Welcome to The Visible Embryo
Home-- -History-- -Bibliography- -Pregnancy Timeline- --Prescription Drugs in Pregnancy- -- Pregnancy Calculator- --Female Reproductive System- -Contact

Welcome to The Visible Embryo, a comprehensive educational resource on human development from conception to birth.

The Visible Embryo provides visual references for changes in fetal development throughout pregnancy and can be navigated via fetal development or maternal changes.

The National Institutes of Child Health and Human Development awarded Phase I and Phase II Small Business Innovative Research Grants to develop The Visible Embryo. Initally designed to evaluate the internet as a teaching tool for first year medical students, The Visible Embryo is linked to over 600 educational institutions and is viewed by more than one million visitors each month.

Today, The Visible Embryo is linked to over 600 educational institutions and is viewed by more than 1 million visitors each month. The field of early embryology has grown to include the identification of the stem cell as not only critical to organogenesis in the embryo, but equally critical to organ function and repair in the adult human. The identification and understanding of genetic malfunction, inflammatory responses, and the progression in chronic disease, begins with a grounding in primary cellular and systemic functions manifested in the study of the early embryo.

WHO International Clinical Trials Registry Platform

The World Health Organization (WHO) has created a new Web site to help researchers, doctors and
patients obtain reliable information on high-quality clinical trials. Now you can go to one website and search all registers to identify clinical trial research underway around the world!




Pregnancy Timeline

Prescription Drug Effects on Pregnancy

Pregnancy Calculator

Female Reproductive System

Contact The Visible Embryo

News Alerts Archive

Disclaimer: The Visible Embryo web site is provided for your general information only. The information contained on this site should not be treated as a substitute for medical, legal or other professional advice. Neither is The Visible Embryo responsible or liable for the contents of any websites of third parties which are listed on this site.
Content protected under a Creative Commons License.

No dirivative works may be made or used for commercial purposes.


Pregnancy Timeline by SemestersFetal liver is producing blood cellsHead may position into pelvisBrain convolutions beginFull TermWhite fat begins to be madeWhite fat begins to be madeHead may position into pelvisImmune system beginningImmune system beginningPeriod of rapid brain growthBrain convolutions beginLungs begin to produce surfactantSensory brain waves begin to activateSensory brain waves begin to activateInner Ear Bones HardenBone marrow starts making blood cellsBone marrow starts making blood cellsBrown fat surrounds lymphatic systemFetal sexual organs visibleFinger and toe prints appearFinger and toe prints appearHeartbeat can be detectedHeartbeat can be detectedBasic Brain Structure in PlaceThe Appearance of SomitesFirst Detectable Brain WavesA Four Chambered HeartBeginning Cerebral HemispheresFemale Reproductive SystemEnd of Embryonic PeriodEnd of Embryonic PeriodFirst Thin Layer of Skin AppearsThird TrimesterSecond TrimesterFirst TrimesterFertilizationDevelopmental Timeline
CLICK ON weeks 0 - 40 and follow along every 2 weeks of fetal development
Google Search artcles published since 2007

Home | Pregnancy Timeline | News Alerts |News Archive Dec 24, 2014

The hippocampus region of the brain in children born prematurely — is smaller.
And this part of the brain is essential for forming and retrieving contextual memories.




Context memory function in preterm babies

Children born prematurely show differences in a subtle but important aspect of memory: their ability to form and retrieve memories about context — such as what, when, and where something has happened.

This type of memory is important, but can be missed on the usual set of assessment tests. New research suggests that it may be valuable to find ways to help strengthen this aspect of memory in children born preterm. The study also found that the hippocampus region of the brain in children born prematurely — is smaller — yet this part of the brain is essential for forming and retrieving contextual memories.

The research appears in the journal Child Development.

"Our study provides evidence that prematurity can result in problems with a particular subprocess of recollection.

"The specific modification in the memory network is so subtle that it could be overlooked because it doesn't manifest itself as clear memory impairment. But memory deficits can appear in situations in which retrieving contextual information is essential."

Kerstin H. Kipp PhD, principal investigator of the research project when at the University of Saarland. Kipp is now with the State University of Music and Performing Arts Stuttgart and the University of Ulm, Germany.

In everyday life, not having good context memory could lead to problems like forgetting where you put your keys or trying to remember the color of a car in a traffic accident you witnessed.

"Our results have important implications for improving the treatment of children born preterm. Instead of applying unspecific memory training, the affected children might benefit more from learning how to strengthen associations between different elements of memories," she notes.

The study examined 33 German 8 to 10 year-olds, 18 of whom were born preterm (defined as born at 26 to 33 weeks) and 15 of whom were born full term (defined as born at 39 to 42 weeks.) Researchers used magnetic resonance imaging to measure the volume of the hippocampi.

The children performed a memory task on which they were asked to learn and recognize certain items: previously seen pictures of line drawings were mixed in with new pictures, and the children had to indicate whether the picture was old or new. Their brain activity was measured by an electroencephalogram (EEG) as they did this, which allowed researchers to gauge the processes involved in memory retrieval.

The ability to recognize whether the picture was old or new was not reduced in the children who were born prematurely. However, the EEG index of recollection-based memory retrieval, which is important for remembering contextual information, was reduced. A follow-up experiment ruled out the possibility that this occurred due to general cognitive deficits. The EEG index of familiarity, a retrieval process that's thought to operate independently of the hippocampus, remained unchanged.

The EEG index of recollection correlated with the child's gestational age: The earlier a child was born, the larger the adverse effect on recollection-based retrieval.

Even though the preterm group showed a reduced EEG index for recollection, their general memory performance was equal to that of children not born prematurely. The researchers hypothesize that this occurred because they compensated for their impaired contextual recollection using their overall memory function. But because contextual memory continues to be important for specific tasks, compensation by overall memory won't rule out the possibility that prematurely born children can have more difficulty with context memory.

The research lays the groundwork for steps to help children strengthen these particular aspects of memory.

The German Research Foundation supported the study.

Prematurity may cause hippocampal compromise. Therefore, hippocampus-dependent memory processes (recollection-based retrieval) may be more impaired than hippocampus-independent processes (familiarity-based retrieval). The memory of 18 children born preterm with reduced hippocampal volumes, without neonatal complications (weeks of gestation < 34, weight < 1,600 g), and 15 controls (8–10 years) was tested using an item recognition task. While groups were equal in memory performance, dissociation was found: The event-related potential (ERP) correlate of familiarity was intact in the preterm group, whereas the correlate of recollection was attenuated. A follow-up experiment ruled out that this was due to general cognitive deficits. Furthermore, gestational age correlated with the ERP index of recollection. Thus, recognition memory in preterm children may be characterized by a compensation of attenuated recollection by familiarity.

Summarized from Child Development, Modifications of Recognition Memory Processes in Preterm Children: An Event-Related Potential Study by Kipp, KH (currently at the State University of Music and Performing Arts Stuttgart and the University of Ulm, formerly at the University of the Saarland), Mecklinger, A (University of the Saarland), Brunnemann, N (currently at the University of Konstanz, formerly at University of the Saarland), Shamdeen, MG (currently at University Hospital Gießen and Fulda, formerly at Saarland University Hospital), Meng-Hentschel, J (currently at the University of Bern, formerly at Saarland University Hospital), and Gortner, L (Saarland University Hospital). Copyright 2014 The Society for Research in Child Development, Inc. All rights reserved.

Return to top of page