GAMETOGENESIS Flashcards
Type of reproduction under mitosis?
ASEXUAL
Type of reproduction under meiosis?
SEXUAL
Count of daughter cells under meiosis?
Count of daughter cells under mitosis?
2;4 DAUGHTERS
Allele difference between parent and daughter cells mitosis?
Allele difference between parent and daughter cells meiosis?
IDENTICAL; DIFFERENT
Altered number of chromosomes under mitosis?
Altered number of chromosomes under meiosis?
SAME; HALVED
Count of cell division cycle?
1&2
It is a cell division that produces the same number of chromosomes from the parent cell, and produces two identical daughter cells.
MITOSIS
It is the half of mitosis
PROPHASE
What are the two main stages of meiosis and the other term of each stages?
Meiosis I or Reduction Stage/ Meiosis II or Division Stage
What is 1st phase in the reproduction of animal?
gametogenesis
Primitive germ cell or?
Primordial sex cells
Embryo development 6 stages?
Fertilized egg- zygote 1st cleavage- 4 cells- morula- blastocyst
Formation of cells of the same kind
Cell reproduction
Maintenance of an organism stages (wound healing)
Hemostasis- inflammatory- proliferative- remodeling
Part of interphase in which cell duplicates its DNA and centrosome
S- phase or synthesis phase
Part of interphase in which cell grows some more
Gap 2/ g-2phase
Nucleus disappear and chromatin condenses into chromosomes
Prophase
Nuclear membrane breaks down, kinetochore microtubules invade nuclear space, and attach to kinetochore, polar microtubules push against each other, moving centrosomes apart
Prometaphase
Chromosomes break at centromeres, and sister chromatids move to opposite ends of the cell.
Anaphase
Nuclear membrane reforms, nucleoli reappear, chromosomes unwind into chromatin.
Telophase and cytokinesis
Cell leaves the cell cycle, it is the resting phase
Gap 0 g0
Interphase
G1 phase, s phase, g2 phase
Non sex cells
Autosomes
– process of absorption of nutrients and materials from extracellular fluid to increase cell size
Protoplasmic synthesis
Centrioles are duplicated and polar microtubules (for–) are formed. Becomes the mitotic apparatus
Plants
- process of absorption of nutrients and materials from extracellular fluid to increase cell size
- Metabolically active in the synthesis of RNA and proteins
- Cellular content like the organelles are duplicated except for the nucleus
G1
- DNA are completely replicated
- Chromosomes are doubled
- Protoplasmic synthesis reoccurs
- Centrioles are duplicated and polar microtubules (for plants) are formed. Becomes the mitotic apparatus
G2
- DNA start to duplicate
- Each chromosomes will form 2 sister chromatids
- Complete and identical set of genes
- Other compounds and organelles are synthesized
S PHASE
Cell division occurs
* Formation of two daughter cells
* 4 stages
➢Prophase
➢ Metaphase
➢Anaphase
➢Telophase
MITOTIC PHASE/MITOSIS
2 cell reproductive processes
➢ Mitosis
➢ Meiosis
Half of Mitosis
* Nuclear membrane breaks downs to form several small vesicles as the nucleolus disintegrates
* Centrosome duplicates itself and migrate to opposite ends of the cell
* Centrosomes organize the production of microtubules which will form the spindle
fibers for the mitotic spindle
* Chromosomes condensed into tightly packed sister chromatids held together by a
centromere
Prophase
Sister chromatids align
together at the imaginary
metaphase plate at the
equatorial plane led by
the centromeres
* Spindle fibers bind to the
kinetochores
Metaphase
- Also know as cytokinesis
telophase
- Also know as cytokinesis
- Nuclear membrane reforms
around the chromosomes - Chromosomes uncoil and
diffuse - Spindle fiber disappears
- Constriction of the cytoplasm
separates the daughter cells. - Daughter cells enter
interphase
Telophase
Contains a single copy of chromosomes
meiosis
Produces haploid sex cells or gametes
* Contains a single copy of each
chromosome
* Involves DNA replication followed by
2 nuclear divisions
* Meiosis I
* Meiosis II
* Random alignment of maternal and paternal chromosomes and sister chromatid
Meiosis
Through exchange of
genetic materials
between homologous
chromosomes during
Meiosis I
* Facilitates random
alignment of parental
chromosomes in
Meiosis I and sister
chromatids in Meiosis II.
GENETIC DIVERSITY
two daughter cells are produced and the chromosomal number of each is reduced in ½
Meiosis I or Reduction Stage
production of four daughter cells, each cell containing haploid number of chromosomes.
Meiosis II or Division Stage
- Condensation of
chromosomes - Chromosomes similar in
shape and size and
partnered as
homologous
chromosome pairs - Form bivalents (pairs
of chromosomes)
consisting of four
chromatids (tetrads)
Synapsed of homologous pair of chromosomes
Meosis1 prophase 1
Due to close
association, or synapsis, overlapping of chromatids may
occur which may lead to crossing over between pairs of homologous
chromosomes
Reciprocal to the exchange of genes on
the same loci of the
homologous
chromosomes.
Formation of spindle
fibers by their
kinetochores
Meiosis I: PROPHASE I
Prophase begins chromosomes starts to condense
leptotene
5 stages of prophase in meiosis in order
leptotene-zygotene-pachytene-diplotene-Diakinesis
Synapsis begins synaptonemal complex forms
zygotene
Crossing over- DNA exchanged by non-sister sister chromatids
pachytene
Synapsis ends- Chiasma visible within bivalent
diplotene
Prophase ends nuclear membrane disintegrates
diakinesis
Homologous pairs
move to the metaphase plate by the growing length of
spindle fibers
Meiosis I: METAPHASE
Homologous pairs are
separated, divided, or
pulled to the opposite
poles of the cell due
to the shortening
length of the spindle
fiber.
Meiosis I: ANAPHASE I
- 2 daughter cells
- Nuclear membrane
reappears, the nucleus
divides into two nuclei. - Half the original
number of
chromosomes - Each chromosome is in
its duplicated state
Meiosis I: TELOPHASE
Spindle apparatus
reappears
* Nuclear membranes
and nucleoli
disappears, and
chromosomes area
attached to the
spindle fibers
Meiosis II: PROPHASE II
- Nuclear membrane and
nucleolus of each cell
reappears. - Nucleus of each cell divides
into two nuclei following
the division of two cells
forming of 4 daughter cells - Each daughter cell has a
haploid
Meiosis II: TELOPHASE II
(2n) or primary oocyte-> secondary oocyte-> 3 polar body and an ovum
oogenesis
primary spermatocyte -> secondary spermatocyte -> 4 spermatids-> sperm
Spermatogenesis
Haploid 23 chromosomes (n) in human (sperm/egg or ovum)
Germ line (germ cells)
Diploid 46 chromosomes 2n in human (muscle & skeletal, blood, fat, neuron, organ and tissue, stem cells)
Somatic cells
Process of the formation of sex
cells for the male and female
gametes which will also undergo
transformation to become
specialized cells
Gametogenesis
Male – Formation of sperm
cells via
Female – Formation of egg
cell or ova via
spermatogenesis, oogenesis
Major processes
involved during gametogenesis
Cell Proliferation, Cell growth, Cell maturations
primitive germ cells or primordial sex cells repeatedly
divide by mitosis into identical cells
Cell Proliferation
cessation of mitosis in favor of the acquisition of raw
materials for the synthesis of protoplasm
Cell Growth
2 successive cell divisions (mitosis) take place. This is
accompanied by chromosomal divisions, which results in
the reduction of the chromosomes number by one half.
Cell Maturation
occurs in the seminiferous tubules in the testes.
Spermatogenesis
Spermatogenesis occurs in the________testis
Seminiferous tubules
Structures found in frog testis
- Mesorchium
- Tunica Albuginea
- Seminiferous Tubules
- Spermatocyst/Cell Nest/ Follicular Cyst
- Sertoli/Sustentacular Cell
- Insterstitial Cell
- Ova
Portion of the peritoneum that suspends the testes to
the dorsal body while immediately ventral to the kidney and between
the layers of which passed the tubes of the vas deferens
Mesorchium
____ is the outer connective tissue which covers the testes
known as the _____, this tough tissue extends into the substance of the testis and partitions it into
many compartments containing the seminiferous tubules
Tunica Albuginea; intertubular connective tissue or septula
much coiled to build containing the clusters of spermatogenic cells undergoing the same stage of development and nurse cells, the Sertoli cells
Seminiferous tubules
nurse cells or?
sertoli cells
A cluster of similar cells
undergoing the same stage of development is surrounded by follicle cells.
Spermatocyst/Cell Nest/ Follicular Cyst
is a specific stage in spermatogenesis, the process by which male germ cells (spermatogonia) develop into mature sperm cells (spermatozoa).
specifically focuses on the final transformation of spermatids into mature, functional sperm cells.
Spermiogenesis
Functionally under cell, supply nutrients to the cluster of cells. they are associated with the primary spermatogonia and spermatocytes as follicle cells.
Sertoli/Sustentacular Cell
Small cluster of cells found interspersed with the
intertubercular connective tissue.
Interstitial Cells
egg cell seen between seminiferous tubules of some male individuals thus making the male organ an Ovotestis.
Ova
Look for the following structures:
* Seminiferous Tubules
* Sertoli Cells (Active and
Inactive/Resting)
* Spermatogenic Cells
* 3 types of Spermatogonia (Type A, Type
B, and Intermediate Spermatogonia)
Mouse Testes
Produce testosterone
interstitial or leydig cells
Sustentacular or nerve cells
which are spaced at fairly regular intervals against the basement membrane and are
around the circumference of the seminiferous tubules. they have distinct outlines and large, Oval, often indented nuclei with compound nucleoli.
Sertoli Cells
form the blood-testes barrier: nutrients, and circulating substances do not directly reach the germ cells
determines which substances reach the germ cells
produce antigen-binding proteins which are necessary for spermiogenesis
Function of: Sertoli cells
fulfilling normal functions and they are pyramidal in shape with the apex directed towards the lumen and the nucleus perpendicular to the tubule
wall
Active Sertoli Cells
polygonal in shape the
nucleus is parallel to the wall of the tubule
Inactive Sertoli Cells
polygonal in shape, pyramidal
inactive sertoli; active
Three Types of Spermatogonia
Type A Spermatogonia; type b; intermediate
chromatin particles appear fine
and evenly dispersed. a single prominent chromatin
nucleolus, whose nature is not known, usually appears in
an eccentric position. These usually are the germ cell line.
Type A Spermatogonia
presence of course granules or
flakes of heavily stained chromatin associated with the
nuclear membrane and nucleolus. this is the most
common gonia, and therefore outnumbers type A and
immediate spermatogonia. this is the last stage before
they transform into primary spermatocytes.
Type B Spermatogonia
– chromophilic chromatin
in the form of delicate crust or flakes attached to the
nuclear membrane . They have prominent nucleoli usually
appearing in a central rather than peripheral position
Intermediate Spermatogonia
occurs in the - follicles of the ovary
Oogenesis
to locate in this animal: * Mesentery
* Oogonium and Oocytes
* 2 connective tissues
Frog Ovary (Anura)
double layered extension of the peritoneum that attaches
the ovary to the dorsal body wall
Mesovarium
collective term for theca externa, theca interna, and the
follicle cells
Ovarian follicle
– outermost connective tissues surrounding the ovary and
is continuous with the mesovarium and is the region of rupture during
ovulation to allow the egg to escape into the body cavity. Thousands of
individual sacks containing the eggs are suspended in the covering.
Theca externa
– inner connective tissue vascularized issue surrounding
the ovary and each egg.
Theca interna
derived from the oogonia. These contain oval and granular
nuclei and surround the developing oocyte.
Follicle cells
located to the periphery of the ovary and much smaller than
the oocyte. They have no pigment and contain little, if any, yolk.
Oogonia
potential ovum that is bigger than the oogonia. The lightly
stained structure at its center is a germinal vesicle or immature nucleus.
Oocytes
a non-cellular transparent membrane between the
follicle cells and each mature egg. Probably derived from both the ovum
and follicle cells and it’s probably developed during the maturation
process
Vitelline membrane
– fluid filled space formed between the egg and the
vitelline membrane after fertilization
Perivitelline space
Look for the following structures of this organism:
- Cortex and Medulla
- Germinal Epithelium
- Oogonia
- Tunica Albuginea
- Stroma
- Different Stages of Follicles and its structures
Cat Ovary (felis catus)
the epithelial lining of the
ovary that is composed of cuboidal cells
Germinal Epithelium
all fibrous connective tissue
beneath the germinal epithelium
Tunica Albuginea
connective tissue immediately beneath the tunica albuginea and penetrating the substance of the ovary and consisting of
connective tissue fibers and spindle shaped cells
Stroma
potential ovum with vesicular
nucleus with a prominent nucleolus. these are found embedded in the stroma and occurring in clusters. These small oogonia without the follicle
cells surrounding them are in early stages.
Oogonium
peritoneum of the ovary
that continues into the oviduct. Consists of squamous epithelial cells
Periovarial membrane
space between the
membrane and the ovary
Periovarial space
convulated structure attached to the periovarial membrane.
Oviduct
Gonadotrophin independent phase (intraovarian regulation)
primordial, primary, secondary follicle
Gonadotrophin responsive phase (acquisition of FSH- dependence)
preantral; early antral follicle
Gonadotrophin dependent phase (FSH dependence to LH dependence)
antral follicle -(selection)- graafian follicle- (ovulation) - corpus luteum
Antral or?
Graafian
What is the arrest phase of oogenesis?
Prophase 1 specifically diplotene stage
Graafian Follicles
Antrum, Cumulus oophorus, Stratum granulosum, Corona radiata, Zona Pellucida and Liquor Folliculi, Theca Folliculi, Theca Interna, Theca Externa
lined by granulose cells (stratum granulosum) – thick layer of follicle cells
Antrum
thick layer of follicle cells
stratum granulosum
aka Follicular Cavity
Antrum
Primordial follicles consist of oocytes surrounded by a single layer of _____ follicular cells.
Squamous
- An ovarian follicle progresses through several
distinct phases before it releases its ovum. - During the first five months of development, a
finite number of primordial follicles form in the
fetal ovary. - These follicles consist of oocytes surrounded
by a single layer of squamous follicular cells. - These primordial follicles remain in the process
of the first meiotic division. - At puberty, they begin to develop further and
become primary follicles
Primordial Follicle
Stage
- 1-few layers of flattened follicle cells and an oogonium
- Early to Late Primary Follicle Stage
Primary Follicle Stage
- Follicle Cells – now several layers and
consisting of low columnar cuboidal
cells enclosing the oocyte. - Antrum – aka Follicular Cavity.
Precipitation of proteins may give the
cavity a granular appearance. - Liquor Folliculi – viscous follicular fluid
appearing light pink coagulum within
the antrum. - Oogonium/Primary Oocyte – separated
from the granulosa cell by the zona
pellucida
Growing Follicle Cell
viscous follicular fluid
appearing light pink coagulum within the antrum.
Liquor Folliculi
separated from the granulosa cell by the zona pellucida
Oogonium/Primary Oocyte
- Antrum – lined by granulose cells (stratum granulosum)
– thick layer of follicle cells - Cumulus oophorus – eccentric mound of follicle cells
surrounding the egg cells - Primary oocyte – stage of development of the cell
- Stratum granulosum – layers of follicle cells bordering
the Graafian - Corona radiata – layers of follicles cells of the cumulus
oophorus that lie nearest to the oocyte - Zona Pellucida and Liquor Folliculi
- Theca Folliculi – stroma immediately adjacent to the
follicle that forms a capsule around the follicle - Theca Interna – between theca externa and granulose
cells of the capsule consisting of large stromal cells with
the oval nuclei and capillaries. Richly vascularized and
the cells are secretory. - Theca Externa – outer layer of the capsule composed of
the spindled shape dense connective tissue fibers.
Graafian Follicles
between theca externa and granulose cells of the capsule consisting of large stromal cells with the oval nuclei and capillaries. Richly vascularized and the cells are secretory.
Theca Interna
– outer layer of the capsule composed of
the spindled shape dense connective tissue fibers.
Theca Externa
layers of follicles cells of the cumulus oophorus that lie nearest to the oocyte
Corona radiata
Unsuccessful follicles undergoing degenerative process
Atretic Follicles
- Lutein Cells – from stratum granulosum of the ovulated Graafian follicle at the periphery of the corpus luteum.
- Capillaries – network of small blood vessels
- Capsule – layer surrounding the corpus luteum that consists of connective tissue fibers and fusiform cells.
Corpus Lutea/ luteum
from stratum granulosum
of the ovulated Graafian follicle at the periphery of the corpus luteum.
Lutein Cells
– layer surrounding the corpus
luteum that consists of connective tissue fibers and fusiform cells
Capsule
- Usually found at the central portion of the ovary
- Formed when fertilization doesn’t take place
- Stroma forms a capsule around the regressing corpus luteum invades the regressing luteal cells and replaces them as they degenerate leaving a white hyalinized scar.
Corpus Albicans
- Tunica Albuginea and Stroma (more
prominent in humans) - Corpus Lutea – may be in various stages
of regression, thus an active corpus
luteum may not be seen. The
degenerating corpus in human, unlike
those of the cat, has a large cavity filled
with loose connective tissue and
remnants of lutein cells. - Blood Vessels – distinguish between a
vein and an artery
Human Ovary
(more
prominent in humans)
Tunica Albuginea and Stroma
may be in various stages
of regression, thus an active corpus luteum may not be seen.
Corpus Lutea (in humans)
The degenerating corpus in _____, unlike
those of the cat, has a large cavity filled with loose connective tissue and
remnants of lutein cells.
humans
– distinguish between a vein and an artery
Blood Vessels
eccentric mound of follicle cells surrounding the egg cells
Cumulus oophorus
