Spermatogenesis Flashcards
What effect does LH have on gonads. State the cells they act on, what the downstream affects are including enzymes.
What is function of stAR protein?
Stimulates cAMP production , increase Ca+ and therefore promote transport /conversation of cholesterol to/in mitocondria to conversion to pregnenolone. via demolase.
StAR protein inhanced synthesis
What is FSH’s role in spermatogenesis
FSH binds to GPCR receptors of sertoli cells and initiate the proliferation. They are also responsible for increased aromatase.
Without FSH @postnatal- no onset of sperm production.
without FSH in adulthood= no affects
What stimulates inhibit production. Name what it is, what it acts on, what is downstream affect
Inhibin is released from FSH stimulated sertoli cells. Inhibit acts at level of Anterior pituitary to inhibit FSH release. (negative feedback)
What is the feedback control for LH & FSH
LH release regulated by negative feedback of Testosterone from leydig cells.
FSH is regulated from inhibit released from sertoli cells and acting at levels of anterior pituitary
What are expected results of ____hormone levels after a castration 1) control 2) castration 2)castration+T
FSH levels are not inhibited due to no inhibit release from sertoli cells.
1) LH level rise as normal
2) erratic variation and high concentration LH
3) No LH increased release
Where is Testosterone released from, how is it stimulated, what affect does it have at brain levels. Where are its R at brain levels.
LH–> leydig cells–> testosterone release. This acts at the level of AP and hypothalamus. suppresses responsiveness to GnRH by down regulation of receptors and suppresses releases of GnRH @hypo
Where does Inhibit have its affects., Where is inhibit released from (what type of cells). What what stimulates those cells
AP–>FSH –> sertoli cells –> inhibin release –>negative–>AP.
- inhibin release of FSH at AP @gonadotrops
- inhibin synthesis for FSH B-Subunit
What androgens act on sertoli cells and where are those androgens released from
Testosterone and androgens from adrenal medulla act on serology cells. deficiency in testosterone or androgens results in infertility
Other than releasing inhibit, what other affect does FSH binding to sertoli cells illicit. and what downstream affect does that have
FSH binding to serology cells stimulate production of androgen-binding protein (ABP). this sequesters testosterone ensuring large amount are continuously available to support spermatogenesis
How do the sertoli cells sustain spermatogenesis . what are they stimulated by and what do they release to bind to the androgen that is required for spermatogenesis
Sertoli cells are stimulated by FSH. They release androgen binding protein (ABP) which captures testosterone before it is released into circulation and uses it for sperm maturation instead.
Define the stages of spermatogenesis
Spermatocytogenesis- mitotic proliferation during which spermatogonia form primary spermatocytes
Meiosis- primary spermatocytes undergo reduction division to form round spermatids w. haploid nuclei
Cytodifferentiation (spermigenesis) - spermatids undergo metamorphosis forming spermatozoa (packaged sperm for delivery to oocyte)
Give the stages of spermatogonium division. what happens to get it to next stage? what is name of next stage of spermatogenesis
- Type A1
- Type A2, A3, A4
- Intermediate Spermatogonium
- Spermatogonium type B
- Resting primary spermatocyte
When primary spermatocyte puts pressure on tight junction, it leads into meiotic division (stage2)
What allows regeneration of spermatogonia
The reversion of SECOND A2 back to an A1 cell allows for stem cell regeneration as other A2 cels is further differentiated. There is variation of this regeneration between species which dictates efficiency
Give stages of spermatocytogensis in human. include which step has decreased proliferation. Also include numbers
A1: A1 + A2 (A1 reversion)
A2(1)>I(2)>B1(4)>1(8)>2(16)>TIDS (32)
INTERMEDIATE STEP is site of mutation and also decreased proliferation in humans. therefore decreased viability/ efficiency of humans
What compartment does meiosis and mitosis happen in. Where is the spermacytotogenesis and meiosis steps ?
Spermatocytogensis (mitosis) is inthe basal compartment of the seminephorous tubule spermatagonia to spermatocyte
meiosis occurs inthe adluminal compartments. now a primary spermatocyte going under meiotic differentiation
Explain steps of spermatogenesis that happen in sertoli cells (and identity their compartments). then explain what step is associated with the lumen.
Mitosis and meiosis are both associated with the nursing of the sertoli cells. in the mitotic process, this is located in the basal compartment. the meiotic process is in the adluminal compartment.
The release of SPERMATOZOA is located in the lumen.
When does karyokinesis occur (stage +anatomy)? When does complete cytokinesis occur ?
Karyokinesis occurs in mitotic division in the basal compartment.
Cytokinesis occurs in last stages of spermatogenesis. While also surrounded by sertoli cells
give meiosis process beginning with resting primary spermatid –>round spermatids
Where are most susceptible to damage? where is reduction occurring
Resting 1spermatocyte> Leptotene>Zygotene>pachytene>diplotene>2spermatocyte> 2 round spermatids = 4 round spermatids.
prophase (pachytene.diplotene) are most susectible to damage. mitotic reduction and division at secondary step
Explain the process of spermiogenesis. What does it start at, what does it end at? what stage of sperm development is this? give the process and explain fate of organelles
During cytpdifferenciation, the round spermatid id developing into a swimming spermatazoa. Golgi- creates acrosomal vessicles with granulosa enzyme> fuse with nucleus > =devlopment of acrosomal cap> centriole form at distal+ proximal ends> =form axonome–tail + neck > cytoplasmic movement (axonome), nuclear elongation (tail). Microtubules = machete, SR-dissapear, mitocondria=move distal=midpeice , now, we’re swimmin.
What is function of machete? What does it develop with?
Function is to surround lower (distal) portion of nucleus and direct cytoplasm downward. Develops along with flagella
What separates the head from the tail
The capitulum
Draw out sperm. Identify:
- Head, midpiece, prinicpal, end piece
- nucleus, acrosomal cap, post nuclear cap, capitulum, Post acrosomal sheath
GO !
Define/ give function/ location of following:
- Protamine
- annulus
- post nuclear cap
- connecting piece
- Capitulum
- 9:2
- Post acrosomal sheath
- packing DNA into more compact form. Better than histones
- Under mitocondria. (f)= separate the mid piece from principal tail
- believe derived from machete. plays role in fertilization
- allow for flexibility of flagella. located at the mid piece and surrounded by mitcondrial helix
- Capitulum separate head from tail
- 9 axonome : 2 microtubules (motility via dynein)
- also attached and used for oocyte fertilization
What is definition of spermatogenic cycle? why do we consider it a spatial AND temporal process. What are the days for spermatogenic cycle. What are days for spermatogenesis?
The time it takes for TWO different STEAM cells to initiate mitotic division at the SAME location within the seminiferous tubule.
Spatial- SAME location
Temporal- DIFFERENT times
64 days spermatogenesis (48)
16 days for spermatogenic cycle (12 days Rat)
Compare Rat and human cycles start to finish
DO IT with group
List 8 functions of sertoli cells during spermatogenesis
- (pachytene - communication/ receiving of material via gap junctions.
- ectoplasmic specializations for anchoring + remodeling
- Elongation of spermatids + andherens that move material during cytoplasmic condensation
- blood testes barrier
- phagocytosis pf defective sperm
- androgen binding protein
- convert testosterone to E
- produce inhibin
