Immunoreactive insulin-like growth factor I in human follicular fluid

Recent studies in laboratory animals suggest that insulin-likegrowth factor I (IGF-I) plays an important role in the regulationof granulosa cell function. The purpose of the present studywas to investigate the presence of immunoreactive IGF-I in humanfollicular fluid (FF) and compare the levels of follicular IGF-I(64 follicles) with those detectable in serum (n= 19) in hyperstimulatedcycles from 25 infertile patients. Also, the FF IGF-I levelswere correlated to corresponding follicular volume (n= 62) andoocyte maturation (n= 37). Levels of IGF-I were determined usinga specific radioimmunoassay after acidification and extractionby reversed phase chromatography. Levels of IGF-I in serum weresignificantly higher than those in FF (37.1± 10.1 versus24.0± 9.3 nmol/I, n= 19, P< 0.001). A positive correlationwas found between follicular and serum IGF-I concentrations(r= 0.73). No significant differences were found in FF IGF-Ilevels derived from follicles of different size or from follicleshaving oocytes with different grades of maturation. These dataindicate that immunoreactive IGF-I is present in human FF innanomolar concentrations and that FF IGF-I levels correlatewith those detectable in serum. The source of FF IGF-I and itsregulatory role in humans remains to be elucidated.     

Insulin-like growth factor binding protein-1 inhibits the DNA amplification induced by insulin-like growth factor I in human granulosa-luteal cells.

In order to study the effects of insulin-like growth factor (IGF-I) and insulin-like growth factor binding protein (IGFBP-1) on human granulosa cell proliferation after in vitro fertilization, cells were obtained after oocyte retrieval and cultured in the presence or absence of graded amounts of recombinant IGF-I, purified IGFBP-1 and [3H]thymidine. Physiological concentrations of IGF-I (2-200 ng/ml) were found to stimulate [3H]thymidine incorporation into the cells in a concentration-dependent manner. Half-maximal stimulation of [3H]thymidine incorporation was obtained with 10 ng/ml exogenous IGF-I, which was chosen for suppression experiments with graded amounts of purified IGFBP-1. Suppression of IGF-stimulated thymidine incorporation was observed when 200 ng/ml or more of IGFBP-1 was added to the culture medium. The same concentration of IGFBP-1 also markedly inhibited binding of [125I]iodotyrosyl IGF-I to the cells. It is concluded that: (i) after a refractory period, granulosa cells from hyperstimulated follicles retained their mitogenic activity; (ii) IGF-I is capable of stimulating DNA amplification in granulosa cells; and (iii) IGFBP-1 inhibits the IGF-I stimulated proliferation in these cells. In view of our previous studies showing that IGFBP-1 is synthesized by the granulosa cells as they luteinize, the present results suggest that IGFBP-1 is one of the endogenous factors locally regulating the growth and differentiation of granulosa cells.     

宫内发育迟缓大鼠血清胰岛素样生长因子Ⅰ、Ⅱ、BP3的变化及L-精氨酸的保护作用

目的通过L-精氨酸孕期干预后大鼠血清胰岛素样生长因子-Ⅰ、Ⅱ及结合蛋白3水平的变化,探讨L-精氨酸的保护作用及其机制。方法采用被动吸烟法造大鼠IUGR模型,孕鼠随机分为4组:对照组、模型组、L-精氨酸小剂量和大剂量防治组,每组9只。孕21d剖宫取胎,测量胎鼠体重。应用酶联免疫吸附法检测各组大鼠血清IGF-Ⅰ、IGF-Ⅱ及IG-FBP-3水平。结果对照组、模型组与小、大剂量L-精氨酸防治组IUGR发生率分别为3.92%,54.95%,5.55%和9.09%。模型组大鼠血清IGF-Ⅰ、IGF-Ⅱ水平较对照组明显降低(P<0.01),小剂量和大剂量L-精氨酸防治组与模型组相比,IGF-Ⅰ、IGF-Ⅱ水平明显增高(P<0.01)。模型组大鼠血清IGFBP-3水平较对照组明显增高(P<0.01),小剂量和大剂量L-精氨酸防治组与模型组相比,IGFBP-3水平明显降低(P<0.01),与对照组亦有明显差异(P<0.01)。结论L-精氨酸可增高被动吸烟致宫内发育迟缓大鼠血清胰岛素样生长因子-Ⅰ、Ⅱ的水平,降低胰岛素样生长因子结合蛋白3的水平,从而促进胎鼠发育,防治IUGR的发生。     

Expression of insulin-like growth factor 1 in sarcomas

The expression of insulin-like growth factor-1 (IGF-1) was studied in normal tissues, in eight benign lesions and in 50 sarcomas. In palmar fibromatosis the spindle cells in cell-dense areas exhibited a strong immunoreactivity. IGF-1 was variably found in leiomyosarcomas (7/8), malignant schwannomas (7/9), synovial sarcomas (2/3), liposarcomas (3/6), fibrosarcomas (1/3), malignant fibrous histiocytomas (10/18) and in one angiosarcoma. Two rhabdomyosarcomas failed to express IGF-1 and only the spindle cell component of synovial sarcomas was positive. Immunoreactivity for IGF-1 in 10 malignant filrous histiocytomas (MFH) appeared to be related to co-expression of smooth muscle actin. These findings imply that MFHs can be subdivided into a group of tumours which are devoid of morphological and immunophenotypic evidence of differentiation and a group which manifest immunophenotypic differentiation.     

Expression and localization of placenta growth factor and PlGF receptors in human meningiomas

It has previously been suggested that in human brain tumours, endothelial cell proliferation during angiogenesis is regulated by a paracrine mechanism involving vascular endothelial growth factor (VEGF) and its receptors (VEGF receptor 1 and VEGF receptor 2). The mechanism of growth factor up-regulation is based on hypoxic activation of mRNA expression and mRNA stabilization and genetic events, leading to an increase of growth factor gene expression. The role of the other newly discovered VEGF family members with a high specificity for endothelial cells in the pathogenesis of glial neoplasms is unknown. To investigate which other members of the VEGF family are overexpressed in human brain tumours, the mRNA levels of placenta growth factor (PlGF), VEGF-A, and VEGF-B genes were determined by northern blot analysis in surgically obtained human meningiomas. In the 16 meningiomas examined, the mRNA for PlGF was highly expressed in four tumours and VEGF-A mRNA was highly abundant in three tumour samples. There was no close correlation between PlGF mRNA levels and VEGF-A expression levels. VEGF-B mRNA was abundantly expressed in all tumour samples at uniform levels. In a PlGF-positive tumour sample, immunoreactive VEGFR-1 and VEGFR-2 were detected in endothelial cells of the blood vessels. PlGF protein was detectable in most but not all capillaries of the tumour. PlGF is thus highly up-regulated in a subset of human meningiomas and may therefore have functions, in some tumour vessels, connected to endothelial cell maturation and tube formation. These findings suggest that PlGF, in addition to VEGF-A, may be another positive factor in tumour angiogenesis in human meningiomas. Copyright © 1999 John Wiley & Sons, Ltd.     

Mesenchymal dysplasia of the placenta

A severe case of placental mesenchymal dysplasia occurred in association with intrauterine fetal death (IUFD). The gravida-1, para-1 mother was a 26-year-old Japanese. The first pregnancy was unremarkable and a healthy female infant was delivered. The present pregnancy had been uneventful until 34 weeks of gestation when IUFD was detected. The 1516-g (mean +/- SD, 2050 +/- 387 g) stillborn infant had no external abnormalities and the karyotype was 46,XX. The placenta was markedly enlarged (1050 g; mean +/- SD, 452 +/- 202 g), and approximately 80% was occupied by extraordinary enlarged villous structures with a myxoid appearance. Histologically, the dysplastic villi had myxoid stroma and a decreased number of, occasionally obliterated, fetal vessels. There was no abnormal trophoblastic proliferation. Large-sized fetal vessels in the chorionic plate frequently contained organized thrombi. This is the first case of placental mesenchymal dysplasia, which possibly lead to the IUFD.     

斑马鱼类胰岛素生长因子信号途径及作用机制研究进展

斑马鱼是研究早期发育中类胰岛素生长因子（insulin-like growth factors, IGF）信号途径的模式生物,斑马鱼IGF信号系统主要包括IGF配体、受体、结合蛋白（IGFBPs）。IGF配体包括IGF-1,IGF-2。受体为IGF-1R,该受体有两种全长结构（igf-1ra和igf-1rb）。结合蛋白包括IGFBP-1,IGFBP-2,IGFBP-3,IGFBP-5和 IGFBP-6,它们的结构特征已经阐明,从斑马鱼模式动物中获得的信息不仅可以为斑马鱼胚胎发育生物学提供新的观点,还可以进一步加深我们对一般意义上的脊椎动物的生长和发育的理解。本文就近年来斑马鱼IGF系统的进展作一综述。     

Expression and distribution of insulin-like growth factor-1 receptor in human carcinomas

The insulin-like growth factor-1 receptor (IGF1-R) is a cellular receptor overexpressed in many tumor cell lines and in some human tumors that seems to play a critical role in transformation, tumorigenicity, and metastasis. To date, a comprehensive evaluation of tissue distribution of IGF1-R in human carcinomas from different anatomical sites has been lacking. Using stage-oriented human cancer tissue microarrays, we studied IGF1-R expression and distribution in a group of 152 human carcinomas from a variety of anatomical sites and from 63 normal tissues through immunohistochemistry. The tumors included carcinomas from breast (8), ovary (9), endometrium (7), esophagus (5), stomach (7), pancreas (7), liver (4), colon (10), kidney (14), bladder (17), prostate (11), head and neck (31), salivary glands (8), lung (13), and skin (1). Formalin-fixed, paraffin embedded tissues of each case were immuno-stained using the avidin-biotin peroxidase method and an anti-IGF1-R rabbit polyclonal antibody. High-membranous IGF1-R staining was observed in 7 of 8 (87.5%) breast carcinomas, in 9 of 9 (100%) ovarian carcinomas, in 7 of 7 (100%) endometrial carcinomas, in 5 of 7 (71.1%) gastric carcinomas, in 4 of 7 (57.1%) pancreatic carcinomas, in 9 of 10 (90%) colon adenocarcinomas, in 11 of 13 (84.6%) lung carcinomas, in 6 of 11 (54.5%) prostatic adenocarcinomas, and in 17 of 17 (100%) transitional cell carcinomas of the bladder. Only a minority of squamous cell carcinomas of the head and neck and esophagus (34), salivary gland tumors (5), and renal cell carcinomas (14) were IGF1-R positive. This study demonstrates the overexpression of IGF1-R across a wide variety of human carcinomas of glandular or transitional cell origin.     

Progesterone production by human granulosa cells cultured in serum free medium: effects of gonadotrophins and insulin-like growth factor I (IGF-I).

There is evidence that insulin-like growth factor I (IGF-I) is a potent regulator of oestradiol synthesis by human granulosa and luteal cells; however, the question of whether IGF-I regulates progesterone synthesis by these cell types has yet to be answered. As a first step towards this goal, we have compared the effects of IGF-I, follicle stimulating hormone (FSH), and human chorionic gonadotrophin (HCG) on progesterone production by human granulosa cells obtained from individual dominant and cohort follicles, and granulosa luteal cells from preovulatory follicles of patients undergoing in-vitro fertilization (IVF). Granulosa cells from normal, unstimulated follicles cultured in serum-free medium as controls (no additions) produced some progesterone spontaneously. In all cases, FSH stimulated basal progesterone levels (10-fold average increase) and the effect was dose-dependent (ED50 of FSH = 9.1 +/- 3.9 ng/ml). Similar effects were observed when granulosa cells from large follicles were incubated with HCG (ED50 of HCG = 6.9 +/- 2.8 ng/ml). By comparison, the effects of IGF-I on progesterone production were not marked, being absent in 80% of the follicles tested. However, granulosa cells from healthy follicles co-incubated with IGF-I and FSH or HCG produced more progesterone compared with cells treated with the gonadotrophins alone; this effect of IGF-I was dose dependent (ED50 of IGF-I = 10 ng/ml). When the effect of each agonist was tested on IVF granulosa luteal cells, HCG but not FSH or IGF-I stimulated basal progesterone levels but the HCG effect required a two-day lag phase.(ABSTRACT TRUNCATED AT 250 WORDS)     

The role of insulin-like growth factor binding protein-1 phosphoisoforms in pregnancies with impaired placental function identified by doppler ultrasound.

This study was performed to investigate the hypothesis that insulin-like growth factor binding protein-1 (IGFBP-1) is involved in the pathogenesis of trophoblast invasion and impaired placentation in human pregnancy. The role of total and non-phosphorylated IGFBP-1 in women with fetal growth restriction and in high risk pregnancies identified by uterine artery Doppler ultrasound screening was examined. This was a prospective study of women booked for antenatal care having second trimester anomaly scans and Doppler screening between 22-26 weeks gestation. Women were divided into three groups and compared: normal uterine artery Doppler and normal fetal growth (control group, n = 10); abnormal Doppler and normal fetal growth [bilateral uterine artery notches (BN; n = 16); abnormal Doppler and intrauterine growth restriction (IUGR; n = 8)]. Maternal serum was collected, stored and assayed simultaneously for total and non-phosphorylated IGFBP-1. There was elevated total and non-phosphorylated IGFBP-1 (mean 44.99 +/- 12.19 and 29.61 +/- 10.38 microg/l respectively) in the IUGR group compared with controls (mean 17.96 +/- 3.24 and 12.18 +/- 1.55 microg/l, P < 0.05). This finding suggests that the various IGFBP-1 isoforms, the degree of phosphorylation and the ratios of these different forms locally may be important during trophoblast invasion and may be implicated in clinical manifestations of impaired placentation later in the second trimester.     

Quantitative microscopy in studies of intrauterine growth retardation

In the past, the detection of fetal damage has tended to be restricted to the naked eye identification of major malformations, with the period of organ maturation being relatively neglected. Increasingly, however, unbiased design-based stereology is being used in developmental toxicological studies. In the field of intrauterine growth retardation, such methods are capable of providing new insights into fetal vulnerability during critical periods in organogenesis, with consequences for both post-natal and adult disease. © 1997 John Wiley & Sons, Ltd.     

Insulin and the IGF system in the human placenta of normal and diabetic pregnancies

The insulin/insulin-like growth factor (IGF) system regulates fetal and placental growth and development. In maternal diabetes, components of this system including insulin, IGF1, IGF2 and various IGF-binding proteins are deregulated in the maternal or fetal circulation, or in the placenta. The placenta expresses considerable amounts of insulin and IGF1 receptors at distinct locations on both placental surfaces. This makes the insulin and the IGF1 receptor accessible to fetal and/or maternal insulin, IGF1 and IGF2. Unlike the receptor for IGF1, the insulin receptor undergoes a gestational change in expression site from the trophoblast at the beginning of pregnancy to the endothelium at term. Insulin and IGFs are implicated in the receptor-mediated regulation of placental growth and transport, trophoblast invasion and placental angiogenesis. The dysregulation of the growth factors and their receptors may be involved in placental and fetal changes observed in diabetes, i.e. enhanced placental and fetal growth, placental hypervascularization and higher levels of fetal plasma amino acids.     

白藜芦醇上调碱性成纤维细胞生长因子、胰岛素样生长因子1表达治疗骨骼肌损伤

文题释义： 白藜芦醇：非黄酮类的多酚化合物,分子式为C₁₄H₁₂O₃,相对分子质量228.25,为白色针状晶体,易溶于乙醚、氯仿、甲醇、乙醇、丙酮、乙酸、乙酯等有机溶剂。别名：3,4',5-三羟基芪、虎杖甙元,是相关植物在受到病菌侵染或环境恶化时产生的植物抗毒素,主要存在于葡萄、虎杖、决明、花生、桑葚等植物中。 骨骼肌急性钝挫伤：钝挫伤指在钝器作用下,造成以皮内或皮下及软组织出血为主要改变的闭合性损伤。骨骼肌急性钝挫伤指钝器在短时间内伤到肌肉层造成皮下及软组织出血,肌肉没有断裂或者撕裂的闭合性损伤。临床上90%的骨骼肌损伤属于钝挫伤与扭伤。 背景：近年来国内外对白藜芦醇抑制机体组织纤维化方面做了大量研究,但其在肌组织损伤康复方面的作用却鲜有报道。 目的：观察骨骼肌急性钝挫伤修复过程中碱性成纤维细胞生长因子、胰岛素样生长因子1蛋白表达规律,探讨白藜芦醇促进受损骨骼肌结构与功能恢复的作用机制。 方法：33只新西兰兔随机分为3组：正常组(3只)、自然恢复组(15只)、白藜芦醇组(15只),除正常组外均采用钝性暴力法制造骨骼肌钝挫伤模型,损伤后自然恢复组不予处理,白藜芦醇组给予白藜芦醇灌胃治疗,分别于伤后1,3,7,14,21 d处死动物,采用苏木精-伊红染色、Masson染色观察炎症细胞浸润情况、胶原纤维形成情况,免疫组织化学、免疫印记法检测骨骼肌中碱性成纤维细胞生长因子、胰岛素样生长因子1蛋白表达。 结果与结论：①苏木精-伊红染色显示：正常组兔肌纤维多边形、形态规则、排列紧密,肌核均匀分布于肌膜下,无增生与固缩,肌膜完整;自然恢复组伤后1 d见血细胞渗出,3 d炎症细胞开始浸润,至7 d达峰值,21 d肌纤维形态基本恢复正常;白藜芦醇组在炎症细胞浸润、修复时间上整体优于自然恢复组;②Masson染色显示：正常肌细胞中胶原纤维含量极少;自然恢复组随着瘢痕组织的形成,胶原纤维逐渐增加,于14 d达高峰;白藜芦醇组胶原纤维含量低于自然恢复组;③免疫组织化学和免疫印记检测显示：碱性成纤维细胞生长因子、胰岛素样生长因子1蛋白在骨骼肌修复过程中呈现先升高后降低的变化规律,两组均于7 d达高峰,21 d时仍高于正常,且白藜芦醇组峰值高于自然恢复组;④整体来看,白藜芦醇组在炎症反应以及修复程度上均优于自然恢复组,白藜芦醇通过上调碱性成纤维细胞生长因子、胰岛素样生长因子1蛋白表达来促进骨骼肌修复,但其并不改变骨骼肌损伤修复过程中蛋白表达量的整体变化规律。 ORCID: 0000-0001-6570-2052(刘杏) 中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程     

Immunohistochemical analysis of neural cell adhesion molecule (N-CAM) and pan-cadherin in the small intestine of intrauterine growth-retarded newborn rats caused by maternal protein malnutrition

Cell-cell and cell-matrix adhesion molecules play an important role in morphogenesis, cell signaling and are involved in cell proliferation, cell death, cell polarization and differentiation. In the present study, we investigated N-CAM and pan-cadherin expression in small intestine of intrauterine growth-retarded (IUGR) newborn rats after maternal protein malnutrition during pregnancy. N-CAM and pan-cadherin immunostaining was increased in small intestine of IUGR newborn rats. This increase was evident in epithelial cells on villi, lamina propria, submucosa, muscularis mucosa and muscularis externa. The increase in numbers of villous N-CAM-positive and pan-cadherin-positive epithelial cells was statistically significant (p < 0.001). In most areas, crypts did not show any immunopositive epithelial cells or showed decreased expression of the adhesion molecules. Although the villous height was decreased in IUGR rats, the decrease was statistically not significant. Expression and recruitment of N-CAM and pan-cadherin in small intestine of newborn IUGR rats may indicate a direct or indirect involvement of adhesion mechanisms or signaling in the growth retardation process.     

IGF-I与宫内发育迟缓及其结合蛋白的关系

目的：检测宫内发育迟缓（IUGR）儿脐血胰岛素样生长因子-I（IGF-I）、胰岛素样生长因子结合蛋白-3（IGFBP-3）水平,分析这些指标的变化程度与胎儿期生长的关系。方法：将86例脐血标本分为IUGR（即小于胎龄儿）组和适于胎龄儿（AGA）组。采用放射免疫分析（RIA）测定IGF-I水平,免疫放射分析（IR-MA）测定IGFBP-3水平。两组间比较用t检验,两变量之间的关系采用相关回归分析。结果：与AGA组相比,IUGR组脐血IGF-I和IGFBP-3水平显著降低（P均〈0.01）;IGF-I、IGFBP-3均随胎龄及出生体重增加而增加（P均〈0.01）;IGFBP-3与IGF-I呈正相关（P〈0.01）。结论：脐血IGF-I和IGFBP-3的含量可作为判断新生儿生长发育程度的一项客观指标。     

HGF在胎儿生长受限胎盘中的表达及其意义

目的检测胎儿生长受限(FGR)的胎盘组织肝细胞生长因子(HGF)的表达,探讨其与FGR的关系。方法应用免疫组织化学SP法检测15例晚期正常妊娠胎盘和15例FGR胎盘HGF的表达。结果FGR组胎盘中HGF染色强度明显高于正常妊娠组(P<0.01)。结论FGR胎盘HGF的高表达可能是子宫胎盘血流减少导致绒毛滋养细胞增殖的结果。     

Physiology: In-vivo studies on ovarian insulin-like growth factor I concentrations in human preovulatory follicles and human ovarian circulation

In some recent hypotheses, the ovary has been indicates as asource of insulin-like growth factor (IGF)-I, with synthesisregulated from local steroidal and non-steroida substances.We measured IGF-I concentrations in both serum and follicularfluid of women undergoing in-vitro fertilization (IVF) and embryotransfer, in both induced and spontaneous cycles. It was foundthat serum anc follicular IGF-I concentrations were correlatedwith follicular morphology, oocyte maturity, steroid concentrationsand clinical characteristics of IVF cycles In addition, we measuredIGF-I concentrations in bott peripheral and ovarian circulationto gain further detailed information on the contribution ofthe ovary tc IGF-I production. The results of our study supportto hypothesis that follicular IGF-I is probably derived by diffusionfrom peripheral circulation and that local produc tion appearsunlikely.     

胰岛素样生长因子-Ⅰ受体与肿瘤

胰岛素样生长因子Ⅰ受体(insulin-like growth factor Ⅰ receptor,IGF-IR)为跨膜蛋白,是酪氨酸蛋白激酶类受体家族的主要成员之一.IGF-IR在多种恶性肿瘤中均有表达,它可促进肿瘤细胞的增殖、抑制肿瘤细胞的凋亡,在肿瘤的发生发展中起重要作用.现已在多种肿瘤细胞中证实,用抗IGF-IR的抗体或相关药物及以反义IGF-IR RNA封闭IGF-IR来阻断IGF-IR信号转导,可以抑制肿瘤细胞的生长和增殖,促进其凋亡.因此针对IGF-IR靶向治疗将是恶性肿瘤生物治疗值得关注的一个研究方向.     

胰岛素样生长因子-I受体与肿瘤

胰岛素样生长因子I受体(insulin-like growth factor I receptor,IGF-IR)为跨膜蛋白，是酪氨酸蛋白激酶类受体家族的主要成员之一。IGF-IR在多种恶性肿瘤中均有表达，它可促进肿瘤细胞的增殖、抑制肿瘤细胞的凋亡，在肿瘤的发生发展中起重要作用。现已在多种肿瘤细胞中证实，用抗IGF-IR的抗体或相关药物及以反义IGF-IR RNA封闭IGF-IR来阻断IGF-IR信号转导，可以抑制肿瘤细胞的生长和增殖，促进其凋亡。因此针对IGF-IR靶向治疗将是恶性肿瘤生物治疗值得关注的一个研究方向。     

Molecular interactions during pregnancy: Expression of leukaemia inhibitory factor (LIF) receptor in human placenta: a possible role for LIF in the growth and differentiation of trophoblasts

Leukaemia inhibitory factor (LIF) is a cytokine that displaysmultiple activities in various tissues and is essential forblastocyst implantation in mice. In the human uterus, LIF isexpressed in endometrial tissue and the decidua. To elucidatethe role it plays, the mRNA levels for two LIF receptor (R)subunits, LIF-R and gp130, were examined in human endometrium,placenta and decidua by Northern blot hybridization. The expressionof LIF-R gene was detected in the chorionic villus during thefirst trimester, in term placenta, and at lower levels in thedecidua. The expression of LIF-R gene was not detectable innon-pregnant endometrium. The expression of the gp130 gene wasdetected in all tissues examined. During pregnancy, there wasno significant change in the mRNA concentration of LIF-R inthe placenta, while that of gp130 increased after the secondtrimester. The human choriocarcinoma cell line, BeWo, was foundto express LIF-R and gp130. LIF inhibited forskolin-inducedhuman chorionic gonadotrophin (HCG)-B production by BeWo ina dose-dependent manner, and it ameliorated forskolin-inducedgrowth suppression. These findings suggest that LIF plays aregulatory role in trophoblast growth and differentiation duringpregnancy in human placenta.