Table Of ContentF. F. Nogales (Ed.)
The Human Yolk Sac
and Yolk Sac Tumors
Foreword by G. B. Pierce
With 216 Figures and 25 Tables
Springer-Verlag
Berlin Heidelberg New York
London Paris Tokyo
Hong Kong Barcelona
Budapest
Dr. Francisco F. Nogales
Professor of Pathology, Head of Department
University Hospital, E-18012 Granada, Spain
ISBN-13: 978-3-642-77854-4 e-ISBN-13: 978-3-642-77852-0
DO I: 10.1007/ 978-3-642-77852-0
Library of Congress Cataloging-in-Publication Data.
The Human yolk sac and yolk sac tumors 1 F. Nogales (ed.). p. cm.
Includes bibliographical references and index. ISBN 3-540-56031-9 (alk. paper) : OM 460.00. L Yolk sac -
Cancer. 2. Tumors. Embryonal. 3. Yolk sac.
I. Nogales, Ortiz, Francisco. [DNLM: L Gonads. 2. Mesonephroma. 3. Urogenital Neoplams. 4. Yolk Sac.
WI 160 H918 1993]
RC280. P7H85 1993 616.99'2 - dc20 DNLMlDLC 92-48512
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Foreword
I am honored to have been invited to write a foreword for this book,
because tumors of the yolk sac have been a preoccupation of mine
since the days of my residency, now more than 3 decades ago. At that
time, a 3-year-old boy died of a testicular cancer of unknown histo
genesis. It was bad enough that the child died, but it bothered me even
more that medical science did not know the histogenesis of the tumor
that destroyed him, and I decided to study testicular cancer. For re
search training I sought out F. J. Dixon, who had written the Armed
Forces Fascicle on testicular tumors.
Dr. Dixon and I showed that embryonal carcinoma was a multipoten
tial malignant stem cell that differentiated into the three embryonic
germ layers of murine teratocarcinoma. This led to the idea that the
normal counterpart of embryonal carcinoma must also be multi
potent, and we focused on the preimplantation embryo for the histo
genesis of the tumor. This idea was strengthened by the discovery that
embryonal carcinoma cells made embryoid bodies in the ascites and it
was possible to observe the development of these bodies in vitro.
These observations led to the idea that embryonal carcinoma was a
caricature (gross misrepresentation) of early development, and car
cinomas in general were a caricature of the process of renewal of their
normal counterpart.
Included in the tissues derived from embryonal carcinoma was an
exception to the rule that they were benign: a carcinoma of unknown
histogenesis was isolated, the cells of which were embedded in a pecu
liar hyaline matrix. We knew of amyloid-producing tumors, but this
matrix was not amyloid and we named the tumor "carcinoma with
hyalin" until its histogenesis could be established.
Capitalizing on the idea that teratocarcinoma was a caricature of early
development, we searched for a hyalin matrix in the early embryo and
decided that Reichert's membrane that lay between trophoblast on the
maternal side and parietal endoderm on the embryonic side might be
the counterpart of the neoplastic hyalin. The cellular source of Rei
chert's membrane was unknown, but our in vitro studies proved it was
made in situ by adjacent cells. Combined histochemical, immunohis
tochemical, and ultrastructural studies identified the tumor as a pari
etal yolk sac carcinoma and thus normal parietal yolk sac as the source
of Reichert's membrane. Prior to our studies, no electron micrographs
of yolk sac had been published because the exposed cells usually ex-
VI Foreword
ploded in methacrylate mixtures used for embedding tissues. As evi
denced in this book, extensive ultrastructural work now exists on the
human yolk sac.
The neoplastic hyalin was composed of about 75 % protein and 15 %
carbohydrate. Amino acid analyses demonstrated glycine, proline,
and hydroxyproline and X-ray diffraction demonstrated repeating
units compatible with the presence of collagen. We concluded that the
hyalin was in fact basement membrane and that it contained collagen
and an antigenic glycoprotein both of which were synthesized by epi
thelium. This laid to rest the idea that basement membrane was a con
densation of ground substance and that collagen was synthesized only
by mesenchymal cells. Later, Timpl showed the glycoprotein to be
laminin, and parietal yolk sac carcinomas have been used in many
laboratories as sources of basement membrane.
Derivative experiments emerged from these studies. We demonstrated
experimentally that chronic injury to epithelial cells resulted in synthe
sis of excess basement membrane, just as fibroblasts synthesized colla
gen in the presence of a foreign body or chronic inflammation. We
concluded that thick basement membrane was a marker of cell injury,
as seen for example in the thick bronchial basement membranes of
long-standing asthmatics and the thickened glomerular basement
membranes in nephritis. In addition, Paul Nakane worked out the
enzyme-labeled antibody technique on the basement membranes of
the parietal yolk sac carcinoma. I had been attempting to develop
phosphatase-labeled antibody for ultrastructural localization of base
ment membrane antigens in parietal yolk sac cells, but when Paul Na
kane joined us he conjugated horseradish peroxidase to antibodies
and used Morris Karnovsky's method for localizing the labeled anti
body. This was the first useful reagent for ultrastructural localization
of antigens, and Paul Nakane did miracles in developing techniques to
obtain adequate fixation of antigen and penetration of antibody into
cells.
To return to yolk sac carcinomas: everything discussed to this point in
volved murine tissue. The human yolk sac lacked visceral and parietal
layers, and there was no counterpart of Reichert's membrane in the
human yolk sac. Gunnar Teilum identified a group of human testicular
neoplasms as endodermal sinus tumors. The tumor to which the little
boy succumbed was an endodermal sinus tumor now known as yolk
sac carcinoma. Teilum came to the diagnosis by comparing cells of the
rodent embryo to those of the human cancers, and then confirmed the
observations by finding similarities between the embryonic yolk sacs
of rodents and humans. Red Bullock, Bob Huntington, and I con
firmed Teilum's diagnosis using comparative pathology of murine and
human tumors and named them yolk sac carcinomas. By the way,
when you examine a tumor that you think may be a yolk sac carci
noma, stain it with periodic acid-Schiff. Although the human yolk sac
lacks a well-defined Reichert's membrane, human yolk sac carcinomas
Foreword VII
have abundant basement membrane that stains with PAS. It goes un
noticed unless you look for it. When you do find it, you will be sur
prised at its abundance. It is a good but unrecognized marker for the
histopathological diagnosis of yolk sac carcinoma. Francisco Nogales
did the first electron microscopy of human yolk sac carcinomas and
demonstrated basement membrane in them.
I would like to discuss a final point which concerns the yolk sac and
the histogenesis of testicular tumors. There is a controversy regarding
the relative roles of seminoma and embryonal carcinoma in the histo
genesis of testicular tumors. F. J. Dixon thought they were separate
entities each derived from germ cells; the seminomas a caricature of
spermatogenesis, and the embryonal carcinoma a caricature of
embryogenesis. R. Friedman thought that seminoma was the primary
germ cell tumor that gave rise to embryonal carcinoma.
Our ultrastructural observations led us to the conclusion that semino
mas were a caricature of spermatogenesis even though most of them
failed to differentiate recognizable features of cells undergoing sper
matogenesis. That was considered unimportant because the stem cells
of many tumors fail to differentiate in vivo.
Seminomas have been described with trophoblastic giant cells or yolk
sac elements or embryonal carcinoma. Derek Raghavan has described
experiments suggesting that cells of a seminoma when put in culture
gave rise to yolk sac carcinoma. Recently, molecular studies of semi
noma and yolk sac carcinoma show similarities interpreted to the ef
fect that seminomas may give rise to yolk sac directly. These argu
ments would be supportive of Friedman's ideas concerning the posi
tions of seminoma and embryonal carcinoma in the histogenesis of
these tumors. However, I believe, for the following reasons, that semi
noma is a tumor distinct from embryonal carcinoma.
It is accepted that the primordial germ cell arises in the extraem
bryonic yolk sac and is multipotent, because its malignant counterpart
embryonal carcinoma is multipotent, Primordial germ cells eventuate
spermatogonia which are multipotent and differentiate sperm which
are unipotent and serve only as genetic torpedoes in the process of fer
tilization. How does the primordial germ cell lose its multipotency in
spermatogenesis? Does it lose it all at once in one cell division or does
it lose it over several cell divisions? When we selected a teratocarci
noma for its fastest growing cells, the tumors lost their differentiated
tissues in the reverse order an embryo acquires them. We obtained tu
mors composed of yolk sac and trophoblast with or without embryonal
carcinoma. Again, arguing by analogy, as the primordial germ cell
loses its multipotency, could it evolve a stem cell capable of expressing
features of its newfound potential (spermatogenesis) yet retain some
of its old features as evidenced by the ability to express trophoblast or
yolk sac? If the above is true, then the molecular biology should show
similarities beween seminoma and yolk sac, not because one is de
rived from the other but because each is derived from a common pre-
VIII Foreword
cursor stem cell, which in the normal lineage is in the process of losing
its multipotency in favor of the potential to produce sperm. Search
should be made for such stem cells. In addition, search should be
made for the origin of the primordial germ cells. It is known that inner
cell mass cells are totipotent and give rise to primitive endoderm. It is
not known if primitive endoderm cells in the blastocyst are totipotent,
but these cells give rise to proximal and distal endoderm, and even
tually extraembryonic endoderm. Is extraembryonic endoderm toti
potent? The germ cells arise in extraembryonic endoderm and either
inherit multipotency from it or, if the extraembryonic endoderm is not
multipotent, possible primordial germ cells arise as a particular differ
entiation from it that is totipotent. Sorting out these questions will be
anticipated by the readers of this book.
The foregoing is what happens when an editor asks an about-to-retire
professor to write an informal personal introduction to his book. It
amazes me why the rodent embryo is so dependent upon a yolk sac
placenta but that of the human is not. More amazing is the tremend
ous understanding of the yolk sac, its function, and its failure in preg
nancy, and the understanding of its tumors that has been achieved
over the past, decades and which are discussed herein.
April 1992 G. BARRY PIERCE
American Cancer Society,
Distinguished Professor
Preface
When confronted with the task of editing a book about a little-known
and transitory subject such as the yolk sac, an organ only active during
the first few weeks of embryonal life, there is a risk of entering the
realm of the too academic or the too obscure.
However, I feel that this small, and to date largely ignored, structure
may have a vital and interesting part to play in human embryonal de
velopment, comparable to its proven evolutionary importance in
other animals. The yolk sac is the primary source of blood and germ
cells, having a complex protein secretion and an equally intricate
ultrastructure. It is very possible that it plays an important role in the
initial mechanisms of pregnancy maintenance and the early growth
and welfare of the embryo. The recent impact of teratology and high
resolution ultrasonography have shown the human yolk sac to be a
protagonist during the first stages of pregnancy.
As an intensive search in the literature for information about this or
gan of increasingly recognized importrance only reveals disconnected
and frequently overspecialized reports, I felt the time had come to
gather together as much relevant data as possible from the various
groups working on the yolk sac at the present time. In order to provide
as complete a picture as possible it is necessary to call on embryol
ogists, histologists, experimental and anatomical pathologists, and
clinicians .. Much can also be learnt from yolk sac tumors, which, al
though they do not originate in the yolk sac, do partially reproduce its
structure and even certain aspects of its phylogeny. Indeed, the identi
fication of the yolk sac tumor as a germ cell tumor was made by com
paring its growth pattern and that of the murine yolk sac placenta.
This tumor, or perhaps even tumor group, has become more and more
interesting during the last decade as new data emerge from experi
mental and histopathological research; tumors originating from so
matic tissues and until recently unknown types of somatic differentia
tion found in human tumors make the yolk sac tumor a unique, fasci
nating Proteus among tumors.
The present book provides a wealth of information from both clinical
and pathological fields, in a depth not possible in standard textbooks
and in a way that interconnects the available facts, although this in
evitably leads to the slight overlapping and occasional conflict of data
that is bound to happen when results and ideas are collected from re
searchers worldwide.
X Preface
I would like to express my gratitude to Springer-Verlag for accepting
and encouraging this publication, to my wife Heather Fulwood, MB
ChB, for her invaluable and enthusiastic help with editing, to my
children Lorenzo, Miguel, Ana, and Marina for the interest they have
always shown for my work, and to my dear friends Cristina and Gon
zalo Zuleta and Cristina and John Noble for keeping me sane through
out the project.
Granada, February 1993 FRANCISCO F. NOGALES
Contents
Chapter 1. Comparative Development
of the Mammalian Yolk Sac
(B. F. KING and A. C. ENDERS) . . . . . . . . . . . . . . . . . . . . .. 1
Chapter 2. Development of the Human Yolk Sac
(A. C. ENDERS and B. F. KING) . . . . . . . . . . . . . . . . . . . . .. 33
Chapter 3. Histology of the Secondary Human Yolk
Sac with Special Reference to Hematopoiesis
(T. TAKASHINA) ................................ , 48
Chapter 4. Kinetics of Hematopoiesis in the Human Yolk Sac
(G. MIGLIACCIO and A. R. MIGLIACCIO). . . . . . . . . . . . . . . .. 70
Chapter 5. Macrophages in the Human Yolk Sac
(H. ENZAN) .................................. , 84
Chapter 6. a-Fetoprotein and Other Proteins
in the Human Yolk Sac
(D. BUFFE, C. RIMBAUT, and J. A. GAILLARD) ............. 109
Chapter 7. Yolk Sac Abnormalities: A Clinical Review
(N. EXALTO) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
Chapter 8. Experimental Models of Injury
in the Mammalian Yolk Sac
(E. A. REECE, E. PINTER, and F. NAFrOLIN) . . . . . . . . . . . . . . 135
Chapter 9. Ultrasonography of the Human Yolk Sac
(E. FERRAZZI and S. GARBO). . . . . . . . . . . . . . . . . . . . . . . . 161
Chapter 10. Morphological Changes of the Secondary
Human Yolk Sac in Early Pregnancy Wastage
(F. F. NOGALES, E. BELTRAN, and F. GONZALEZ) ........ '. ... 174
Chapter 11. Yolk Sac Carcinoma: History of the Concept
and the Experimental Models
(1. DAMJANOV, A. DAMJANOV, and U. M. WEWER). . . . . . . . . . . 195
Chapter 12. Immunohistochemical Markers of Yolk Sac Tumors
(E. SAKSELA) .................................. 216
