A Developmental and Histochemical Study of the Female Reproductive System in Ornithogalum Caudatum Ait
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Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1978 A developmental and histochemical study of the female reproductive system in Ornithogalum caudatum Ait. using light and electron microscopy Varien Russell Tilton Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Botany Commons Recommended Citation Tilton, Varien Russell, "A developmental and histochemical study of the female reproductive system in Ornithogalum caudatum Ait. using light and electron microscopy " (1978). Retrospective Theses and Dissertations. 6432. https://lib.dr.iastate.edu/rtd/6432 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. 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Requests can be made to our Dissertations Customer Services Department. 5. Some pages in any document may have indistinct print. In all cases we have filmed the best available copy. UniversiV Micrdîilms International 300 N ZEEB ROAD, ANN ARBOR, Ml 48106 18 BEDFORD ROW, LONDON WCIR 4EJ, ENGLAND 7907295 TILTOS, VARIEN RUSSELL A DEVELOPMENTAL A%ID HI STQCHEMI CftL STUDY OF THE FEMALE REPRaDJCFIVE SYSTEM IN ORNITHQ&ALUM CAUD4TJM AIT. USING LIGHT iNO ELECTRON MICROSCOPY. (VOLUMES 1 AND 2» IOWA STATE JNIVERSITV, PH.D., 1978 Universiv Micrcxilms International SOON ZEEBROAD, ANNARBOR.MI^AIOE Â developmental and hlstochemlcal study of the female reproductive system In Omlthogalum caudatum Alt. using light and electron microscopy by Varlen Russell Tllton Volume 1 of 2 A Dissertation Submitted to the Graduate Faculty In Partial Fulfillment of The Requirements for the Degree of DOCTOR OF PHILOSOPHY Department: Botany and Plant Pathology Major: Botany (Morphology) Signature was redacted for privacy. Malor Work Signature was redacted for privacy. For the Major Department Signature was redacted for privacy. For the Gramiate College Iowa State University Ames, Iowa 1978 il TABLE OF CONTENTS Page PREFACE Iv INTRODUCTION 1 LITERATURE REVIEW 8 Inflorescences and Floral Morphology: An Overview 8 The Gynoecium: General Considerations 13 Carpels 25 Stigma 48 Style 51 Transmitting Tissue 53 Plant Glands 61 Stigma Receptivity 65 Stigmatlc Exudate 67 Stylar Exudate 71 Pollen Tube Growth 74 Postpollination Changes in Flowers 87 History of Sexuality in Plants 91 Megasporogenesls 99 Megagametogenesls 109 Fertilization 159 Post Fertilization Central Cell 167 Zygote 168 Aberrant Ovules 172 MATERIALS AND METHODS 176 T.4 17A Electron Microscopy (EM) 178 OBSERVATIONS 180 Carpels 180 Style and Stigma 197 Ovules 204 DISCUSSION 224 Carpels, 'style, Stlana. and Ovule Ontogeny 224 Some Brief Comments on Events Preceding Fertilization 271 ill SUMMARY 281 Carpels 281 Stigma and Style 283 Ovules 284 LITERATURE CITED 287 ACKNOWLEDGMENTS 350 APPENDIX A, " KEY TO LABELING 351 APPENDIX B. FIGURES 353 APPENDIX C. FORMULAE AND SCHEDULES 582 APPENDIX D. BINUCELLATE OVULE 591 iv PREFACE "...see what everybody else has seen, and think what nobody else has thought." Dr. Albert Szent-Gyorgyi At the outset of this adventure, I had intended to investigate the anatomy of ovule Initiation, megasporogenesis, and megagametogenesis. This, with the hopes of being able to deduce some sort of heretofore, unthought-of brainstorm as to the functional role of the various parts. Well, for one reason or another, this was not to be. The original plan has blossomed into a look at the entire female reproductive system, the growth of pollen tubes from stigma to ovule, and some of the physiological reactions of the flower in response to germinating pollen and incipient fertilization. When I began to really rummage around in the Iowa State University library, I was captivated by the literature available there. Going beyond books and review papers back to the original papers, many from the 19th Century, was most satisfying. It made me realize that many of the ideas which I had thought I was so clever in dreaming up on ray own had been around for a long time. I was also greatly impressed with many of the illustrations by the early Germans and Japanese, but particularly the Germans. Well anyway, the point is that in order to give credit where credit is due, I had to dust off a few volumes in the library. I was really amazed and feel greatly rewarded by the experience. So there I was amidst all that wonderful knowledge, and I figured that I had best take advantage while I had the chance. What better V opportunity to try and understand the nature of the flower, in its entirety, as a biologically functional reproductive system? In my attempt to accomplish this task, I necessarily had to include some liter ature not directly pertinent to my own researches; but, in order to under stand the whole, one must know very well all its parts. To understand all aspects of the flower and the reproductive process with equal clarity would require a lifetime of study and research. 1 have only completed page one. I look upon this dissertation as a founda tion for whatever I may accomplish a la manana. It has afforded me the opportunity to put all of my thoughts on the matter, correct or otherwise, into a coherent (I hope) text, and has provided me with ideas for future research. The quest for my doctoral degree has at times been a royal pain in the ass—some of the courses and Jerk instructors; the hours of toll and sweat with the dictionary and that German grammar; the frustration of running out of swearwords when things went wrong in the lab; the picnics that never got picnicked: the beer that somebody else drank: my beautiful bride whose company I never got to enjoy.... But, there have been regards too—I was really tickled to get into some of the original German papers; some of the courses were excellent and the Instructors a truly stimulating Influence; and my own research has been very satisfying to me. Has it been worth it all? I don't know yet--I don't think I will be able to answer that question for several more years. 1 INTRODUCTION Although gynoecla from a wide variety of plants have been studied in part and parcel by many botanists, there are only a very few studies which include the development and structure of the entire gynoeclum from any given plant. In this paper, the gynoeclum as a whole, and all of the tissues which comprise it, have been investigated with both light and electron microscopy. In addition, pollen tube growth and some of the physiological responses of the flower to pollen germinating on the stigma and incipient fertilization were Investigated. Most of the literature on carpels deals with floral morphology for theoretical, phylogenetic, and taxonomic purposes, bypes of placentation, and vascular patterns. There also has been some work done on carpel initiation and carpel fusion, but there is relatively little information on carpel anatomy per se. In particular, there is a great lack of ultra» structural information. One of the aims of this study, then, has been to follow the development of the carpels in Ornithogalum from an anatomical viewpoint. This proved to be very interesting, and the carpels were found to be a great deal more complex than first thought. As with the carpels, the structure and function of styles has been taken pretty well for granted. In only a very few plants has the style been studied with electron microscopy. As of this writing, the list con sists of just five dicots and only one monocot; a rather appalling lack of knowledge about such an important organ. In this study, stylar devel opment was followed through the entire sequence of events in Ornithogalum. It was Indeed a most interesting phenomenon to observe. 2 The heart of this study was to follow the development of the ovules. Although the list of plants from which ovules have been studied ultra- structurally is a bit longer than that for carpels and styles, there is still an amazing paucity of knowledge about the ultrastructure of ovules.