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132 Cards in this Set
- Front
- Back
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what are descendant of primordial germ cells that originate in the wall of the yolk sac of the embryo and migrate into the gonad region?
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gametes (oocytes and spermatazoa)
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What are produced in the adult by either oogenesis or spermatogenesis, processes that involve meiosis?
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gametes (oocytes and spermatazoa)
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What occurs olny during the production of gametes?
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meiosis
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what consists of two cell divisions and results in the formation of gametes containing only 23 chromosomes and 1N amound of DNA?
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meiosis
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What process promotes the exchange of small amounts of maternal and paternal DNA via crossover?
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meiosis
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what comes from the wall of the yolk sac, arrives in the ovary at week 4 of embryonic development and differentiates into oogonia? (46, 2N)
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primordial germ cells
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What enters meiosis I and undergoes DNA replication to form primary oocytes?
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oogonia
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ALL primary oocytes are formed by the ____ month of fetal life and remain dorman in prophase (diplotene) of Meiosis I until puberty.
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5th
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During a woman's ovarian cycle, a _____ oocyte complete meiosis I to form a secondary oocyte (23, 2N) and a first polar body, which probably degenerates.
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primary
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In oogenesis, What enters meiosis II, and ovulation occurs when the chromosomes align at metaphase?
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secondary oocyte
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the secondary oocyte remains arrested in _____ of meiosis II until fertilization occurs.
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metaphase
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After fertilization, the _____ oocyte completes meiosis II to form a mature oocyte and a second polar body.
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secondary
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Concerning the hormonal control of the female reproductive tract, what does the hypothalamus secrete?
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gonadotropin-releasing hormone (GnRH)
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in response to GnRH, the adenohypophysis secretes gonadtropins, which are which two hormones?
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FH and LSH
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___ stimulates the development of a secondary follicle to a Graafian follicle within the ovary.
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FSH
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Granulosa cells of the secondary and Graafian follicle secrete ____.
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estrogen
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Estrogen stimulates the endometrium of the uterus to enter the ____ phase.
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proliferative
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____ stimulates the endometrium of the uterus to enter the proliferative phase.
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estrogen
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___ stiumlates ovulation.
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LH
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Following ovulation, granulosa lutein cells of the corpus luteum secrete _____.
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progesterone
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Following ovulation, ___ ____ cells of the corpus luteum secrete progesterone.
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granulosa lutein
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_______ stimulates the endometrium of the uterus to enter the secretory phase.
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Progesterone
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primordial germ cells from the wall of the yolk sac arrive in TESTES at week _ of embryonic development and remain dormant until puberty.
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WEEK 4
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at puberty, primodrial germ cells differentiate into type ___ spermatogonia.
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TYPE A
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TYPE A spermatogonia undergo ____ to provide a continuous supply of stem cells throughout the reproductive life of the male (called spermatocytogenesis).
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mitosis
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TRUE/FALSE - Some type A spermatogonia differentiate into TYPE B spermatogonia, which then go on to make spermatids.
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TRUE
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TRUE/FALSE - TYPE B spermatogonia (46, 2N) enter meiosis I and undergo DNA replication to form primary spermatocytes (46, 1N).
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FALSE - primary spermatocytes are 4N, and have duplicated chromosomes, (double chromatids), since this is prior to completion of Meisosis. Secondary spermatocytes are completed meiosis I cells and have 23, 2N.
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primary spermatocytes complete ____ to form 2 secondary spermatocytes (23, 2N)
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meiosis I
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secondary spermatocytes undergo meiosis II to form FOUR ____ (23, 1N).
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spermatids
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What cells undergo a postmeitotic series of morphological changes (called spermiogenesis) to form sperm (23, 1N).
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spermatids
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newly ejaculated sperm are incapable of fertilization until they undergo capacitation, which occurs where?, and involves the unmasking of sperm glycosyltransferases and removal of proteins coating the surface of the sperm.
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female reproductive tract - specifically the zona pellucida, some texts say the corona radiata, but Dr. Krueger says it’s a BS question and should be zona pellucida
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What is the primary cause of Down Syndrome in the cell?
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the primary cause of Down Syndrome is maternal meiotic nondisjunction.
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What are two abnormalities seen with advanced paternal age?
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Achondroplasia and Marfan syndrome
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a fertile male produces how many sperm pr mL of semen?
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20 to over 100 million sperm/mL
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a sterile male produces how many sperm pr mL of semen?
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less than 10 million sperm /mL
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normally what percent of sperm is abnormal?
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10%
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some women have inadequate levels of what two hormones?, leading to an absence of ovulation?
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LH and FSH
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if a women is not having normal ovulations due to a lack of hormonal levels, what is a treatment and how does it work?
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clomiphene citrate - works by competing with estrogen for binding sites in the hypothalamus, thereby shutting down a negative feedback loop and increasing GnRH secretion and consequently the LH and FSH hormones necessary for ovulation to occur
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Week 1 - Fertilization - Where does fertilization occur?
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ampulla of the uterine tube
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Week 1 - Fertilization - the sperm binds to the zona pellucida of the secondary oocyte arrested in metaphase of Meiosis II and triggers what?
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the acrosome reaction, causing the release of acrosomal enzymes. (ie. acrosin).
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Week 1 - Fertilization - thanks to acrosomal enzymes - penetration of the zona pellucida occurs, causing what?
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cortical reaction - rendering the secondary oocyte impermeable to other sperm.
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Week 1 - Fertilization - all mitochondria in the recently fertilized zygote are of ____ origin.
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maternal
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Week 1 - Fertilization - with penetration and production of the male pronucleus, the _____ oocyte completes meiosis II creating a mature ovum, the nucleus of which is the female pronucleus.
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secondary
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Week 1 - Cleavage - the zygote cytoplasm is successively cleaved to form a ____ consisting of increasing smaller _____.
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blastula; blastomeres. (blastula is the whole zygote, blastomeres are the cells. Ie. a 2- blastomere/celled blastula, 4-blastomere/celled blastula.
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Week 1 - Cleavage - at the ___ to ___ cell stage, the blastomeres form a morula consisting of an inner cell mass and an outer cell mass.
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16 to 32
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Week 1 - Cleavage - blastomeres are considered totipotent up until what stage?
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the 8-cell stage. Each blastomere can become a complete embryo by itself )
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Week 1 - Blastocyst Formation - when does this stage occur?
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when fluid secreted within the morula forms the blastocysts cavity
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Week 1 - Blastocyst Formation - the inner cell mass, which will become the embryo, is now called what?
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embryoblast
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Week 1 - Blastocyst Formation - the outer cell mass, which will become the placenta, is now known as what?
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trophoblast
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Week 1 - Implantation - before implantation can occur, what must degenerate?
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zona pellucida
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Week 1 - Implantation - what part of the uterus does the blastocyst implant on?
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posterior superior wall
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Week 1 - Implantation - in what phase of the menstrual cycle does the blastocyst implant on the functional layer of the endometrium?
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secretory phase
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Week 1 - Implantation - what does the trophoblast differentiate into during this stage?
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cytotrophoblast and syncytiotrophoblast
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Week 2 - Embryoblast - what does the embryoblast (which was the inner cell mass of the blastocyst), differentiate into?
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dorsal epiblast, and ventral hypoblast
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Week 2 - Embryoblast - what do the epiblast and the hypoblast together form?
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a flat ovoid-shaped disk called the bilaminar embryonic disk
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Week 2 - Embryoblast - within the epiblast, clefts develop and eventually coalesce to form what structure?
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amniotic cavity
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Week 2 - Embryoblast - hypoblast cells migrate and line the inner surface of the cytotrophoblast and eventually delimit a space called what?
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the definitive yolk sac
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Week 2 - Embryoblast - the epiblast and hypoblast eventually fuse to form the ___ ___, which marks the future site of the mouth.
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prochordal plate
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Week 2 - Trophoblast - the syncytiotrophoblast continues its growth into what and what does it do?
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the endometrium to make contact with endometrial blood vessels and glands.
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Week 2 - Trophoblast - how does the syncytiotrophoblast grow?
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this division does NOT divide mitotically. Instead the cytotrophoblast divides and adds to this structure.
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Week 2 - Trophoblast - the syncytiotrophoblast secretes what?
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hCG
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Week 2 - Trophoblast - what is formed by the cytotrophoblast and protrudes into the syncytiotrophoblast?
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primary chorionic villi
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Week 2 - Extraembryonic Mesoderm - what is this derived from?
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this is a new layer of cells dervied from the epiblast.
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Week 2 - Extraembryonic Mesoderm - lines the cytotrophoblast, forms the connecting stalk, and covers the amnion. What is this also known as?
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somatopleuric mesoderm
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Week 2 - Extraembryonic Mesoderm - the conceptus is suspended by the connecting stalk within what cavity?
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chorionic cavity
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Week 2 - Extraembryonic Mesoderm - what is the wall of the chorionic cavity called and made up of?
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its known as the Chorion, and its made up of three adjacent layers: 1. extraembryonic somatic medsoderm (aka somatopleuric mesoderm) 2. cytotrophoblast 3. syncytiotrophoblast
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Week 2 - Extraembryonic Mesoderm - what does the visceral mesoderm cover? (akas the splanchnoplueric mesoderm)
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primary umbilical vessicle (the yolk sac)
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Week 2 - Extraembryonic Mesoderm - the 14-day embryo still has the form of a flat bilaminar disc, but the hypoblastic cells in a localized area are now columnar and form a thickened circular area - the ____ ____ - which indicates the future site of the mouth and is an important organizer of the head region.
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prechordal plate
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implantation begins and ends in when?
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Begins at End of first week and ends at the end of the 2nd week.
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the zona pellucida degenerates by day ___.
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5
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Week 2 - What erodes endometrial blood vessels, allowing maternal blood to seep in and out of lacunar networks, thereby establishing a uteroplacental circulation?
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syncytiotrophoblast
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Week 2 - what is the decidual reaction?
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the endometrial changes (resulting from the adaptation of these tissues in preparation for implantaion).
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Week 2 - the ____ umbilical vessel becomes smaller and gradually disappears as the ____ umbilical vessel develops.
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primary, secondary
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Week 2 - the ____ cavity appears as a space between the cytotrophoblast and the embryoblast.
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amniotic
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in which week does gastrulation occur?
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Week 3
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what signals in week 3 that gastrulation is occuring?
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primitive streak - a thickening of the epiblast at the caudal end of the embryonic disc
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the primitive streak starts from the cranio or caudal end?
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caudal
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what results from migration of epiblastic cells to the median plane of the embryonic disc?
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the primitive streak
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invagination of the epiblastic cells from the primitive streak gives rise to mesenchymal cells that migrate ventrally, laterally, and cranially between what two layers?
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the epiblast and hydroblast.
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as soon as the primitive streak begins to produce mesenchymal cells, the epiblast undergoes a name change to what?
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embryonic ectoderm
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during gastrulation, some cells of the epiblast displace the hypoblast and form what?
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embryonic endoderm
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by the end of the 3rd week, mesoderm exists between the ectoderm and endoderm everywhere but what 3 places?
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1. the orophrayngeal membrane, 2. in the median plane occupied by the notochord; AND 3. the cloacal membrane
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What is the fate of the primitive streak?
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disappears by the end of the fourth week
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Early in the third week, mesenchymal cells from the primitive streak form the ____ ____, between the embryonic ectoderm and endoderm.
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notochordal process
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Week 3 - Where does the notochordal process extend to and from?
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from the primitive node to the prechordal plate.
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Week 3 - the notochordal canal has openings that develop in the floor that eventually come together and form a notochordal ____.
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plate
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Week 3 - The _____ plate infolds to form the ____, which is the primordial axis of the embryo around which the axial skeleton forms. (ie. vert column).
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notochordal plate; notochord.
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Week 3 - The neural plate appears as a thickening of the embryonic ____, induced by the developing notochord.
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ectoderm
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Week 3 - A longitudinal neural groove develops in the neural plate, which is flanked by what?
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neural folds.
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Week 3 - Fusion of the neural folds forms what structure? What is it a primordial structure of?
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the neural tube, the primordium of the CNS
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Week 3 - as the neural folds fuse to form the neural tube, _____ cells forms a neural crest between the surface ectoderm and the neural tube.
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neuroectodermal
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the mesoderm on the each side of the notochord condenses to form longitudinal columns of paraxial mesoderm, which, by the end of the 3rd week, give rise to ____.
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somites
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What cavity within the embryo arises as isolated spaces in the lateral mesoderm and cardiogenic mesoderm?
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the coelom.
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What vessicles subsequently coalesce to form a single, horseshoe-shaped cavity that eventually gives rise to the body cavities?
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The coelomic vesicles
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Where do blood vessels first develop?
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Blood vessels first appear in the wall of the umbilical vesicle (yolk sac), allantois, and chorion. They develop within the embryo shortly thereafter.
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The heart is represented by paired endocardial heart tubes. By the end of the ____ week, the heart tubes have fused to form a tubular heart that is joined to vessels in the embryo, umbilical vesicle, chorion, and connecting stalk to form a primordial cardiovascular system.
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third
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TRUE/FALSE Fetal and adult erythrocytes develop from the same hematopoietic precursors.
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FALSE - different
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Primary chorionic villi become secondary chorionic villi as they acquire what?
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mesenchymal cores
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Before the end of the ____ week, capillaries develop in the secondary chorionic villi, transforming them into tertiary chorionic villi. Cytotrophoblastic extensions from these stem villi join to form a cytotrophoblastic shell that anchors the chorionic sac to the endometrium.
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3rd
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At the beginning of the fourth week, folding in the median and horizontal planes converts the flat ____ embryonic disc into a C-shaped, cylindrical embryo.
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trilaminar
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Week 4-8 - The formation of the head, caudal eminence, and lateral folds is a continuous sequence of events that results in a constriction between the embryo and what structure?
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the umbilical vesicle (yolk sac).
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Week 4-8 - As the head folds ventrally, part of the ____ layer is incorporated into the developing embryonic head region as the foregut.
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endodermal
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Week 4-8 - Folding of the head region also results in what two structures being carried ventrally?
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oropharyngeal membrane and heart
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Week 4-8 - As the caudal eminence folds ventrally, part of the endodermal germ layer is incorporated into the caudal end of the embryo as the ___.
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hindgut.
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Week 4-8 - The terminal part of the hindgut expands to form the ____.
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cloaca
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Week 4-8 - Folding of the caudal region also results in the cloacal membrane, allantois, and connecting stalk being carried to the DORSAL or VENTRAL surface of the embryo?
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ventral
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Week 4-8 - Folding of the embryo in the horizontal plane incorporates part of the endoderm into the embryo as the ___.
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midgut.
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Week 4-8 - What structure remains attached to the midgut by a narrow omphaloenteric duct (yolk stalk)?
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The umbilical vesicle
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Week 4-8 - During folding of the embryo in the ____ plane, the primordia of the lateral and ventral body walls are formed.
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horizontal
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Week 4-8 - As the amnion expands, it envelops what THREE structures, thereby forming an epithelial covering for the umbilical cord?
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connecting stalk, omphaloenteric duct, and allantois
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True/False - By Week 10 the three germ layers differentiate into various tissues and organs so that by the end of the embryonic period, the beginnings of all the main organ systems have been established.
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FALSE - between weeks 4-8
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Week 4-8 - The ___ appearance of the embryo is greatly affected by the formation of the brain, heart, liver, somites, limbs, ears, nose, and eyes. As these structures develop, the appearance of the embryo changes so that it has unquestionably human characteristics at the end of the 8th week.
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external
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Developmental disturbances during what period may give rise to major congenital anomalies of the embryo?
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Week 4-8 - Because the beginnings of most essential external and internal structures are formed during the fourth to eighth weeks, this is the most critical period of development.
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What can the following list be used to do? 1) the day of onset of the last normal menstrual period (LNMP), 2) the estimated time of fertilization, 3) ultrasound measurements of the chorionic sac and embryo, and 4) examination of external characteristics of the embryo.
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Reasonably estimate the age of the embryos.
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The fetal period begins __ weeks after fertilization (or how many weeks after the LNMP)?
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9 (or 11 weeks after LNMP)
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What period is characterized by rapid body growth and differentiation of tissues and organ systems?
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Fetal period - 9-38 weeks
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While everything else is growing in the fetal period, what specifically has a decrease in the speed of growth?
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An obvious change in the fetal period is the relative slowing of head growth compared with that of the rest of the body.
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By the beginning of the ___ week, lanugo and head hair appear, and the skin is coated with vernix caseosa.
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20th week
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What is lanugo?
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downy hair - (Fetal period - 20th week)
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What is the cheesy substance coating babies' skin by the 20th week?
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vernix caseosa
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The eyelids are closed during most of the fetal period but begin to reopen at approximately ___ weeks.
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26 weeks
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At 26 weeks, the fetus is usually capable of extrauterine existence, mainly because of the maturity of its ____ system.
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respiratory
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Until approximately ___ weeks, the fetus appears reddish and wizened because of the thinness of its skin and the relative absence of subcutaneous fat.
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30 weeks
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Fat usually develops rapidly during the last ___ to ___ weeks, giving the fetus a smooth, plump appearance.
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6 to 8 weeks
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The fetus is less vulnerable to the teratogenic effects of drugs, viruses, and radiation, but these agents may interfere with growth and normal functional development, especially of the ___ and ____.
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brain and eyes
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The physician can now determine whether a fetus has a particular disease or a congenital anomaly by using various diagnostic techniques, such as what?
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amniocentesis, CVS, AFP, ultrasonography, and magnetic resonance imaging, spectrophotometric studies, sex chromatin, cell cultures and chrosomal analysis, fetal transfusion, fetoscopy, PUBS, CT, fetal monitoring
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TRUE/FALSE - In selected cases, treatments can be given to the fetus, e.g., the administration of drugs to correct cardiac arrhythmia or thyroid disorders.
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TRUE
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True/False - Surgical correction of some congenital anomalies in utero (Fig. 6-18) is also possible (e.g., fetuses that have ureters that do not open into the bladder).
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TRUE
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when can the sex genitalia be distinguished externally?
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12 weeks
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at what week can external ears be seen?
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16
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fingernails appear which week?
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24
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in which week are digital hand rays visible?
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5, more clearly in week 6
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