhualian pigs. The expression of Ob-Rb mRNA was higher in Large White pigs than that in Erhualian pigs (P< 0.01). The results suggest that the serum leptin level and leptin gene expression in adipose tissue highly correlate with adiposity.

Dehydroepiandrosterone attenuates preadipocyte growth in primary cultures of stromal-vascular cells.

The purpose of this study was to determine whether the antiobesity actions of dehydroepiandrosterone (DHEA) are due to an influence on preadipocyte proliferation and/or differentiation in primary cultures of pig and rat stromal-vascular (SV) cells. Pig SV cells were isolated from dorsal subcutaneous adipose tissue of 7-day-old pigs. For the proliferation assays, pig SV cells were grown for 4 days in plating medium containing DHEA at 0, 15, 50, or 150 microM. For the differentiation assays, pig SV cells were grown in plating medium for 3 days and then switched to a serum-free medium containing DHEA at 0, 15, 50, or 150 microM for the next 6 days. Rat SV cells were isolated from inguinal fat pads of 5-wk-old male rats. Rat SV cells were exposed to DHEA at 0, 5, 25, or 75 microM during proliferation. For the differentiation assays, rat SV cells were grown for 8 days in a serum-free medium containing DHEA at 0, 5, 25, or 75 microM. Preadipocyte differentiation [lipid staining, glycerol-3-phosphate dehydrogenase (GPDH) activity] and proliferation (preadipocyte-specific antigen staining) decreased with increasing levels of DHEA in cultures of pig SV cells. In cultures of rat SV cells, preadipocyte differentiation (lipid staining, GPDH activity) and proliferation ([3H]thymidine incorporation) were decreased in the 25 and 75 microM DHEA groups compared with the control and 5 microM DHEA groups. The level of expression of CCAAT enhancer binding protein-alpha, a master regulator of adipogenesis, in cultures of pig SV cells treated with 150 microM DHEA was 38% of control cultures. These data support the hypothesis that DHEA directly attenuates adipogenesis via attenuation of preadipocyte proliferation and differentiation.

Influence of nutritional weaning on porcine adipocyte beta-adrenergic and adenosine A1 receptors.

Obese and crossbred (X-Bred) pigs were removed from sows at 14 d of age and given ad libitum access to a high-fat, milk-based diet. A subset of pigs fed this diet were killed at 28 and 49 d of age. At 28 d, another subset of pigs was given ad libitum access to a low-fat, grain-based diet and were killed at 31, 35, and 49 d of age (nutritionally weaned for 3, 7, and 21 d, respectively). Dorsal subcutaneous adipose tissue was obtained at death and adipocytes were prepared by incubation with collagenase. A portion of the cells was fixed with osmium to determine size and number; remaining cells were lysed in hypotonic media and centrifuged to yield a crude membrane fraction. The beta-adrenergic receptor (beta-AR) and A1 adenosine receptor (A1R) affinity and number were measured in the membranes by equilibrium saturation ligand binding. Obese pigs had a lower body weight than X-Bred pigs at all ages (P < .05). Obese pigs tended (P for volume > .1 but < .2) to have larger adipocytes than X-Bred pigs. The beta-AR affinity did not differ between obese and X-Bred pigs. There were fewer beta-AR per milligram of membrane protein in obese than in X-Bred pigs at 28 and 49 d of age when fed the high-fat, milk-based diet (P < .01). However, beta-AR number expressed per cell or unit cell surface area did not differ between genetic groups. As pigs of either genetic group continued to be fed the low-fat, grain-based diet, the beta-AR decreased when expressed per milligram of protein or unit cell surface area (P < .05) and tended to decrease when expressed per cell. Obese and X-Bred pigs fed the high-fat, milk-based diet had more beta-AR than respective pigs fed the low-fat, grain-based diet when data were expressed per milligram of protein (P < .01) but not when expressed per cell or unit surface area. The A1R were only detectable in 2 of 16 X-Bred litters but were more developed in adipocytes of obese pigs, being measurable in 8 of 14 litters. The A1R number, expressed per milligram of protein, was lower in obese pigs fed the milk-based diet than in those fed the grain-based diet (P < .05). These findings suggest the decreased beta-AR number after nutritional weaning, or the transition from a high-fat to low-fat diet, may contribute to fat accretion in pigs. Furthermore, the lower number of beta-AR in obese than in X-Bred pigs may contribute to the obesity.

Flow cytometric analysis of porcine preadipocyte replication

In the present study, a technique is described for measuring proliferation of primary porcine preadipocytes. Cultures of stromal-vascular (S-V) cells from dorsal subcutaneous adipose tissue were maintained under several growth conditions. Cells were isolated from cultures at various times and DNA was labeled with propidium iodide (PI) and analyzed by flow cytometry. Treatment of cultures with colchicine allowed identification of S-V cells in mitosis. The relative proportion of replicating cells was dependent on several factors, including serum concentration and cell density at the time of harvest. Using the AD-1 anti-preadipocyte/adipocyte monoclonal antibody, the preadipocyte subpopulation within the S-V cells was identified. Furthermore, by labeling cells with PI concomitant with AD-1, the proportion of replicating preadipocytes was quantified. It is now possible to identify and quantify replicating preadipocytes rapidly under various experimental conditions.

In vitro differentiation of preadipocytes from hypophysectomized pig fetuses

Hypophysectomy of the pig fetus alters the number of fat cells and fat cell clusters as well as lipogenic enzyme activities in tissues compared with littermate controls. The objective of the present study was to determine whether the altered endocrine environment in vivo affected subsequent development and differentiation of preadipocytes in vitro. Hypophysectomy was performed in utero at 70 d of gestation. At 105 d of gestation, stromal-vascular cells from dorsal subcutaneous adipose tissues were cultured in several differentiation media. Overall, stromal-vascular cultures from hypophysectomized fetuses contained fewer fat cell clusters and concomitantly lower glycerol-3-phosphate dehydrogenase specific enzyme activity than did cultures from littermate controls. Fluorescence-activated flow cytometry using a monoclonal anti-adipocyte/preadipocyte antibody designated AD-1 revealed that hypophysectomy also reduced the proportion of cells expressing the AD-1 cell surface antigen. These results demonstrated that effects of fetal hypophysectomy on cells from adipose tissues are maintained and measurable in culture. In addition, one of the consequences of fetal hypophysectomy may be diminution in the relative proportion of adipocyte precursors.

Comparative changes in the lipogenic enzyme activities and in the in vivo fatty acid synthesis in liver and adipose tissues during the post-weaning growth of male rats

Changes in the specific activities of acetyl-CoA-carboxylase (ACX), malic enzyme (ME) and glucose-6-phosphate dehydrogenase (G-6-PD) were compared to changes in de novo lipogenesis measured by in vivo incorporation of [3H] of tritiated water into fatty acids of liver and of perirenal and dorsal subcutaneous adipose tissues. In the adipose tissues, the specific activities of the three enzymes rather closely followed fluctuations in the rate of fatty acid synthesis. In the liver, ACX and especially ME activities were satisfactory indicators of de novo lipogenesis; G-6-PD activity did not depend on de novo lipogenesis.

Histochemistry of connective tissue cells in subcutaneous adipose tissue of normal and decapitated pig fetuses.

Connective tissue cells that are histochemically and morphologically distinct from 'fibroblasts' are localized around developing hair follicles in the pig and rat. Immature adipose tissue is limited to small areas immediately around fully descended hair follicles in the rat hypodermis. In the present study, connective tissue around large nerves and blood vessels in fetal pig subcutaneous tissue was examined for the presence of enzymes typical of adipocytes. Samples from decapitated pig fetuses were studied so that the effects of an altered hormonal profile could be examined. Samples of dorsal subcutaneous adipose tissue were obtained from fetuses at 65, 70, 85, 90, 110, and 112 days of gestation. Fetuses were decapitated in utero at 45 days of gestation, and adipose tissue samples were obtained from these fetuses at 110 days of gestation. A close spatial relationship was observed between the growth of large blood vessels and nerves and fat cell cluster development in the older (greater than 70 days) fetuses. Connective tissue cells that were contiguous with fat cell clusters were histochemically identical to adipocytes. The lipid histochemistry of the reactive connective tissue cells (histochemically identical to adipocytes) was variable in young fetuses. In all 110-and 112-day-old fetuses, the reactive cells contained lipid, whereas the reactive cells in decapitated fetuses were devoid of lipid. The reactive connective tissue cells were not associated with capillaries and did not contain basement membranes. The histochemistry of these cells suggests that they respond to a particular hormonal or metabolic profile as do adipocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose tissue development in the fetal pig after decapitation.

The effect of fetal decapitation on adipose tissue development in utero was studied in the pig. Pig fetuses were decapitated at 45 days of gestation, and dorsal subcutaneous adipose tissue was analyzed at 110 days of gestation. The histology, histochemistry, ultrastructure, size and lipoprotein lipase activity of adipocytes from decapitated and sham-decapitated control fetuses were determined. Decapitation resulted in a poorly developed dermis and epidermis, a poorly developed outer layer of adipose tissue and larger fat cells that were metabolically and structurally more mature. Fewer fat cell clusters in decapitated fetuses were associated with fewer blood vessels in the subcutaneous layers. The results of this study demonstrate that fat cell development in subcutaneous tissues may be an integral aspect of the development of skin and associated structures.