Male reproductive Flashcards
(63 cards)
Describe the relationship of the testes and scrotum
- testes are within the scrotum which allows them to reside outside of the body and be kept at a lower temperature which is required for sperm production
describe the descending of the testes
- occurs prior to birth
- they originate near the kidneys and move down through the abdominal cavity into the scrotum
- by 4 months of pregnancy, they have moved to the inguinal rings and are pulled downward by contraction of the gubernaculum.
- by 8 months they have almost completed their descent
inguinal rings
openings in the body wall that provide access to scrotal sac
gubernaculum
fibrous gland whose contraction pulls the testes down
tunica albuginea
- fibrous capsule covering the testes composed of mainly collagen with large blood vessels
- contains both fibroblasts and myofibroblasts
- septa extend from it inward and divide the testes into ~250 lobules
myofibroblast
contractile and subjects the seminiferous tubules to rhythmic contractions
seminiferous tubules
- produce sperm which is collected by a network of ducts and carried out of the testes by efferent ductules
- they are coiled within the interior of the testes within each lobule
- there are 1-4 in each lobule
epididymis
- efferent ductules connect to this
- proximal, highly coiled region of the sperm duct
ductus deferens
the sperm duct
vas deferens
the sperm duct
spermatogenesis
- production of sperm from undifferentiated cells called spermatogonia
- occurs within the tubule wall of the seminiferous tubules
describe spermatogenesis
Spermatogonia are located at the periphery of the seminiferous tubules and undergo repeated mitotic division to assure continuous supply of sperm. They will eventually enter meisos and begin moving toward the tubule lumen. When finished they are haploid and called spermatids. They are located within the inner surface of the tubule wall and project into the lumen. They must still undergo morphological changes to become sperm or spermatozoa.
where are spermatogonia at the beginning of spematogeneis?
near the tubule periphery
where are spermatognia at the end of spermatogenesis?
near the tubule lumen
spermatids
haploid cells formed by meiosis during spermatogenesis. Must still undergo morphological changes prior to becoming sperm
spermatozoa
the end product of spermatogenesis
sperm
Sertoli cells
- support and nourish the developing sperm
a. Partially enclose developing sperm and move them toward the tubule lumen
b. They mediate the exchange of nutrients
c. Secrete factors that mediate spermatogenesis
d. Secrete fluid into the tubule lumen
c. Phagocytosis of discarded sperm cytoplasm
Describe the factors secreted by Sertoli cells that impact spermatogenesis
- androgen binding protein
- traps testosterone within the epithelium
- it is required to initiate and maintain spermatogenesis
spermiogenesis
formation of mature sperm
process of spermiogenesis
- Chromatin within the nucleus becomes very compact and the nucleus decreases in size
- The nucleus then assumes a thin pointed shape which streamlines the sperm to facilitate swimming
- Most organelles degenerate
- Mitochondria remain and become localized within the middle piece of mature sperm – provide ATP needed for swimming
- Flagellum begins to grow from the centriole located behind the nucleus forming a long tail in the mature sperm
- Most of the cell cytoplasm is shed
- The streamlined sperm is released into the lumen of the seminiferous tubule
Leydig cells
i. Secrete testosterone
ii. Lie within the connective tissue between seminiferous tubules
rete testes
- Network of ducts which collects sperm produced by the seminiferous tubules
- It is within the testes connected to the many seminiferous tubules within the testicular lobules
- All seminiferous tubule converge in the rete testis region
histology of rete testes
- Consists of thin channels lined by simple, cuboidal epithelium with a single cilia on each epithelial cell
efferent ductules
- Connected to the epididymis
- Drain the rete testis and transport sperm out of the testes into the epididymis
- Sperm not yet mobile, will acquire the ability to swim once through the epididymis