Ch 27: Reproductive System Goals: Identify the structures of the male and female reproductive systems, including the gross and microscopic anatomy of the organs, structures and accessory glands and their basic functions. Explain meiosis, spermatogenesis and oogenesis. Discuss the changes that occur in the female reproductive system during pregnancy.
General Organization Gonads gametes & hormones Ducts transport of . . . ? Glands secrete fluid Perineal structures = external genitalia
Male Reproductive Anatomy • Primary reproductive organs produce gametes • Secondary reproductive organs . . . • Male reproductive and urinary tracts are partially shared Fig 27-1
Testes(paired glands) 4 month • Develop adjacent to kidneys • Descend into scrotum through inguinal canal (function of gubernaculum testis) • Peritoneal lining is carried along lining of scrotum • Spermatic cord: bundle containing all the “duct work” • Cryptorchidism Figs 27-2/3
Cremaster muscle Scrotum Function: supports and protects testes Structure: Skin & underlying superficial fascia • Dartos musclein dermis • Cremaster muscle - continuous with abdominal wall muscles (?) Involuntary contraction (cremasteric reflex) in response to ________ Scrotal sac forms 2 separate chambers
Structure of Testes • Fibrous capsule – tunica albuginea – surrounds testes • Scrotal cavity – lined by tunica vaginalis – parietal and visceral layers • 200-300 lobules • 3 seminiferous tubules Figs 27-4/5
From Spermatocyte to Spermatozoon • Spermatogenesis: Meiosis of primary spermatocytes spermatids • Spermiogenesis: Spermatid maturation into spermatozoa within Sertoli cells • Spermiation: Spermatozoon released into lumen
Sustentacular (Sertoli) Cells • Maintenance of blood testis barrier special lumen fluid high in sex hormones, K+ and aa protection from immune attack (due tosperm specific ag) • Suspend spermatids and support spermatogenesis and spermiogenesis FSH and Testosterone work via Sertoli cells • Secretion of inhibin to slow sperm production • Secretion of androgen-binding protein (ABP)
Anatomy of a Spermatozoon Mature sperm has 3 portions: • Head with acrosome (containing _______ ) • Middle piece with nucleus and lots of ? • Tail - flagellum - (rotating in corkscrew fashion) See fig 27-6
Epididymis ~ 7 m long Head - superior, receives spermatozoa Body - distal and inferior Tail - leads to ductus deferens Functions: 1) Monitors and adjusts tubular fluid (stereocilia!) 2) Recycles damaged spermatozoa 3) Stores sperm and facilitates maturation Rete testis and Efferent ductules
Pathway of Sperm • Seminiferous tubules • Rete testis • Epididymis • Vas (ductus) deferens • Ampulla of vas deferens • Ejaculatory duct • Prostatic urethra • Membranous urethra • Penile (spongy) urethra Fig 27.8
Accessory Glands Provide for 95% of the seminal fluid 1) Seminal Vesicles • Paired, on back wall of urinary bladder • Tubular (~ 15 cm) • Produce 60% of semen, hormones, fructose, etc. • Activate sperm (leading to motility) Fig. 27.8
Prostate Gland 20 - 30% of seminal fluid Single, doughnut-shaped Secretion contains: • Citrate • Seminal plasmin (mild antibiotic) • Prostate specific antigen (PSA) – blood test for ?
Bulbourethral glands (Cowper’s glands) Pea size, paired, at base of penis Produce about 10% of semen Alkaline mucus - function??
Semen 2-5 ml ejaculate Ejaculation of semen by pelvic floor and penile muscles (Sympathetic division induces peristalsis in tract) Constituents: 1. sperm - 20 - 100 million sperm/ ml 2. seminal fluid - see above glands 3. enzymes - proteases and seminalplasmin
Penis Root - fixed to ischial ramus Body with erectile tissues Glans – enlargement of corpus spongiosum Prepuce - foreskin – partially covers glans and surrounds external urethral meatus (may be removed in circumcision) Preputial glands - produce smegma (supports bacterial growth, such as E. coli) Fig 27.9 The End