Male Histology Flashcards
what do ‘indifferent gonads’ develop from ebryologically?
Develop from thickening of intermediate mesoderm (steroidogenic) – genital/ gonadal ridge
development of the primordial gonad is linked with degeneration of what?
degeneration of the mesonephros
primitive sex/gonadal cords develop from what, ebryologically?
Primitivesex/gonadalcords– develop from epithelial cells of degenerating mesonephric tubules and glomerular capsules that invade the mesenchyme of genital ridge
* Epithelial cells form clusters and incorporate PGCs
in the indifferent stage of gonadal development, both sexes have what?
Both sexes have male (Wolffian, mesonephric) and female (Mullerian, paramesonephric) genital ducts
effect of testosterone on the development of genital ducts - ie effect on mesonephric and paramesonephric ducts
- In the presence of testosterone, paramesonephric (Mullerian) ducts degenerate
- Mesonephric (Wolffian) ducts persist
– Form ductus deferens and the epididymis
what structure gives rise to the seminiferous tubules in the male? how? What about the efferent ductules, retes testis, and accessory sex glands?
- Gonadal cords hypertrophy and become seminiferous cords/tubules
- Efferent ductules and rete testis form from mesonephric tubules
- Accessory sex glands develop as evagination from epithelium of associated ductwork
what type of gland is the testicle?
compound tubular
-exocrine and endocrine
where does spermatogenesis occur? WHat are its stages?
seminiferous tubules of the testis
Spermatogenesis = Spermatocytogenesis + Spermiogenesis
-what are type A(d) cells and what is their role in spermatogenesis? what is their characteristic appearance?
-what are type A(p) cells and what is their role in spermatogenesis? what is their characteristic appearance?
-what are type B cells and what is their role in spermatogenesis? what is their characteristic appearance?
-Type A(d) cells, with dark nuclei. These cells replicate to ensure a constant supply of spermatogonia
-Type A(p) cells, with pale nuclei. These cells divide by mitosis to produce Type B cells.
-Type B cells, which divide to give rise to primary spermatocytes (diploid, in prophase of meiosis I)
cells of the seminiferous tubules
germ cells- spermatogenic cells
Sertoli Cells (Sustentacolar Cells)
Interstitial Cells of Leydig
structural character of sertoli cells? where are they found?
- Columnar cells with oval to angular nucleus
- Cytoplasmic processes forming gap junctions
- Surround the developing sperm
- A single Sertoli cell extends from the basement membrane to the lumen of the seminiferous tubule
structural character of interstitial cells of leydig? what do they produce?
- Species differences in # and morphology
- Steroid hormone producing cell
- Cytoplasmic stains eaosinophilic
- EM shows large amount of ER, Golgi, mitochondria and lipid droplets
function of sertoli cells
- Provide structural and metabolic support to the developing sperm cells
- A single Sertoli cell extends from the basement membrane to the lumen of the seminiferous tubule
- Maintain the right environment for development and maturation (blood-testis barrier)
- Secrete substances initiating meiosis
- Secrete supporting testicular fluid
- Secrete ABP, which concentrates testosterone in close proximity to the developing gametes
- Secrete hormones affecting pituitary gland control of spermatogenesis (e.g. inhibin)
- Phagocytose residual cytoplasm left over from spermiogenesis
- Protect spermatids from the immune system of the male (blood- testis barrier)
what is the hormonal control mechanism of spermatogenesis? what feedback loops are involved?
-hypothalamus sends GnRH to anterior pituitary
-AP sends FSH and LH to testis
-FSH acts on sertoli cells, causing the release of inhibin and also secretion of substances to support spermatogenesis
>inhibin gives negative feedback to the AP
-LH acts on the leydig cells causing the release of testosterone
>testosterone is important for spermatogenesis
>testosterone also gives negative feedback to AP and hypothalamus
structural function and components of the spermatic cord?
Testis are suspended in the scrotum by the spermatic cord
Components:
* Spermatic/testicular artery
* Spermatic veins
* Lymphatics
* Cremaster muscle
-pampiniform plexus
