第18章 胎盘（Placenta）

基本概念（Basic Concepts）

The gestational sac begins as a spherical structure, with the fetus surrounded by an amnion, a chorion, and placental villi. One surface of the gestational sac implants into the endometrium and becomes the placenta; the villi on the opposite surface degenerate. When you look at placental slides, you can see the layers of the amnion and chorion both in the membrane section (Figure 18.1) and on the fetal surface. In both locations, amnion is on the fetal side, chorion on the maternal side. The two membranes can be peeled apart grossly, because there is no tissue connection between the two.

起初，孕囊是球形结构，胎儿被羊膜、绒毛膜和胎盘绒毛包围。孕囊的一面植入子宫内膜，成为胎盘；对面绒毛退化。观察胎盘切片时，在胎儿面和胎膜部位（图18.1），你都能看到羊膜层和绒毛膜层。在这两个部位，羊膜位于胎儿侧，绒毛膜位于母体侧。大体检查时，这两层膜可以剥离，因为两者之间没有组织连接。

Figure 18.1. Placental membranes. In the membrane section, you can see amnion (1), an artifactual space (2) between amnion and chorion (3), and underlying decidua (4).

图18.1 胎膜。胎膜切片中可以看到羊膜（1），羊膜和绒毛膜（3）之间的人为空隙（2），以及下方的蜕膜（4）。

The villi are fetal structures; they grow downward from the fetal surface in a branching architecture, like the roots of a tree. Vessels and cells inside the villi are fetal. There should not be any maternal vessels in the placenta itself. The spiral arteries of the decidua (endometrium), invaded by trophoblastic cells, spray maternal blood into the space between the villi.

绒毛是胎儿的结构；它们从胎儿面向下生长，形成分支结构，就像树根一样。绒毛内的血管和细胞是胎儿的成分。胎盘本身不应有任何母体血管。蜕膜（子宫内膜）的螺旋动脉被滋养层细胞侵入，将母体血液输送到绒毛之间。

Immature villi have an open and pale appearance (Figure 18.2); they are large compared with the terminal villi of the full-term placenta (when surface area is most required). They are lined by two cell layers, an outer syncytiotrophoblast and an inner cytotrophoblast layer. Very early villi may have a large intermediate trophoblastic proliferation on the surface, but it should be polar (only on one surface, like Don King’s hair). Circumferential proliferation is suspicious for hydatidiform mole.

未成熟绒毛是开放的，淡染（图18.2）；和足月胎盘的终末绒毛相比，它们体积更大（此时最需要表面积）。它们被覆两层细胞，外层为合体滋养细胞，内层为细胞滋养细胞。非常早期的绒毛表面可能有大量中间滋养细胞增殖，但它应该有极性（只在一面上增殖，像唐•金的头发）。环周增殖应怀疑葡萄胎。

Figure 18.2. Immature villi versus terminal villi. (A) Villi at around 8–10 weeks are large in diameter and have a double layer of cells lining the surface (arrow). Tiny fetal capillaries have nucleated red blood cells inside (arrowhead). (B) Taken at the same magnification as A, this shows mature villi at approximately 38 weeks. The villi are much smaller, the fetal capillaries are more prominent, and the cytotrophoblasts have pulled away from the gas-exchange surface into syncytial knots (arrow). Maternal blood and fibrin are visible between villi.

图18.2 未成熟绒毛与终末绒毛。（A）8-10周左右的绒毛直径较大，表面有双层细胞排列（箭）。微小的胎儿毛细血管内，可见有核红细胞（箭头）。（B）与图A相同的放大倍数，显示约38周的成熟绒毛。绒毛更小，胎儿毛细血管更加明显，细胞滋养细胞被从气体交换表面拉进合胞体结节（箭）。绒毛间可见母血和纤维素。

（译注：唐•金的头发，补充图片如下）

Mature villi acquire syncytial knots and perivillous fibrin (like hyaline membranes lining the villi). They become tiny—just large enough to hold a few capillaries (see Figure 18.2).

成熟绒毛形成合胞体结节切和绒毛周围纤维素（就像被覆在绒毛表面的透明膜）。成熟绒毛变得很小，刚好足够容纳一些毛细血管（见图18.2）。

Twin placentas are divided into categories based on how many cell layers they share. Two separate eggs fertilized by two sperm will always form two separate placentas, although they may mash into each other. With two placentas you will see two chorionic plates and two complete sets of membranes (Figure 18.3); this is called diamnionic-dichorionic (di-di). An ovum that splits very early can also produce two entirely separate placentas, so a di-di placenta may be either monozygotic or dizygotic twins.

双胎胎盘根据其共有多少细胞层进行分类。双卵双精总是形成两个独立的胎盘，尽管它们可能会相互挤压。有两个胎盘时，你将看到两个绒毛膜板和两套完整的胎膜（图18.3）；这称为双羊膜双绒毛膜胎盘（di-di）。很早分裂的卵子也可能产生两个完全分离的胎盘，因此di-di可能是单卵双胎或双卵双胎。

Figure 18.3. Twin placentas. (A) In a diamnionic, dichorionic placenta, the dividing membrane is captured here between the arrowheads. Amnion is seen on both surfaces (a), and a double layer of chorion is sandwiched in the middle (c). (B) In a diamnionic, monochorionic placenta, no chorion is present between the layers (arrowheads) of amnion (a).

图18.3 双胎盘。（A）在双羊膜双绒毛膜胎盘中，在两个箭头之间捕捉到分隔膜。两面都有羊膜（A），双层绒毛膜被夹在中间（C）。（B）在双羊膜单绒毛膜胎盘中，两层羊膜（箭头）之间没有绒毛膜（a）。

An ovum that splits a little later, after it has already formed a chorion, will produce two separate amnions and two fetuses; this is a diamnionic-monochorionic placenta (di-mo). An even later split produces two fetuses in the same amnionic sac, or monoamnionic-monochorionic (mo-mo). If the split occurs any later than this, conjoined twins will develop.

一个卵子在形成绒毛膜后稍晚分裂，将产生两个单独的羊膜和两个胎儿；这是双羊膜单绒毛膜胎盘（di-mo）。更晚的分裂在同一羊膜囊中产生两个胎儿，这是单羊膜单绒毛膜胎盘（mo-mo）。如果分裂发生的时间再晚，就形成连体双胎。

切片观察方法（Approach to the Slides）

脐带（Umbilical Cord）

In the umbilical cord, look at the vessels on low power (Figure 18.4). There should be two arteries (usually with constricted lumens) and a vein (open lumen, or the mouth on the surreal Mr. Bill faces that are found on the walls of most histology laboratories). The number of vessels is always noted on sign out, because a two-vessel cord often indicates a fetal abnormality.

低倍镜下观察脐带的血管（图18.4）。应该有两条动脉（通常管腔狭窄）和一条静脉（管腔开放，或者比尔先生脸上的嘴）。病理报告总是记录血管的数量，因为双血管脐带（译注，即单脐动脉，SUA）通常提示胎儿异常。

Figure 18.4. An umbilical cord in cross section, showing two arteries (A) and one vein (V).

图18.4 脐带横截面，显示两条动脉（A）和一条静脉（V）。

（译注：Mr. Bill的嘴脸，补充图片如下）

Study the muscular wall of each vessel to look for neutrophils. Umbilical phlebitis, or neutrophils migrating into the vein wall, is an indicator of early funisitis (a fetal inflammatory response). More advanced funisitis involves the arteries (arteritis), and the most severe cases show neutrophils in the Wharton’s jelly (Figure 18.5).

仔细观察血管壁，以寻找中性粒细胞。脐静脉炎，或中性粒细胞迁移到静脉壁，提示早期脐带炎（一种胎儿炎症反应）。更严重的脐带炎涉及动脉（动脉炎），最严重的病例显示华通胶内中性粒细胞（图18.5）。

Figure 18.5. Funisitis. Neutrophils (arrowheads) can be seen squeezing through the muscular layer of an umbilical artery (A). This migration is a fetal response to infection.

图18.5 脐带炎。可以看到中性粒细胞（箭头）挤进脐动脉的肌层（A）。中性粒细胞迁移是胎儿对感染的反应。

（译注：脐带炎非常漂亮的图文见https://healthjade.net/funisitis/）

胎膜（Placental Membranes）

The membrane roll is evaluated for the following:

对胎膜卷进行以下评估：

• Chorionitis and chorioamnionitis: Look for neutrophils invading the chorion and/or amnion. Neutrophils in the decidua (below the chorion) are okay (Figure 18.6). Table 18.1 summarizes staging and grading of chorioamnionitis. Inflammation may result in a very reactive (tall, papillary) amnion. Unlike funisitis, this is a maternal response.

• 绒毛膜炎和绒毛膜羊膜炎：寻找侵入绒毛膜和/或羊膜的中性粒细胞。蜕膜（位于绒毛膜下方）中的中性粒细胞是正常的（图18.6）。表18.1总结了绒毛膜羊膜炎的分期和分级。炎症可能导致非常剧烈的羊膜反应（高细胞，乳头状）。与脐带炎不同，这是一种母体反应。

Figure 18.6. Chorioamnionitis. A collection of neutrophils (pus) has formed between the amnion and chorion (arrow). Neutrophils can also be seen beneath the amnion (arrowhead). Inflammation in the decidua (oval) may be physiologic and is not sufficient to diagnose chorioamnionitis. This is a maternal response to infection.

图18.6 绒毛膜羊膜炎。羊膜和绒毛膜之间聚积了一群中性粒细胞（脓液）（箭）。羊膜下也有中性粒细胞（箭头）。蜕膜（卵圆形图示）的炎症可能是生理性的，不足以诊断绒毛膜羊膜炎。这是母体对感染的反应。

Table 18.1. Criteria for staging of acute chorioamnionitis and funisitis

表18.1 急性绒毛膜羊膜炎和脐带炎的分期标准

Grade 1 = focal disease; grade 2 = extensive disease.

1级=局灶性疾病；2级=广泛性疾病。

• Meconium staining: If, on low power, the amnion has a flat and autolyzed look, with edema separating amnion from chorion, look closely for meconiophages (Figure 18.7). These are histiocytes eating meconium (baby bile) pigment, and they appear granular and brown-gold. The attenuated look of the amnion is due to the caustic nature of the meconium, just as gallbladders look when they have been sitting around for a day or so.

• 胎粪染色：如果在低倍镜下，羊膜呈扁平自溶状，水肿将羊膜与绒毛膜分离，则仔细观察有无吞噬胎粪的组织细胞（图18.7）。这是吞噬胎粪（婴儿胆汁）色素的组织细胞，呈颗粒状和棕黄色。羊膜变薄的原因是胎粪腐蚀，就像胆囊放置一天左右后的样子。

Figure 18.7. Meconiophages between the amnion and chorion, with deposits of brown pigment (arrow-heads).

图18.7 羊膜和绒毛膜之间的吞噬胎粪的组织细胞（箭头），有棕色色素沉积。

• Decidual vasculopathy: The membrane roll usually shows a nice lining of decidua, which is where you will find maternal vessels. Evaluate these for fibrinoid necrosis, a common finding in preeclampsia (Figure 18.8).

• 蜕膜血管病：胎膜卷通常显示一层很完整的蜕膜被覆在表面，你在蜕膜里面会发现母体血管。评估血管壁的纤维素样坏死，常见于先兆子痫（图18.8）。

Figure 18.8. Fibrinoid necrosis. The dark pink condensation of the wall of this small artery (arrow) is an early sign of fibrinoid necrosis, which may be seen in preeclampsia.

图18.8 纤维素样坏死。小动脉壁的深染粉红色浓缩物（箭）是纤维素样坏死的早期迹象，可见于先兆子痫。

胎儿面（Fetal Surface）

On the fetal surface, look for the following:

在胎儿面，查看以下内容：

• Subchorionitis: Subchorionitis is the earliest manifestation of chorioamnionitis (maternal response). Neutrophils line up in the fibrin layer below the chorionic plate (see Table 18.1 for staging and grading chorionitis).

• 绒毛膜下炎：绒毛膜下炎是绒毛膜羊膜炎（母体反应）的最早表现。中性粒细胞聚积在绒毛膜板下方的纤维素层中（关于绒毛膜炎的分期和分级，见表18.1）。

• Fetal vasculitis: The vessels that coalesce to become the umbilical vessels arborize on the fetal surface, sandwiched between the amnion and chorion. This is another place to look for a fetal phlebitis or arteritis.

• 胎儿血管炎：合并成脐血管的血管在胎儿面呈树枝状，夹在羊膜和绒毛膜之间。这是寻找胎儿静脉炎或动脉炎的另一个部位。

• Subchorionic fibrin: Subchorionic fibrin is normal, and you may see large deposits in full-term placentas (Figure 18.9). Do not call it an infarct.

• 绒毛膜下纤维素：绒毛膜下纤维素是正常的，足月胎盘可见大量纤维素沉积（图18.9）。不要称为梗死。

Figure 18.9. Fibrin, subchorionic. Subchorionic deposits of fibrin (arrow) are normal in a term placenta and should not be mistaken for infarct. The amnion lies atop the fetal surface (arrowhead).

图18.9 绒毛膜下纤维素。纤维素（箭）沉积于绒毛膜下，在足月胎盘是正常的，不要误认为梗死。羊膜位于胎儿面的表面（箭头）。

Below the fetal surface and above the maternal surface you will find the villi, the massive gas- and nutrient-exchange surface area of the placenta. In very early villi, such as in spontaneous or elective abortion, look for changes suggestive of a hydatidiform mole (Figure 18.10).

在胎儿面下方和母体表面上方，你会发现绒毛，在这里进行大量气体和营养物质交换。在非常早期的绒毛中，如在自然流产或选择性流产中，要注意寻找提示葡萄胎的改变（图18.10）。

Figure 18.10. Molar villi. The villi are markedly enlarged, some with central cavities or cisterns (arrowhead). Dense trophoblastic proliferation is visible (arrow); on higher power, the cells may be very pleomorphic. This is a complete mole, so there are no fetal capillaries within the villi.

图18.10 葡萄胎绒毛。绒毛明显增大，有些绒毛有中内空腔或中央池（箭头）。可见致密的滋养细胞增生（箭头）；高倍镜下，细胞多形性可能非常明显。这是完全性葡萄胎，因此绒毛内没有胎儿毛细血管。

These changes include large swollen villi with no internal fetal vessels, circumferential and atypical trophoblast proliferation, and lack of fetal parts (in a complete mole). A complete mole is diploid with two paternal genomes and by definition has no fetus. A partial mole is triploid, one maternal and two paternal copies, and has a fetus, as well as two distinct populations of villi: normal and hydropic (edematous). An incidentally discovered early partial mole can be very subtle.

这些改变包括巨大的水肿绒毛，绒毛间质内没有胎儿血管，非典型滋养细胞环周增生，以及缺乏胎儿成分（完全性葡萄胎）。完全性葡萄胎具有两套父系基因组（二倍体），根据定义没有胎儿。部分性葡萄胎是三倍体（母一父二），有胎儿，并有两群不同的绒毛：正常绒毛和水肿绒毛。偶然发现的早期部分性葡萄胎，形态学表现可能非常轻微。

In a more mature placenta, such as an obstetric specimen, evaluate the villi for the following:

对于更成熟的胎盘，如产科标本，评估绒毛的以下情况：

• Villous maturity: A full-term placenta should have a dense network of tiny terminal villi, each full of capillaries and lined with syncytial knots. A preterm placenta (< 32 weeks or so) should have more immature villi, with larger contours, few syncytial knots, and myxoid stroma. A mismatch in gestational age and maturity is called hyper- or hypomaturity. Hypermaturity may indicate ischemia.

• 绒毛成熟度：足月胎盘由终末绒毛构成致密网络，每个终末绒毛充满毛细血管，被覆合胞体结节。早产胎盘（<32周左右）应有更多未成熟绒毛，轮廓更大，合胞体结节很少，间质呈粘液样。胎龄和成熟度的不匹配称为过成熟或欠成熟。过成熟可能提示缺血。

• Fibrin: Perivillous fibrin, which looks like hyaline membranes outlining the villi, increases with maturity, especially around the larger stem villi. Massive deposition may look like an infarct.

• 纤维素：绒毛周围纤维素，就像绒毛周围的透明膜，随着成熟而增多，尤其是在较大的干绒毛周围。大量纤维素沉积可能貌似梗死。

• Villitis: An increase in chronic inflammation within the villi may indicate a cytomegalovirus or syphilis infection. Often no organism can be found, in which case it is villitis of uncertain etiology.

• 绒毛炎：绒毛内慢性炎症的增加可能提示巨细胞病毒或梅毒感染。通常无法发现病原体，此时称为病因不明的绒毛炎。

• Infarct: Usually visible grossly as dense white patches, a true infarct has the look of coagulative necrosis (loss of nuclei and cell structure) with the mummified villi touching each other (Figure 18.11). Do not confuse this with perivillous fibrin deposition, in which fibrin encases a wide area of villi (encased villi should still show nuclear detail and be separated by abundant surrounding fibrin).

• 梗死：肉眼观，通常为致密的白色斑块，真正的梗死看似凝固性坏死（失去细胞核和细胞结构），木乃伊样绒毛相互接触（图18.11）。梗死要区分绒毛周围纤维素沉积，后者纤维素中包裹了大片绒毛（包裹的绒毛仍应显示细胞核细节，并被周围丰富的纤维素隔开）。

Figure 18.11. Infarct versus perivillous fibrin. (A) In an infarct, there is loss of basophilia and cellular detail with residual apoptotic bodies, as in coagulative necrosis elsewhere. (B) In a mass of perivillous fibrin, while the low power impression is a sheet of consolidated pink, on high power you can see the villi remain viable, with good nuclear detail.

图18.11 梗死与绒毛周围纤维素。（A）梗死失去嗜碱性和细胞细节，并有残余的凋亡小体，就像其他部位的凝固性坏死。（B）绒毛周围大量纤维素，低倍印象为一层浓缩的粉红色，高倍可见绒毛仍然存活，具有良好的细胞核细节。

Hematoma: A large acellular mass of fibrin, complete with lines of Zahn, is evidence of a prior hemorrhage. The hematoma may be subchorionic, intraplacental, or retroplacental (clinical abruption).

血肿：大块无细胞的纤维素，伴有扎恩线，是先前出血的证据。血肿可能位于胎盘下、胎盘内或胎盘后（临床上的胎盘早剥）。

（译注：lines of Zahn，扎恩线，是血栓的特征，粉色为血小板和纤维素，红色为红细胞。补充图片如下）

• Fetal capillaries: After prolonged death in utero, these capillaries collapse and the villi become fibrotic. Also look for nucleated red blood cells, which are abnormal in third trimester placentas.

• 胎儿毛细血管：在子宫内长期死亡后，这些毛细血管塌陷，绒毛纤维化。同时也要寻找有核红细胞，这在妊娠晚期胎盘中是不正常的。

• Intervillous inflammation: Neutrophils or abscesses in the intervillous space are unusual but indicate maternal sepsis, such as from Listeria.

• 绒毛间炎症：绒毛间隙的中性粒细胞或脓肿少见，提示母体败血症，如李斯特菌所致。

母体面（Maternal Surface）

The maternal surface shows a layer of decidua, with implantation site changes. Trophoblasts invade the maternal muscular arteries, dissolving their muscular wall to create wide-open pipes (Figure 18.12). This invasive but normal process leaves behind a fibrinous layer—do not mistake this for fibrinoid necrosis or vasculopathy. True fibrinoid necrosis is best seen on the small maternal vessels in the membrane roll and also has an inflammatory component. However, in the maternal floor, the persistence of muscular arteries is a form of maternal vasculopathy, because it means the trophoblasts did not do their job, and the placenta may be ischemic. This is another component of preeclampsia.

母体表面有一层蜕膜，着床部位有变化。滋养细胞侵入母体肌性动脉，溶解肌壁，形成宽大开放的血管腔（图18.12）。这种侵入是正常过程，会留下一层纤维素，不要误认为纤维素样坏死或血管病变。真正的纤维素样坏死在羊膜卷中的母体血管明容易观察，也有炎症成分。然而，在母体底板，肌性动脉的持续存在是一种母体血管病变，因为这意味着滋养细胞没有发挥作用，胎盘可能缺血。这是先兆子痫的另一个组成部分。

Figure 18.12. Trophoblasts in vessels. Intermediate trophoblasts (arrow) invading the wall of the maternal arteries. This is a normal process, opening fire hoses of blood to supply the placenta.

图18.12 血管中的滋养细胞。中间滋养细胞（箭）侵入母体动脉壁。这是一个正常的过程，就像打开消防软管，使血液供应胎盘。

A maternal floor infarct is not really a true infarct but a dense rind of fibrin encasing all of the villi along the maternal surface. Placenta accreta is the implantation of trophoblastic cells directly into myometrium. Histologically you may see placental villi very close to smooth muscle, with no intervening decidua. Accreta is a cause of postpartum hemorrhage. 

母体底板梗死并非真正的梗死，而是一种致密的纤维素外壳，包裹着母体表面的所有绒毛。胎盘植入是将滋养细胞直接植入子宫肌层。组织学上，胎盘绒毛非常靠近平滑肌，中间没有分隔的蜕膜。胎盘植入是产后出血的原因之一。

The features of preeclampsia are the following:

先兆子痫的特征如下：

• Decidual vasculopathy, also called acute atherosis: fibrinoid necrosis of decidual vessels, with accumulation of fibrin and foamy macrophages in the lumen and destruction of the arterial wall

• 蜕膜血管病，也称为急性动脉粥样硬化：蜕膜血管的纤维素样坏死，管腔内纤维素和泡沫样巨噬细胞积聚，动脉壁破坏

• Hypertrophic vasculopathy (retained muscular wall) of the maternal floor vessels

• 母体基底血管的肥大性血管病（血管肌壁残留）

• Increased perivillous fibrin, syncytial knots, and villous maturity

• 绒毛周围纤维素、合胞体结节和绒毛成熟度增加

来源：

The Practice of Surgical Pathology：A Beginner’s Guide to the Diagnostic Process

外科病理学实践：诊断过程的初学者指南

Diana Weedman Molavi, MD, PhD

Sinai Hospital, Baltimore, Maryland

ISBN: 978-0-387-74485-8 e-ISBN: 978-0-387-74486-5

Library of Congress Control Number: 2007932936

© 2008 Springer Science+Business Media, LLC

仅供学习交流，不得用于其他任何途径。如有侵权，请联系删除。