The Male Reproductive System

Ch 27: Reproductive SystemCh 27: Reproductive SystemGoals:Goals:

1.1. Identify the structures of the male Identify the structures of the male and female reproductive systems, and female reproductive systems, including the gross and including the gross and microscopic anatomy of the microscopic anatomy of the organs, structures and accessory organs, structures and accessory glands and their basic functions.glands and their basic functions.

2.2. Explain meiosis, spermatogenesis Explain meiosis, spermatogenesis and oogenesis.and oogenesis.

3.3. Discuss the changes that occur in Discuss the changes that occur in the female reproductive system the female reproductive system during pregnancy.during pregnancy.

General OrganizationGeneral Organization

GonadsGonads gametes & hormonesgametes & hormones

DuctsDucts transport of . . . ?transport of . . . ?

GlandsGlands secrete fluidsecrete fluid

Perineal structures = external genitaliaPerineal structures = external genitalia

Male Reproductive AnatomyMale Reproductive Anatomy

Primary reproductive organs produce Primary reproductive organs produce gametesgametes

Secondary reproductive organs . . . Secondary reproductive organs . . .

Male reproductive and urinary tracts Male reproductive and urinary tracts are partially sharedare partially shared

Fig 27-1

TestesTestes (paired glands)(paired glands)

Develop adjacent to kidneysDevelop adjacent to kidneys

Descend into scrotum through inguinal canal Descend into scrotum through inguinal canal (function of (function of gubernaculum testis)

Peritoneal lining is carried along Peritoneal lining is carried along lining of lining of scrotumscrotum

Spermatic cord: bundle containing all the “duct Spermatic cord: bundle containing all the “duct work”work”

CryptorchidismCryptorchidism Figs 27-2/3

4 month

ScrotumScrotumFunction: supports and protects testes Function: supports and protects testes

Structure: Skin & underlying Structure: Skin & underlying superficial fasciasuperficial fascia

Dartos muscleDartos muscle in dermisin dermis Cremaster muscleCremaster muscle - - continuous with

abdominal wall muscles (?)

Involuntary contraction (cremasteric Involuntary contraction (cremasteric reflex) in response to ________reflex) in response to ________

Scrotal sac forms 2 Scrotal sac forms 2 separate chambersseparate chambers

Cremaster muscle

Structure of TestesStructure of Testes

Fibrous capsule – Fibrous capsule – tunica albugineatunica albuginea – – surrounds testes surrounds testes

Scrotal cavity – lined Scrotal cavity – lined by by tunica vaginalistunica vaginalis – – parietal and visceral parietal and visceral layers layers

200-300 lobules200-300 lobules

3 seminiferous 3 seminiferous tubulestubules

Figs 27-4/5

From Spermatocyte to SpermatozoonFrom Spermatocyte to Spermatozoon

Spermatogenesis: Meiosis of primary spermatocytes spermatids

Spermiogenesis: Spermatid maturation into spermatozoa within Sertoli cells

Spermiation: Spermatozoon released into lumen

Sustentacular (Sertoli) CellsSustentacular (Sertoli) Cells

Maintenance of blood testis barrierMaintenance of blood testis barrierspecial lumen fluid high in sex hormones, Kspecial lumen fluid high in sex hormones, K++ and aa and aa

protection from immune attack (due to sperm specific ag)sperm specific ag)

Suspend spermatids and support and support spermatogenesis and spermiogenesisspermatogenesis and spermiogenesis FSH and Testosterone work via Sertoli cellsFSH and Testosterone work via Sertoli cells

Secretion of inhibin to Secretion of inhibin to slow sperm production

Secretion of androgen-binding Secretion of androgen-binding protein (ABP)protein (ABP)

Anatomy of a SpermatozoonAnatomy of a Spermatozoon

Mature sperm has 3 Mature sperm has 3 portions:portions:

1.1. Head with acrosome Head with acrosome (containing _______ )(containing _______ )

2.2. Middle piece with Middle piece with nucleus and lots of ?nucleus and lots of ?

3.3. Tail - flagellum Tail - flagellum - (rotating - (rotating in corkscrew fashion)in corkscrew fashion)

See fig 27-6

EpididymisEpididymis

~ 7 m long~ 7 m long

HeadHead - superior, receives spermatozoa - superior, receives spermatozoa

BodyBody - distal and inferior - distal and inferior

TailTail - leads to ductus deferens - leads to ductus deferens

Functions:Functions:

1) Monitors and adjusts tubular fluid 1) Monitors and adjusts tubular fluid (stereocilia!)(stereocilia!)

2) Recycles damaged spermatozoa2) Recycles damaged spermatozoa

3) Stores sperm and facilitates 3) Stores sperm and facilitates maturationmaturation

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 GlandsAccessory Glands

Provide for 95% of the seminal fluidProvide for 95% of the seminal fluid

1) Seminal Vesicles1) Seminal Vesicles Paired, on back wall of urinary bladderPaired, on back wall of urinary bladder Tubular Tubular (~ 15 cm)(~ 15 cm)

Produce 60% of semen, hormones, fructose, Produce 60% of semen, hormones, fructose, etc.etc.

Activate sperm (leading to motility)Activate sperm (leading to motility)

Fig. 27.8

Prostate GlandProstate Gland

20 - 30% of seminal fluid 20 - 30% of seminal fluid

Single, doughnut-shapedSingle, doughnut-shaped

Secretion contains:Secretion contains: Citrate Citrate Seminal plasmin (mild Seminal plasmin (mild

antibiotic)antibiotic) Prostate specific antigen Prostate specific antigen

(PSA) – blood test for ?(PSA) – blood test for ?

Bulbourethral glands Bulbourethral glands (Cowper’s glands)(Cowper’s glands)

Pea size, Pea size, paired, at base of penis

Produce about 10% of semen

Alkaline mucus - Alkaline mucus - function??function??

SemenSemen

2-5 ml ejaculate2-5 ml ejaculate

Ejaculation of semen by pelvic floor and penile Ejaculation of semen by pelvic floor and penile muscles (Sympathetic division induces muscles (Sympathetic division induces peristalsis in tract)peristalsis in tract)

Constituents:Constituents:1. sperm - 20 - 100 million sperm/ ml1. sperm - 20 - 100 million sperm/ ml2. seminal fluid - see above glands2. seminal fluid - see above glands3. enzymes - proteases and 3. enzymes - proteases and

seminalplasminseminalplasmin

PenisPenisRootRoot - fixed to ischial ramus - fixed to ischial ramus

BodyBody with with erectile tissueserectile tissues

GlansGlans – enlargement of – enlargement of corpus spongiosumcorpus spongiosumPrepucePrepuce - foreskin – partially - foreskin – partially

covers glans and surrounds covers glans and surrounds external urethral meatus external urethral meatus (may be removed in (may be removed in circumcisioncircumcision))

Preputial glands - produce Preputial glands - produce smegma (supports bacterial smegma (supports bacterial growth, such as growth, such as E. coliE. coli))

Fig 27.9