Lect. 3 - Gametogenesis III Flashcards Preview

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Flashcards in Lect. 3 - Gametogenesis III Deck (18):

List the stages of spermatogenesis and the major meiotic events that occur at each stage.

*spermatogonium - DNA replication: 2N, 4c
*Primary spermatocyte: 1st meiotic division in progress - 2n, 4c
*2 secondary spermatocytes - second meiotic division in progress; 1n, 2c
*4 spermatids - immature haploid gametes; 1n, 1c
*4 spermatozoa - haploid gametes; 1n, 1c


Where are the Leydig cells located and what is their function?

Interstitial cells located in the testis - produce testosterone.


What are the 4 stages of spermiogeneis?

Golgi phase, cap phase, acrosomal phase, maturation phase.


Golgi phase

proacrosomal and acrosomal vesicles


Cap phase

mature acrosome forms a cap over the nucleus


Acrosomal Phase

rotation of sperm so acrosomal pole faces wall of seminiferous tubule - cytoplasm displaced toward tail


Maturation phase

completion of flagellum and nuclear condensation


What is the location of Sertoli cells?

They form an immunological barrier b/w the forming sperm cells and the rest of the body and spermatogonia


Functions of the sertoli cells

Physical support and maintenance, maintain and coordinate spermatogenesis.
Secrete estrogen, inhibit and anti-Mullerian factor
Maintain blood testis barrier
Secrete tubular fluid
Phagocytize residual bodies of sperm cells


Sertoli cells and blood testis barrier

Sertoli cells form an immunologic barrier b/w the forming sperm cells and the rest of the body and spermatogonia
*surface adhesion compelxes bind surfaces of Sertoli cells to late spermatids
*they also break down and release spermatids into lumen
*laminin fragments from surface adhesion complexes plus sytokines and proteinase break down the tight-junctional proteins of the blood testis barrier and allow developing spermatocytes to move closer to the lumen


What role does testosterone play in the blood-testis barrier?

It stimulates the formation of a new blood-testis barrier closer to the basal lamina


What is the action of LH on interstitial cells and Sertoli cells w/ regard to sperm cell production?

LH (secreted by anterior pituitary in response to GnRH from hypothalamus) binds to LH receptors on interstitial cells of Leydig
*testosterone is synthesized by Leydig cells from cholesterol and is then carried via the blood to Sertoli cells (binds to cytoplasmic receptors) and to secondary sexual tissues (prostate, seminal vesicle epididymis, ductus deferens, peni, scrotum)


what is the synonymous process to oogenesis in male ?



What are the two types of spermatogonia?

type a: stem cells
Type b: leave mitotic cycle and enter meiotic cycle under influence of RA


what do primary oocyte mature from and what is their ploidy?

from type B spermatogonia and they are 2N


secondary spermatocytes

ploidy = N (two of them after second meiosis)


acrosomal enzymes

synthesized under influence of mRNA synthesized during pre-leptotene stage of meiosis; hyaluronidase; zona lysin; and more


LH and FSH effect on sperm production

increase it