Carnegie Stages
ثبت نشده
چکیده
Historically the exact age of human embryo specimens has long perplexed embryologists. With the menstrual history of the mother often unknown or not exact, and the premenstrual and postmenstrual phases varying considerably among women, age sometimes came down to a best guess based on the weight and size of the embryo. Wilhelm His [5] was one of the first to write comparative descriptions of human embryos in the late 1800s. Soon afterward, Franklin P. Mall, the first director of the Carnegie Institution of Washington?s (CIW) Department of Embryology, expanded upon His? work. Mall?s first efforts were to place embryos into stages based on menstrual ages and body length. This method ran into problems, however, when it became apparent that obtaining menstrual ages was often impossible or simply too inaccurate even if the information could be obtained from the women who carried the embryos. Mall decided instead to look for patterns among embryos to come up with some type of staging system whereby embryo age could be more accurately determined.
منابع مشابه
Morphological and molecular characteristics of living human fetuses between Carnegie stages 7 and 23: developmental stages in the post-implantation embryo.
Determination of embryonic age groups or stages has been based on the Carnegie Institute collection started in 1887. Improved technology has enabled the building of a new collection of embryos of < 9 weeks gestation; these were then used to compare with the original Carnegie collection. The results suggest that in providing definitive stages that are rigidly bound by developmental events, limit...
متن کاملDEVELOPMENTAL STAGES IN HUMAN EMBRYOS DEVELOPMENTAL STAGES IN HUMAN EMBRYOS Including a Revision of Streeter's ''Horizons" and a Survey of the Carnegie Collection
متن کامل
Embryonic staging using a 3D virtual reality system.
BACKGROUND The aim of this study was to demonstrate that Carnegie Stages could be assigned to embryos visualized with a 3D virtual reality system. METHODS We analysed 48 3D ultrasound scans of 19 IVF/ICSI pregnancies at 7-10 weeks' gestation. These datasets were visualized as 3D 'holograms' in the BARCO I-Space virtual reality system. Embryos were staged according to external morphological fe...
متن کامل3D modelling, gene expression mapping and post-mapping image analysis in the developing human brain.
As human brain development proceeds, there are complex changes in size and shape, most notably in the developing forebrain. Molecular technologies enable us to characterise the gene expression patterns that underlie these changes. To interpret these patterns the location of expression must be identified and, often, gene expression patterns compared for several genes or across several developmen...
متن کاملRegional and cellular specificity of the expression of TPRD, the tetratricopeptide Down syndrome gene, during human embryonic development
The TPRD gene (tetratricopeptide (TPR) containing Down syndrome gene) is one of the candidate genes in the Down syndrome chromosomal region-1. Duplication of this gene may be the cause of major phenotypic features of Down syndrome. Here we show that the TPRD expression is developmentally regulated during human embryogenesis. At the earliest stages of development (Carnegie 8-12) TPRD expression ...
متن کاملAnalytical models for predicting performance in human-computer interaction
Human Computer Interaction (HCI) is an integral part of computer programming. Key issues in HCI design include specification of system performance expectations, analysis of performance predictions and evaluation of performance after implementation. Keystroke models provide reliable predictions of alternative system designs but require complete implementation or specification of the system. Simu...
متن کامل