Male Anatomy Embryogenesis Chapters 3 & 4

Seminiferous Tubules ComponentsComponents EpitheliumEpithelium Sertoli cellsSertoli cells developing germ cellsdeveloping germ cells peritubular cellsperitubular cells

Figure 3-12

Sertoli Cells Produce variety of substancesProduce variety of substances –Androgen binding protein –sulfated glycoprotein 1 & 2 –transferrin –inhibit Have tight junctionsHave tight junctions Form blood-testis barrier with peritubular cells around STForm blood-testis barrier with peritubular cells around ST

Excurrent Ducts EfferentsEfferents Epididymal ductEpididymal duct ductus deferensductus deferens Extragonadal reserves of spermExtragonadal reserves of sperm

Figure 3-14

Cytoplasmic Droplet ProximalProximal TranslocatingTranslocating DistalDistal High proportion of ejeaculated spermatozoa with a droplet indicates faulty epididymal maturationHigh proportion of ejeaculated spermatozoa with a droplet indicates faulty epididymal maturation

Seminal Plasma Fluids from epididymis & accessory sex glandsFluids from epididymis & accessory sex glands Not required for fertility, but important in natural inseminationNot required for fertility, but important in natural insemination

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

Penis Consists of:Consists of: –base –shaft –glans penis Fibroelastic penisFibroelastic penis –Stiffening without a change in diameter Cavernosum penisCavernosum penis –Blood collects & increases in diameter with stiffening

Figure 3-16

Review from last lecture Comparative evaluation of accessory sex glandsComparative evaluation of accessory sex glands

Differentation of Tissue EndodermEndoderm –Gut –Lungs –Liver

Differentation of Tissue MesodermMesoderm –Muscle –Skeleton –Cardiovascular –Reproductive

Differentation of Tissue EctodermEctoderm –Nervous system –Skin –Hair Know Table 4-1Know Table 4-1

Figure 4-1

Pituitary 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 = pituitaryHypophysis = pituitary Adneohypophysis=Anterior pit.Adneohypophysis=Anterior pit. Neurohypophysis=Posterior pit.Neurohypophysis=Posterior pit.

Fig 4-3

Sexual Differentiation Starts with XY chromosomesStarts with XY chromosomes Primordial germ cells migrate from yolk sac to genital ridgePrimordial germ cells migrate from yolk sac to genital ridge Primordial gonad undifferentiatedPrimordial gonad undifferentiated Primordial germ cells undergo mitosis & increase in number.Primordial germ cells undergo mitosis & increase in number. Primordial germ cells that don’t make it to gonad diePrimordial germ cells that don’t make it to gonad die

Sexual Differentiation Primordial renal systemPrimordial renal system PronephrosPronephros Mesonephros (ducts called Wolffian ducts)Mesonephros (ducts called Wolffian ducts) Metanephros (final system) - last 2/3rds of gestationMetanephros (final system) - last 2/3rds of gestation

Sexual Differentiation Testis Determining FactorTestis Determining Factor Anti-Mullerian HormoneAnti-Mullerian Hormone Figure 4-5Figure 4-5

Figure 4-5

Sexual Differentiation Descent of the testis - 3 PhasesDescent of the testis - 3 Phases –Testis starts by ribs –Growth & elongation of the body away from the testes –Rapid growth of the distal gubernaculum –Regression of gubernaculum

Sexual Differentiation Growth of gubernaculum controlled by testes factorGrowth of gubernaculum controlled by testes factor Low molecular weightLow molecular weight “descendin”“descendin” Control of gubernaculum contraction unknownControl of gubernaculum contraction unknown CryptochidismCryptochidism Inguinal herniaInguinal hernia

Fig 4-7

Sexual Differentiation Females have X chromosome that lacks TDF geneFemales have X chromosome that lacks TDF gene No development of Sertoli cells, so no AMHNo development of Sertoli cells, so no AMH Oviducts, uterus, cervix & anterior vagina develop from paramesonephric ductsOviducts, uterus, cervix & anterior vagina develop from paramesonephric ducts Female tract located outside peritoneumFemale tract located outside peritoneum

Figure 4-5

Sexual Differentiation FreemartinFreemartin Common blood supply between fetal bull & heiferCommon blood supply between fetal bull & heifer AMH is transferred to femaleAMH is transferred to female