Chapter 3 Flashcards
These ___ are controlled by the hypothalamus. Gonadotropin-releasing hormone (GnRH), produced by the hypothalamus, acts on cells of the anterior lobe (adenohypophysis) of the pituitary gland, which in turn secrete gonadotropins
sexual cycles
These sexual cycles are controlled by the hypothalamus. Gonadotropin-releasing hormone (GnRH), produced by the hypothalamus, acts on cells of the anterior lobe (adenohypophysis) of the pituitary gland, which in turn secrete ____
gonadotropins
These sexual cycles are controlled by the hypothalamus. ____, produced by the hypothalamus, acts on cells of the anterior lobe (adenohypophysis) of the pituitary gland, which in turn secrete gonadotropins
Gonadotropin-releasing hormone (GnRH)
These hormones,____ and ____, stimulate and control cyclic changes in the ovary
follicle-stimulating hormone (FSH) - luteinizing hormone (LH)
When a follicle becomes atretic, the oocyte and surrounding follicular cells degenerate and are replaced by connective tissue, forming a ____
corpus atreticum
FSH also stimulates the maturation of ___ cells surrounding the oocyte
follicular (granulosa)
In the meantime, the surface of the ovary begins to bulge locally, and at the apex, an avascular spot, the ___, appears.
stigma
Those contractions extrude the oocyte, which together with its surrounding granulosa cells from the region of the cumulus oophorus breaks free (____) and floats out of the ovary
ovulation
Some of the cumulus oophorus cells then rearrange themselves around the zona pellucida to form the ___
corona radiata
Under the influence of LH, these cells develop a yellowish pigment and change into ___, which form the corpus luteum and secrete estrogens and progesterone
lutein cells
Under the influence of LH, these cells develop a yellowish pigment and change into lutein cells, which form the corpus luteum and secrete estrogens and ___
progesterone
Under the influence of LH, these cells develop a yellowish pigment and change into lutein cells, which form the ___ estrogens and progesterone
corpus luteum
Progesterone, together with some estrogen, causes the uterine mucosa to enter the _____ in preparation for implantation of the embryo
progestational or secretory stage
Subsequently, the corpus luteum shrinks because of degeneration of lutein cells (___) and forms a mass of fibrotic scar tissue, the ____
luteolysis - corpus albicans
If the oocyte is fertilized, degeneration of the corpus luteum is prevented by ___, a hormone secreted by the syncytiotrophoblast of the developing embryo
human chorionic gonadotropin
The corpus luteum continues to grow
and forms the ____ (corpus luteum graviditatis)
corpus luteum of pregnancy
Fertilization, the process by which male and female gametes fuse, occurs in the ____
ampullary region of the uterine tube
The corpus luteum continues to grow
and forms the corpus luteum of pregnancy (_____)
corpus luteum graviditatis
____ is a period of conditioning in the female reproductive tract that in the human lasts approximately 7 hours
Capacitation
Spermatozoa are not able to fertilize the oocyte immediately upon arrival in the female genital tract but must undergo;
1.
2.
(1) capacitation and (2) the acrosome reaction to acquire this capability
The ____, which occurs after binding to the zona pellucida is induced by zona proteins
acrosome reaction
The phases of fertilization include the following:
Phase 1, penetration of the corona radiata
Phase 2, penetration of the zona pellucida
Phase 3, fusion of the oocyte and sperm cell membranes
This contact results in release of lysosomal enzymes from ___ lining the plasma membrane of the oocyte
cortical granules
In turn, these enzymes alter properties of the zona pellucida (___) to prevent sperm penetration and inactivate species-specific receptor sites for spermatozoa on the zona surface
zona reaction
The spermatozoon, meanwhile, moves forward until it lies close to the female pronucleus. Its nucleus becomes swollen and forms the ___
male pronucleus
____ are another commonly used form of contraception.
Hormonal methods
___ of contraception include the male condom, made of latex and often containing chemical spermicides, which fits over the penis, and the female condom, made of polyurethane, which lines the vagina
Barrier methods
A ____ has been developed and tested in clinical trials. It contains a synthetic androgen that prevents both LH and FSH secretion and either stops sperm production [70% to 90% of men] or reduces it to a level of infertility.
male “pill”
____ are used as birth control measures that may prevent pregnancy if taken 120 hours after sexual intercourse. These pills may be administered as high doses of progestin alone or in combination with estrogen [Plan B]
Emergency contraceptive pills [ECPs]
The ____ is a small T—shaped unit and there are two types: hormonal and copper
intrauterine device [IUD]
____ is another form of birth control. The method for men is a vasectomy, which
prevents the release of sperm by blocking the ductus deferens, the tube that transports sperm from the testes to the penis. For women, it is tubal sterilization in which the uterine tubes are blocked or
ligated. These procedures for both men and women can be reversed in some cases.
Sterilization
____ of human ova and embryo transfer is the standard procedure used by laboratories throughout the world
In vitro fertilization [IVF]
___ is a problem for 14% to 15% of couples. Male infertility may be a result of insufficient numbers of sperm and/or poor motility. Infertility in a woman may be due to a number of causes, including occluded uterine tubes [most commonly caused by pelvic inflammatory disease], hostile cervical mucus, immunity to spermatozoa, absence of ovulation, and others.
Infertility
One percent to 2% of all pregnancies in the
United States occur using _____
assisted reproductive technology [ART]
____ is a drug used to increase FSH concentrations to stimulate ovulation. The drug is given early in the menstrual cycle to cause ovulation in women who do not ovulate or who ovulate irregularly
Clomiphene citrate [Clomid]
Severe male infertility, in which the ejaculate contains very few live sperm [____] or even no live sperm [___], can be overcome using ___
oligozoospermia - azoospermia - ICSI
Severe ____, in which the ejaculate contains very few live sperm [oligozoospermia] or even no live sperm [azoospermia], can be overcome using ICSI.
male infertility
These cells, which become smaller with each cleavage division, are known as ____
blastomeres
This process, ___, segregates inner cells, which communicate extensively by gap junctions, from outer cells
compaction
Approximately 3 days after fertilization, cells of the compacted embryo divides again to form a 16-cell ___ (mulberry)
morula
Gradually, the intercellular spaces become confluent, and finally, a single cavity, the ___, forms. At this time, the embryo is a ___
blastocele - blastocyst
Cells of the inner cell mass, now called the ___, are at one pole, and those of the outer cell mass, or ____, flatten and form the epithelial wall of the blastocyst
embryoblast - trophoblast
Inner cells of the morula constitute the ___, and surrounding cells compose the ____
inner cell mass - outer cell mass
The inner cell mass gives rise to tissues of the ___, and the outer cell mass forms the ___, which later contributes to the ___
embryo proper - trophoblast - placenta
ES cells may be obtained from embryos after ___, a process called ____. This approach has the disadvantage that the
cells may cause immune rejection because
they would not be genetically identical to their hosts
IVF - reproductive cloning
____ are derived from the inner cell mass of the embryo. Because these cells are ___ and can form virtually any cell or tissue type, they have the potential for curing a variety of diseases, including diabetes, Alzheimer and Parkinson diseases, anemias, spinal cord injuries, and many
others
Embryonic stem cells [ES cells] - pluripotent
Under the influence of fibroblast growth factors (FGFs) at the early blastocyst stage, cells in the embryoblast differentiate into ___ and ____
epiblast - hypoblast cells
In addition, some of the hypoblast cells are specified to form the ____, and these cells migrate to what will become the cranial end of the embryo
anterior visceral endoderm (AVE)
New studies suggest that ____ on trophoblast cells and its ____ on the uterine epithelium mediate initial attachment
of the blastocyst to the uterus
L—selectin - carbohydrate receptors
Adult tissues contain stem cells that may also prove valuable in treating diseases. These cells are restricted in their ability to form different cell types and, therefore, are ___, not pluripotent, although scientists are finding methods to circumvent this disadvantage
multipotent
The exact number of _____ formed is unknown because they are usually lost within 2 to 3 weeks of fertilization, before the woman realizes she is pregnant, and therefore, are not detected.
abnormal zygotes
With the use of a combination of IVF and ___, molecular screening of embryos for genetic defects is being conducted.
polymerase chain reaction
The wall of the uterus consists of three layers:
- Endometrium or mucosa lining the inside wall
- Myometrium, a thick layer of smooth muscle
- Perimetrium, the peritoneal covering lining the outside wall
Estimates indicate that as many
as _____ and that half of these losses are a result of chromosomal abnormalities
50% of pregnancies end in spontaneous
abortion
As a result, three distinct layers can be recognized in the endometrium: a superficial____, an intermediate ___, and a thin___
compact layer - spongy layer - basal layer
The results of fertilization are the following:
- Restoration of the diploid number of
chromosomes - Determination of chromosomal sex
- Initiation of cleavage
During this menstrual cycle, the uterine endometrium passes through three stages:
- Follicular or proliferative phase
- Secretory or progestational phase
- Menstrual phase
When the ____ begins, blood escapes from superficial arteries, and small pieces of stroma and glands break away. During the following 3 or 4 days, the
compact and spongy layers are expelled from the uterus, and the basal layer is the only part of the endometrium that is retained
menstrual phase
This layer, which is supplied by its own arteries, the ___, functions as the regenerative layer in the rebuilding of glands and arteries in the proliferative phase
basal arteries
This layer, which is supplied by its own arteries, the basal arteries, functions as the regenerative layer in the rebuilding of glands and arteries in the ____
proliferative phase
As soon as the spermatocyte has entered the oocyte:
1. The oocyte finishes its second meiotic division and forms the ____.
2. The zona pellucida becomes impenetrable to other spermatozoa.
3. The head of the sperm separates from the tail, swells, and forms the ____
female pronucleus - male pronucleus
