California Rabbits Research Articles

The effects of low-dose radiotherapy on fresh osteochondral allografts: An experimental study in rabbits

ObjectiveThe aim of this study was to investigate the effects of low-dose fractionated radiotherapy on cartilage degeneration after distal femoral fresh massive osteochondral allograft transplantation. MethodsTwenty-four New Zealand White rabbits were divided into three groups of 8 rabbits each. All rabbits underwent distal femoral medial condyle fresh massive osteochondral allograft transplantation from California rabbits. The group 1 underwent transplantation without any preliminary process. The group 2 underwent fractionated local radiotherapy of 100 cGy for five days starting on the transplantation day. The group 3 included the rabbits to which the grafts transplanted after radiating in vitro by a single dose radiation of 1500 cGy. The hosts were sacrificed twelve weeks later. Anteroposterior and lateral radiographs were taken. Synovial tissue, cartilaginous tissue, and subchondral bone were assessed histopathologically. ResultsNonunion was present in three cases of group 2 and one of group 3 in which cartilage degeneration was more severe. Synovial hypertrophy and pannus formation were more obvious in non-radiated rabbits. Hypocellularity and necrosis of the subchondral bone were rare in group 2. More cartilage tissue impairment was present in group 3 compared to group 1. ConclusionIn osteochondral massive allograft transplantations, the immune reaction of the host could be precluded with radiotherapy, and the side-effects can be prevented by low-dose fractionated regimen. The total dose of fractionated radiotherapy for an immune suppression should be adjusted not to damage the cartilage tissue, but to avoid articular degeneration in the long term.

Ultrasonography and Low-field Magnetic Resonance Imaging of the Common Calcanean Tendon in a Rabbit Model for Tendinopathy Research: a Descriptive Study of Normal Anatomy.

In spite of recent advances in treatment protocols, tendinopathies continue to challenge orthopaedists and surgeons. Due to the complexity of both tendon injuries and the healing processes, animal models are essential for addressing fundamental questions in tendinopathy research. Diagnostic imaging could contribute to the evaluation of animal models, thus providing information, which could be translated to human tendinopathies. The objective of our study was to evaluate in situ appearance of the rabbit common calcanean tendon with ultrasonography and magnetic resonance imaging. Additionally, we sought to assess and compare the feasibility and usefulness of these techniques in a rabbit model while focusing on the imaging of the particular structures involved in calcaneal tendon disorders. Eight California rabbits were used for post-mortem sonographic and low-field magnetic resonance examination. Morphometry was performed on longitudinal sonograms and sagittal MRI scans. The craniocaudal diameter of the tendon was measured at four points of interest. Ultrasonography and magnetic resonance provided good visualisation of the tendon origin, the paratenon and the pre-Achilles fat pad. Magnetic resonance images presented in more detail the structure of the calcaneal insertion. Both modalities failed to visualise the individual components of the common calcanean tendon and the bursa of the calcaneal tendon. Statistical analysis of measurements obtained showed that the craniocaudal diameter of the common calcanean tendon in a rabbit increases significantly with a growing length from the calcaneal tuber. Both magnetic resonance and ultrasonography are feasible, and should be considered complementary, not alternative imaging techniques in a rabbit common calcanean tendon model.

Effects of crossbreeding between New Zealand and California rabbits on litter weaning traits

Con el objeto de evaluar la heterosis individual y materna y los efectos maternos sobre el tamano de la camada, el peso y la sobrevivencia al destete, se establecieron cruces F1, entre las razas nueva Zelanda (NZ) y California (CAL). En una segunda etapa, las hembras cruzadas fueron apareadas a machos de la raza Azul de Viena (AV). Para estimar los efectos del grupo genetico, la capacidad materna y la heterosis, se utilizaron modelos lineales generales. En F1, se encontraron diferencias en el tamano de la camada y la sobrevivencia al destete entre cruces reciprocos, sin diferencias entre razas. La raza CAL, como madre en los cruces, presento superioridad, al compararla con NZ. La heterosis individual en el peso al destete fue de 12,2%, sobresaliendo el cruce NZ x CAL, en el que tambien se complemento su mayor tamano de camada, presentandose como el mas productivo. El cruce terminal de hembras F1 apareadas a machos AV obtuvo mayor numero de gazapos al destete, con relacion a las hembras de razas puras; la heterosis materna fue de 2,78 y 1,46%, para el peso y la sobrevivencia al destete, respectivamente. En definitiva, se recomienda el cruzamiento entre estas razas, utilizando a la raza California como base materna en F1, apareada en cruzamiento terminal a una tercera raza paterna, como la Azul de Viena, para mejorar la productividad de los sistemas de produccion cunicola.

Effect of dietary inclusion of processed Mucuna pruriens seed meal on growing rabbits

The current study was conducted to evaluate the effect of including differently processed Mucuna pruriens seed meals as tropical feed resource on growth performance, apparent nutrient digestibility, carcass characteristics, and economical efficiency of growing rabbits. Forty eight growing California rabbits aged 7 weeks, allocated in individual cages, were randomly distributed into four experimental groups of 12 rabbits each; the animals were assigned to four dietary treatments containing 25% of cooked Mucuna seed meal (MSM), alkaline treated MSM, or autoclaved MSM as well as the control diet that did not contain MSM. The results showed that cooking or autoclaving M. pruriens seeds did not affect the chemical composition of the seeds, however, the alkaline process reduced CP, aNDF, ADF, and EE content of the seeds by 6.03%, 6.38%, 17.74%, and 26.17%, respectively compared to the raw seeds. There was no significant difference between the control group and each of cooked and alkaline treated MSM regarding final body weight being 2066 vs. 2015 and 1999g, respectively; but the autoclaved MSM was significantly lower by 4.85% than the control group. Autoclaved and alkaline treated MSM groups had significantly lower daily weight gain (29.0 and 29.8g) than the control group (31.4g), but the cooked MSM treatment (30.1g) was not different from the control group. There were no significant differences regarding DM, OM, or GE digestibility among the experimental groups, the highest CP digestibility coefficient was recorded by the control and cooked MSM groups (0.75 and 0.72, respectively), whereas cooked MSM group showed significantly the highest digestibility coefficient of aNDF and ADF. No significant differences were detected among the treatments in the dressing percentage. The inclusion of cooked, alkaline treated or autoclaved MSM improved the economical efficiency by 63%, 53%, and 36%, respectively in comparison with the control group. The results of this study revealed that cooking treatment is the best method of processing Mucuna seeds; therefore 25% of cooked MSM could be included in the rabbit diets without any deleterious effect on performance or carcass traits with higher economical efficiency of growing rabbits.

Genetic Polymorphism in Growth hormone receptor Gene and its Relationship with Growth Trait in Pure and Hybrid Rabbit Breeds

Single Nucleotide polymorphism (SNP) techniques were used for association between exon 1 of growth hormone receptor (GHR1) gene and marketing body weights in three rabbit breeds; New Zealand White rabbit breed (pure breed), V-line (Hybrid breeds from New Zealand and California rabbit), and Alexandria breed (Hybrid from V-Line and black Egyptian Baladi rabbit). DNA from blood samples of each kid of the three rabbit breeds were extracted to amplify 263-bp of the gene encoding GHR1. The purified PCR products were sequenced in those had the highest and lowest body weight in each breed. Sixteen new SNPs were detected in GHR1 gene in New Zeland rabbits. In V-line rabbits, three SNPs were detected. Also two SNPs were found in Alex. breed. All these SNPs were related to high body weight as they were reported in higher body weights in the three breeds, and were non synonymous, which led to amino acids substitution. Restriction analysis of PCR product using MSP1 do not produce restriction fragments. Statistically, the results indicated that there were significant correlation between growth performance and GHR1 gene polymorphisms. The results were effective in selection for rabbits that have high growth performance (marker assisted selection). Also, the analysis of this study confirmed that GHR1 gene could be a candidate gene for application in marker assisted selection (MAS) in rabbits.

Effect of hyaluronic acids as chondroprotective in experimental model of osteoarthrosis

Objectiveto analyze the effects of hyaluronic acid of different molecular weights in an experimental model of osteoarthritis in rabbits. Methodsforty‐four male California rabbits were divided randomly into three groups and underwent resection of the anterior cruciate ligament in his right knee. After three weeks of the surgical procedure began three weekly intra‐articular injections of hyaluronic acid native (Polireumin®)‐PR, hyaluronic acid branched chain (Synvisc®)‐S and 0.9% saline‐P. All animals were sacrificed after twelve weeks of surgery and tibial plateau infiltrated the knees were dissected. Histological cartilage of the support areas of the tibial plateaus were stained with Alcian Blue pH 1.0, Alcian Blue pH=2.5 and toluidine blue for research on the amount of proteoglycans. The intensity of staining was quantified on a Zeiss microscope apparatus Imager Z2 MetaSystems and analyzed by software MetaferMsearch. Resultsthe effect of chondroprotetor hyaluronic acids used in the study was confirmed when compared to the control group, but the comparison made between them, there was no statistically significant difference regarding chondroprotetion. Conclusionthe hyaluronic acids tested had chondroprotective effect, with no statistical difference with regard to the different molecular weights.

Efeito dos ácidos hialurônicos como condroprotetores em modelo experimental de osteoartrose

Objectiveto analyze the effects of hyaluronic acid of different molecular weights in an experimental model of osteoarthritis in rabbits. Methodsforty-four male California rabbits were divided randomly into three groups and underwent resection of the anterior cruciate ligament in his right knee. After three weeks of the surgical procedure began three weekly intra-articular injections of hyaluronic acid native (Polireumin®)-PR, hyaluronic acid branched chain (Synvisc®)-S and 0.9% saline-P. All animals were sacrificed after twelve weeks of surgery and tibial plateau infiltrated the knees were dissected. Histological cartilage of the support areas of the tibial plateaus were stained with Alcian Blue pH 1.0, Alcian Blue pH = 2.5 and toluidine blue for research on the amount of proteoglycans. The intensity of staining was quantified on a Zeiss microscope apparatus Imager Z2 MetaSystems and analyzed by software MetaferMsearch. Resultsthe effect of chondroprotetor hyaluronic acids used in the study was confirmed when compared to the control group, but the comparison made between them, there was no statistically significant difference regarding chondroprotetion. Conclusionthe hyaluronic acids tested had chondroprotective effect, with no statistical difference with regard to the different molecular weights.

GROWTH PERFORMANCE OF FATTENING RABBITS AS AFFECTED BY STOCKING DENSITY AND ADDED DIETARY ORGANIC ACIDS

An experiment of 3×2 factorial arrangement of treatments was undertaken to investigate the influence of stocking density and dietary supplementation with organic acids on growth performance, carcass characteristics, and some blood parameters of fattening rabbits. A total of 54, 7-week-old New Zealand White × California rabbits were randomly divided into 6 experimental groups, of three replicates of 2, 3 or 4 rabbits each. Two experimental pelleted diets (a basal diet and a 0.4% Salkil-supplemented diet; Salkil is a mixture of formic and propionic acids.) were formulated and used from 7 to 13 weeks of age. The rabbits were individually weighed, kept in battery cages at three stocking densities (8.6, 12.9 and 17.2 rabbits/m2), fed their respective experimental diets and managed similarly up to 13 weeks of age. Criteria of response were the performance of rabbits for growth, feed intake and feed conversion, mortality rate, economic efficiency of feeding, and some carcass traits. Some blood plasma parameters (levels of glucose, total protein, albumin, triglycerides and cholesterol as well as activity of the transaminases: alanine aminotransferase and aspartate aminotransferase) were also determined. The results obtained could be summarized as follows: No deaths of rabbits occurred during the course of this study. Regardless of the effect of dietary supplemental organic acids, growth performance of rabbits was not significantly affected by stocking density during the whole experimental period, whereas means of daily feed intake, daily weight gain and performance index of rabbits insignificantly decreased when stocking density reached 17.2 rabbits/m2. Neither carcass traits nor blood parameters of rabbits, measured herein, was affected by stocking density. Irrespective of the effect of stocking density, added dietary organic acids did not significantly affect growth performance, carcass traits or blood parameters of the experimental rabbits. No significant interaction effects of stocking density and added dietary organic acids were detected for all criteria examined in the present study. Taking the performance of rabbits and economic aspect into account, the results revealed that the maximum rate of cage density (17.2 rabbits/m2) had no adverse effects under the condition of the present experiment during the spring season. The dietary inclusion of Salkil at a level of 0.4% was an extravagance; because it had no positive effects on either growth performance or economic efficiency of rabbit production, under the conditions of the present study.

Rabbit, rat and pig corneas: main characteristics and storage in organ culture

AbstractPurpose Except for primates, animal models of corneal are far from human. Animal models of corneal storage are virtually non‐existent. Aim: to update the main characteristics (especially for endothelial cells (EC)) of the cornea of 3 easily available animals, as well as their ability to be stored in organ culture (OC)Methods 30 corneas of 6 month‐old Large White pig, 20 of 10 week‐old California rabbits and 10 of 8 week‐old Lewis rats were investigated. Macroscopic data: 1/horizontal and vertical diameters (digital calliper), 2/transparency (analysis of modulation and contrast transfer functions), 3/ corneal thickness (CT) (ultrasound pachymetry). Microscopic data: 1/ histology on Hematein‐Eosin‐Safran stained cross sections and ultrastructure, 2/ EC density (ECD) and morphometry, 3/ EC proliferative status (Ki67 and 5‐Ethynyl‐2’‐Deoxyuridine incorporation (Clik‐it EdU)), differentiation status (Na+/K+ ATPase, ZO‐1, JAM‐1), and existence of stem cells (Nestin, ABCG2, Telomerase). Fresh corneas were organ cultured in 2 commercially available media. CT was measured every 2h during 6h, then every 12h. Transparency and EC survival was determined after 2, 3 and 4 days of OCResults We constituted a complete database of ex vivo corneal characteristics of the 3 species. ECD, polymorphism and polymegathism were higher than in human. CT increased rapidly (up to 3 times) in both OC media, resulting in biconvex tissues with almost complete loss of transparency and significant endothelial folding. EC survival decreased especially in foldsConclusion Corneas of the 3 animals cannot be stored more than 2 to 3 days in OC media designed for human. Specific media should be developed to obtain reliable models of animal corneal OC

Physiological Response and Stress Indicators of California Rabbits under Intensive Conditions in Egypt

Physiological Response and Stress Indicators of California Rabbits under Intensive Conditions in Egypt

Reproductive Performance, Meat Chemical Composition and Quality of Sudan Baladi, New Zealand White and California Rabbit Breeds

Reproductive Performance, Meat Chemical Composition and Quality of Sudan Baladi, New Zealand White and California Rabbit Breeds

Histochemical and biochemical characteristics of weaning rabbit intestine

The aim of this research was to study rabbit digestive system at two ages during weaning by evaluating alkaline phosphatase (ALP) intestinal distribution and morphological, biochemical and haematological variables. Two groups of six New Zealand White × California rabbits, of 21 and 35 d of age respectively, were used. Significant differences between the two ages on live body weight (P<0.001), small intestine length (P<0.01) and pancreas weight (P<0.01) were noticed, being higher in 35 d rabbits. No differences were observed in the a-amylase activity of the jejunum. Nevertheless, a-amylase activity of blood serum was almost twice in 35-d rabbits compared to younger rabbits (P<0.05). Blood glucose concentration was lower in 35 d rabbits (P<0.05). The values of haematological profile were significantly higher in older rabbits for haematocrit (P<0.001), red blood cell count (P<0.05), haemoglobin concentration (P<0.001) and mean corpuscular volume (P<0.01). No differences due to age were observed for mean corpuscular haemoglobin concentration and mean corpuscular haemoglobin. A strong ALP reaction was observed along the brush border of the villous epithelial cells of the small intestine at both ages, being this reaction more intense at 35 d. There was no ALP positive or a faint /discontinuous reaction along the brush border of the caecum at 21 d while a positive reaction was observed at 35 d. The proximal colon presented an ALP positive reaction at 21 d but stronger at 35 d of life while the colon distal was ALP negative at both ages.

Association between single nucleotide polymorphism of &lt;I&gt;MC4R&lt;/I&gt; gene and carcass traits in rabbits

Single nucleotide polymorphisms in the coding sequence of melanoeortin-4 receptor (MC4R) gene were detected by PCR-SSCP and DNA sequencing method in Harbin white rabbit, Tianfu black rabbit, Belgian hare, ZIKA rabbit, and California rabbit breeds. A-->G conversion mutation at base position 237 was found with high frequency in Harbin white rabbit, Belgian hare, and Zika rabbit and low frequency in Tianfu black rabbit and California rabbit. The allele A was pre-dominant allele for each of meat rabbit breeds. AA genotype frequency was higher than AG genotype in the five studied rabbit breeds. GLM analysis for the effect of genotypes on performance traits demonstrated that AG genotype was significantly associated with body weight, eviscerated weight and feed conversion efficiency (P<0.05), but not significantly associated with cooking loss (P>0.05). It was concluded from the results that MC4R gene could be a candidate modifier gene that affects or controls body weight and carcass traits of rabbit.

The correlations between polymorphism of growth horm- one receptor gene and butcher traits in rabbit

Five rabbit populations (Belgian hare, Tianfu black rabbit, Great line of Zika rabbit, Harbin white rabbit, and California rabbit) were used to analyze the polymorphism of growth hormone receptor (GHR) gene by PCR-SSCP. Results indicated that there were two mutation sites (C705T and C810T) in the 5 populations. The least square analyses showed that the live weight, visceraste weight, and slaughter percentage of AA and MM genotypes were significantly lower than BB and NN genotypes (P<0.05). In contrast, the GHR polymorphism had no significant difference for least squares means of feed transformation efficiency (P>0.05). It suggested that GHR gene may be a candidate gene responsible for butcher trait in rabbit.

Correlation analysis between single nucleotide polymorphism of &lt;I&gt;FGF5&lt;/I&gt; gene and wool yield in rabbits

Single nucleotide polymorphism (SNP) in exon 1 and 3 of fibroblast growth factor (FGF5) gene was studied by DNA sequencing in Yingjing angora rabbit, Tianfu black rabbit and California rabbit. A frameshift mutation (TCT insert) at base position 217 (site A) of exon 1 and a T/C missense mutation at base position 59 (site B) of exon 3 were found in Yingjing angora rabbit with a high frequency; a T/C same-sense mutation at base position 3 (site C) of exon 3 was found with similar frequency in three rabbit breeds. Least square analysis showed that different genotypes had no significant association with wool yield in site A, and had high significant association with wool yield in site B (P<0.01) and significant association with wool yield in site C (P<0.05). It was concluded from the results that FGF5 gene could be the potential major gene affecting wool yield or link with the major gene, and polymorphic loci B and C may be used as molecular markers for im-proving wool yield in angora rabbits.

Avaliação pós-transplante de ovários íntegros e fatiados sem anastomose vascular

To assess the natural pregnancy and to determine the morphofunctional aspects of ovaries of rabbits submitted to bilateral oophorectomy and orthotopic allogeneic or autologous intact and sliced ovarian transplantation without a vascular pedicle. Fifty-six female New Zealand White and California rabbits were studied. The ovaries were removed and orthotopically transplanted or replaced without vascular anastomoses: Group 1 (n = 8), only laparotomy and laparorrhaphy were performed; Group 2A (n = 8) intact ovaries were reimplanted on both sides; Group 2B (n = 8) both ovaries were sliced and orthotopically reimplanted; Group 2C (n = 8), an intact ovary was reimplanted on one side and a sliced ovary on the other side; Group 3A (n = 8) intact ovaries were transplanted on both sides, Group 3B (n = 8) both ovaries were sliced and orthotopically transplanted, Group 3C (n = 8), an intact ovary was transplanted on one side and a sliced ovary on the other side. Three months later, the females were paired with males for copulation. Estradiol, progesterone, follicle stimulating hormone and luteinizing hormone levels were assessed. The morphological aspect of the ovaries was studied and the number of pregnancies and litters were also determined. The number of successful pregnancies and the number of litters was compared between the groups by the chi-square test. One-way ANOVA and the Tukey-Kramer tests compared the hormonal dosages. The significance was of p < 0.05. Pregnancies occurred in seven (87.5%) rabbits of Group 1, in 37.5% in Groups 2A and 3A, in 50% of groups 2B, 2C and 3B, and in 62.5% of group 3C. Hormone levels and histology confirmed the vitality of all ovaries. Intact or sliced orthotopic allogeneic and autologous ovarian transplantation without a vascular pedicle is viable in rabbits, and preserves their fertility and hormonal functions.

Avaliação endócrina e morfológica de transplante ovariano homógeno

INTRODUÇÃO: A insuficiência ovariana decorre de ooforectomia bilateral em diversas afecções do ovário, como neoplasia e sepse, além de quimioterapia, radiação pélvica e fatores relacionados à idade. Suas complicações sistêmicas, como insuficiências hormonais, podem ser de difícil controle. OBJETIVOS: Avaliar aspectos endócrinos e histológicos ovarianos após seu transplante ortotópico, sem anastomose vascular e submetidos à imunossupressão pela ciclosporina. MATERIAL E MÉTODO: Foram utilizadas 12 coelhas da raça Nova Zelândia Branca (n = 6) e Califórnia (n = 6), divididas em dois grupos: grupo 1 (n = 4), de controle, submetido apenas a laparotomia, sem outro procedimento cirúrgico; e grupo 2 (n = 8), submetido a ooforectomia bilateral e transplante ortotópico dos ovários, que foram trocados entre as duas raças de animais. De um lado, foi transplantado o ovário íntegro e, do outro, o ovário fatiado. Não houve anastomose vascular. As coelhas foram imunossuprimidas com ciclosporina (10mg/kg ao dia). No final do período de acompanhamento de seis meses, foram feitas dosagens de estradiol, progesterona, hormônio foliculoestimulante (FSH) e hormônio luteinizante (LH), além de estudo histológico de ovários, tuba uterina e útero. RESULTADOS: Os ovários transplantados estavam rodeados por tecido conjuntivo, bem vascularizados, mostrando folículos em diferentes estádios de desenvolvimento. A histologia tubária e uterina também foi preservada em ambos os grupos. A dosagem hormonal foi normal em todas as coelhas, indicando que, do ponto de vista endócrino, o ovário transplantado estava funcionando. O transplante ovariano homógeno ortotópico, sem pedículo vascular e submetido à imunossupressão pela ciclosporina, foi eficaz para a manutenção de hormônios ovarianos em níveis normais.

Biodisponibilidade de diferentes fontes de zinco para coelhos

Utilizaram-se 140 coelhos das raças Nova Zelândia Branco e Califórnia, com 60 dias de idade, de ambos os sexos, distribuídos em 14 tratamentos experimentais, com o objetivo de determinar a biodisponibilidade de zinco (Zn) de três fontes inorgânicas, óxido de zinco (OZ), sulfato de zinco (SZ) e carbonato de zinco (CZ) e uma orgânica, quelato de zinco (QZ) usados nas concentrações de 0, 50, 100, 150 e 200 ppm para determinação da curva padrão. O maior consumo de ração ocorreu nos tratamentos 50OZ e 100OZ e o menor nos tratamentos 200OZ, 100SZ, 200SZ e 200QZ (R²= 0,18). Para ganho de peso os melhores resultados foram para os tratamentos 50OZ, 100CZ, 200CZ, 100SZ, 200SZ, 100QZ e 200QZ; os tratamentos 0OZ e 100OZ apresentaram os menores resultados (R²=0,23). Para conversão alimentar os tratamentos 0OZ, 100OZ, 150OZ e 150SZ apresentaram os maiores valores e os menores foram para os tratamentos 200SZ, 200QZ, 200CZ, 100QZ e 100SZ, respectivamente (R²= 0,26). Para concentração de zinco no fígado os tratamentos 100OZ, 150OZ e 150SZ apresentaram os maiores valores, e 100CZ e 200CZ os menores. Não houve diferença com relação ao sexo, mas os animais Nova Zelândia Branco apresentaram maior deposição de zinco. Pelosresultados chegou-se à equação de regressão: Y Zn= 1,11 + 0,66 x1 + 0,55 x2 + 0,57 x3 + 0,56 x4 + 0,56 x5 (R² = 0,59).

Maize Replacement Value of Cassava Peels Soaked in Water for Different Time Periods in Grower Rabbit Ration

Shoremi, O.I.A., Ayoade, J.A. and Akinwale, V.O. 1999. Maize replacement value of cassava peels soaked in water for different time periods in grower rabbit ration. J. Appl. Anim. Res., 15: 87–91. In a study that lasted 84 days, 20 crossbred (New Zealand x California) rabbits (20-weeks, 1.07 kg) were used to evaluate the partial maize replacement value of unsoaked and soaked (1, 3 and 5h in water) cassava peels and incorporated at 45% maize substitution. Results indicated that the HCN content of the cassava peel meal decreased with increased duration of soaking. Feed intake and water consumption significantly increased (P<0.05) as the duration of soaking increased but other parameters remained unaffected. Further studies with larger number of younger rabbits is advocated.

In utero partial liver resection in the rabbit model: a study on fetal tissue regeneration.

In this study we developed a model of in vivo intrauterine partial liver resection in the fetal rabbit to analyze fetal liver regeneration. After intravenous anesthesia, 12 time-dated pregnant, California rabbits underwent a midline laparotomy and minimal hysterotomy at 24-25 days of gestational age. One fetus was exposed from each pregnant doe and the fetal liver was partially resected. Cesarean sections were performed 24, 48 and 72 h and 4 days after surgery. Three fetuses operated at 24 days of gestational age and 3 fetuses operated at 25 days were alive at retrieval. The fetuses and the sampled livers were weighed at retrieval and fetal liver weight showed a well-maintained value in all cases. Fetal livers were processed for the common histologic stains. Lymphocytes, polymorphonuclear leukocytes and phagocytes were counted from sections obtained in areas close to the edge of resection. Inflammatory cells showed a peculiar pattern of infiltration at different stages of repair, with a constantly increased number of phagocytes peaking 48 h after resection. Fetal liver seems to present a specific pattern of repair that differs from both the adult liver and other fetal tissues healing after injury.