Male Reproductive System Components Scrotum Testes Duct system

Male Reproductive System

Components • • • Scrotum Testes Duct system Penis Accessory glands

Scrotum Skin Dartos muscle (smooth) Septum Cremaster muscle (skeletal)

Scrotum Temperature 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

Testes – gross anatomy ~4 cm long, 2. 5 cm wide Tunica vaginalis Tunica albuginea (capsule) Septa 250 -300 lobules Seminiferous tubules Epididymis

Descent of the Testes 3 mos. 7 mos. birth

Seminiferous tubules Spermatogenic cells Spermatogenesis begins at puberty ~400 million sperm/day

Spermatogenic cells • Spermatogonia • On basal lamina • Mitosis • Primary spermatocytes • 1 st meiotic division • Secondary spermatocytes • 2 nd meiotic division • Spermatid • Haploid • 4 from each 1° spermatocyte

Seminiferous tubules Spermatogenesis Spermatogonia 1° spermatocyte 2° spermatocyte Spermatid

Hormones Spermatogenesis controlled by FSH (follicle stimulating hormone) from pituitary Testosterone from Leydig (interstitial) cells of testes secretions from Sertoli cells

Spermiogenesis Spermatid spermatozoan Head Nucleus Acrosome (lysosome) Midpiece Base of tail Mitochondria Tail Long flagellum 24. 5

Spermiogenesis Spermatid spermatozoan 24. 5

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

Sustentacular cells 2 Sertoli cells with associated spermatogenesis cells.

Interstitial (Leydig) cells Secretes testosterone s. ER for steroid production Controlled by LH from pituitary

Ducts Epididymis Ductus deferens Ejaculatory duct (urethra) 24. 1

Epididymis Located in scrotum Between seminiferous tubules and vas deferens ~6 m long

Epididymis Pseudostratified columnar epithelium With stereocilia (long microvilli) Smooth muscle Sperm mature and stored

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

Ductus deferens Microscopic anatomy Pseudostratified epithelium Lamina propria Muscularis Inner longitudinal Middle circular Outer longitudinal 24. 6 b

Urethra Shared with urinary system Prostatic urethra Membranous urethra Spongy (penile) urethra

Accessory Glands Seminal vesicle 60% of semen Fructose to nourish sperm

Prostate Gland Prostate gland Surrounds prostatic urethra 30% of semen Supports sperm

Penis Thin skin Spongy urethra Erectile bodies Corpus spongiosum 2 corpora cavernosa Capsule Vascular spaces

Erection Sexual excitement (parasympathetic) blood flow to erectile bodies Squeezes veins shut blood pressure in erectile bodies

Ejaculation Sympathetic activation Peristaltic contraction of smooth muscles in ducts and glands - ejaculation Constriction of arteries blood pressure in erectile bodies