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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.

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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
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Home | Pregnancy Timeline | News Alerts |News Archive Dec 8, 2014

"It is less well known that sperm DNA quality, can affect
development and health in a man's offspring.
" Sheri Johnson, PhD

 






 

 

Sperm quality decreases with age

Prior evidence regarding men’s semen quality declining with age — lowering their fertility — is established by a new review of data from 90 previous studies done around the world.

A systematic review and meta-analysis of data from those studies was done by researchers from the University of Otago, Departments of Zoology and Anatomy, which found consistent age-related declines in semen volume and sperm performance. There were also increases in malformed and DNA-damaged sperm as well. Semen volume and performance are indicators of male fertility.

Study author Sheri Johnson PhD, believes that understanding how age affects fertility is increasingly important as couples delay childbearing.


“While female age is well known to have negative effects on fertility, reproductive success and the health of their offspring, the influence of male age on a couple’s fertility has been largely neglected.

“The effects of declining semen quality and performance with increasing age have largely been ignored because of inconsistencies in the literature. However, our work suggests that male age affects a variety of sperm traits. It is well recognised that sluggish sperm performance can affect pregnancy success. But it is less well known that sperm DNA quality, can affect development and health in a man's offspring.”

Sheri Johnson PhD, Departments of Zoology and Anatomy, University of Otago


Johnson and her co-authors synthesised the current state of knowledge from 90 individual studies, spanning about 94,000 volunteers/patients from more than 30 countries. Their Marsden-funded study will appear in the international journal, Ageing Research Reviews, in Volume 19, January 2015, Pages 22–33.

“Our study made no attempt to estimate the rate of decline, but some well-controlled clinic-based studies have observed consistent declines with increasing age, whereas others project declines after age 35 for some traits and after age 40 for others” she says.

Co-author Neil Gemmell, says the consistency in its findings suggests that further examination of the potential consequences of male age on reproductive outcomes is needed.

“Older males contribute to increased risk of obstetric complications, miscarriage, and offspring disorders such as autism, Down syndrome, epilepsy, and schizophrenia. In addition, increasing male age may be an overlooked component of couple infertility, leading to our increased use and dependency on fertility treatments, such as IVF.”

Overall, the authors advise that clinicians and the general public need to be made aware of the risks associated with male age on fertility. Clinical analysis of the percent of DNA-fragmented sperm along with a greater focus on how well sperm swim, may lead to better fertility outcomes during treatments of ageing couples.

“These are likely more accurate and consistent predictors of a man’s fertility than those commonly measured traits of semen volume, sperm concentration and total sperm count,” Johnson adds.

Abstract
Reduced fertility typically occurs among women in their late 30s, but increasing evidence indicates that advanced paternal age is associated with changes in reproduction as well. Numerous studies have investigated age-based declines in semen traits, but the impact of paternal age on semen parameter values remains inconclusive. Using data from 90 studies (93,839 subjects), we conducted a systematic review and meta-analysis to quantify the effect of male age on seven ejaculate traits (semen volume, sperm concentration, total sperm count, morphology, total motility, progressive motility and DNA fragmentation). Age-associated declines in semen volume, percentage motility, progressive motility, normal morphology and unfragmented cells were statistically significant and results generally seemed to be robust against confounding factors. Unexpectedly, sperm concentration did not decline with increasing male age, even though we found that sperm concentration declined over time. Our findings indicate that male age needs more recognition as a potential contributor to the negative pregnancy outcomes and reduced offspring health associated with delayed first reproduction. We suggest that greater focus on collection of DNA fragmentation and progressive motility in a clinical setting may lead to better patient outcomes during fertility treatments of aging couples.


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