Male repro 1 Flashcards
testis function
- production of spermatozoa
- production of hormones for sperm development and maturation, and development and maintenance of associated glands and of secondary sex characteristics
what is found in the seminiferous tubules
-adluminal/abluminal compartments
what is found in the interstitial tissue
- peritubular myoid cells
- leydig cells
- connective tissue and vessels
name the four seminiferous tubule events
- spermatogenesis (spermatocytogenesis
- meiosis
- spermiogenesis
- spermiation
spermatogenesis
- proliferation of spermatogonia
- generation of primary spermatocytes (all mitotically)
meiosis in the seminiferous tubule
-reductional (M1) and equational (M2) spermatocyte division resulting in haploid spermatids
spermiogenesis
-cytodifferentiation of round spermatids to elongated forms
spermiation
-release of spermatozoa from sertoli cells
how long does the diff and development of spermatogenic cells take
75 days
how many sperm produced each day
200-200 million
when does production of sperm stop
-never
what is the ideal temp for spermatogenesis
32-35C (2 to 5 below 37)
going from the basal lamina of the seminiferous tubules upwards, what are the stages of the cells present
-what cell type is between the developing sperm cells
- spermatogonium
- primary spermatocyte
- secondary spermatocytes
- early spermatids
- in between these cells, laterally, are ssertoli cells
what cell type is just below the basal lamina in the seminiferous tubules?
-myoid cells
what is the morphology of spermatogonia
-small, round cells with oval to round nuclei
where are spermatogoni found?
they are resting on the basal lamina of the seminiforous tubules
characteristics of spermatogonia type A
- remain undifferentiated stem cells
- these divide by mitosis
characteristics of spermatogonia B cels
-undergo meiosis to form primary spermatocytes
distinguishing A and B spermatogonia
-can not be done microscopically
- where are primary spermatocytes found?
- what does their genome look like? and how many sets of chromosomes? why?
- what event takes place in this stage?
- found above the basal lamina, not attached
- they are diploid, 4n because they are in M1
- long prophase so they are visible in most sections, have thick chromosomes
- crossing over takes place here
what process finishes in order to create a secondary spermatocyte?
- what is their chromosome number
- divisional characteristic
- M1 finishes to produce secondary spermatocytes
- haploid, 2n
- these rapidly finish M2 division
where are early spermatids found?
- what is their morph?
- ploidy
- are they meioticcally active?
- what process do they undergo and what happens
- close to the lumen of the seminiferous tubule
- small round to elongated
- haploid, 1n DNA
- do not divide any further
- undergo spermiogenesis which is the differentiation into a spermatozoa
where, specifically, does sperm differentiation and maturation take place and what is this called?
- the cells are embedded in sertoli cells
- called spermiogenesis
wht are the two events that take places during spermiogenesis
- development of the acrosome
- formation of the tail (flagellum elongation)
what is the acrosome
- golgi-derived
- contains enzymes to break through granulosa cells and zona pellucida
what happens to the excess cytoplasm during spermiogensis
- these are called residual bodies
- they are discarded and sperm released into lumen (spermiation)
are sperm motile when they are released from sertoli cells
-no
what is unique about the way that sperm cells develop
-what is the technical term for this
- they are all unique yet groups of them share a cytoplasmic bridge
- complete karyokinesis but incomplete cytokenesis
what do the development of clonal groups yield?
heterogeneous seminiferous tubule wall
morph of sertoli “nurse” cells?
- what R is found on their surface?
- -what does the cytoplasm surround
- large, euchromatic nucleus and contains a prominent round nucleolus, usually erpendicular to basal lamina
- FSH
- spermatogenic cells
5 functions of sertoli cells
- spermatogenic
- blood
- clean up
- secretions
- release
- provide physical and nutritive support for developing spermatogenic cells (control all access from blood to lumen)
- form the blood-testis barrier (protection from autoimmune attack)
- phagocytosis of residual bodies shed during spermatozoa maturation
- secrete fluid and produce androgen binding protein, inhibin and activin to regulate FSH, endothelin to promote tubule contraction
- facilitate release of sperm into tubular lumen
sertoli sertoli cell junctions form
- the blood testis barrier
- this is necessary since the primary spermatocytes have undrgone crossing over
- this is formed using actin connections
myoid cells are found where?
- characteristics
- function
- receptors
- interstitial tissue
- myofibroblast-like
- function in tubular contractility and sperm transport (they are not yet mobile)
- contain receptors for endothelin (made by sertoli cells) which stimulates contraction
where are leydig cells found?
- characterisstics
- secrete what?
- receptors
- found in the interstitial tissue of the seminiferous tubules
- secrete cholesterol ester, have abundant SER, and tubular christae
- secrete testosterone
- possess LH receptors (interstitial cell stimulating hormone) and prolactin receptors
function of testosterone
- essential for spermatogenesis
- secondary sex characteristics
- accessory gland development
cryptorchidism
- one or both testis fail to descend
- if bilaterla fertility is near zero
- cancer rates are increased
- leydig and sertoli cells unaffected so these people have normal sex characteristics
