male anatomy embryogenesis chapters 3 & 4. seminiferous tubules componentscomponents...

Male AnatomyMale AnatomyEmbryogenesisEmbryogenesis

Chapters 3 & 4Chapters 3 & 4

Seminiferous TubulesSeminiferous Tubules

• ComponentsComponents

• EpitheliumEpithelium

• Sertoli cellsSertoli cells

• developing germ cellsdeveloping germ cells

• peritubular cellsperitubular cells

Figure 3-12

Sertoli CellsSertoli Cells

• Produce variety of substancesProduce variety of substances– Androgen binding proteinAndrogen binding protein– sulfated glycoprotein 1 & 2sulfated glycoprotein 1 & 2– transferrintransferrin– inhibitinhibit

• Have tight junctionsHave tight junctions• Form blood-testis barrier with peritubular Form blood-testis barrier with peritubular

cells around STcells around ST

Excurrent DuctsExcurrent Ducts

• EfferentsEfferents

• Epididymal ductEpididymal duct

• ductus deferensductus deferens

• Extragonadal reserves of spermExtragonadal reserves of sperm

Figure 3-14

Cytoplasmic DropletCytoplasmic Droplet

• ProximalProximal

• TranslocatingTranslocating

• DistalDistal

• High proportion of ejeaculated High proportion of ejeaculated spermatozoa with a droplet indicates spermatozoa with a droplet indicates faulty epididymal maturationfaulty epididymal maturation

Seminal PlasmaSeminal Plasma

• Fluids from epididymis & accessory sex Fluids from epididymis & accessory sex glandsglands

• Not required for fertility, but important Not required for fertility, but important in natural inseminationin natural insemination

Accessory Sex glandsAccessory Sex glands

• AmpullaAmpulla

• Seminal vesicles (vesicular glands)Seminal vesicles (vesicular glands)

• prostate glandprostate gland

• bulbourethral glands (Cowper’s glands)bulbourethral glands (Cowper’s glands)

• What’s the difference between species in What’s the difference between species in Fig 3-15?Fig 3-15?

PenisPenis

• Consists of:Consists of:– basebase– shaftshaft– glans penisglans penis

• Fibroelastic penisFibroelastic penis– Stiffening without a change in diameterStiffening without a change in diameter

• Cavernosum penisCavernosum penis– Blood collects & increases in diameter with Blood collects & increases in diameter with

stiffeningstiffening

Figure 3-16Figure 3-16

Review from last lectureReview from last lecture

• Comparative evaluation of accessory sex Comparative evaluation of accessory sex glandsglands

Differentation of TissueDifferentation of Tissue

• EndodermEndoderm– GutGut– LungsLungs– LiverLiver

Differentation of TissueDifferentation of Tissue

• MesodermMesoderm– MuscleMuscle– SkeletonSkeleton– CardiovascularCardiovascular– ReproductiveReproductive

Differentation of TissueDifferentation of Tissue

• EctodermEctoderm– Nervous systemNervous system– SkinSkin– HairHair

• Know Table 4-1Know Table 4-1

Figure 4-1

Pituitary GlandPituitary Gland

• Both neural & epithelial in originBoth neural & epithelial in origin

• Rathke’s pouchRathke’s pouch

• Fig 4-2 (know development)Fig 4-2 (know development)

• Hypophysis Hypophysis = = pituitarypituitary

• AdneohypophysisAdneohypophysis == Anterior pit.Anterior pit.

• NeurohypophysisNeurohypophysis == Posterior pit.Posterior pit.

Fig 4-3

Sexual DifferentiationSexual Differentiation

• Starts with XY chromosomesStarts with XY chromosomes• Primordial germ cells migrate from yolk Primordial germ cells migrate from yolk

sac to genital ridgesac to genital ridge• Primordial gonad undifferentiatedPrimordial gonad undifferentiated• Primordial germ cells undergo mitosis & Primordial germ cells undergo mitosis &

increase in number.increase in number.• Primordial germ cells that don’t make it to Primordial germ cells that don’t make it to

gonad diegonad die

Sexual DifferentiationSexual Differentiation

• Primordial renal systemPrimordial renal system

• PronephrosPronephros

• Mesonephros (ducts called Wolffian Mesonephros (ducts called Wolffian ducts)ducts)

• Metanephros (final system) - last 2/3rds Metanephros (final system) - last 2/3rds of gestationof gestation

Sexual DifferentiationSexual Differentiation

• Testis Determining FactorTestis Determining Factor

• Anti-Mullerian HormoneAnti-Mullerian Hormone

• Figure 4-5Figure 4-5

Figure 4-5

Sexual DifferentiationSexual Differentiation

• Descent of the testis - 3 PhasesDescent of the testis - 3 Phases– Testis starts by ribsTestis starts by ribs– Growth & elongation of the body away from Growth & elongation of the body away from

the testesthe testes– Rapid growth of the distal gubernaculumRapid growth of the distal gubernaculum– Regression of gubernaculumRegression of gubernaculum

Sexual DifferentiationSexual Differentiation

• Growth of gubernaculum controlled by Growth of gubernaculum controlled by testes factortestes factor

• Low molecular weightLow molecular weight

• ““descendin”descendin”

• Control of gubernaculum contraction Control of gubernaculum contraction unknownunknown

• CryptochidismCryptochidism

• Inguinal herniaInguinal hernia

Fig 4-7

Sexual DifferentiationSexual Differentiation

• Females have X chromosome that lacks Females have X chromosome that lacks TDF geneTDF gene

• No development of Sertoli cells, so no No development of Sertoli cells, so no AMHAMH

• Oviducts, uterus, cervix & anterior vagina Oviducts, uterus, cervix & anterior vagina develop from paramesonephric ductsdevelop from paramesonephric ducts

• Female tract located outside peritoneumFemale tract located outside peritoneum

Figure 4-5

Sexual DifferentiationSexual Differentiation

• FreemartinFreemartin

• Common blood supply between fetal bull Common blood supply between fetal bull & heifer& heifer

• AMH is transferred to femaleAMH is transferred to female