31.7
精子の輸送
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Q1: How do sperm move through the seminiferous tubules and into the epididymis?
Sertoli cells within seminiferous tubules produce fluid that pushes non-motile sperm through straight tubules into the rete testis. From this interconnected network, sperm enters the efferent ductules and then the epididymis, where they begin their maturation journey over two to three weeks.
Q2: What changes occur to sperm during their time in the epididymis?
During their two to three week transit through the epididymis, sperm acquire motility and maturity necessary for fertilization. Peristaltic contractions of the epididymis facilitate this transformation and propel the mature sperm into the vas deferens, where they can be stored for extended periods.
Q3: How long can sperm remain viable in the vas deferens?
Mature sperm stored in the vas deferens maintain a low metabolic rate and can remain viable for months without losing their fertilizing potential. This storage capability allows the body to preserve sperm until sexual arousal triggers ejaculation through peristaltic contractions.
Q4: What role do peristaltic contractions play in sperm transport?
Peristaltic contractions propel sperm through multiple reproductive structures. These muscular waves move mature sperm from the epididymis into the vas deferens and, during sexual arousal, push stored sperm toward the ejaculatory ducts for eventual expulsion during male sexual response erection ejaculation.
Q5: Where do the ejaculatory ducts deliver sperm before ejaculation?
The ejaculatory ducts pierce through the prostate gland and empty sperm into the prostatic urethra. During ejaculation, mature sperm and fluid from accessory glands of the male reproductive system are expelled from the body through the urethra during this process.
Q6: What is the role of the rete testis in sperm transport?
The rete testis is an interconnected network of tubules that receives non-motile sperm from the seminiferous tubules. This structure acts as a crucial intermediate pathway, directing sperm from the straight tubules into the efferent ductules and ultimately into the epididymis for maturation.
Q7: How does sympathetic nervous system stimulation affect sperm transport during ejaculation?
During sexual arousal and ejaculation, sympathetic nervous system stimulation triggers peristaltic contractions in the vas deferens. These coordinated muscular contractions propel stored sperm toward the ejaculatory ducts, combining with fluids from accessory glands before expulsion through the urethra during this process.