Failed to understand "prior to the generation of egg and sperm"

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Does "the generation of egg and sperm" refer to "the production of egg and sperm"? If so, only mature adults (man and woman) can produce eggs and sperms.

Context:

Reprogramming of DNA observed in human germ cells for first time
Date: June 4, 2015
Source: University of Cambridge
Summary:
A team of researchers has described for the first time in humans how the epigenome -- the suite of molecules attached to our DNA that switch our genes on and off -- is comprehensively erased in early primordial germ cells prior to the generation of egg and sperm. However, the study shows some regions of our DNA -- including those associated with conditions such as obesity and schizophrenia -- resist complete reprogramming.

More:
http://www.sciencedaily.com/releases/2015/06/150604141754.htm

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@oristarA,

oristarA wrote:

Does "the generation of egg and sperm" refer to "the production of egg and sperm"? If so, only mature adults (man and woman) can produce eggs and sperms.

Context:

Reprogramming of DNA observed in human germ cells for first time
Date: June 4, 2015
Source: University of Cambridge
Summary:
A team of researchers has described for the first time in humans how the epigenome -- the suite of molecules attached to our DNA that switch our genes on and off -- is comprehensively erased in early primordial germ cells prior to the generation of egg and sperm. However, the study shows some regions of our DNA -- including those associated with conditions such as obesity and schizophrenia -- resist complete reprogramming.

More:
http://www.sciencedaily.com/releases/2015/06/150604141754.htm

Sort of. The epigenomes of stem cells are completely erased before the stem cell becomes either egg or sperm, I think. This happens in vivo, based on the context. In the human, a stem cell can become either an egg or a sperm, and before that, its epigenome is wiped clean (mostly). Since the female fetus is born with all the eggs she'll ever produce (I think), that means this happens in utero for her. Not so in males, I think. If there's a doctor in the house, s/he may correct me on this.

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@FBM,

Quote:

Since the female fetus is born with all the eggs she'll ever produce (I think), that means this happens in utero for her.

This has always been my understanding also. At about the 20th week of gestation, a female fetus will contain around 7 million immature eggs; at birth around 2 million are left; at puberty around 300,000; around 1,000 die every month; one per month is released to possibly be fertilised; when all are gone menopause occurs. At least that has been the received wisdom over the last 60 years. Some stem cell researchers have reported finding cells in the ovaries of young women that may mean that new eggs are produced during a woman's fertile years. However this is by no means certain or proven. (By the way I am not a doctor).

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@Tes yeux noirs,

Excellent.

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Failed to understand "prior to the generation of egg and sperm"

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