Testis by Dr Pandian M
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The document provides an overview of the male testis, detailing its embryonic development, anatomy, and functions as both an exocrine and endocrine gland. Key components include seminiferous tubules where spermatogenesis occurs, the supportive role of Sertoli and Leydig cells, and the structural layers of the scrotum. It also explains the hormonal influences during development and the descent of the testes into the scrotum.
Testis by Dr Pandian M
- 2. SYNOPSIS Introduction to testis Embryonic development of testis Anatomy Scrotum layers Tunica vaginalis Tunica albuginea Tunica vasculosa Seminiferous tubules Spermatogenic cell Sertoli cell Leydig cells Rete testis Efferent ductules Testicular arteris Summary References.
- 3. TESTIS Male gonad. Mixed exocrine and endocrine gland because they produce sperm and Secreting male sex hormones. They are contained within the scrotal sac, which is located directly behind the penis and in front of the anus.
- 4. EMBRYONIC DEVELOPMENT OF TESTES During mammalian development, the gonads are at first capable of becoming either ovaries or testes. week 4, the gonadal rudiments are present within the intermediate mesoderm adjacent to the developing kidneys. week 6, sex cords develop within the forming testes.
- 5. In males, the sex-specific gene SRY that is found on the Y-chromosome initiates sex determination by downstream regulation of sex-determining factors, (such as GATA4, SOX9 and AMH), which leads to development of the male phenotype. first trimester gestation -Testosterone and its potent derivative, dihydrotestosterone, play key roles in the formation of male genitalia in the fetus but do not play a role in the actual formation of the testes.
- 6. seventh month of gestation- the testes are formed in the abdominal cavity and descend into the scrotum, its stimulated by androgens. The production of testosterone by the fetal testes is stimulated by human chorionic gonadotropin, a hormone secreted by the placenta.
- 7. Anatomy: Paired, oval gland in the scrotum. Length = 4-5cm Diameter = 2.5cm Mass = 10-15gm(single) Temperature = 35°c
- 8. STRUCTURE
- 9. SCROTUM LAYERS The scrotum consists of loose skin and subcutaneous layers and supports the testis. Tunica vaginalis Tunica albuginea Tunica vasculosa
- 10. Tunica vaginalis Outer thin ,serous sac . Derived from peritoneum. Forms during the descent of the testis. Partially covers the testes.
- 11. Tunica albuginea Internal to the tunica vaginalis. Tough, White fibrous capsule composed of dense irregular connective tissue called tunica albuginea. It extents inward Form septa Divide testis into serious of internal compartments called lobules. Each 200-300 lobules contain 1-3 tightly coiled tubules called seminiferous tubules(semin-seed,fer-carry).
- 12. Tunica vasculosa Testicular artery descends to the inferior pole just deep to tunica albuginea.
- 13. Seminiferous tubules Each lobules of the testis contain one or three tightly coiled seminiferous tubules. Uncoiled-70cm in length. Functional unit of testis . Because the spermatogenesis occurs here. Within the Seminiferous tubules : Spermatogenic cell: Here, germ cells develop into spermatogonia, spermatocytes, spermatids and spermatozoon through the process of spermatogenesis.
- 14. Sertoli cell Sertoli cell (a kind of sustentacular cell) is a 'nurse' cell of the testes that is part of a seminiferous tubule. It is activated by follicle-stimulating hormone and has FSH-receptor on its membranes. Extend from the basement membrane to the lumen of the tubule. Internal to the basement membrane and spermatogonia, tight junction joins neighboring sertoli cells to one another. These junction form obstruction known as blood- testes barrier.
- 15. EXOCRINE FUNCTIONS: Mechanical support. Nourishment. Phagocytosis of cytoplasmic fragments. Release of spermatozoa. Blood testis barrier. ENDOCRINE FUNCTIONS: anti-Müllerian hormone (AMH) inhibin and activin. androgen binding protein. Estradiol. Transferrin.
- 16. Between tubules (interstitial cells): Leydig cells : cells localized between seminiferous tubules . produce and secrete testosterone and other androgens sexual development and puberty, secondary sexual characteristics. supporting spermatogenesis. Testosterone also controls testicular volume.
- 17. Rete testis: Once the sperm produced,they move through the Seminiferous tubules and enter the rete testes for further maturation. Cilia are located on some cells of the rete testis persumably for moving the sperm.
- 18. Efferent ductules: sperm Transported out of the testis into epididymis through the series of efferent ductules. Testicular arteris: Arises from the abdominal aorta below the origin of renal arteris. Testis receive blood through the testicular arteris.
- 19. Summary It’s a male gonad, paired oval gland in the scrotum. seventh month of gestation- the testes are formed in the abdominal cavity and descend into the scrotum, its stimulated by androgens. Scrotum layer Seminiferous tubules. Rete testis Efferent ductules Testicular arteris Function-spermatogenesis and steroidogenesis.