Lecture 14: 80 - Reproduction 2 Flashcards
Hormones are only from the _____ (not prostate or seminal vesicles)
What value is classified as oligospermia?
Testes are normally ____ core temperature.
What type of mechanism allows the heat flow to decrease in the testes but increase near the body? What hormone uses this mechanism but in reverse?
- testes
- oligospermia is 20 million or less
- 1-2 degrees Celsius below
- Countercurrent
- Testosterone
Define the following:
- Spermatogensis
- Spermiogenesis
- cellular remodeling of what? - Spermeation
What is found right next to the area that sperm are produced?
What cells provide nutrients for the sperm?
- Spermatogenesis - Process of sperm production, includes:
- Spermiogenesis- cellular remodeling of spermatids into spermatozoa (round to tadpole)
- Spermeation- extrusion of flagellated spermatozoa into the lumen of the tubule.
- Right where sperm cells produced, the Leydig cells are right next to it producing Testosterone
- Sertoli cells make the structure of seminiferous tubule
- support the gametes with nutritional elements
Events in Normal Spermatogenesis:
- Stems cells that develop into ______ lie along basement membrane of seminiferous tubule (basal compartment)
- Where are they located?
- Majority undergo continuous ____ division
- Minority – committed to further differentiation, undergo ______
- spermatogonia
- Spermaotgonia are outside the blood/testis barrier
- Spermatogonia serve as a pool of undifferentiated cells committed to differentiation - mitotic
- meiosis
What happens to the minority of spermatogonia cells that undergo meiosis?
Where does differentiation occur?
After meiosis → mature to spermatozoa
Differentiation to spermatozoa occurs in the INNER (adluminal) compartment
Spermatids:
- Lie near what?
- Attached to adjoining SERTOLI cells by?
- Connected to secondary spermatocytes by?
- what is the purpose of these structures?
- Lie near lumen of seminiferous tubules
- Attached to adjoining Sertoli cells by specialized “tight” junctions
- Connected to secondary spermatocytes by intercellular bridges
- Synchronizes development of a group of cells, allows sharing of resources. Large enough to pass organelles by microtubule-based transport.
What happens in the first division? What type of spermatocytes? What is produced?
What happens in the second division? What is yielded?
First division, occurs in - primary spermatocytes,
***producing daughter cells (secondary spermatocytes) with 23 chromosome pairs
***Second division, occurs in secondary spematocytes yielding
SPERMATIDS with 23 single chromosomes each
- cytoplasmic bridges connect the spermatids
- left as residual bodies
What is the progression from spermatogonium to mature spermatozoa?
(7)
When does Meiosis I and II occur?
- Spermatogonium
- Spermatogonia
- Primary spermatocyte
* * meiotic division I - Secondary Spermatocytes
* * Meiotic Division II - Spermatids
- Differentiating spermatids (loss of residual bodies)
- Mature Spermatozoa
SPERMIOGENESIS
- Period of extensive remodeling produces _____, which differentiate into flagellated _______.
- what is condensed?
- Shrinkage of the ____
- Formation of the ______**
- Development of _____
1.spermatids
spermatozoa
- Nuclear condensation
- cytoplasm
- acrosome
- tail
What is the cap of membranes containing digestive enzymes called?
What is spermeation?
Where does this occur?
What is removed and what forms?
ACROSOME
- war head of torpedo
- as sperm hits the egg, dumps digestive enzymes and can burrow through
Spermeation:
- Process of extruding flagellated spermatozoa in LUMEN of the tubule
- Most remaining cytoplasm is removed and “residual body” is formed
What provides the energy for movement?
What forms as a result of Spermatogenesis?
What forms as a result of Spermeation?
What protects the sperm from the immune system?
Mitochondria
- 4 spermatids - immature haploid gametes
- remodeling - 4 SPERMATAZOA
- haploid gametes
- extruded from lumen
Sertoli cells and their TIGHT JUNCTIONS
Spermiogenesis = making 4 spermatids SPERMATOGENESIS = whole process
What is the function of the following:
- Epididymus
- Prostate
- Seminal Vesicles
Which is responsible for alkaline secretions?
Which stabilizes acrosome
Which secretes prostaglandins? What does this do?
Epididymus;
a) sperm maturation, gain motility, lose cytoplasm
b) reservoir for sperm
c) STABILIZE ACROSOME
Prostate:
2. alkaline secretions to neutralize acidic vaginal secretions
Seminal Vesicle:
- secretions of PROSTAGLANDINS
- allow for contraction of uterus and fallopian tubes considered important in sperm movement
What is prostatic specific antigen? What is it often used for?
PSA –> used for determining prostate cancer
How is the paracrine and endocrine function of inhibit and Activin different.
State both.
What is the neuroendocrine axis?
What is the affect of dopamine and Endorphins on the hypothalamus and GnRH?
INHIBIN
Endocrine:
inhibits the pituitary
paracrine: stimulates testosterone secretion
Activin
endocrine: activates the pituitary
paracrine: inhibits testosterone secretion
- Hypothalamus
- GnRH on pituitary
- release FSH and LH
male: testosterone
- negative feedback at PITUITARY and HYPOTHALAMUS - Dopamine & Endorphins have a NEGATIVE affect on GnRH
Where is GnRH released from?
What is its function?
How do dopamine, endorphins, NE and stress (CRH) affect GnRH?
What type of release is GnRH? (constant/pulsatile)
How can one inhibit FSH and LH secretion knowing the type of secretion pattern?
- Arcuate N. and Preoptic Area
- Increases synthesis and secretion of gonadotropics in ANTERIOR pituitary
- Dopamine, Endorphins, NE, stress INHIBIT GnRH
- Release of GnRH is pulsatile
– 8 to 14/24 hrs - continuous exposure to GnRH is inhibitory to FSH and LH release
GnRH receptors on gonadotrophs… activation triggers _____ of stored trophic hormones and stimulates transcription of _____ and ___
What is the major regulator of LH?
What is this hormone converted to in the hypothalamus?
Why do steroid abusing bodybuilders shut down GnRH release? How do they do this?
- exocytosis
- LH and FSH -subunit genes
- testosterone
- estrogen
- inject hCG to mimick LH action after finishing T doses to recover endogenous steroidogenesis.
- stimulates testes to make more testosterone
What stimulates Leydig cells to secrete TESTOSTERONE?
What does this hormone bind?
What does it activation?
What does it increase expression of? (important in steroidogenesis)
- LH
- binds G protein coupled receptor
- activates PKA = increase gene transcription to support testosterone synthesis
- increases expression of sterol-carrier protein & sterol activating protein
Sertolli cells are stimulated by ____ and ____ to facilitate the development of what?
Describe the actions of FSH on the cell:
What is the effect?
- Androgens & FSH
- Sperm development
- binds G protein
- PKA increeases gene transcription
- increased proteins (ABP - androgen binding proteins) - Keeps testosterone high near developing sperm
State the major functions of FSH. (6)
Sertoli cells? (3)
- increase ABP
- keeps T high near developing cells
- increases androgen receptors
- activates AROMATASE (T to E2)
- increases growth factors to stimulate spermatogonia, spermatocytes, spermatids, motility
- increases INHIBIN synthesis
Sertoli:
- Mechanical support
- Secrete anti-mullerian hormone
- Contributes to the blood testes border
