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
this cycle recurs approximately every four week from puberty through menopause
▪ occurs in female of reproductive age
Menstrual Cycle
Two kinds of menstruation:
Overt menstruation
Covert menstruation
where there is blood flow from the vagina occurs primarily in humans and close evolutionary relatives such as chimpanzees;
Overt menstruation
where there is no blood flow, the endometrium is completely resorbed by the animal at the end of its reproductive cycle; occurs in females of other species of placental mammals that have estrous cycle
Covert menstruation
Menstrual cycle can be divided into several phases: 3
o Menstruation
o Follicular phase
o Luteal phase
defines the transition from the follicular phase to the luteal phase.
Ovulation
Stimulated by gradually increasing amounts of __ in the ___ phase, the lining of the uterus thickens
estrogens; follicular
The dominant follicle releases an ___ in an event called __.
ovum, or egg; ovulation
After ovulation, the remains of the dominant follicle in the ovary become the ____; this so called yellow body has a primary function of producing large amounts of ___.
corpus luteum; progesterone
Under the influence of ___, the endometrium (uterine lining) changes and thickens in preparation for possible ___ of an embryo to establish ___.
progesterone;
implantation;
pregnancy
If implantation does not occur within approximately two weeks, the corpus luteum will disintegrate and die, causing sharp drops in levels of both ____
progesterone and estrogens
Drop in the level of hormone concentration, causes the uterus to shed its lining in a process termed as ___.
menstruation
The ____ also comprises the recurring physiologic changes that are induced by reproductive hormones in most mammalian placental females
estrous cycle
Estrous cycles start after puberty in sexually mature females and are interrupted by ___
anestrous phases
Mammals share the same reproductive system:
-regulatory hypothalamic system= releases ____ in pulses,
-pituitary= secretes ___ and ___
-ovary = releases ___ and ___
gonadotropin releasing hormone;
follicle stimulating hormone and luteinizing hormone;
sex hormones; estrogens and progesterone.
A woman’s first menstruation is termed ___, and is one of the later stages of puberty in girls
menarche
The cessation of menstrual cycles at the end of the woman’s reproductive life is termed ___.
menopause
menstrual cycle can be divided into the following parts: 2
1.) ovarian cycle; and
2.) uterine cycle
OVARIAN CYCLE is further divided in 3 phases:
Follicular phase
Ovulation
Luteal phase
time from the first day of menstruation until ovulation when a mature egg is released from the ovary
Follicular phase
growth and maturation of the egg is taking place inside the follicle, a small sac where the egg matures.
Follicular phase
occurs around day 14 of the cycle, in response to a surge of luteinizing hormone (LH) that occurs just before the egg is released from the ovary.
Ovulation
is the time from when the egg is released (ovulation) until the first day of menstruation
Luteal phase
2 phases of uterine cycle:
Proliferative phase
Secretory phase
This uterine cycle phase is the time after menstruation and up to ovulation.
Proliferative phase
When menstruation is over, the endometrium grows and thickens during this period to prepare for implantation of an embryo (fertilized egg). What uterine phase?
Proliferative phase
This uterine cycle phase is the time after ovulation and before the start of a woman’s period. Glands within the endometrium secrete proteins in preparation for a fertilized egg to implant.
Secretory phase
During each cycle, the brain’s ___ and __ send hormone signals back and forth with the __.
hypothalamus and pituitary gland;
ovaries
The hormones __ and ___ play the biggest roles in how the uterus changes during each cycle.
estrogens and progesterone
this hormone build up the lining of the uterus;
whereas this hormone increase after an ovary releases an egg at ovulation in the middle of the cycle.
Estrogens;
Progesterone
chemical substances formed in tissues organs carried by the blood; stimulates or inhibits the growth or function
Hormones
Hormones in Reproduction and Development (5)
- Gonadotropin-releasing hormone (GnRH)
- Follicle-stimulating hormone
- Luteinizing hormone
- Estrogens
- Progesterone
produced by the hypothalamus; stimulates the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the pituitary gland
- Gonadotropin-releasing hormone (GnRH)
▪ produced by the anterior pituitary gland
▪ stimulates the growth of follicles in the ovaries which secrete estrogens
- Follicle-stimulating hormone
▪ also produced by the anterior pituitary gland
▪ works with the FSH to cause ovulation and later the release of estrogens and progesterone.
- Luteinizing hormone
hormones secreted by the ovarian follicles and corpus luteum
▪ stimulates thickening of the uterine wall, maturation of an egg, and development of the female sex characteristics
▪ also provides feedbacks to inhibit FSH secretion and increase LH secretion.
- Estrogens
▪ hormones secreted by the corpus luteum
▪ stimulates thickening of the uterine wall and formation of mammary ducts
- Progesterone
▪ __ stimulates enlargement of a few primary ovarian follicles and the subsequent maturation of the dominant follicle.
FSH
▪ FSH with the involvement of LH promotes estrogen secretion by ___
follicular cells.
___ stimulates the thickening of the uterine lining and exerts a negative feedback inhibition on ___ by the hypothalamus.
estrogen; GnRH secretion
A rapid rise in __ concentration peaks on day __ as the dominant follicle enlarges.
estrogen; 12
__ transforms the ruptured follicle into a corpus luteum and stimulates the corpus luteum to secrete increasing amounts of __ and __ during days ___
LH;
progesterone and estrogen;
17 to 23.
Progesterone exerts a negative feedback on GnRH secretion by the hypothalamus, inhibiting the release of ___ from the __
FSH and LH; anterior pituitary.
Female Disorders (9)
a.) Amenorrhea
b.) Dysmenorrhea
c.) Endometriosis
d.) Adenomyosis
e.) Pelvic inflammatory disease (PID)
f.) Use of an intrauterine device (IUD)
g.) Uterine fibroids and uterine polyps
h.) Infertility
i.) Cancer
hormone-like substances involved in pain and inflammation, trigger uterine muscle contractions.
Prostaglandins,
absence of menstruation
a.) Amenorrhea
___ is the failure of a woman to begin menstruation, and is caused by endocrine disorders or abnormal reproductive development
Primary amenorrhea
___ is the absence of one or more menstrual periods without pregnancy.
Secondary amenorrhea
painful menstruation that prevents a woman from doing her normal activity for one or more days during her menses
b.) Dysmenorrhea
Experts believe that ___ are the direct cause of dysmenorrhea. Increased ___ – substances involved in inflammation also may be a contributing factor.
prostaglandins; leukotriene levels
a painful condition, the type of tissue that lines the uterus becomes implanted outside the uterus, most commonly in the fallopian tube, ovaries, or the tissue lining the pelvis.
c.) Endometriosis
a condition that occurs when the tissue that lines the uterus begin to grow within the muscular walls of the uterus.
d.) Adenomyosis
infection of the female reproductive organs caused by sexually transmitted bacteria.
e.) Pelvic inflammatory disease (PID)
a small, plastic, T-shaped birth control device inserted into the uterus may cause increased cramping, particularly during the first few months after insertion.
f.) Use of an intrauterine device (IUD)
are non-cancerous tumors and growth that protrude from the lining of the uterus.
g.) Uterine fibroids and uterine polyps
inability to conceive. It may be caused by tubal obstruction, ovarian disease, or lack of maintenance of the uterine lining.
h.) Infertility
is a slow-growing cancer caused by ____ infections of sexual partners and associated with multiple sex partners. It can usually be detected early by a Pap smear. Annual
Cervical cancer; human papillomavirus
