Ultrastructural changes of the early visceral yolk sac layer of mouse embryos after maternal injection of trypan blue

Summary The ultrastructural features of the early visceral yolk sac epithelium of normal mouse embryos on day 9 were compared to those whose mothers had received a single subcutaneous injection of 100 mg/kg trypan blue on day 8. The following results were obtained: In normal embryos the visceral yolk sac cells are predominantly characterized by numerous membrane bounded inclusions localized in the supranuclear cytoplasm. In embryos of animals treated with trypan blue, at about 12h after injection large single and only partly membrane bounded vacuoles are observed occupying most of the apical cytoplasm. Up to 24h after injection large cytoplasmic areas are seen which are in a stage of autodigestion possibly due to leakage of the vacuolar content. These alterations are exclusively limited to the visceral yolk sac epithelium whereas in the cells of the embryonic part, e.g. head process, no changes could be found. The observations are discussed in relation to the mechanism of the teratogenic activity of trypan blue.This investigation has kindly been supported by a grant of the Deutsche Forschungsgemeinschaft (Schl 166/1)     

Ovarian yolk sac tumor with virilization during pregnancy: immunohistochemical demonstration of Leydig cells as functioning stroma

A case is reported of yolk sac tumor occurring in the left ovary and complicated by pregnancy. The 22-year-old patient presented at 28 weeks gestation with virilization and elevated serum levels of testosterone and alpha-fetoprotein. The tumor showed the typical features of yolk sac tumor with a mixture of islands of Leydig cells. The accumulations of Leydig cells were well demarcated from the cellular components of the yolk sac tumor and were distributed throughout the tumor, although with predominant localization at the periphery. By immunohistochemistry the Leydig cells were intensely positive for vimentin and negative for cytokeratins, allowing clear distinction from the cell components of the yolk sac tumor, which were positive for cytokeratins and negative for vimentin. Testosterone was also identified in the cytoplasm of the Leydig cells. After tumor resection the testosterone and alpha-fetoprotein levels declined simultaneously; this, together with the immunohistochemical demonstration of testosterone, indicates that the Leydig cells were responsible for the endocrine manifestations. Furthermore, antibodies against inhibin alpha-subunit and calretinin could be used to detect the Leydig cells. The present case, a combination of yolk sac tumor and Leydig cells acting as a functioning stroma and causing virilization during pregnancy, is very rare.     

原发性性腺外卵黄囊瘤40例临床病理分析

目的：探讨原发性性腺外卵黄囊瘤( extragonadal yolk sac tumor, eYST)的临床病理特征、组织来源、形态学特点、免疫表型及鉴别诊断。方法回顾性分析40例原发性eYST的临床病理资料、形态学和免疫表型特征,结合文献对其临床病理特点进行分析。结果40例eYST中男性24例、女性16例,年龄6个月~42岁,平均12岁,≥12岁者17例,占42.5%。肿瘤分别位于纵隔16例(40.0%)、骶尾12例(30.0%)、腹膜后5例(12.5%)、松果体4例(10.0%)、阴道3例(7.5%)。40例患者中32例为纯YST(80.0%),8例(20.0%)含有1~2种其他类型的生殖细胞肿瘤(germ cell tumor, GCT)成分。结论原发性eYST少见,纵隔和骶尾是eYST最常见的解剖部位;发生在纵隔的肿瘤患者大部分限于成年男性,患者平均年龄明显大于骶尾、腹膜后、松果体和阴道肿瘤的患者(P<0.05),发生在其他部位的eYST多限于青春期前的儿童;一些成人eYST的病例包含其他类型的GCT成分,儿童eYST总是为纯YST;eYST表现出多形性的组织学特征,结合免疫表型对明确诊断、鉴别诊断有一定价值。     

Identification of erythroid-enriched gene expression in the mouse embryonic yolk sac using microdissected cells.

Little is known about the genes that control the embryonic erythroid program. Laser capture microdissection was used to isolate primitive erythroid precursors and epithelial cells from frozen sections of the embryonic day 9.5 yolk sac. The RNA samples were amplified and labeled for hybridization to Affymetrix GeneChip Mouse Genome 430A 2.0 arrays. Ninety-one genes are expressed significantly higher in erythroid than in epithelial cells. Ingenuity pathway analysis indicates that many of these erythroid-enriched genes cluster in highly significant biological networks. One of these networks contains RBTN2/LMO2, SCL/TAL1, and EKLF/KLF1, three of the very few genes required for primitive erythropoiesis. Quantitative real-time polymerase chain reaction was used to verify that platelet factor 4, reelin, thrombospondin-1, and muscleblind-like 1 mRNA is erythroid-enriched. These genes have established roles in development or differentiation in other systems, and are, therefore, good candidates for regulating primitive erythropoiesis. These results provide a catalog of genes expressed during primitive erythropoiesis.     

Gastric cancer with choriocarcinoma and yolk sac tumor components: case report

Choriocarcinoma- and yolk sac tumor-like differentiation have rarely been reported in gastric cancers. We report a case of gastric adenocarcinoma, concurrently possessing choriocarcinoma and yolk sac tumor components, of a 74-year-old man. A hemorrhagic, 11 × 8 × 3 cm, tumor with ulceration was located in the body and pre-pylorus of the stomach. Histological examination of the resected specimens demonstrated intermingled proliferation of three different components, namely, adenocarcinoma, choriocarcinoma and yolk sac tumor, which were immunoreactive for carcinoembryonic antigen (CEA), beta-subunit of human chorionic gonadotropin (HCG) and alpha-fetoprotein (AFP), respectively. Gastric cancers with germ cell tumor components are uncommon and this is the second reported case of gastric cancer with choriocarcinoma and yolk sac tumor components.     

Development of the secondary human yolk sac: correlation of sonographic and anatomical features.

Transvaginal ultrasound examination of the secondary yolk sac was performed in 145 first trimester pregnancies with a normal outcome (Group A), in 10 normal pregnancies undergoing artificial termination (Group B) and in 25 pregnancies that subsequently failed (Group C) due to embryonic death (n = 17) or to spontaneous abortion of a live embryo (n = 8). The yolk sac structure of all cases from Group B and from 12 cases of Group C were examined morphologically, in order to investigate the changes secondary to normal yolk sac senescence or to pregnancy complication and to evaluate the relationship existing between these changes and ultrasound features. The yolk sac diameter measured in vivo increased significantly between 6 and 10 weeks of gestation and then decreased significantly. Morphologically, the yolk sac showed degenerative changes after 9 weeks of gestation suggesting that the disappearance of the yolk sac in normal pregnancies was a spontaneous event of embryonic development rather than the result of mechanical compression by the expanding amniotic cavity. Yolk sac measurements in complicated pregnancies were not predictive of pregnancy outcome. Irrespective of gestational age, important degenerative changes were found in pregnancies complicated by embryonic death or disappearance, suggesting that variation of yolk sac size and appearance in these cases is the consequence of abnormal embryonic development of death rather than being the primary cause of early pregnancy failure.     

Ovarian hepatoid yolk sac tumours: morphological, immunohistochemical and ultrastructural features

AIM: The clinicopathological, immunohistochemical and ultrastructural features of two ovarian hepatoid yolk sac tumours (H-YST) from our files are reviewed. METHODS AND RESULTS: Using avidin-biotin-peroxidase complex technique, the immunoprofile of these tumours was compared to that of a classic yolk sac tumour and to that previously reported for hepatocellular carcinomas. The clinicopathological and morphological features of our cases are similar to the seven previously reported ovarian cases. This rare germ cell tumour occurs in young females (mean age = 17.6 years) and presents most commonly with abdominal pain and a large ovarian mass (average size = 140 mm). Histologically, the tumours display a striking resemblance to hepatocellular carcinoma. The absence of an associated typical pattern of yolk sac tumour or other germ cell neoplasm may make it difficult to recognize the germ cell origin of this lesion. Our cases demonstrated positive staining for alpha-fetoprotein and alpha-1-antitrypsin. In addition, there was immunoreactivity with polyclonal carcinoembryonic antigen (CEA) antiserum in a canalicular pattern, focal staining for inhibin, oestrogen and progesterone receptors and absence of immunoreactivity for CK7 that contrasts with the immunophenotype of a usual yolk sac tumour. CONCLUSIONS: Ovarian H-YST and hepatocellular carcinoma share a similar immunoprofile. Ovarian H-YST is a highly aggressive tumour, most patients exhibit recurrence or die of disease within 2 years of diagnosis.     

A light and electron microscopic study of the mouse visceral yolk sac endodermal cells in the middle and late embryonic periods, showing the possibility of definitive erythropoiesis

Hematological studies have revealed the importance of the visceral yolk sac (VYS) in the primitive erythropoiesis of mouse embryos at an early stage before day 12. We examined the possibility of the occurrence of extra-embryonic erythropoiesis at a stage later than embryonic day 12 by light and electron microscopic analyses. Surprisingly, a novel structure in the form of erythrocyte-like globules was observed in the VYS endodermal cells. They were consistently present in the VYS endodermal cells from embryonic day 12 until day 18 (birth is day 19), by immunocytochemical and enzyme histochemical analyses. They were immuno-positive for mouse erythrocyte antibody and also positive for the benzidine reaction showing the presence of hemoglobin. The erythrocyte-like globules were shown to be the erythrocytes present in the cytoplasm. These results indicated that erythropoiesis in the VYS endodermal cells continues from the early embryonic stage, as primitive erythropoiesis, until the late stage.     

Escape of the yolk sac: a hypothesis to explain the embryogenesis of gastroschisis

Gastroschisis is a significant birth defect that in many countries has shown an increased prevalence in recent decades, and the change has affected primarily younger mothers. Despite numerous epidemiological studies no other consistent associated risk factor has been identified. In this paper we review the five main theories related to the pathogenesis of this malformation and outline the reasons why we think none fully explains the embryogenesis of gastroschisis. We briefly present some clinical observations we have made that we consider germane to the pathogenesis and outline a hypothesis that we think can account for the origins of this malformation. Our proposal is that the determining defect in gastroschisis is failure of the yolk sac and related vitelline structures to be incorporated into the umbilical stalk. Otherwise, ventral closure of the lateral abdominal walls occurs normally, thus orphaning the vitelline duct and yolk sac outside both the main body stalk and the abdominal wall. Thus, in addition to the umbilicus, the abdominal wall has a separate perforation through which the midpoint of the gut is attached to the exteriorized vitelline structures. This connection through the ventral wall prevents normal egress of the gut into the umbilical cord during the second month of development and acts as the egress point for the gut resulting in gastroschisis.     

Freeze-fracture observations on the visceral yolk sac placenta of rats, mice and hamsters

Summary Freeze-fracture replicas of visceral yolk sac from rats, mice and hamsters in late stages of gestation were studied by electron microscopy. Special attention was directed toward determining the types of junctional specializations that exist between the columnar endoderm cells of this placental membrane. In all three species, well-developed, zonular tight (occluding) junctions were found on the contiguous lateral surfaces of the endoderm cells. The tight junctional network, located in an immediate subluminal position, was from 0.2–0.5 m in depth and consisted at any point of 2–5, interconnecting, 9 m wide, strands (P-face) or shallow furrows (E-face). Patch-like aggregations of irregular intramembrane particles, characteristic of desmosomes (maculae adherentes), also were observed at scattered sites below the tight junctions. However, no evidence of gap (communicating) junctions was encountered. The endoderm cells of the rodent visceral yolk sac have been shown to play a central role in the selective transport of macromolecular substances from the maternal to the fetal system. Tight junctions may be vital to this endodermal cell function by preventing random paracellular fluxes of macromolecules.This investigation was supported by U.S. National Institutes of Health Grant HD-09585     

Cytomorphology of yolk sac tumor of the liver in fine-needle aspiration: a pediatric case

Yolk sac tumors (YST) in extragonadal locations are rare. Cytologic diagnosis of YST on fine-needle aspiration (FNA) smears may be a challenge to the cytopathologist. Further neo-adjuvant therapy may be based on cytologic diagnosis making accuracy important. We studied FNA material from a hepatic mass in a pediatric patient to further define the cytomorphologic features of hepatic YST. Features include large pleomorphic balls of tumor cells with high nuclear to cytoplasmic ratios, papillary or microglandular pattern of growth, cytoplasmic and intranuclear vacuoles, and prominent nucleoli. Positive immunohistochemical studies included alpha-fetoprotein, cytokeratin AE1/AE3, and CAM 5.2, which are useful in supporting the diagnosis. We report a pediatric patient in whom the diagnosis of hepatic YST was made by cytologic, histologic, and immunohistochemical studies. The subsequent liver biopsy was consistent with the FNA diagnosis. Our findings may further help to characterize the cytomorphologic features of this rare lesion.     

Erythropoietin and erythropoietin-receptor producing cells demonstrated by in situ hybridization in mouse visceral yolk sacs

We have previously demonstrated that mRNAs for erythropoietin and the erythropoietin receptor temporarily express on the visceral yolk sacs on days 9–11 of gestation in mice. In order to investigate the sites of expression, we performed in situ hybridization on visceral yolk sacs. Visceral yolk sacs from 10-day-old mice embryos were frozen in liquid nitrogen, and processed for cryosections. Sections were hybridized with a ³⁵S-labeled RNA probe complementary to mRNA coding for erythropoietin or erythropoietin receptor. Erythropoietin mRNA was detectable in 57.6% of the endodermal epithelial cells, while erythropoietin-receptor mRNA was discerned in 90.8% of the endodermal cells and mesodermal cells, including hemocyteblasts. Moreover, erythropoietin protein was detectable in 52.8% of the endodermal epithelial cells, and on the surface of hemocyteblasts and mesothelial cells. Erythropoietin-receptor protein was discernible in 87.2% of the endodermal cells and in the corresponding mesodermal cells to those where erythropoietin protein was expressed by immunohistochemical examinations. The results indicate that erythropoietin-synthesizing cells are located in half of the endodermal epithelial cells, while the majority of cells in the visceral yolk sac are erythropoietin-receptor-producing cells, indicating that almost all cell population in the visceral yolk sac is erythropoietin-responding cells via both autocrine and paracrine routes.     

人卵黄囊间质干细胞的分离纯化及诱导成脂的实验研究

目的:分离纯化及体外定向诱导人卵黄囊间质干细胞(YS-MSC)分化为脂肪细胞。方法:显微分离人卵黄囊, 经酶消化得到卵黄囊细胞, 卵黄囊细胞经贴壁培养、传代纯化得到人YS-MSC, 流式细胞仪检测YS-MSC表面抗原表达, 钙钴法测定碱性磷酸酶(AKP)活性;地塞米松、消炎痛、胰岛素定向诱导YS-MSC分化为脂肪细胞。油红O检测中性脂肪。结果:人卵黄囊间质干细胞易于分离、纯化, 体外培养增殖潜能大。卵黄囊间质干细胞CD29、CD44、CD166及CD105表达阳性, CD34、CD45和CD86为阴性;AKP弱阳性。卵黄囊间质干细胞经成脂诱导转化为大小不等的园形或椭圆形细胞, 可见胞浆内有少量微小脂滴形成, 随时间延长, 胞浆中脂滴相互融合, 胞核被挤于细胞的一侧, 经油红O染色脂滴染橘红色, 符合脂肪细胞的生物学特征。结论:人卵黄囊间质干细胞与成体间质干细胞表型一致, 在体外可以分化为脂肪细胞。     

An extragonadal yolk sac tumor presumed to be of postmeiotic germ cell origin by genetic zygosity analysis via single nucleotide polymorphism array

An extragonadal yolk sac tumor (YST) is a rare malignant germ cell tumor that usually occurs in childhood. The pathogenesis of extragonadal YST remains largely unknown, especially with regards to its cell of origin. Herein, we report a case of extragonadal YST arising in the uterine round ligament. A 31‐year‐old Japanese woman, para 2, underwent partial resection of a left‐sided, 5‐cm, solid inguinal mass. Intraoperative findings showed enlargement of the uterine round ligament in the inguinal canal. Pathological evaluation diagnosed the mass as YST with a mature teratoma (MT) component. The preoperative α‐fetoprotein level was markedly elevated, at 24 790 ng/mL. Postoperative magnetic resonance imaging revealed a right ovarian MT and a 3‐cm mass remaining in the left lower abdominal wall. The patient underwent total abdominal hysterectomy, bilateral adnexectomy, and left inguinal mass resection. We sampled three frozen tissues (YST, right ovarian MT, and left normal ovary) and performed a single nucleotide polymorphism (SNP) array. Pathological evaluation revealed remnant extragonadal YST in the left inguinal region. The SNP array demonstrated a completely homozygous YST genotype. Copy number variations were gains of 1p, 1q, 2p, 3p, 7p, 8p, 10q, 14q, 18p, 20q, Xp, and Xq and losses of 12q, 20p, and Xq. The right ovarian MT and left normal ovary were partially homozygous and heterozygous, respectively. The evidence suggests that this neoplasm is presumed to be a postmeiotic germ cell origin.     

Formation of hematopoietic colonies of donor's type in the bone marrow of irradiated chicks after transplantation of quail yolk sac and limb bud cells into their bone marrow

Ability to form hematopoietic cell colonies from the yolk sac and limb bud of a quail embryo at the 60 h incubation stage (i.e., before establishment of a closed circulation) was studied in the bone marrow of sublethally irradiated 3-week-old chicks. The experimental results are based on the ability to distinguish between quail and chick cells by means of a natural marke (Feulgen-positive nucleolus). After transplantation of limb bud cells roughly 3 times more hematopoietic colonies were found to be formed than after transplantation of yolk sac cells of the quail embryo. With the dose of irradiation used, about 75% of exogenous (quail) and 25% of endogenous (chick) hematopoietic colonies were identified in the bone marrow.Department of Histology and Cytology, Moscow University. (Presented by Academician of the Acad of Medical Sciences of the USSR A. D. Ado.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny Vol. 88, No. 10, pp. 432–434, October, 1979.     

Glypican 3 has a higher sensitivity than alpha‐fetoprotein for testicular and ovarian yolk sac tumour: immunohistochemical investigation with analysis of histological growth patterns

Zynger D L, McCallum J C, Luan C, Chou P M & Yang X J
(2010) Histopathology 56, 750–757
Glypican 3 has a higher sensitivity than alpha‐fetoprotein for testicular and ovarian yolk sac tumour: immunohistochemical investigation with analysis of histological growth patterns Aims: Glypican 3 (GPC3) has been reported to be overexpressed in yolk sac tumour (YST), but the sensitivity has not been compared with α‐fetoprotein (AFP). YST can form numerous growth patterns and the expression of GPC3 in these patterns has not been studied. The aim was to address these aspects. Methods and results: Sections from testicular or ovarian YST were subjected to immunohistochemistry using GPC3 (n = 39) and AFP (n = 24). Overall immunoreactivity for each case and specific histological patterns were semiquantitatively evaluated (0–3+) and intensity of reactivity was scored (0–3). All cases expressed GPC3 (1+, 5%; 2+, 8%; 3+, 87%) with strong intensity (2.9). The majority expressed AFP (58%) but immunoreactivity was often focal (0, 42%; 1+, 33%; 2+, 25%) and intensity was low (1.0). Using GPC3, >75% of the microcystic (n = 38), macrocystic (n = 26), solid (n = 21), glandular‐alveolar (n = 8), endodermal sinus (n = 7), polyvesicular vitelline (n = 5), enteric (n = 4) and micropapillary (n = 2) growth patterns displayed 2+ or 3+ positivity. Conclusions: YST can display a variety of growth patterns that can be confused with other germ cell tumour components. GPC3 detects all growth patterns tested and has a higher sensitivity for detecting YST than AFP.     

心脏原发性卵黄囊瘤1例及文献复习

目的 :探讨心脏卵黄囊瘤临床病理特征。方法 :采用光镜、电镜和免疫组化标记对 1例心脏卵黄囊瘤进行观察。结果 :组织学瘤组织由多形性瘤细胞排列呈腺样、血管套样或网状结构 ,瘤细胞浆内外有玻璃样小滴。免疫组化显示瘤细胞AFP、AACT阳性。电镜下 :肿瘤细胞胞浆内有微囊及致密电子颗粒 ,胞外亦见类似致密电子小体。结论 :发生于心脏的卵黄囊瘤是极为罕见且高度恶性的 ,它的诊断主要依靠病理组织学及免疫组化检查。电镜检查可作为重要的辅助诊断手段。     

The amniotic, allantoic and yolk sac epithelia of the cat: SEM and TEM studies

Summary The epithelial layers of the feline allantoamnion and yolk sac between the 23rd day and full term were studied using SEM, TEM, and light microscopical histochemistry. Amniotic, allantoic and yolk sac fluid were analysed. The attenuated and relatively inert amniotic epithelium sloughs off completely around the 54th day, the amniotic cavity is then lined by fibrous connective tissue only. The exocoelomic epithelium is regarded as the source of the abundant macrophages, rich in lysosomal enzymes, that are seen in the allantoamniotic membrane after obliteration of the exocoelomic cleft. The allantoic epithelium has been mistaken for the amniotic one by many authors. Its cuboidal, glycogen-rich cells develop coral-like luminal outgrowths after the 45th day, which contain almost all kinds of organelles. The basal cell poles form large interdigitations, and the nuclei become heavily lobulated. The changes are accompanied by drastic alterations in the ionic composition of the allantoic fluid. The yolk sac endoderm differs greatly from the allantoic endoderm. It is the most active epithelium of the accessory fetal membranes. The yolk sac mesothelium retains many long microvilli over the whole gestational period. The nutritional value of the yolk sac fluid is only higher than that of the amniotic fluid in its glycerol and cholesterol values.