C3: Gametogenesis and Hormones in Reproduction and Development Flashcards
four phases of gametogenesis:
a.) the extraembryonic origin of the germ cells and their migration into the gonads,
b.) an increase in the number of germ cells by mitosis,
c.) a reduction in chromosomal number by meiosis, and
d.) structural and functional maturation of the eggs and spermatozoa
the process of sperm cell production
▪ prolific and continuous process in the adult male
▪ occurs in the paired male gonads, or testes, specifically in the seminiferous tubules
Spermatogenesis
Primordial germ cells of the embryonic testes differentiate into ___, the diploid cells that are the precursors of sperm.
spermatogonia
are undifferentiated cells located near the outer wall of the seminiferous tubules.
Spermatogonia
In a mature male, about 3 million spermatogonia per day differentiate into ___
primary spermatocytes
Each primary spermatocyte undergoes first meiotic division producing ___
haploid secondary spermatocytes.
In the second meiotic division, each secondary spermatocyte gives rise to ___
two haploid spermatids.
what are produced from the original primary spermatocyte?
Four spermatids
Spermatids then differentiate into ______ The differentiation of the spermatids into sperm cells is called ___.
into a mature sperm cell or spermatozoa.;
spermiogenesis
Spermatogenesis involves association of the developing sperm with large ____, which transfer nutrients to the spermatozoa.
Sertoli cells
The release of a sperm cell from its connection to a Sertoli cell is known as ___.
spermiation
During spermatogenesis, the developing sperm are gradually pushed toward the _____, flow toward ___ and make their way to the ___ where they acquire motility.
center or lumen of seminiferous tubules;
ducts of the testes;
epididymis
Each mature sperm consists of a ___, ___, and ___.
head, midpiece, and flagellum (tail)
The head of sperm consists of the ___ and the nuclear material DNA and a cap called ___ that produces enzymes ___ and ___ that aid sperm cell to penetrate the secondary oocyte.
nucleus;
acrosome; hyaluronidase and proteinases
Numerous mitochondria, located in the ___ of the sperm (provides the energy (ATP) for locomotion).
midpiece
flagellum has a typical eukaryotic arrangement of _____propels the sperm along its way.
9+2 microtubules
differentiation of the spermatids into sperm cells; corresponds to the final part of spermatogenesis
Spermiogenesis
Stages of Spermiogenesis (6)
1.) Formation of the Acrosomal Cap
2.) Condensation of the Nucleus
3.) Development of the Flagellum
4.) Sheath Arrangement of the Mitochondria
5.) Cytoplasm Reduction
6.) mature sperm enveloped by plasma membrane
The development of the acrosomal cap is due to the coalescence of the vesicles of the Golgi apparatus which pinch off from it and forms a membranous structure called ____.
acrosome
contains enzymes that play important role in the penetration through the zona pellucida of the oocyte.
Acrosome
This organelle supports the developing flagellum which extends into the lumen of the tubule.
centriole
▪ development of ova (mature, unfertilized egg) from oogonia
▪ involves meiosis and occurs in the ovaries (the female gonad)
Oogenesis
___arises from the primordial germ cell dividing by meiosis in the ovary into ___
Oogonium; oocyte
During prenatal development, the oogonia increase in size and become ___.
primary oocyte
By the time of birth, primary oocyte are in the __ of the ___. At this stage, they enter a resting phase that last throughout childhood and into the adult life.
prophase of the first meiotic division
primary oocyte and the cluster of cells surrounding it together make up a __
follicle.
With the onset of puberty a few follicles develop each month in response to __ secreted by the anterior pituitary gland.
FSH
The two cells produce are different in size. The smaller one, the ___, may later divide forming two polar bodies bit eventually disintegrate.
The larger cell, the ____, proceeds to the second meiotic division but remains in ___ until it is fertilized.
first polar body;
secondary oocyte; metaphase
When meiosis does not continue, the second meiotic division gives rise to a ___ and a ___
single ovum; second polar body.
Each primary spermatocyte gives rise to ___ .
In contrast, each primary oocyte generates ___
four sperm;
only one ovum.
As follicle develops, it becomes separated from its surrounding follicle cells by a thick membrane, the ___
zona pellucida.
At ovulation, the ___ is ejected through the wall of the ovary and into the ___
secondary oocyte; pelvic cavity.
The portion of the follicle that remains in the ovary develops into the ___ (temporary endocrine gland) wherein it secretes ____
corpus luteum;
estrogens and progesterone.
Once the secondary oocyte exits the ovary, it begins to travel down the ___
uterine (fallopian tube).
The second meiotic division only occurs when ___ happens
fertilization
▪ in the process known as ___, the follicle ruptures releasing a secondary oocyte
ovulation
Production of ova begins with mitosis of the primordial germ cells in the embryo, producing ____. Each oogonium develops into ___, which is also diploid.
diploid oogonia (2n); primary oocyte
cyclic, physiologic changes in the levels of hormones that cause the release of an egg from the ovary and thickening of the lining of the uterus (endometrium) in preparation of receiving and nourishing a fertilized egg
Menstrual Cycle