MALE REPRODUCTIVE SYSTEM testis-03

MALE REPRODUCTIVE SYSTEM  TESTES  EPIDIDYMIS  VAS DEFERENS  SEMINAL VESICLES  PROSTATE testes within scrotum; temperature 2-3 degrees C below body temperature which is essential for sperm production descent of testes during development (tunica vaginalis)  BULBOURETHRAL GLANDS  URETHRA

TESTIS H&E SEMINIFEROUS TUBULES testis-01

INTERSTITIAL CONN. TISSUE TESTIS H&E SEMINIFEROUS TUBULES SEMINIFEROUS TUBULES INTERSTITIAL CONN. TISSUE testis-02

INTERSTITIAL CONN. TISSUE TESTIS H&E SEMINIFEROUS TUBULES SEMINIFEROUS TUBULES testis-03 INTERSTITIAL CONN. TISSUE

MALE REPRODUCTIVE SYSTEM  SPERMATOGENESIS SPERMATOGONIA 1º SPERMATOCYTE 2º SPERMATOCYTE SPERMATIDS SPERMATIDS 2º SPERMATOCYTE tight junctions of lateral processes may temporarily open to permit the passage of spermatogenic cells toward the lumen 1º SPERMATOCYTE SERTOLI CELLS: - columnar with adjoining lateral processes - extend from basal lamina to lumen - Sertoli-Sertoli junctions divide seminiferous tubules into basal and adluminal compartments SERTOLI CELLS SPERMATOGONIA

MALE REPRODUCTIVE SYSTEM SEMINIFEROUS TUBULES  SPERMATOGENESIS THREE PHASES: (1) Spermatogonial Phase (Mitosis) - spermatogonia proliferate by mitotic divisions to provide stem cells and cells which will proceed through spermatogenesis (1º spermatocytes) (2) Spermatocyte Phase (Meiosis) - diploid cells (2n) created in spermatogonial phase give rise to haploid cells (1n) - Meiosis I (reduction division) & Meiosis II (equatorial division) - 1º spermatocytes enter Meiosis I to form 2º spermatocytes which then enter Meiosis II and result in spermatids 5 exchange of genetic material in MI via crossing over (3) Spermatid Phase (Spermiogenesis) - spermatid differentiation into spermatazoa

MALE REPRODUCTIVE SYSTEM  HORMONAL REGULATION OF MALE REPRODUCTIVE FUNCTION HYPOTHALAMUS REGULATES ACTIVITY OF ANTERIOR PITUITARY (ADENOHYPOPHYSIS) ADENOHYPOPHYSIS SYNTHESIZES HORMONES (LH and FSH) THAT MODULATE ACTIVITY OF SERTOLI AND LEYDIG CELLS Luteinizing Hormone (LH): stimulates testosterone production by Leydig cells Follicle Stimulating Hormone (FSH): stimulates production of sperm in conjunction with testosterone by regulating activity of Sertoli cells SERTOLI CELLS STIMULATED BY FSH AND TESTOSTERONE RELEASE ANDROGEN BINDING PROTEIN WHICH BINDS TESTOSTERONE; THEREBY INCREASING TESTOSTERONE CONCENTRATION WITHIN THE SEMINIFEROUS TUBULES AND STIMULATING SPERMATOGENESIS

EFFERENT DUCTULES EPIDIDYMIS epididymus-07

epididymus-08 EPIDIDYMIS

Functions of Leydig Cells Production of High Levels of Testosterone ( 5mg/day in adults ) Direct Production of Estradiol Production of Dihydrotestosterone (DHT) Production of dehydroepiandrosterone (DHEA) and androstenedione Production of Progesterone and 17a -prog. LKS

Functions of Sertoli Cells Support Production of Spermatozoa Production of Androgen-Binding Protein Intratesticularly (TeBG) Form Blood-Testes Barrier Produce Inhibin Produce Seminiferous tubule fluid (bathing medium, nutrients, capacitation, motility) LKS

End product: special structures

Spermatozoa Structure and Functions in Review Head Acrosome: Nucleus: Midpiece Centrioles: Mitochondria: Tail: flagellum Microtubules: Figure 26-10: Sperm structure

Regulation of Spermatogenesis GnRH  LH  Leydig cells  testosterone  sex charact. GnRH  FSH  Sertoli cells  spermatoctye maturation Inhibin feedback – FSH, testosterone – short & long loops