The provided reference does not discuss changes in the proportion of male and female sperm as men age. Instead, it explains that sperm production declines with age in men.
Understanding Male Fertility and Aging
While the question implies a shift in the ratio of sperm carrying X and Y chromosomes (female and male), there isn't any evidence suggesting this occurs. The reference provided focuses solely on the overall decline in sperm production, volume, and fertility as men age.
Here's what we know from the provided reference:
- Sperm Production: Unlike women who have a finite number of eggs, men continually produce sperm throughout their lives. However, this production decreases over time.
- Semen Volume: As men age, the volume of semen they produce also decreases.
- Sperm Count: The number of sperm per ejaculate is reduced as men get older.
- Fertility Decline: Male fertility typically begins to decline between the ages of 40 and 45.
Addressing the Question
The question as it stands is a little misleading. It assumes that the ratio of X and Y bearing sperm shifts with age. The referenced text does not support that claim and instead focuses on decreased production. So it would be more accurate to ask: "How does male sperm production change as men age?". Then, we can answer accurately based on the provided reference. The updated question would have this answer:
The reference indicates that men experience a decline in sperm production, semen volume, and the number of sperm per ejaculate as they age, generally starting around 40 to 45 years. However, the reference does not address any shifts in the ratio of X or Y bearing sperm as men age.
