Talk:Embryonic Development

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Cite this page: Hill, M.A. (2021, January 24) Embryology Embryonic Development. Retrieved from

  • Three-dimensional sonographic volumetry of the gestational sac and the amniotic sac in the first trimester. Odeh M, Hirsh Y, Degani S, Grinin V, Ofir E, Bornstein J. J Ultrasound Med. 2008 Mar;27(3):373-8. PMID: 18314515


Structural anomalies in early embryonic death: a 3-dimensional pictorial essay

J Ultrasound Med. 2010 Mar;29(3):445-53. Bromley B, Shipp TD, Benacerraf BR.

Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA. Abstract OBJECTIVE: The purpose of this pictorial essay was to determine whether 3-dimensional (3D) surface rendering of a dead first-trimester embryo can provide any information for the loss. METHODS: Three-dimensional surface rendering was performed on a collection of dead first-trimester embryos with crown-rump lengths between 12 and 27 mm. These were compared with 2-dimensional (2D) images of the same embryos and with 2D images and 3D surface renderings of normally developing embryos. RESULTS: Surface rendering of dead embryos showed a variety of abnormalities in the contour and limb formation. CONCLUSIONS: The use of 3D sonography may provide insight into the etiology of first-trimester embryonic death.

PMID: 20194939

Further observations on the empty "amnion sign"

J Clin Ultrasound. 2010 Mar-Apr;38(3):113-7. Yegul NT, Filly RA.

Department of Radiology, University of California, San Francisco, L374, 505 Parnassus Avenue, San Francisco, CA 94143-0628, USA. Abstract OBJECTIVE: To assess the positive predictive value of the empty "amnion sign" (visualization of an amnion without concomitant visualization of an embryo) for the diagnosis of early pregnancy failure. METHODS: Retrospective study of 882 1st trimester sonographic examinations with abnormal findings among women who were threatening to abort. Eight hundred six met the inclusion criteria. RESULTS: In the study cohort 286 (35.5%) had no identifiable embryo and 71 of those without an identifiable embryo had a visible amnion (24.8%). The breakdown of the mean sac diameter of the study cohort was as follows: those measuring less than 16 mm (n = 16); those measuring 16-20 mm (n = 20); those measuring 21 mm or more (n = 35). Sixty-eight of the 71 patients had adequate follow-up. Pregnancy failure was confirmed in all 68 patients (positive predictive value = 100%). CONCLUSIONS: The data from this study indicate that visualization of an amnion without concomitant visualization of an embryo (the empty "amnion sign") confirms pregnancy failure regardless of the mean sac diameter and with a sufficiently high positive predictive value to make a definitive diagnosis. Copyright 2010 Wiley Periodicals, Inc.

PMID: 20127965

The yolk stalk sign: evidence of death in small embryos without heartbeats

J Ultrasound Med. 2010 Feb;29(2):237-41. Filly MR, Callen PW, Yegul NT, Filly RA.

Department of Radiology and Biomedical Imaging, University of California, 505 Parnassus Ave, San Francisco, CA 94143-0628 USA. Abstract OBJECTIVE: The purpose of this study was to assess the positive predictive value for confirming early embryonic death in the clinical sonographic scenario wherein an embryo is identified without a visible heartbeat; the embryonic crown-rump length (CRL) is 5 mm or less; and the embryo is not immediately adjacent to the yolk sac. METHODS: A retrospective study of 882 first-trimester sonograms was performed among women who had an intrauterine pregnancy of uncertain viability based on 1 or more sonographic findings (eg, no visible heartbeat in an embryo with a CRL of < or =5 mm). Eight hundred six cases met the inclusion criteria. RESULTS: Among the cohort of 806 cases, 520 (64.5%) had an identifiable embryo. One hundred fifty-nine of these embryos had no demonstrable heartbeat and a CRL of 5 mm or less. The CRLs of these embryos ranged from 1.7 to 5.4 mm. This cohort's sonograms were reviewed to determine whether there was a separation between the embryo and yolk sac. Twenty-one cases were discovered. Recall that as a retrospective study, no specific effort was made to show this finding. Thus, a computation of the sensitivity of this finding would result in an underestimate of indeterminate magnitude. All of these cases were subsequently proven to be failed pregnancies. CONCLUSIONS: The positive predictive value of the "yolk stalk sign" in determining early pregnancy failure for an embryo with a CRL of 5 mm or less and no visible heartbeat was 100% in this cohort.


Variability in human embryonic development and its implications for the susceptibility to environmental teratogenesis

Birth Defects Res A Clin Mol Teratol. 2009 Aug;85(8):661-6.

Shiota K.

Department of Anatomy and Developmental Biology and Congenital Anomaly Research Center, Kyoto University Graduate School of Medicine, Sakyo-ku, Kyoto, Japan.

Abstract Considerable variability is observed in the size and developmental stage among human embryos at a given gestational age, suggesting that prenatal development does not proceed at the same speed in every embryo. Such variability in embryonic development seems to occur in many (probably all) animal species, and is probably a normal "biologic" phenomenon to some extent. In the case of humans, some other factors (e.g., maternal memory bias, difficulty in assessing the timing of ovulation and fertilization) make it more difficult to assess the developmental stage of embryos in utero. Such facts related to human embryonic development should be taken into account when the teratogenic risk of a human embryo is considered.

(c) 2009 Wiley-Liss, Inc.

PMID: 19606457


Fetal cardiac activity at 4 weeks after in vitro fertilization predicts successful completion of the first trimester of pregnancy

Fertil Steril. 2008 Nov;90(5):1711-5. Epub 2007 Dec 3. Seungdamrong A, Purohit M, McCulloh DH, Howland RD, Colon JM, McGovern PG.

Department of Obstetrics, Gynecology, and Women's Health, University of Medicine and Dentistry of New Jersey, New Jersey Medical School, Newark, New Jersey 07101-1709, USA. Abstract OBJECTIVE: To determine the predictive value of fetal cardiac activity (FCA), measured at 6 weeks' gestation, on first-trimester pregnancy success after IVF. DESIGN: Retrospective cohort study. SETTING: University-based reproductive endocrinology and infertility practice. PATIENT(S): One hundred thirty-nine women, without a history of recurrent miscarriage, who were undergoing fresh IVF cycles from August 1, 2004 to February 28, 2005. INTERVENTION(S): Transvaginal ultrasound. MAIN OUTCOME MEASURE(S): First-trimester pregnancy success. RESULT(S): Ninety-three percent (51/53) of gestational sacs with FCA completed the first trimester (positive predictive value of 93%). Eighty-seven percent (13/15) of sacs without FCA failed in the first trimester (negative predictive value of 87%). In singletons, the positive and negative predictive value of FCA on first-trimester success was 100%. All twin pregnancies (n = 11) successfully completed the first trimester. CONCLUSION(S): This analysis, which was performed strictly in an IVF population with no history of recurrent pregnancy loss, demonstrates that positive FCA at 6 weeks' gestation is an excellent predictor of first-trimester pregnancy outcome.

PMID: 18061592


Human post-implantation embryo collection: medical and surgical techniques

Early Hum Dev. 1998 Jul 10;51(3):213-21.

Bullen PJ, Robson SC, Strachan T.

Department of Fetal Medicine, University of Newcastle upon Tyne, Royal Victoria Infirmary, UK. Abstract Knowledge of the genetic control of early human development is limited with most information being extrapolated from studies in animal models. There is compelling evidence that undertaking gene expression studies in human embryos can be expected to dramatically enhance our understanding of embryonic formation and malformation. Such studies require the systematic and coordinated collection, storage and study of human embryos. We have successfully collected intact embryos from cases undergoing termination of pregnancy (TOP). Embryonic material was collected from 62% of attempts using a technique of surgical aspiration carried out under ultrasound guidance. Collection rates were lower after medical termination of pregnancy (41%) although the proportion of undisrupted embryos was identical with the two methods (26%). Surgical aspiration provided intact embryos between Carnegie stages (CS) 16-22 while earlier developmental stages were collected from medical terminations. Our collection of over 60 intact specimens, spanning Carnegie stages 10 to 22 (about 21 to 53 days of development) covers a huge window of critical developmental events and hence represents an exciting and valuable research resource.

PMID: 9692791

Early (34-56 days from last menstrual period) ultrasonographic measurements in normal pregnancies

Hum Reprod. 1996 Aug;11(8):1771-4.

Coulam CB, Britten S, Soenksen DM.

Genetics & IVF Institute, Fairfax, VA 22031, USA. Abstract To assess early embryonic growth and development, 361 pregnancies were studied from 34 to 56 days from last menstrual period. All pregnancies had a subsequent successful outcome. Transvaginal ultrasonography was performed using an Acuson 128 x P/10 with a 5-7.5 MHz probe. Gestational sac diameter, embryonic pole length and embryonic heart rates were measured. Embryonic heart rates were determined by M-mode. Gestational sac diameter, embryonic pole length and embryonic heart rate increased linearly relative to gestational age and to each other. Regression equations comparing gestational sac diameter and embryonic pole length as well as comparing embryonic heart rate with gestational sac diameter and embryonic pole length were constructed. To be normal, gestations that have (i) sac diameter of 20 mm and 30 mm should contain at least a 2 mm and 5 mm embryo with embryonic heart rates of at least 75 and 100 beats per min, respectively, and (ii) embryos measuring 2 mm, 5 mm, 10 mm and 15 mm should display embryonic heart rates of at least 75, 100, 120 and 130 beats per minute respectively.

PMID: 8921130 [PubMed - indexed for MEDLINE]

Embryonic death in early pregnancy: a new look at the first trimester

Obstet Gynecol. 1994 Aug;84(2):294-7. Goldstein SR.

Department of Obstetrics and Gynecology, New York University School of Medicine, New York. Abstract OBJECTIVE: To examine the frequency of pregnancy loss following successful development of anatomical embryonic landmarks identified with endovaginal ultrasound. METHODS: Two hundred thirty-two women with positive urinary pregnancy tests and no antecedent history of vaginal bleeding had endovaginal sonography performed at the initial visit and at subsequent visits as indicated clinically. The presence of anatomical and embryonic structures (gestational sac, yolk sac, embryo) and cardiac activity was recorded. Patients were followed until delivery unless sonographic evidence of nonviability was seen or spontaneous loss occurred. RESULTS: Twenty-seven losses occurred during the embryonic period, four losses occurred in the fetal period, and there were 201 live births. If a gestational sac developed, subsequent loss of viability in the embryonic period occurred in 11.5%; loss rates were 8.5% with a yolk sac, 7.2% for an embryo up to 5 mm, 3.3% for an embryo of 6-10 mm, and 0.5% for an embryo larger than 10 mm. No pregnancies were lost between 8.5 and 14 menstrual weeks. The fetal loss rate after 14 weeks was 2.0%. CONCLUSIONS: The rate of early pregnancy loss decreases successively with gestational age and is virtually complete by the end of the embryonic period (70 days after onset of the last menstrual period). Subsequent pregnancy losses in the fetal period occur between 14 and 20 weeks. This pattern of early pregnancy death suggests a period of embryonic loss distinct from one of fetal loss. Based on these data, the physiologic significance of the traditional boundary of the first trimester as an appropriate dividing time line for early pregnancy may be questioned.

PMID: 8041550 [PubMed - indexed for MEDLINE]


Comparative development of the nervous, respiratory, and cardiovascular systems

Environ Health Perspect. 1976 Dec;18:55-60.

Monie IW.

Abstract The timing of some key embryological events is given for man, rat, chick, and certain other animals. Such times, however, are approximations, and variations occur among members of the same strain and even among members of the same litter. Some differences in developmental patterns are indicated.

PMID: 829490 Environ Health Perspect. 1976 Dec;18:55-60. Comparative development of the nervous, respiratory, and cardiovascular systems. Monie IW.

Abstract The timing of some key embryological events is given for man, rat, chick, and certain other animals. Such times, however, are approximations, and variations occur among members of the same strain and even among members of the same litter. Some differences in developmental patterns are indicated.

PMID: 829490