Reproduction: Male PA 481 C Anatomy & Physiology Dr. Tony Serino Misericordia University Biology Dept.

Reproduction Function: –Survival of species –Production of sex cells (gametes) –Transport the gametes toward each other –Allow gametes to meet (fertilization) –Promote the generation, maintenance and rearing of progeny

Human Life Cycle

Gonads: undergo Meiosis to produce gametes Meiosis (divided into Meiosis I and II) –Meiosis I Assorts chromosomes by homologous pairs Then separates the pairs randomly Reduces the number of chromosomes by half; Diploid to Haploid (2n  n) –Meiosis II Separates sister chromatids Progeny cells now have one DNA per chromosome

Mitosis vs. Meiosis

Male Reproduction Gonads: Testis Gamete: Spermatozoa (sperm) Duct system: to store and transport sperm from gonad to external environment Supporting structures: –Allow sperm maturation –Allow survival of sperm in ext. environment –Deposit sperm into female vagina –Sensory functions

Male Reproductive Anatomy

Spermatogenesis

Sperm Anatomy

Sperm on Ovum

Testis Anatomy Spermatic cord Septum dividing testis into lobules

Seminiferous Tubule Sertoli Cell (Leydig Cells)

Sertoli and Leydig cells Leydig cells

Sperm leave tubules by ducts and proceed to epididymis

Ductus Deferens: carries sperm from epididymis to ejaculatory duct Passes through inguinal canal back into peritoneal cavity

Accessory Sex Glands Add seminal fluid to sperm to form semen; seminal fluid accounts for 90-95% of semen volume Seminal fluid will include water, alkaline buffers, mucous, fructose, prostaglandins and enzymes (clotting and de-clotting, anti- bacterial) Three glands: –Seminal Vesicle ~60% of semen volume –Prostate Gland ~30% of semen volume –Bulbourethral (Cowper’s) Gland <5%

Accessory glands (medial view)

Accessory Sex Glands (posterior view)

Prostate

Male Urethra

Scrotum and Spermatic Cord

Inferior abdominal wall Parietal Peritoneum Transversalis fascia Transverse abdominal Internal oblique External oblique Scarpa’s fascia Camper’s fascia Tunica vaginalis Int. spermatic fascia Ext. spermatic fascia Dartos tunic Conjoint tendon Superficial inguinal ring Cremasteric pouch

Inguinal canal Deep inguinal ring Superficial inguinal ring In males: contains spermatic cord In females: contains round ligament

Descent of Testes Begins at 7 months gestational The testes are attached at their inferior margin to the scrotal swelling by the gubernaculum Growth of the individual and retraction of the gubernaculum allow the testes to descend into the scrotum An extension of the parietal peritoneum (Vaginal process) maintains an opening into the scrotum and forms the inguinal canal and tunica vaginalis In female, gubernaculum becomes the ovarian and round ligaments

Adult scrotum Obliterated vaginalis process Tunica vaginalis Int. spermatic fascia Ext. spermatic fascia Cremasteric pouch Skin ad Dartos tunic

Scrotum and Spermatic cord Provide physical support to testes Regulate testicular temperature –Cremaster muscle position can change tesits temp. –Pampiniform plexus acts as heat counter current exchanger with testicular artery

Penis: Erectile Tissue and support Corpus Spongiosum (Crura) Root of Penis (Bulb) Penis suspensory lig.

Penis Anatomy

Smegma

Penis (X.S.)

Male Hormones ABP

Male Sexual Response Arousal –Sexual excitement –Triggered by: Touching of genital skin Mechanical stimulation of pressure receptors in penis Erotic sights, sounds, and smells Thoughts and memories –Increased myotonia (muscle tension) throughout body, BP, breathing and HR –Sexual stimulation leads to erection of penis Plateau –Increased accumulation of blood in erectile tissues –Bulbourethral gland secretes small amount of mucoid fluid to neutralize male urethra and lubricate glans –The testes are drawn upward by increased contractions vas deferens and cremaster muscles Orgasm –Ejaculation –rhythmic contractions propel semen out of the penis

Sexual Excitation: Erection Enlargement and stiffening of the penis Parasympathetic (through the local release of NO) vasodilation of arterioles leading to the erectile tissue of penis As corpora cavernosa enlarge they reduce blood flow through the penile veins; this increases engorgement Erection reflex controlled by both the brain and the sacral spinal cord

Male Orgasm Begins when stimulation reaches a critical point (accompanied by feelings of inevitability) 2 part spinal reflex: –Emission –movement of semen into the urethra Vas deferens, ejaculatory duct, prostate and seminal vesicle contract and push their fluids into the urethra through sympathetic stimulation The external sphincter of the urethra remains closed as pressure builds The bladder sphincter muscle constricts preventing urine and semen from mixing (sympathetic control) –Ejaculation –expulsion of semen from the urethra The external sphincter relaxes as a second spinal reflex triggers rapid rhythmic contractions of the bulbospongiosus and ischiocavernosus muscles and urogenital diaphragm; propels semen out (200in/sec) Contractions of muscles throughout body Accompanied with intense pleasure, increased HR, BP, respirations Followed by a quick relaxation and refractory period