Normal Table of Xenopus Laevis (Daudin)

A Systematical & Chronological Survey of the Development from the Fertilized Egg till the End of Metamorphosis

J. Faber, P. D. Nieuwkoop, J. Faber, P. D. Nieuwkoop

• Publisher: Garland Science
• Year: 2020
• ISBN:
  9781000144215
• Edition: 1
• Topic: Biological Sciences
• Subtopic: Science General
• Index: Biological Sciences

This book is the culmination of an international collaboration of zoologists to describe the embryology of Xenopus, including the origins of the organ systems, with the purpose of promoting the use of Xenopus as a model amphibian for embryological study.

CHAPTER I
GENERAL INTRODUCTION

The project of the elaboration of a Normal Table of the development of the South African toad, Xenopus laevis, has been set up by the staff of the Hubrecht Laboratory for two main reasons.

Xenopus laevis has become a common laboratory animal since the detection of its usefulness for pregnancy tests and other hormonal reactions. It has turned out to be a very good laboratory animal, which, being an aquatic form, can easily be kept and reproduces readily in captivity after hormonal stimulation. The eggs develop quite satisfactorily and the larvae can be reared very smoothly up to metamorphosis, which period is also passed without great difficulties. At present Xenopus laevis is therefore found in many biological, medical and veterinary institutes throughout the world. Although some approaches have already been made towards dividing its development into convenient stages (cf. PETER, 1931, WEISZ, 1945), a great want was generally felt for an extensive and well elaborated Normal Table of this species.

Although only very fragmentarily known, the development of Xenopus laevis is quite interesting from a descriptive and comparative as well as from an experimental embryological point of view. Preliminary experiments demonstrated that the egg of Xenopus laevis, notwithstanding its very rapid development, is quite suitable for experimental work. Since the number of Anuran species for which this is true, is very restricted, a good basic knowledge of the normal development of this species seems to open new perspectives for experimental analysis in this group of Vertebrates. The rather aberrant development of this systematically somewhat isolated species suggests, moreover, interesting possibilities for descriptive and comparative embryological studies.

The second reason for setting up the project falls in line with the international character of the Hubrecht Laboratory. This institution tries to promote embryological research and tries to stimulate international cooperation. Since the study of the normal development of a species can adequately be subdivided into a large number of well circumscribed separate subjects, a Normal Table can be elaborated from data provided by an international team, stimulating international cooperation in a very practical form.

For these two reasons in 1949 the first editor took the initiative for the organization of this project.

The division of the development of Xenopus into stages for the purposes of the table has been carefully considered. Up till now stages in the various Normal Tables have not been directly comparable with each other, since the tables were made independently. This very unsatisfactory situation has led already to an enormous confusion in the literature, the more so since the Normal Tables cited are usually not available and partially even entirely unknown to the majority of the readers. We have therefore decided that the most adequate Normal Table should be used as a basis of comparison. As such we have chosen the Normal Table of Amblystoma punctatum established by R. G. HARRISON. Unfortunately this Normal Table has never been published; only the external appearance of the successive stages has been reproduced (cf. HAMBURGER, 1547; RUGH, 1948). In the experimental literature it has, however, been referred to very extensively. The stages of the present Normal Table have been made as nearly as possible analogous with those of HARRISON’S table. (See also Chapter HI.)

In order to resolve the present confusion of stages in the various tables of Anuran development, a comparison between them has been compiled. This is presented in Chapter VIII on page 189.

A further difficult decision had to be taken with regard to the form in which this Normal Table should appear. The individual contributions varied so much in size and form—some were much more extensive and detailed than others—that most of the contributions needed considerable adaptation for the sake of uniformity. In several cases the text had to be shortened greatly. The editors tried nevertheless to preserve as far as possible the personal character of the individual contributions. The study of this material by a team of about twenty scientists has led evidently to a more detailed description of the development of the various organ systems than that given in other Normal Tables. This fact, together with serious typographical objections, made publication in the usual tabular form almost impossible. The editors therefore decided to give up the tabular form. The alternative was the writing of a systematically arranged continuous text. (See further in Chapter vi.) The first editor has therefore changed the text of the various contributions into the present form, for which he is entirely responsible. The individual collaborators remain, however, responsible for the data of their personal contributions.

In order to make the Normal Table more adequate for stage determinations of the entire embryo as well as of the individual organ systems, a separate chapter containing well defined stage criteria has been added. This chapter contains the external and internal stage criteria, while also the corresponding age and size measurements are given.

It seemed desirable that a short chapter on the systematic position and geographical distribution of Xenopus laevis should be included, and that also some data should be given about the natural ecological conditions of this species and about methods of rearing it under laboratory conditions. (See Chapter iv and v on page 9 and page 13).

We hope that the new form in which this Normal Table appears, will meet most of the requirements to be fulfilled for a comprehensive but nevertheless easily accessible Normal Table. Suggestions for improvements in form and organization will be highly appreciated in order that the most adequate form of publication may gradually be achieved, and a standard might be set up for the publication of other Normal Tables.

Any national, but particularly any international project set up with a large number of collaborators, faces the difficulty of special time requirements, which difficulty in this project was greatly increased by the technical troubles met with in working out the older stages, the animals being of considerable dimensions. The personal responsibilities of the individual collaborators often interfered with an investigation of the material within the time-limits proposed, so that dead-lines had to be changed several times. In some cases more serious difficulties arose, so that new collaborators had to be found, a problem to be coped with up till the last moment. Notwithstanding these unavoidable complications the work has gradually become completed. It is a very great pleasure for the editors to present this work to their colleagues, and to express here their thanks and appreciation to all the collaborators for their personal interest and the accuracy with which they have carried out their part of the work.

This project has been made possible by generous financial support from Dutch and from International Organizations. For the collecting of the material in South Africa financial support has been received from the following organizations: “Jan Dekker Stichting”; “Utrechts Universiteits Fonds”; “Hollandsche Maatschappij van Wetenschappen”; “Provinciaal Utrechts Genootschap”; “Nederlands Natuuren Geneeskundig Congres”; “Nederlandse Organisatie voor Zuiver Wetenschappelijk Onderzoek” and “Biologische Raad van Nederland”. The publication of the work in book-form has been made possible by the generous support received from the “International Council of Scientific Unions”. The editors want to express their most sincere thanks to all these organizations for the interest and support received.

They are highly indebted also to the Professors C. G. S. DE VILLIERS and C. A. DU TOIT of the Zoological Institute, University of Stellenbosch, for the hospitality and help given in their institute to the second editor during his stay in South Africa, and to Dr. D. HEY of the Jonkershoek Inland Fisheries Department in Stellenbosch for his permission and help during the collecting of the material from the ponds of the Jonkershoek Fish Hatchery.

The plates, which are based on pencil drawings by the second editor, were made by the artist Mr. J. J. PRIJS of Utrecht, whom we should like to thank very cordially for his valuable work.

Wc should like to express our sincere gratitude for the personal cooperation received from the publishers, which have contributed very much to the ultimate form of this work.

Our sincere thanks are also due to Miss D. THOMASON, Ph. D., of the Royal Free Hospital School of Medicine, University of London, who has made some final corrections of the English text.

CHAPTER II
THE ORGANIZATION OF THE NORMAL TABLE PROJECT

As mentioned in the general introduction, this Normal Table project was completed from data provided by an international team. The opportunity of practising international team work was met with great interest and appreciation, and led to the collaboration of about twenty scientists from three continents. Among them South Africa and the Netherlands are rather well represented. The South African zoologists were very much interested in this project, which concerned one of their native amphibien species. The number of Dutch collaborators increased particularly during the last one or two years when time became gradually too restricted to interest a foreign scientist in a subject from which the original collaborator had to withdraw. The development of the ear, by Miss M. Th. C. van Egmond, the development of the skin, by G. A. van Erkel and the development of the skull and visceral muscles up till metamorphosis, by P. H. van Doesburg, have thus recently been studied at the Hubrecht Laboratory, while both editors filled in some gaps which became apparent when the Normal Table was being written.

The following collaborators have taken part in the elaboration of the Normal Table:

The division of the material into stages was first planned by the editors in collaboration with CHR. P. RAVEN (Utrecht, Holland). The definitive division into stages and the fixation of the material was carried out by J. FABER during his stay in South Africa.

The external development, including the pigmentation pattern and the external appearance of the lateral line system, was studied on living material in South Africa by J. FABER.

The systematic position and geographical distribution of Xenopus laevis have been discussed by H. W. PARKER, (London, England).

The ecological data and rearing methods have been given byj. FABER.

The development of the separate organ systems has been studied by: The early development from the fertilized egg up to a late neurula stage (stage 20) by P. D. NIEUWKOOP (Utrecht, Holland).

The early development from a late neurula stage up to an advanced tail bud stage (stage 29/30) by J. PASTEELS (Brussels, Belgium),

The development of the skin and lateral line system by G. A. van ERKEL (Utrecht, Holland).

The development of the brain by J. ARIËNS KAPPERS (Groningen Holland).

The development of the cephalic nerves and ganglia by CHR. P. RAVEN (Utrecht, Holland).

The development of the spinal cord, ganglia and nerves ¹⁾ by J. J. KOLLROS (Iowa City, U.S.A.).

1) Some additional data on the development of the spinal nerves, the meninges and the sympathetic nervous system have been given by P. D. NIEUWKOOP (Utrecht, Holland).

The development of the olfactory organ by S. TOIVONEN and L. SAXéN (Helsinki, Finland).

The development of the eye by Miss J. H. BIJTEL (Groningen, Holland).

The development of the ear vesicle by Miss M. TH. C. VAN EGMOND (Utrecht, Holland).

The development of skeleton and muscles of the head up to stage 54 by P. H. van DOESBURG (Utrecht, Holland).

Idem, from stage 55 till the end of metamorphosis by S. N. SEDRA and M. I. MICHAEL (Alexandria, Egypt).

The development of the muscles of the trunk by P. A. J. RYKE (Pot chefstroom, South Africa).

The development of the skeleton of the trunk by A. L. SMIT (Stellenbosch, South Africa).

The development of skeleton and muscles of the tail by D. R. NEWTH (London, England).

The development of skeleton and muscles of shoulder girdle and forelimbs by R. VAN PLETZEN (Bloemfontein, South Africa).

The development of skeleton and muscles of the pelvic girdle and hindlimbs by D. R. NEWTH (London, England).

The development of heart and vascular system up to stage 48 by Mrs. N. A. H. MILLARD (Cape Town, South Africa).

Idem, from stage 48 till the end of metamorphosis byj. FABER (Utrecht, Holland).

The development of the n...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Foreword
• Contents
• Chapter I: General Introduction
• Chapter II: The organization of the Normal Table project
• Chapter III: Material
• Chapter IV: The taxonomic position and geographical distribution of the genus Xenopus
• Chapter V: Some ecological data and methods of rearing of Xenopus laevis under laboratory conditions
• Chapter VI: The systematic description of the internal development of Xenopus laevis
• Chapter VII: External and internal stage criteria in the development of Xenopus laevis
• Chapter VIII: A comparative table of Anuran Normal Tables
• Chapter IX: A bibliography of Anuran development (systematically arranged).
• Chapter X: Index