Featured Research

from universities, journals, and other organizations

An embryo that is neither male nor female: Impact of three unexpected sex determination factors analyzed

Date:
January 3, 2013
Source:
Université de Genève
Summary:
Is it a girl or a boy? This is the first question parents ask at the birth of an infant. Though the answer is obvious, the mechanism of sex determination is much less so. Researchers attempt to shed light on this complex process by identifying the crucial role played by insulin and IGF1 and IGF2 growth factors, a family of hormones known for its role in metabolism and growth.

So, is it a girl or a boy? This is the first question parents ask at the birth of an infant. Though the answer is obvious, the mechanism of sex determination is much less so. Researchers at the University of Geneva (UNIGE) attempt to shed light on this complex process by identifying the crucial role played by insulin and IGF1 and IGF2 growth factors, a family of hormones known for its role in metabolism and growth. In the absence of these factors at the time of sex determination, embryos do not differentiate into either male or female and have no adrenal glands. The results of this study, published in the journal PLOS Genetics, allow us to better understand sexual development and will eventually improve diagnosis and genetic counseling practices for individuals with disorders of sex development.

In mammals, sexual development is a long process beginning at conception when the sperm's transmission of an X or Y sex chromosome will determine the genetic sex of the embryo. The following developmental stages will translate this genetic sex into gonadal sex, that is, either ovaries or testes, which will secrete hormones that will masculinize or feminize the fetus.

The intention of the study conducted by Serge Nef, Professor at the Department of Genetic Medicine and Development at UNIGE, is to better understand the first stages of sexual development.

Growth, metabolism and reproduction

The researchers were interested in the role of a class of hormones, insulin-like growth factors (IGFs), and their receptors in cells. These factors, known to be involved in the regulation of metabolism and growth, also have a key role in the regulation of reproductive capacities of the individual, whether male or female. Reproductive function is, in fact, closely linked to metabolism and growth. This is actually quite logical: the growth of an individual cannot progress normally without adequate energy intake and there is no point in reproducing if this caloric intake is insufficient. This may explain why some women with anorexia have anovulatory cycles and may suffer from infertility. Conversely, people with morbid obesity also have significant disturbances in their fertility. Though it is now recognized that the interactions between metabolism, growth and reproductive capacity are regulated by common factors such as insulin and IGFs, Professor Nef's study shows that these interactions are even more important than previously believed because the insulin and IGF receptors are also essential for primary sex determination in mammals.

To analyze the impact of these hormones on sex determination, Professor Nef's group used genetically modified mice. The scientists genetically inactivated the receptors for insulin and IGFs in mouse embryos. They then discovered that in the absence of these factors, at the time of sex determination, the gonads of mutant embryos were unable to develop into testes or ovaries. As such, the embryo and its gonads remained stuck in a fully undifferentiated state for several days demonstrating the essential role of these hormones and growth factors in sexual differentiation.

In humans, cases of disorders of sex development are relatively common with about 1 newborn in every 3000 births being affected. Unfortunately, in the majority of cases, the genetic causes of such alterations remain unexplained. "This study provides a better understanding of the basic mechanisms of sexual development and is a step forward towards a better understanding of the causes of sexual ambiguities, which often remain unknown," states Professor Nef. "The research we are conducting will provide the opportunity to refine and improve clinical diagnosis of individuals with disorders of sex development."


Story Source:

The above story is based on materials provided by Université de Genève. Note: Materials may be edited for content and length.


Journal Reference:

  1. Jean-Luc Pitetti, Pierre Calvel, Yannick Romero, Béatrice Conne, Vy Truong, Marilena D. Papaioannou, Olivier Schaad, Mylène Docquier, Pedro Luis Herrera, Dagmar Wilhelm, Serge Nef. Insulin and IGF1 Receptors Are Essential for XX and XY Gonadal Differentiation and Adrenal Development in Mice. PLoS Genetics, 2013 DOI: 10.1371/journal.pgen.1003160

Cite This Page:

Université de Genève. "An embryo that is neither male nor female: Impact of three unexpected sex determination factors analyzed." ScienceDaily. ScienceDaily, 3 January 2013. <www.sciencedaily.com/releases/2013/01/130103192445.htm>.
Université de Genève. (2013, January 3). An embryo that is neither male nor female: Impact of three unexpected sex determination factors analyzed. ScienceDaily. Retrieved September 30, 2014 from www.sciencedaily.com/releases/2013/01/130103192445.htm
Université de Genève. "An embryo that is neither male nor female: Impact of three unexpected sex determination factors analyzed." ScienceDaily. www.sciencedaily.com/releases/2013/01/130103192445.htm (accessed September 30, 2014).

Share This



More Health & Medicine News

Tuesday, September 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

How 'Yes Means Yes' Defines Sexual Assault

How 'Yes Means Yes' Defines Sexual Assault

Newsy (Sep. 29, 2014) — Aimed at reducing sexual assaults on college campuses, California has adopted a new law changing the standard of consent for sexual activity. Video provided by Newsy
Powered by NewsLook.com
Scientists May Have Found An Early Sign Of Pancreatic Cancer

Scientists May Have Found An Early Sign Of Pancreatic Cancer

Newsy (Sep. 29, 2014) — Researchers looked at 1,500 blood samples and determined people who developed pancreatic cancer had more branched chain amino acids. Video provided by Newsy
Powered by NewsLook.com
Colo. Doctors See Cluster of Enterovirus Cases

Colo. Doctors See Cluster of Enterovirus Cases

AP (Sep. 29, 2014) — Doctors at the Children's Hospital of Colorado say they have treated over 4,000 children with serious respiratory illnesses since August. Nine of the patients have shown distinct neurological symptoms, including limb weakness. (Sept. 29) Video provided by AP
Powered by NewsLook.com
Dr.'s Unsure of Cause of Fast-Spreading Virus

Dr.'s Unsure of Cause of Fast-Spreading Virus

AP (Sep. 29, 2014) — Doctors at the Children's Hospital of Colorado say they have treated over 4,000 children with serious respiratory illnesses since August. Nine of the patients have shown distinct neurological symptoms, including limb weakness. (Sept. 29) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins