Pope Francis on Thursday named the next archbishops of two major metropolitan sees – Archbishop Michel Aupetit to Paris and Cardinal Carlos Aguiar Retes to Mexico City, the world's largest diocese.

The appointments were announced in a press release from the Vatican Dec. 7. Both prelates are replacing bishops who have retired upon reaching the age of 75, the normal retirement age for clergy.

Cardinal Aguiar, 67, has held top roles in both the Mexican bishops' conference and the Latin American bishops' conference and is a member of the Pontifical Council for Interreligious Dialogue and the Pontifical Commission for Latin America.

Cardinal Aguiar has been archbishop of Tlalnepantla, Mexico since 2009. He replaces Cardinal Norberto Rivera Carrera, whose retirement was accepted by Pope Francis after reaching the age of 75.

Aguiar was born on Jan. 9, 1950 in Tepic, Mexico. He studied at the Seminary of Tepic, followed by the seminaries of Montezuma in the United States and of Tula. On April 22, 1973 he was ordained a priest for the Diocese of Tepic.

He received a licentiate in Sacred Scripture from the Pontifical Biblical Institute in Rome in 1977.

As a priest he served as a parochial vicar, as well as rector of the Seminary of Tepic. At the same time, he was President of the Organization of Mexican Seminaries (OSMEX) and a member of the board of directors of Latin American Seminaries.

He was later rector of the John XXIII Residence for priests of the Pontifical University of Mexico in Mexico City, where he was also a professor of Sacred Scripture. In 1997 he received a doctorate in Biblical Theology from the Pontifical Gregorian University in Rome.

In June 1997 he was consecrated bishop for the Diocese of Texcoco and in February 2009 he was made Metropolitan Archbishop of the Archdiocese of Tlalnepantla.

From 2004-2006 he was secretary general of the Mexican bishops' conference, and then from 2006-2012, president of the conference. He also held various positions in the Latin American Bishops' Council (CELAM) from 2000-2015, including secretary general, vice-president and president.

He participated in both assemblies of the Synod of Bishops on the family in 2014 and 2015 and was made a cardinal by Pope Francis in the November 2016 consistory. He is also a member of the Pontifical Council for Interreligious Dialogue and the Pontifical Commission for Latin America.

The Archdiocese of Mexico City covers 551 square miles and, as of 2013, contained more than 7 million Catholics. There are nearly 600 diocesan priests and over 1,000 religious priests. There are also more than 7,000 consecrated men and women.

Archbishop Aupetit, 66, a former doctor, is an expert in bioethics. He has been archbishop of Nanterre, France since May 2014.

He replaces Cardinal Andre Vingt-Trois, archbishop of Paris, whose retirement was accepted by Pope Francis after reaching the age of 75.

Archbishop Aupetit was born in Versailles on March 23, 1951. He graduated with a medical degree in 1978, and worked as a medical professional in the northern suburbs of Paris for 12 years.

His specialty was in medical bioethics, which he taught at the Henri Mondor Hospital in Creteil. In 1990 he entered the seminary and in June 1995 he was ordained a priest for the Archdiocese of Paris.

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He served as a parish priest and a high school chaplain for a number of years, as well as vicar general of the archdiocese and a member of the presbyteral council from 2006-2013.

On February 2, 2013 he was appointed auxiliary bishop of Paris. He was consecrated on April 19, 2013. Aupetit was appointed bishop of Nanterre on April 4, 2014.

He is president of the "Family and Society" council of the French bishops' conference and is also a member of the conference's bioethics working group.

The Archdiocese of Paris is 40 square miles and has approximately 1.3 million Catholics, as of 2013. There are over 800 diocesan priests and over 500 religious priests and approximately 2,700 consecrated men and women.