Primary dedifferentiated chondrosarcoma of the lung with a 4-year history of breast cancer:A case report

BACKGROUND Primary dedifferentiated chondrosarcoma(DDCS)of the lung is extremely rare and has a poor prognosis,especially in patients with a history of carcinomas and related treatment.Herein,we report a case of primary DDCS of the lung in a patient with a 4-year history of breast cancer and related treatment.CASE SUMMARY A 49-year-old woman was admitted to our hospital with complaints of headache,dizziness,slurred speech,and dyskinesia in May 2021.Computed tomography(CT)examinations showed multiple nodules in the brain,vertebral body,and both lungs with multiple enlarged lymph nodes in the right hilum and mediastinum,which were considered metastases of breast cancer.No obvious mass was discovered in the right hilum.After several months of related administration,the patient's headache disappeared,and her condition improved.However,new problems of asthma,dyspnea,cough,and restricted activity appeared in late November 2021.Although the CT scan indicated that the lesions in the brain,lung,and vertebral body had shrunk or disappeared,a soft tissue density lesion appeared in her right hilum and blocked the bronchial lumen.To relieve her dyspnea,part of the mass was resected,and a stent was placed via fiberoptic bronchoscopy.Following a complete pathological examination of the tumor,it was confirmed to be a primary DDCS of the lung.The patient then received two rounds of systemic chemotherapy with a regimen of cisplatin+ifosfamide+doxorubicin hydrochloride liposome,palliative radiotherapy for the tumor in her right lung,and four cycles of systemic chemotherapy and targeted therapy with a regimen of temozolomide combined with bevacizumab successively.She was in stable condition after the completion of the systemic chemotherapy and targeted therapy but underwent rapid progression after lung radiotherapy.The CT examinations showed multiple nodules in the brain and in both lungs,and the tumor in the right hilum was increased in size.CONCLUSION This case revealed a rare primary DDCS of the lung with a medical history of breast cancer,meaning a worse prognosis and making it more difficult to treat.

Giant dedifferentiated liposarcoma of the gastrocolic ligament:A case report

BACKGROUND Dedifferentiated liposarcoma(DDLS)has a worse prognosis and occurs most commonly in the retroperitoneal region and rarely in the intraperitoneal region.Histological diagnosis was revolutionized by the combined contributions of histoimmuno-chemistry and molecular biology.Aside from surgery,there is no consensus on the optimal treatment for this chemoresistant cancer.CASE SUMMARY A thirty-year-old black female presented with a large painful abdominal mass occupying nearly the entire abdomen and progressive weight loss was admitted for surgery.Abdominal computed tomography showed a large heterogeneous mass of the mesentery that was sized 18 cm×16 cm in size and had heterogeneous contrast enhancement.During laparotomy,en bloc excision of the large and multilobulated gastrocolic ligament mass was performed.The initial postoperative histopathological diagnosis was undifferentiated sarcoma.Finally,the results of immunohistochemistry and molecular biology allowed us to confirm the diagnosis of DDLS.The tumour followed an aggressive evolution with diffuse metastasis,causing the death of the patient less than 5 mo after the operation.CONCLUSION Dedifferentiated liposarcomas are rare tumours that typically originate in the retroperitoneum but may arise in unexpected locations.

Dedifferentiated fat cells: an alternative source of adult multipotent cells from the adipose tissues

When adipose-derived stem cells （ASCs） arc retrieved from the stromal vascular portion of adipose tissue, a large amount of mature adipocytes are often discarded. However, by modified ceiling culture technique based on their buoyancy, mature adipocytes can be easily isolated from the adipose cell suspension and dediffercn- tiated into lipid-frce fibroblast-like cells, named dediffercntiated fat （DFAT） cells. DFAT cells rc-establish active proliferation ability and undertake multipotent capacities. Compared with ASCs and other adult stem cells, DFAT cells showed unique advantages in their abundance, isolation and homogeneity. In this concise review, the establishment and culture methods of DFAT cells arc introduced and the current profiles of their cellular nature are summarized. Under proper inducti~,n culture in vitro or environment in vivo, DFAT cells could demonstrate adipogenic, osteogenic, chondrogenie and myogenic potentials. In angiogenie conditions, DFAT cells could exhibit perivascular characteristics antt elicit neovascularization. Our preliminary findings also suggested the pericyte phenotype underlying such cell lineage, which supported a novel interpretation about the common origin of mesenchymal stem cells and tissue-specific stem cells within blood vessel walls. Current research on DFAT cells indicated that this alternative source of adult multipotent cells has great potential in tissue engineering and regenerative medicine.

Dedifferentiated fat cells:A cell source for regenerative medicine

The identification of an ideal cell source for tissue regeneration remains a challenge in the stem cell field. The ability of progeny cells to differentiate into other cell types is important for the processes of tissue reconstruction and tissue engineering and has clinical, biochemical or molecular implications. The adaptation of stem cells from adipose tissue for use in regenerative medicine has created a new role for adipocytes. Mature adipocytes can easily be isolated from adipose cell suspensions and allowed to dedifferentiate into lipidfree multipotent cells, referred to as dedifferentiated fat(DFAT) cells. Compared to other adult stem cells, the DFAT cells have unique advantages in their abundance, ease of isolation and homogeneity. Under proper condition in vitro and in vivo, the DFAT cells have exhibited adipogenic, osteogenic, chondrogenic, cardiomyogenc, angiogenic, myogenic, and neurogenic potentials. In this review, we first discuss the phenomena of dedifferentiation and transdifferentiation of cells, and then dedifferentiation of adipocytes in particular. Understanding the dedifferentiation process itself may contribute to our knowledge of normal growth processes, as well as mechanisms of disease. Second, we highlight new developments in DFAT cell culture and summarize the current understanding of DFAT cell properties. The unique features of DFAT cells are promising for clinical applications such as tissue regeneration.

Dedifferentiated liposarcoma of the small bowel mesentery presenting as a submucosal mass

Dedifferentiated liposarcoma(DDLPS) is a variant of liposarcoma but with a more aggressive course.It occurs most commonly in the retroperitoneum and rarely in any other anatomical location.We describe a case of DDLPS arising from the small bowel mesentery presenting as submucosal mass of the small bowel.The current case is unusual as the tumor originated from the small bowel mesentery and a dedifferentiated component transmurally invaded the small bowel wall,including the small bowel submucosa.

Thoracoscopic resection of a huge esophageal dedifferentiated liposarcoma: A case report

BACKGROUND Esophageal liposarcoma is a rare malignant tumor and an esophageal dedifferentiated liposarcoma(DDL)is extremely rare.There are no reports on the treatment of DDL by thoracoscopic surgery.CASE SUMMARY A 38-year-old woman presented with dysphagia and dyspnea.Imaging examination showed a large mass in the posterior mediastinum.The patient also developed respiratory failure and it was unclear whether this was caused by a mass from inside or outside the esophagus.We decided to perform thoracoscopic exploration to relieve the obstruction caused by tracheal compression.The upper segment of the esophagus was split longitudinally,and most of the mass could be removed from the esophageal lumen to the thoracic cavity.The pedicle was excised by linear cutting closers under mirrors.Little residual mass was visualized by gastroscopy.The mucous and muscular layers were closed by interrupted sutures.Pathological examination showed that the mass was a DDL.The patient did not have any dysphagia or dyspnea 2 wk postoperatively and refused any further treatment.Computed tomography and esophagoscopy did not find any recurrence at up to 20 mo postoperatively.CONCLUSION Thoracoscopy can be used to treat large esophageal masses.

Primary gastric dedifferentiated liposarcoma resected endoscopically:A case report

BACKGROUND Liposarcoma is one of the most common adult mesenchymal tumors but is uncommon in the gastrointestinal tract and extremely rare in the stomach.Furthermore,the histological subtypes of liposarcoma usually reported in the stomach are well-differentiated or myxoid,and few reports have been issued on small-sized gastric liposarcomas resected endoscopically and followed up.Herein,we report a case of primary gastric dedifferentiated liposarcoma(DL)that was resected endoscopically.CASE SUMMARY A 67-year-old female Korean patient was referred to our institution for further evaluation of a gastric submucosal tumor(SMT)located in the lesser curvature of the gastric body by esophagogastroduodenoscopy.Endoscopic ultrasound revealed a well-circumscribed,slightly heterogeneous,isoechoic,17 mm×10 mm sized mass originating from the third sonographic layer.Computed tomography showed no evidence of significant lymph node enlargement or distant metastasis.Endoscopic resection was undertaken using the snare resection technique after mucosal precutting to provide a definitive histopathologic diagnosis,which proved to be consistent with DL,based on its morphology and the immunoexpressions of MDM2 and CDK4.The patient was planned for surgery because the deep resection margin was positive for malignancy.After declining any invasive procedure or adjuvant treatment,the patient was placed under close follow-up,and at one year after endoscopic resection,remained disease free.CONCLUSION This is the first reported case of a small primary gastric DL resected endoscopically and followed up.This report demonstrates that when diagnosis of a SMT is uncertain,the use of invasive techniques,including endoscopic resection,should be considered.

Dedifferentiated chondrosarcoma of the middle finger arising from a solitary enchondroma:A case report

BACKGROUND Dedifferentiated chondrosarcoma(DDCS)accounts for 10%of all chondrosarcomas and has the poorest outcome,with a 5-year survival rate of 7%-25%.DDCS commonly occurs in the femur and pelvis,whereas DDCS of the finger is extremely rare.Furthermore,the histological findings of preexisting solitary enchondroma samples are important and valuable for diagnosing malignant transformations.CASE SUMMARY We report our experience with DDCS in the proximal phalanx of the left middle finger of an 87-year-old woman.She had undergone surgery for enchondroma,with curettage and artificial bone grafting,11 years ago,in the same location.Several years after the primary surgery,the left middle finger gradually started to enlarge,and the growth speed increased in the past year.Plain radiographs showed an expansive osteolytic lesion with calcifications and residual grafting material.Owing to the suspicion of malignancy,we performed ray amputation.Histological findings revealed an abrupt transition between the low-grade chondrosarcoma and dedifferentiated sarcoma components.The dedifferentiated components showed the features of a high-grade undifferentiated pleomorphic sarcoma.The patient was diagnosed with DDCS arising from a preexisting enchondroma.She had no local recurrence or distant metastasis and died of pneumonia 6 years and 10 months after the second surgery.CONCLUSION The histological findings of a precursor lesion showed a typical enchondroma,suggesting that DDCS can arise from enchondroma.

The VEGF production by dedifferentiated chondrocytes under synovial fluid stimulation from coxarthrosis and femoral neck fracture patients

Objective To investigate the vascular endothelial growth factor(VEGF)expression level by chondrocytes isolated from patients with osteoarthritis (OA) in hip or femoral neck fracture (FNF) and explore the effect of synovial fluid from OA

Combining surgery with 125I brachytherapy for recurrent mediastinal dedifferentiated liposarcoma: A case report and review of literature

BACKGROUND Dedifferentiated liposarcoma in the mediastinum is an extremely rare malignant neoplasm.A few previous case reports indicate that surgical resection is the major treatment,but frequent recurrence occurs locally.Due to its rarity,its clinical characteristics,optimal treatment and clinical outcomes remain unclear.Here,we report a case of multifocal recurrent dedifferentiated liposarcoma in the posterior mediastinum treated by combining surgery with 125I brachytherapy,and summarize its clinical features,treatment and prognosis.CASE SUMMARY A 75-year-old man was admitted to our hospital with a history of gradual dysphagia for one year and aggravated dysphagia for 3 mo.Contrast-enhanced computed tomography(CT)revealed several large cystic-solid masses with lipomatous density,and calcification in the posterior-inferior mediastinum.The patient received a wide excision by video-assisted thoracoscopic surgery.Pathological analysis confirmed the tumors were dedifferentiated liposarcomas.The tumor locally relapsed 24 mo later,and another operation was performed by video-assisted thoracoscopic surgery.Fifteen months after the second surgery,the tumor recurred again,and the patient received CT-guided radioactive seeds 125I implantation.After 8 mo,follow-up chest CT showed an enlarged tumor.Finally,his condition exacerbated with severe dysphagia and dyspnea,and he died of respiratory failure in July 2018.CONCLUSION We reviewed the literature,and suggest that surgical resection provides beneficial effects for dedifferentiated liposarcoma in the mediastinum,even in cases with local recurrence.125I brachytherapy may be beneficial for recurrent unresectable patients.

Dedifferentiated Chondrosarcoma with a High-Grade Mesenchymal Component Mimicking a Gastrointestinal Stromal Tumor

This report presents a dedifferentiated chondrosarcoma with a unique pathologic feature. A 63-year-old man was referred with pain and a soft tissue mass in the left groin. A plain radiograph showed a mineralization in the proximal femur with partially osteolytic foci and an abnormal shadow in the soft tissue. Magnetic resonance imaging scans showed an inhomogeneous lesion with intermediate to partially low signal intensity on T1-weighted image and intermediate to high signal intensity on T2-weighted image. Microscopically, the tumor in the femur is a low-grade chondrosarcoma and the component of soft tissue was a high-grade sarcomatous lesion with an epithelial arrangement of tumor cells. A diffuse immunoreactivity to both vimentin and c-kit (CD117) antibodies was detected in the high-grade component. A dedifferentiated component is similar to those of gastrointestinal stromal tumor (GIST). This is the first case of dedifferentiated chondrosarcoma with a high-grade component mimicking a GIST.

Benefits of dedifferentiated stem cells for neural regeneration

Dedifferentiation, as one of the mechanisms rerouting cell fate, regresses cells from a differentiated status to a more primitive one. Due to its potential of amplifying the stem/progenitor cell pool and reproducing sizable and desirable cellular elements, it has been attended in the field of regenerative medicine, which will hopefully provide novel therapeutic strategies for currently incurable diseases, such as varieties of central nervous system (CNS) diseases and injuries. In this article, we will first discuss naturally occurring and experimentally induced dedifferentiation, and then set forth principles in stem-cell based therapy in the neural field;beyond that, we will introduce two recent studies that show dedifferentiated stem cells contribute to neural regeneration. Moreover, we also present our recent research results of dedifferentiated muscle stem cells for neurogenic differentiation study in vitro. Further work will be conducted to elucidate the mechanism underlying the dedifferentiation process to facilitate the development of new strategies in regenerative medicine.

Organoid-derived human retinal progenitor cells promote early dedifferentiation of Müller glia in Royal College of Surgeons rats

AIM:To explore whether the subretinal transplantation of retinal progenitor cells from human embryonic stem cell-derived retinal organoid(h ERO-RPCs)could promote Müller glia dedifferentiation and transdifferentiation,thus improving visual function and delaying retinal degenerative progression.METHODS:h ERO-RPCs were subretinally transplanted into Royal College of Surgeons(RCS)rats.Electroretinography(ERG)recording was performed at 4 and 8wk postoperation to assess retinal function.Using immunofluorescence,the changes in outer nuclear layer(ONL)thickness and retinal Müller glia were explored at 2,4,and 8wk postoperation.To verify the effect of h ERO-RPCs on Müller glia in vitro,we cocultured h ERO-RPCs with Müller glia with a Transwell system.After coculture,Ki67 staining and quantitative polymerase chain reaction(q PCR)were performed to measure the proliferation and m RNA levels of Müller glia respectively.Cell migration experiment was used to detect the effect of h ERO-RPCs on Müller glial migration.Comparisons between two groups were performed by the unpaired Student’s t-test,and comparisons among multiple groups were made with one-way ANOVA followed by Tukey’s multiple comparison test.RESULTS:The visual function and ONL thickness of RCS rats were significantly improved by transplantation of h ERO-RPCs at 4 and 8wk postoperation.In addition to inhibiting gliosis at 4 and 8wk postoperation,h ERO-RPCs significantly increased the expression of dedifferentiation-associated transcriptional factor in Müller glia and promoted the migration at 2,4 and 8wk postoperation,but not the transdifferentiation of these cells in RCS rats.In vitro,using the Transwell system,we found that h ERO-RPCs promoted the proliferation and migration of primary rat Müller glia and induced their dedifferentiation at the m RNA level.CONCLUSION:These results show that h ERO-RPCs might promote early dedifferentiation of Müller glia,which may provide novel insights into the mechanisms of stem cell therapy and Müller glial reprogramming,contributing to the development of novel therapies for retinal degeneration disorders.

Adipose tissue in bone regeneration-stem cell source and beyond

Adipose tissue(AT)is recognized as a complex organ involved in major homeostatic body functions,such as food intake,energy balance,immunomodulation,development and growth,and functioning of the reproductive organs.The role of AT in tissue and organ homeostasis,repair and regeneration is increasingly recognized.Different AT compartments(white AT,brown AT and bone marrow AT)and their interrelation with bone metabolism will be presented.AT-derived stem cell populations-adipose-derived mesenchymal stem cells and pluripotentlike stem cells.Multilineage differentiating stress-enduring and dedifferentiated fat cells can be obtained in relatively high quantities compared to other sources.Their role in different strategies of bone and fracture healing tissue engineering and cell therapy will be described.The current use of AT-or AT-derived stem cell populations for fracture healing and bone regenerative strategies will be presented,as well as major challenges in furthering bone regenerative strategies to clinical settings.

A Case of Giant Mediastinal Liposarcoma of Thymic Origin: A Rare Clinical Entity

Thymoliposarcoma is an exceedingly rare tumor of thymus with a very few cases reported till date. This case study presents a 45-year male with rare type of thymoma. On the contrast-enhanced CT images, there was a large mass lesion of predominantly fat attenuation in the pre-vascular compartment of the mediastinum insinuating on both sides of the visceral compartment of the mediastinum, and extending upto the bilateral cardio phrenic and anterior costophrenic angles, anterior to the right ventricle with loss of fat plane with the pericardium, with few sub-centimetric lymph nodes in the right paratracheal and AP window and a calcified right hilar lymph node, suggestive of well-differentiated liposarcoma/thymoliposarcoma. Initial CT guided tru-cut tissue biopsy was inconclusive, and the repeat biopsy revealed as fibro-collagenous tissue with area of necrosis, focal myxoid changes in the background with presence of cells which are spindle to oval in shape with mild nuclear pleomorphism and negative for S100, Cytokeratin, CD34, desmin. The entire tumor was resected en masse after meticulous dissection without the support of cardiopulmonary bypass (CPB) with an intact pericardium. Final histopathology report of the surgical biopsy specimens is consistent with dedifferentiated thymoliposarcoma with focal ganglionic cell differentiation. Postoperative follow-up CECT of thorax revealed no evidence of residual mass in the pre-vascular compartment. The patient is disease-free and asymptomatic after 6-month and he is under routine follow-up under Radiotherapy department since he received 30 Gy of postoperative radiotherapy (PORT).

Mediastinal Liposarcoma: Case Report and Literature Review

Liposarcomas (LS) are the second most common type of soft tissue malignancies in adults;they arise from mesenchymal cells and account for 1% of all adult cancers and 15% of all pediatric cancers. The site of origin can be from anywhere there is fat in the human body. LS are classified based on the primary site of origin, and mediastinal LS are extremely rare. When mediastinal neoplasms are stratified based on histology, they represent less than 1% of all mediastinal tumors. To date, less than 150 cases have been reported in the English literature. This article aims to present an unusual case of an extremely rare malignancy and perform a systematic review of the latest literature. In this report, our group is documenting the presentation, management, and outcome of a 65-year-old male patient with a massive anterior mediastinal primary LS. The tumor was displacing the mediastinum into the right chest, occupying most of the left chest, and pushing the diaphragm into the abdomen. Mediastinal liposarcomas are extremely rare malignancies and can prove to be challenging to diagnose and treat. Aggressive surgical treatment with R0 resection is the gold standard, however, tumor biology in many cases is associated with variable growth rates and encroachment of adjacent vital structures and blood vessels. When complex anatomical structures preclude an R0 resection, there is a high incidence of local recurrence. In cases where there is a high risk of recurrence, radiotherapy is indicated and chemotherapy has a more limited role.

Two Cancers Arising from Different Mesenchymal Origins: An Unexpected Connection over Time and Space

Sarcomas are rare tumours, accounting for 1% of all malignancies. They are histologically diverse, presenting with more than 50 different subtypes. Sarcoma can be broadly divided into two categories—soft tissue sarcoma and bone sarcoma. Extraskeletal osteosarcoma is a unique subtype which is histologically similar to bone osteosarcoma but resides within soft tissue and has no attachments to bone. We present a rare case of a patient who initially presented with an extraskeletal osteosarcoma that was complicated by a chronic chest wall sinus and lymphedema of the left arm. He later developed enlarging left chest wall nodules at the same region that were proven to be dedifferentiated liposarcoma on biopsy 20 years later. We examine the occurrence of both extremely rare diseases of differing pathologies over the same site but separated by an extraordinarily long interval, and possible new associations to account for this phenomenon.

Axon degeneration： make the Schwann cell great again

Axonal degeneration is a pivotal feature of many neurodegenerative conditions and substantially accounts for neurological morbidity. A widely used experimental model to study the mechanisms of axonal degeneration is Wallerian degeneration （WD）, which occurs after acute axonal injury. In the peripheral nervous system （PNS）, WD is characterized by swift dismantling and clearance of injured axons with their myelin sheaths. This is a prerequisite for successful axonal regeneration. In the central nervous system （CNS）, WD is much slower, which significantly contributes to failed axonal regeneration. Although it is well documented that Schwann cells （SCs） have a critical role in the regenerative potential of the PNS, to date we have only scarce knowledge as to how SCs ＇sense＇ axonal injury and immediately respond to it. In this regard, it remains unknown as to whether SCs play the role of a passive bystander or an active director during the execution of the highly orchestrated disintegration program of axons. Older reports, together with more recent studies, suggest that SCs mount dynamic injury responses minutes after axonal injury, long before axonal breakdown occurs. The swift SC response to axonal injury could play either a pro degenerative role, or alternatively a supportive role, to the integrity of distressed axons that have not yet committed to degenerate. Indeed, supporting the latter concept, recent 昀ndings in a chronic PNS neurodegeneration model indicate that deactivation of a key molecule promoting SC injury responses exacerbates axonal loss. If this holds true in a broader spectrum of conditions, it may provide the grounds for the development of new glia-centric therapeutic approaches to counteract axonal loss.

Activation of extracellular signal-related kinases 1 and 2 in Sertoli cells in experimentally cryptorchid rhesus monkeys

Aim： To assess the spatiotemporal changes in the expression of extracellular signal-regulated kinases 1 and 2 （ERK1/ 2）, c-Jun N-terminal kinases （JNK） and p38 mitogen-activated protein kinases （MAPK） in response to heat stress in the cryptorchid testis, and to investigate a possible relation to Sertoli cell dedifferentiation. Methods： Immunohistochemistry and western blot were used to examine the expression and activation of ERK1/2, p38 and JNK in the cryptorchid testis at various stages after experimental cryptorchidism. Results： The abdominal temperature did not obviously change the total ERK1/2 expression but significantly activated phospho-ERK1/2 in the Sertoli cells of the cryptorchid testis. Heat stress increased total JNK expression in the Sertoli cells of the cryptorchid testis but did not activate phospho-JNK. Neither total p38 nor phospho-p38 was induced by heat stress in the Sertoli cells of the cryptorchid testis. Changes in the spatiotemporal expression of cytokeratin 18 （CK18）, a marker of immature or undifferentiated Sertoli cells, were induced in the cryptorchid testis in a pattern similar to the activation of ERK1/2. Condusion： The activation of ERK1/2 in the testis may be related to dedifferentiation of Sertoli cells under heat stress induced by experimental cryptorchidism.

Segment boundaries of the adult rat epididymis limit interstitial signaling by potential paracrine factors and segments lose differential gene expression after efferent duct ligation

The epididymis is divided into caput, corpus and cauda regions, organized into intraregional segments separated by connective tissue septa （CTS）. In the adult rat and mouse these segments are highly differentiated. Regulation of these segments is by endocrine, lumicrine and paracrine factors, the relative importance of which remains under investigation. Here, the ability of the CTS to limit signaling in the interstitial compartment is reviewed as is the effect of 15 days of unilateral efferent duct ligation （EDL） on ipsilateral segmental transcriptional profiles. Inter-segmental microperifusions of epidermal growth factor （EGF）, vascular endothelial growth factor （VEGFA） and fibroblast growth factor 2 （FGF2） increased phosphorylation of mitogen activated protein kinase （MAPK） in segments 1 and 2 of the rat epididymis and the effects of all factors were limited by the CTS separating the segments. Microan＇ay analysis of segmental gene expression determined the effect of 15 days of unilateral EDL on the transcriptome-wide gene expression of rat segments 1-4. Over 11 000 genes were expressed in each of the four segments and over 2 000 transcripts in segment 1 responded to deprivation of testicular lumicrine factors. Segments 1 and 2 of control tissues were the most transcriptionally different and EDL had its greatest effects there. In the absence of lumicrine factors, all four segments regressed to a transcriptionally undifferentiated state, consistent with the less differentiated histology. Deprivation of lumicrine factors could stimulate an individual gene＇s expression in some segments yet suppress it in others. Such results reveal a higher complexity of the regulation of rat epididymal segments than that is generally appreciated. （Asian J Androl 2007 July; 9： 565-573）