Recently, there has been an interest in the role of placenta in the pathogenesis of variety of pregnancy disorders. Considerable advances have been made in understanding the complex fetomaternal relationship in complicated pregnancies and its influence on the intrauterine development of the fetus . Samples from the central part of placentas were collected in this study to avoid areas of fibrosis or calcification . In the present study, histological examination of a normal full-term placenta showed variations in the shape and apparent size of chorionic villi. Each villus had an outer trophoblastic layer and an inner connective tissue core that was interposed between maternal and fetal circulation. The trophoblastic layer had syncytiotrophoblasts and cytotrophoblasts. Similar observations have been documented previously [20,21]. This was in contrast with the findings of some authors , who did not observe the presence of cytotrophoblastic cells at normal full term. In the present work, marked histological differences were found between the diabetic and the normal groups of placentas; the histological sections of diabetic placenta tended to show smaller and numerous chorionic villi in comparison with the normal placentas. This might be a result of the continuous branching of the chorionic villi in response to prolonged ischemia in an attempt to increase the surface area of villi to insure good fetal nutrition . The terminal villi showed changes in maturation and increased vascularization. A huge number of villi showed fibrinoid necrosis. These observations were in agreement with those of many studies [24–26] that attributed these findings to the hypoxia resulting from diabetes. However, these changes might be considered as a morphological landmark for an immunological reaction in the villous stroma . In the present work, cytotrophoblastic hyperplasia and more syncytial knots were frequently observed in the diabetic group, which was in agreement with many studies, which assumed that these knots might act as cellular bridges to protect the villus capillaries from the effect of sudden changes in the intervillus space pressure during labor . However, the increased syncytial knots in diabetic cases might be an indication of active placental growth. This was based on the hypothesis that hyperinsulinemia is a growth stimulus in diabetic pregnancies  or it might be attributed to the inability of syncytiotrophoblasts to proliferate, therefore depending on the cytotrophoblast population for growth and renewal. The proliferating cytotrophoblasts begin to differentiate, leading to fusion of these cells; a second differentiation process occurs in the outer syncytiotrophoblastic layer, in which the aging nuclei are packed into syncytial knots and extruded . A previous study  has reported that the proliferation of cytotrophoblasts was associated with the formation of syncytial knots as a very common finding in pre-eclampsia because of an impairment in vasculature. In addition, syncytial knots were numerous in cases of low oxygen tension as a slow accommodation to chronic hypoxia; thus, these knots might be increased to compensate the loss of syncytium in areas of infarction . Also, areas of fibrinoid material in the connective tissue stroma of diabetic placenta were observed frequently, especially around the fetal blood capillaries. It was suggested that these stromal changes in diabetic placenta might have resulted from an immunological reaction in the villous stroma . Many researchers have reported that the microfibrils and the amorphous components of the fibrinoid substance appear to be synthesized by the residual cytotrophoblasts. They also added that immunohistochemical evidences support the cytotrophoblastic origin and the secretory nature of fibrinoid material, and the cellular debris certainly derives from degeneration of the syncytiotrophoblast that covers the fibrinoid mass [33,34]. Many authors have concluded that most of the placental abnormalities may be because of some unknown constituent factors of the diabetic state, which is only partially influenced by the diet or insulin . In this study, excessive concentric deposition of collagenous fibers in the stroma of many diabetic villi and around fetal blood capillaries was observed. These findings indicated a placental response to altered glycemia that could have important consequences for the fetus, as this perivascular fibrosis might be the cause of congested fetal blood vessels .
In the present work, the electron microscopic examination of placental villi of diabetic mothers showed widespread and sometimes severe damage of syncytium. Multiple cytoplasmic vacuoles of variable sizes were observed, associated with scarce cell organelles and destroyed surface microvilli. In some areas, very short or completely absent microvilli were observed. These syncytial trophoblastic microvilli were believed to be one of the important structures responsible for transplacental metabolism exchanges [36,37]. Apical microvillar density has been reported to be related to the degree of trophoblastic maturation  and had been considered to be the most involved syncytiotrophoblastic structure under oxygen and nutrient exchange . Decreased microvillar density has been observed in intrauterine growth retardation placentas , pre-eclamptic placentas , and in placenta from pregnancies with other complications, including a decreased metabolic exchange state in diabetic placentas. This might be attributed to exposure to hypoxia . In addition, a recent study has reported that several genes related to transplacental metabolic exchange also showed changes in complicated placenta . The present study showed thickening of the trophoblastic basement membrane, which was one of the most characteristic features that was seen in diabetic placenta. In agreement with our study, many authors observed a marked increase in the thickness of the basement membrane of the syncytiotrophoblast in diabetic placentas. Some authors attributed this change to the pathological immune complex, resulting in the pathological immune complex deposition in the area of the basal membranes of a syncytiotrophoblast and vascular endothelium . Many studies [42,44] have suggested that thickening of the basement membrane might be a result of the hypoxic state of diabetes, as some authors have observed thickening and separation of the basement membrane in placenta derived from women who live at high altitudes , indicating that the hypoxic state could alter placental morphology. In addition to the previous studies, many authors have concluded that the pathologic changes in the placentas of diabetic women such as significant thickening of the basement membrane of trophoblasts, separation of basal membranes in basal capillaries, distention and proliferation of endothelial cells, and disarrangements of the perivascular space are significant factors resulting from placental hypoxia, and they contribute toward fetal anoxia in pregnancy complicated by diabetes mellitus . Other researchers  have concluded that the accumulation of histochemical compounds, for example carbohydrates and fat droplets in the basement membrane leads to structural changes such as a thickened basement membrane . A frequent association between villous fibrinoid masses and thickening of the trophoblastic basement membrane has been observed, as already reported in many studies [46,47]. This association, however, is not fully understood. According to previous researches, both fibrinoid deposition and thickening of the basement membrane might be manifestations of antigen–antibody reactions [47,48].
In the present study, the diabetic placenta showed numerous fetal blood capillaries in comparison with control one; these capillaries were in close association with the trophoblast and consequently came in contact with the thinned-out syncytiotrophoblasts. In recent studies, these results have been explained as follows: in a pregnancy complicated by maternal diabetes, fetal hyperglycemia induces changes in the placental vasculature such as increased growth and angiogenesis. Also, the metabolic effects of insulin result in the stimulation of glycogen synthesis and modulation of angiogenesis on the placental arterial endothelium . In addition to this, many authors have observed that the syncytiotrophoblasts come in contact with some peripherally shifted capillaries with no intervening connective tissue stroma in between, forming the so-called vasculosyncytial membrane, which might represent an attenuated form of the placental barrier [28,49]. Also, in this work, the multilaminal basement membrane that surrounded the capillaries showed a huge variation, possibly because of the variation in capillary age . These structural changes resulted in the thickening of the placental barrier, leading to impairment in transplacental transport, and thus decreased placental blood flow, which is crucial for the transport of water, nutrients, and waste from the maternal to the fetal space to sustain normal placental and fetal development .
In the present study, electron microscopic examination of the stroma of the placental villi in the diabetic group showed numerous Hofbauer cells in comparison with the control group. Recent studies  have reported that Hofbauer cells are placental macrophages that are present in the villus across gestation. Although they were identified more than 100 years ago, their specific role in placental function remains largely unelucidated. Many other studies have concluded that Hofbauer cells are present within the core of the chorionic villous of the placenta, particularly numerous in early pregnancies. They are believed to be a type of macrophage and are most likely involved in preventing the transmission of pathogens from the mother to the fetus . Many authors have reported that Hofbauer cells often lie adjacent to a thick basement membrane, which underlies a layer of cytotrophoblast stem cells that are the progenitors of all the trophoblast lineages. Other researchers have added that they are the major cell type of the human placental villous core and are particularly numerous at the beginning of pregnancy. Other workers have concluded that Hofbauer cells are fetal placental antigen-presenting cells that share a number of features with macrophages but also have some distinct properties [54–58]. A recent study hypothesized that the locations and numbers of Hofbauer cells were significantly correlated with the vascular structures within the placental villi core and therefore might be implicated to play roles in placental vasculogenesis and angiogenesis . In agreement with our result, the presence of Hofbauer cells more frequently in the diabetic group, many studies have proved that these cells are present in immature placenta and the placenta of complicated pregnancies and either disappear or become very scanty after the fourth month of normal gestation [60–62]. Also, there has been wide agreement that these cells are a feature of placenta from cases of rhesus incompatibility , villitis of unknown etiology , in placenta from pregnancies with histological chorioamnionitis , and placenta from diabetic women [52,66,67]. Therefore, we concluded that Hofbauer cells might play a key role in placental pathophysiology, and further studies of their isolation and culture are needed.
Many studies have shown that the vast majority of neurological abnormalities present during childhood have a prenatal or a perinatal origin, especially in complicated pregnancies . Until recently, clinical laboratory assessments were based essentially on biochemical parameters, ultrasound and Doppler patterns, and the determination of blood pH and gases. However, the measurement of brain constituents may provide a direct indication of cell damage in the nervous system. The S100 protein, a calcium-binding protein highly concentrated in the nervous system, appears to be a marker in prenatal and perinatal medicine because of its reproducible, simple, and reliable measurements . In the present work, localization of S100 protein was observed in the trophoblastic and villous stroma cells of diabetic placenta, and was almost absent in the control group. In agreement with our result [68,69], many studies have shown that the concentration of S100 protein increased in amniotic fluid and in the cord blood of fetuses with brain damage, suggesting that these tissues may, at least in part, be responsible for the high level found in the fetal circulation of high-risk pregnancies. Also, they added that the significance of placental S100 protein should be taken into account when this protein is used as a marker of brain injury in the fetus or infant at birth. It was suggested that the direct assessment of neurologically adverse effects in the newborn by means of markers in peripheral blood is of great clinical significance. Also, measurements of brain-specific proteins could be used to monitor the effects of pharmacologic interventions to protect the brain as well as to evaluate the possible adverse or beneficial effects of new interventions . It was concluded that significantly higher values of these proteins were found under conditions associated with adverse neonatal outcome, especially after perinatal asphyxia and preterm labor . In addition to this, a strong positive correlation was found between amniotic fluid and villous tissue S100 protein and the oxidative stress resulting from pregnancies, such as chronic fetal hypoxia . Hence, it was suggested that chronic fetal hypoxia increases the intrauterine release of S100 protein .
In the present work, structural abnormalities in the diabetic placental villi have been observed. These histological abnormalities were not observed in every diabetic placenta but they were not completely absent in any. Also, these findings might support the hypothesis that impaired placental function in gestational diabetes was one of the main reasons for the increased frequency of fetal complications in diabetic pregnancies. According to our results, the presence of S100 protein may serve as a marker of brain damage in diabetic pregnancy.
There are no conflicts of interest.
Hiden U, Glitzner E, Hartmann M, Desoye G. Insulin and the IGF system in the human placenta of normal and diabetic pregnancies. J Anat. 2009;215:60–68
Kaufmann P, Mayhew TM, Charnock Jones DS. Aspects of human fetoplacental vasculogenesis and angiogenesis. II. Changes during normal pregnancy. Placenta. 2004;25:114–126
Wolf HJ, Desoye G. Immunohistochemical localization of glucose transporters and insulin receptors in human fetal membranes at term. Histochemistry. 1993;100:379–385
Polin RA, Fox WW, Abman SH Fetal and neonatal physiology. 19982nd ed. Saunders Philadelphia
Desoye G, Myatt LReece EA, Coustan DR, Gabbe SG. The placenta Diabetes in women: adolescence, pregnancy and menopause. 20043rd ed. Philadelphia Lippincott Williams & Wilkins:147–157 In: , pp.
Mayhew TM. Fetoplacental angiogenesis during gestation is biphasic, longitudinal and occurs by proliferation and remodelling of vascular endothelial cells. Placenta. 2002;23:742–750
Evans MJ. Diabetes and pregnancy: a review of pathology. Br J Diabetes Vasc Dis. 2009;9:201–206
Dutta DCDutta DC. Medical and surgical illness complicating pregnancy Textbook of obstetrics. 20046th ed. New central bookAgency (P) Ltd:284–290 In: , (Ed), pp.
Reece EA, Leguizam Ón G, Wiznitzer A. Gestational diabetes: the need for a common ground. The Lancet. 2009;373:1789–1797
World Health Organization (WHO). Definition and Diagnosis of Diabetes Mellitus and Intermediate Hyperglycaemia. 2006 World Health Organization/International Diabetes Federation
Al Okail MS, Al Attasm OS. Histological changes in placental syncytiotrophoblasts of poorly controlled gestational diabetic patients. Endocr J. 1994;41:355–360
Buchanan TA, Xiang A, Kjos SL, Watanabe R. What is gestational diabetes? Diabetes Care. 2007;30(Suppl 2):S105–S111
Singer DB. The placenta in pregnancies complicated by diabetes mellitus. Perspect Pediatr Pathol. 1984;8:199–212
Gewolb IH, Merdian W, Warshaw JB, Enders AC. Fine structural abnormalities of the placenta in diabetic rats. Diabetes. 1986;35:1254–1261
World Health Organization and Department of Noncommunicable Disease Surveillance. Definition, diagnosis and classification of diabetes mellitus and its complications: report of a WHO consultation. Geneva, Switzerland: World Health Organization, Department of Noncommunicable Disease Surveillance; 1999.
Bancroft JD, Stevens A Theory and practice of histological techniques. 19964th ed. New York Churchill Livingstone
Hsu SM, Raine L, Fanger H. Use of avidin-biotin-peroxidase complex (ABC) in immunoperoxidase techniques: a comparison between ABC and unlabeled antibody (PAP) procedures. J Histochem Cytochem. 1981;29:577–580
Romanowicz L, Jaworski S. Collagen of umbilical cord vein and its alterations in pre-eclampsia. Acta Biochim Pol. 2002;49:451–458
Smith SC, Baker PN, Symonds EM. Placental apoptosis in normal human pregnancy. Am J Obstet Gynecol. 1997;177:57–65
Pietryga M, Biczysko W, Wender Ozegowska E, Brazert J, Bieganska E, Biczysko R. Ultrastructural examination of the placenta in pregnancy complicated by diabetes mellitus. Ginekol Pol. 2004;75:111–118
Majumdar S, Dasgupta H, Bhattacharya K, Bhattacharya A. A study of placenta in normal and hypertensive pregnancies. J Anat Soc India. 2005;54:34–38
Moustafa ZF The morphological and histochemical study of human full term placenta of the normal and those of pre-eclampsia. 1968 Cairo Ain Shams Univ Fac Med
Salvatore CA. The placenta in acute toxemia. A comparative study. Am J Obstet Gynecol. 1968;102:347–353
Hekmat AS, Tomader MK, Mona AS, Eman SM. Apoptosis in normal and diabetic human: light and electron microscopic study. Egypt J Histol. 2008;31:84–93
Daskalakis G, Marinopoulos S, Krielesi V, Papapanagiotou A, Papantoniou N, Mesogitis S, Antsaklis A. Placental pathology in women with gestational diabetes. Acta Obstet Gynecol Scand. 2008;87:403–407
Tewari V, Tewari A, Bhardwaj N. Histological and histochemical changes in placenta of diabetic pregnant females and its comparison with normal placenta. Asian Pac J Trop Dis. 2011;1:1–4
Fox H. Fibrinoid necrosis of placental villi. J Obstet Gynaecol Br Commonw. 1968;75:448–452
Mohamed HG Structural changes in the human placenta in cases of pre-eclampsia. 2001 Cairo Cairo Univ Fac Med
Bin Abbas BS, Al Mulhim AN, Sakati NA, Al Ashwal AA. Persistent hyperinsulinemic hypoglycemia of infancy in 38 children. Saudi Med J. 2003;24:890–894
Mayhew TM, Barker BL. Villous trophoblast: morphometric perspectives on growth, differentiation, turnover and deposition of fibrin-type fibrinoid during gestation. Placenta. 2001;22:628–638
Zhang Y, Zhao W, Jiang Y, Zhang R, Wang J, Li C, et al. Ultrastructural study on human placentae from women subjected to assisted reproductive technology treatments. Biol Reprod. 2011;85:635–642
Jansson T, Wennergren M, Powell TL. Placental glucose transport and GLUT 1 expression in insulin-dependent diabetes. Am J Obstet Gynecol. 1999;180(1 I):163–168
Ranjana V, Sabita M, Kaul JM. Cellular Changes in the Placenta in Pregnancies Complicated with Diabetes Int. J. Morphol.. 2010;28(1):259–264
Nanaev AK, Milovanov AP, Domogatsky SP. Immunohistochemical localization of extracellular matrix in perivillous fibrinoid of normal human term placenta. Histochemistry. 1993;100:341–346
Frank HG, Malekzadeh F, Kertschanska S, Crescimanno C, Castellucci M, Lang I, et al. Immunohistochemistry of two different types of placental fibrinoid Acta Anat (Basel). 1994;150:55–68
Verma R, Mishra S, Kaul JM. Cellular changes in the placenta in pregnancies complicated with diabetes. Int J Morphol. 2010;28:259–264
Gude NM, Stevenson JL, Murthi P, Rogers S, Best JD, Kalionis B, King RG. Expression of GLUT12 in the fetal membranes of the human placenta. Placenta. 2005;26:67–72
Sibley CP, Turner MA, Cetin I, Ayukm P, Boyd CA, D'Souza SW, et al. Placental phenotypes of intrauterine growth. Pediatr Res. 2005;58:827–832
Biagini G, Vasi V, Pugnaloni A, Valensise H, Rizzoli R, Miccoli MC, et al. Morphological development of the human placenta in normal and complicated gestation: a quantitative and ultrastructural study. Gynecol Obstet Invest. 1989;28:62–69
Battistelli M, Burattini S, Pomini F, Scavo M, Caruso A, Falcieri E. Ultrastructural study on human placenta from intrauterine growth retardation cases. Microsc Res Tech. 2004;65:150–158
De Luca Brunori I, Battini L, Brunori E, Lenzi P, Paparelli A, Simonelli M, et al. Placental barrier breakage in preeclampsia: ultrastructural evidence. Eur J Obstet Gynecol Reprod Biol. 2005;118:182–189
Esterman A, Greco MA, Mitani Y, Finlay TH, Ismail Beigi F, Dancis J. The effect of hypoxia on human trophoblast in culture: morphology, glucose transport and metabolism. Placenta. 1997;18:129–136
Zhang Y, Cui Y, Zhou Z, Sha J, Li Y, Liu J. Altered global gene expressions of human placentae subjected to assisted reproductive technology treatments. Placenta. 2010;31:251–258
Zybzhitskaia LB, Kosheleva NG, Semenov VV, Nazarova SI, Ailamazian EK. Placental changes in type 1 diabetes mellitus. Arkh Patol. 2008;70:14–17
Wawrzycka B, Zarebska A, Wawrzycki B, Matusiewicz J, Czerny K. Histological and ultrastructural investigations of placenta villi in intrauterine growth restriction of fetuses (IUGR). Ann Univ Mariae Curie Sklodowska Med. 2002;57:409–414
Soma H, Hata T, Oguro T, Fujita K, Kudo M, Vaidya U. Characteristics of histopathological and ultrastructural features of placental villi in pregnant Nepalese women. Med Mol Morphol. 2005;38:92–103
Anderson WR, McKay DG. Electron microscope study of the trophoblast in normal and toxemic placentas. Am J Obstet Gynecol. 1966;95:1134–1148
Sen DK, Langley FA. Villous basement membrane thickening and fibrinoid necrosis in normal and abnormal placentas. Am J Obstet Gynecol. 1974;118:276–281
McCormick JN, Faulk WP, Fox H, Fudenberg HH. Immunohistological and elution studies of the human placenta. J Exp Med. 1971;133:1–18
Burton GJ, Tham W. Formation of vasculo-syncytial membranes in the human placenta. J Dev Physiol. 1992;18:43–47
Asmussen I. Ultrastructure of the villi and fetal capillaries of the placentas delivered by non-smoking diabetic women (white group D). Acta Pathol Microbiol Scand A. 1982;90:95–101
Jansson N, Greenwood SL, Johansson BR, Powell TL, Jansson T. Leptin stimulates the activity of the system A amino acid transporter in human placental villous fragments. J Clin Endocrinol Metab. 2003;88:1205–1211
Tang Z, Abrahams VM, Mor G, Guller S. Placental Hofbauer cells and complications of pregnancy. Ann NY Acad Sci. 2011;1221:103–108
Zaccheo D, Pistoia V, Castellucci M, Martinoli C. Isolation and characterization of Hofbauer cells from human placental villi. Arch Gynecol Obstet. 1989;246:189–200
Schmidt AM, Vianna M, Gerlach M, Brett J, Ryan J, Kao J, et al. Isolation and characterization of two binding proteins for advanced glycosylation end products from bovine lung which are present on the endothelial cell surface. J Biol Chem. 1992;267:14987–14997
Jones CJ, Fox H. Ultrastructure of the normal human placenta. Electron Microsc Rev. 1991;4:129–178
Castellucci M, Zaccheo D. The Hofbauer cells of the human placenta: morphological and immunological aspects. Prog Clin Biol Res. 1989;296:443–451
King BF. The fine structure of the placenta and chorionic vesicles of the bush baby, Galago crassicaudata. Am J Anat. 1984;169:101–116
Castellucci M, Zaccheo D, Pescetto G. A three-dimensional study of the normal human placental villous core. I. The Hofbauer cells. Cell Tissue Res. 1980;210:235–247
Seval Y, Korgun ET, Demir R. Hofbauer cells in early human placenta: possible implications in vasculogenesis and angiogenesis. Placenta. 2007;28:841–845
Wood GW. Mononuclear phagocytes in the human placenta. Placenta. 1980;1:113–123
Hofbauer J. Pathology of the placenta; clinical study and clinical anatomy. Am J Obstet Gynecol. 1925;10:1–14
Wilkin P. Pathologie du Placenta Étude clinique et anatomo-clinique. 1965 Paris Masson
Jones CJ, Fox H. An ultrastructural study of the placenta in materno-fetal rhesus incompatibility. Virchows Arch A Pathol Anat Histol. 1978;379:229–241
Kim JS, Romero R, Kim MR, Kim YM, Friel L, Espinoza J, Kim CJ. Involvement of Hofbauer cells and maternal T cells in villitis of unknown aetiology. Histopathology. 2008;52:457–464
Joerink M, Rindsjö E, Van Riel B, Alm J, Papadogiannakis N. Placental macrophage (Hofbauer cell) polarization is independent of maternal allergen-sensitization and presence of chorioamnionitis. Placenta. 2001;32:380–385
Fox H. The incidence and significance of Hofbauer cells in the mature human placenta. J Pathol Bacteriol. 1967;93:710–717
Desoye G, Kaufmann PDjelmis J, Desoye G, Ivanisevic M. The human placenta in diabetes Diabetology of Pregnancy (Frontiers in diabetes). 2005 Basel Karger Pub:94–109 In: , pp.
Michetti F, Gazzolo D. S100B testing in pregnancy. Clin Chim Acta. 2003;335:1–7
Marinoni E, di Iorio R, Gazzolo D, Lucchini C, Michetti F, Corvino V, Cosmi EV. Ontogenetic localization and distribution of S-100beta protein in human placental tissues. Obstet Gynecol. 2002;99:1093–1099
Wijnberger LD, Nikkels PG, Van Dongen AJ, Noorlander CW, Mulder EJ, Schrama LH, Visserm GH. Expression in the placenta of neuronal markers for perinatal brain damage. Pediatr Res. 2002;51:492–496
Gazzolo D, Vinesi P, Bartocci M, Geloso MC, Bonacci W, Serra G, et al. Elevated S100 blood level as an early indicator of intraventricular hemorrhage in preterm infants. Correlation with cerebral Doppler velocimetry. J Neurol Sci. 1999;170:32–35
Tskitishvili E, Sharentuya N, Temma Asano K, Mimura K, Kinugasa Taniguchi Y, Kanagawa T, et al. Oxidative stress-induced S100B protein from placenta and amnion affects soluble Endoglin release from endothelial cells. Mol Hum Reprod. 2010;16:188–199
Loukovaara M, Teramo K, Alfthan H, Hämäläinen E, Stefanovic V, Andersson S. Amniotic fluid S100B protein and erythropoietin in pregnancies at risk for fetal hypoxia. Eur J Obstet Gynecol Reprod Biol. 2009;142:115–118