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Male Reproductive System
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Components Scrotum Testes Duct system Penis Accessory glands
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Scrotum Skin Dartos muscle (smooth) Septum Cremaster muscle (skeletal)
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Scrotum Temperature Spermatic cord
Optimal for sperm development is 3°C below body temp (~91 F) Controlled by muscles Spermatic cord Testicular artery Plexus of veins Nerves vas deferens
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Testes – gross anatomy ~4 cm long, 2.5 cm wide Tunica vaginalis
Tunica albuginea (capsule) Septa lobules Seminiferous tubules Epididymis
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Descent of the Testes 3 mos. 7 mos. birth
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Seminiferous tubules Spermatogenic cells
Spermatogenesis begins at puberty ~400 million sperm/day
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Spermatogenic cells Spermatogonia Primary spermatocytes
On basal lamina Mitosis Primary spermatocytes 1st meiotic division Secondary spermatocytes 2nd meiotic division Spermatid Haploid 4 from each 1° spermatocyte
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Seminiferous tubules Spermatogenesis Spermatogonia 1° spermatocyte
Spermatid
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Hormones Spermatogenesis controlled by
FSH (follicle stimulating hormone) from pituitary Testosterone from Leydig (interstitial) cells of testes secretions from Sertoli cells
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Spermiogenesis Spermatid spermatozoan Head Midpiece Tail Nucleus
Acrosome (lysosome) Midpiece Base of tail Mitochondria Tail Long flagellum 24.5
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Spermatid spermatozoan
Spermiogenesis Spermatid spermatozoan 24.5
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Sustentacular (Sertoli) cells
Nurse cells Extend from basal lamina to lumen Connected to each other by tight junctions Nourish spermatogenic cells Transport spermatogenic cells Phagocytize excess cytoplasm Secretions regulate spermatogenesis
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Sustentacular cells 2 Sertoli cells with associated spermatogenesis cells.
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Interstitial (Leydig) cells
Secretes testosterone sER for steroid production Controlled by LH from pituitary
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Ducts Epididymis Ductus deferens Ejaculatory duct (urethra) 24.1
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Epididymis Located in scrotum
Between seminiferous tubules and vas deferens ~6 m long
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Epididymis Pseudostratified columnar epithelium
With stereocilia (long microvilli) Smooth muscle Sperm mature and stored
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Ductus (vas) deferens From scrotum to pelvis
Forms ejaculatory duct with seminal vesicle duct Empties into prostatic urethra Thick muscularis Propels sperm during ejaculation 24.1
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Ductus deferens Microscopic anatomy Pseudostratified epithelium
Lamina propria Muscularis Inner longitudinal Middle circular Outer longitudinal 24.6b
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Urethra Shared with urinary system Prostatic urethra
Membranous urethra Spongy (penile) urethra
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Accessory Glands Seminal vesicle 60% of semen
Fructose to nourish sperm
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Prostate Gland Surrounds prostatic urethra 30% of semen Supports sperm
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Penis Thin skin Spongy urethra Erectile bodies Corpus spongiosum
2 corpora cavernosa Capsule Vascular spaces
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Erection Sexual excitement (parasympathetic)
blood flow to erectile bodies Squeezes veins shut blood pressure in erectile bodies
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Ejaculation Sympathetic activation
Peristaltic contraction of smooth muscles in ducts and glands - ejaculation Constriction of arteries blood pressure in erectile bodies
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