1,721,004 research outputs found
The ultrastructure of human reproduction .1. The natural history of the female germ cell: origin, migration and differentiation inside the developing ovary
No full textThis presentation, on both printed copy and CD-ROM, summarizes a series of original data on the ultrastructure of human reproduction produced by our research group, In particular, female germ cell behaviour at the time of migration and colonization of the gonad and germ-somatic cell interactions inside the developing ovary are reviewed from a morphodynamic point of view, The results mostly consist of black-and-white transmission and scanning electron microscopy (TEM and SEM) images, Artificially coloured SEM pictures, light microscopy images and drawings have also been selected for iconography to render complex microanatomical details and their morphofunctional relationships more comprehensible, In all, 35 images are presented in this article, each related to a concise text section and accompanied by a self-explaining caption, A list of pertinent references is also provided
Microscopical survey of the development and differentiation of the epithelium of the uterine tube and uterus in the human fetus.
No full textThe development and differentiation of the coelomic epithelium lining the paramesonephric ducts in human fetus, that gives rise to the female genital organs, have been ultrastructurally examined. The epithelium appeared pseudostratified, consisting of basal, microvillous and ciliated cells. In younger fetuses (12th gestational week) ciliogenic elements could be detected mainly on the developing tubal fimbriae, but most of the cells showed microvilli and often single cilia. In the subsequent phases of development, morphodynamics of cell renewal were documented by aspects of apoptosis. Fully ciliated cells were numerous on the fimbriae and at the utero-tubal junction, but not in the uterus; however, these were less abundant than those showing microvillous. In older fetuses (31st gestational week) microapocrine secretion by microvillous cells, in the form of droplets contacting cilia, could be observed. In the same fetuses the ectocervix was covered by a mature squamous epithelium, made up of polygonal flat desquamating cells, showing labyrinthine surface microplicae. Our observations demonstrated that ciliation in the human female genital organs, like that of other systems, is neither simultaneous nor uniform, and ciliated cells are gathered preferentially in strategic sites, to mediate germ cell migration and blastocyst implantation in adult life. These ultrastructural data seem to indicate that the female genital tract epithelium, at least in its general features, is sketched since fetal life, and cell morphodynamics, including microvillous and ciliated cell differentiation, as well as the secretory activity, are the morphological expression of the complex molecular mechanisms, involved in developmental biology and reproductive physiology
Ultrastructural dynamic features of in vitro fertilization in humans.
No full textThe present study on in vitro fertilization in humans demonstrates that three-dimensional (3-D) fine morphology by high resolution scanning electron microscopy (SEM) combined with parallel light and transmission electron microscopy (TEM) can reveal a number of new cellular detailed findings which cannot be detected with other methods. In this study the following aspects have been investigated in early human embryos. 1. Micro-topographical features of the zona pellucida (ZP), surface blastomeres and polar body. 2. Intracytoplasmic features of mature and healthy oocyte, in vitro fertilized (IVF) oocyte and early embryo development. 3. Comparison of general views of intracytoplasmic sperm injection (ICSI) and conventional IVF (C-IVF) of early embryos. 4. Presence of unusual large tubular smooth endoplasmic reticulum (SER) aggregates in 4, 5, and 6-cell embryos after ICSI. 5. Inside views of 3-D blastocysts such as inner cell mass and trophoblast. To our knowledge, this is the first time that such images are reported by using these techniques
Ultrastructural morphodynamic events of human in vitro fertilization and early embryogenesis
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Ultrastructural dynamics of human testicular cords from 6 to 16 weeks of embryonic development. Study by transmission and high resolution scanning electron microscopy
No full textWhen the embryo is 6-week-old the gonad is composed mostly of migrating primordial germ cells, surface coelomic mesothelium and mesenchymal cells. At 7 weeks of gestation (wg) testicular cords consist of prespermatogonia, larger, with a more regular outline and higher mitotic activity than primordial germ cells, embraced by somatic pre-Sertoli cells. The morphofunctional development of Sertoli cells defines testicular differentiation. Towards 7.5 wg the gonad is finally in its differentiated stage; the basal lamina of the cords becomes distinguishable, testicular cords radially branch and elongate, and Leydig cells are clearly recognized. Primordial germ cells are large and spherical, with rounded and eosinophilic nuclei and large nucleoli. Pre-Sertoli cells, in turn, show round or columnar nuclei and rough endopasmic reticulum. Prespermatogonia and mostly pre-Sertoli cells actively proliferate. Many interdigitations and cytoplasmic processes are observed between neighboring pre-Sertoli cells and between pre-Sertoli cells and prespermatogonia. A sort of compartmentalization is established inside the cords in which pre-Sertoli cells tend to localize closer to the basal membrane embracing the prespermatogonia with long and thin cytoplasmic processes. Between 14 and 16 wg the most significant changes besides maximum development of Leydig cells are differentiation of mesenchymal cells around the cords into future peritubular cells and maturational changes of pre-Sertoli cells. These likely reveal a peak coinciding in time with reported increases in either testosterone production and Mullerian Inhibiting Substance secretion. During the period herein considered testicular cords show no lumen neither any sign of canalization so they cannot be termed "tubules"
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