Download Embryo Exam 1 Study Guide Quiz 1 Primary oocytes Oogonia

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Embryo Exam 1 Study Guide
Quiz 1
 Primary oocytes
o Oogonia entering the first meiotic division late in the fetal
period
o Enter the diplotene stage of prophase I in the early months
after birth
 Oogonia
o Primordial germ cells during the second through fifth month of
pregnancy undergo intense meiosis in the embryonic ovary
o After meiosis they undergo atresia (degeneration)
 Primordial germ cells
o Arise in the extraembryonic mesoderm near the base of the
allantois
o Become recognizable in the lining of the yolk sac
o Migrate to the wall of the gut and the dorsal mesentery as they
make their way to the gonads
 Occurs during 4th -5th weeks
 Multiply my mitosis during migration
o Differentiate into oogonia or spermatogonia
 Spermatogonia
o In males
o Just before puberty primordial germ cells differentiate into
these!
 Spermatocytes
o
 Graffian follicles
o tertiary (Graafian) follicle protrudes at the surface of the ovary (stigma) and
sharp spike in LH from the pituitary leads to completion of meiosis I and
ovulation. The completion of meiosis I now forms a secondary oocyte [1n, 2c],
that is, half the number of chromosomes but they are double the DNA, still
connected by a centromere. A polar body is produced and lies between the zona
pellucida and egg. Meiosis II begins and arrested in metaphase II. About three
hours will pass before ovulation. After ovulation, the Graafian follicle becomes a
corpus luteum. Unless fertilization occurs 24 hours after ovulation, the egg will
die. The layer granulosa cells still adherent to the zona pellucida is called the
corona radiata.
 Puberty
o For males, primordial germ cells continue to divide by mitosis throughout life or
differentiate into spermatogonia just before puberty.
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o Spermatogenesis begins in the seminiferous tubules of the male after the onset of
puberty. Up to that time, spermatogonia maintain their population through
mitosis of type A spermatogonia. After puberty, some type A give rise to type
B spermatogonia that differentiate into primary spermatocytes and enter
prophase I of meiosis but are not held at the diplotene stage, as are the oocytes.
o Shortly before puberty the sex cords acquire lumens, becoming
seminiferous tubules and at puberty primordial germ cells are
transformed into type A spermatogonia [2n, 2c].
o At puberty and just before ovulation (egg breaks free from ovary), the
process continues through diakenesis, metaphase I, anaphase I, and
telophase I.
o Early development of the follicle occurs without the significant influence
of hormones, but as puberty approaches, continued follicular maturation
requires the action of the pituitary gonadotrophic hormone folliclestimulating hormone (FSH) on the granulosa cells, which by this time
developed FSH receptors on their surfaces.
Late in the fetal period
o oogonia enter the first meiotic division late in the fetal period, they are
called primary oocytes
At the time of ovulation
o In the primary oocyte, the first three stages of prophase occur promptly,
but shortly after birth the process is held in the diplotene stage until
ovulation. The diplotene stage is where the homologous pairs exchange
genetic material by crossing over at areas called, chiasma. At puberty and
just before ovulation (egg breaks free from ovary), the process continues
through diakenesis, metaphase I, anaphase I, and telophase I.
After fertilization
o At fertilization, for each of the 23 chromosomes (1n, 1c) donated from the egg
there is a homologous (related and hopefully normal) chromosome donated from
a sperm, and vice versa. When chromosomes condense during mitosis, each half
of the pair is called a chromatid. So, after duplication of DNA, and just when
anaphase begins, there are 92 (2n, 4c) chromatids in the dividing cell. This is still
diploid, but with twice the DNA. After anaphase, each daughter cell is back to
the 46 chromosomes (2n, 2c).
Diplotene stage of prophase I
o oocytes enter the diplotene stage of prophase I in the early months after
birth
Metaphase of meiosis I
o ???
Diplotene stage of meiosis II
o ???
Prophase of meiosis II
o ???
Spermatid
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o Primary spermatocytes give rise to secondary spermatocytes that will go
through meiosis II to make spermatids, and finally, spermatozoa
o Secondary spermatocytes complete meiosis II, becoming spermatids [1n, 1c],
which shed excess cytoplasm, the residual body, and differentiate into
spermatozoa. Spermatogenesis is divided into two parts. (1)
spermatocytogenesis – spermatogonia up to spermatids, and (2) spermiogenesis
– spermatids to mature sperm.
 Secondary spermatocyte
o Primary spermatocytes pass through the blood-testes barrier (made by
Sertoli cells) and complete meiosis I to become secondary
spermatocytes [1n, 2c]. Secondary spermatocytes complete meiosis II,
becoming spermatids [1n, 1c], which shed excess cytoplasm, the residual
body, and differentiate into spermatozoa.
o Metamorphosis of spermatids to spermatozoa includes: formation of and
acrosome (an enzyme-filled structure important for fertilization) and a flagellum
with mitochondria around its proximal part. The sperm cell has a (1) head with
the acrosome and nucleus, (2) midpiece with the centrioles and proximal
flagellum with the mitochondria, and (3) the tail.
 Mesoderm of the gonad
 Surface epithelial cells of the ovary
 Yolk sac endoderm
 Stroma of the ovary
 Theca interna
 Leydig
 Theca externa
 Sertoli
 Corona radiate
 Cumulus oophorus
 Stigma
 Residual body
o Not part of a spermatozoon
 Head of spermatozoon
 Mouthpiece of spermatozoon
 Midpiece of spermatozoon
 Flagellum of spermatozoon
 Leydig cells
 Androgen-binding protein
 LH receptors
 Sertoli cells
 Testosterone
Quiz 2
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Gonadotropin-releasing hormone
FSH
Progesterone
Androgens
10 days
19 days
28 days
36 days
Zona pellucida
Cumulus oophorus
Theca interna
Yolk sac
Polar body
Antrum
Theca externa
Granulosa cells
Estrogens
Testosterone
Granulose lutein cells
Corona radiata
Trophoblast
After egg is fertilized
Several hours before fertilization
In the late fetal period
In the yolk sac
Fimbria
Infundibulum
Ampulla
Isthmus
HCG
LH
Capacitation
Spermiogenesis
An acrosomal reaction
Meiosis II
Ovulation
Fertilization
Zona reaction
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 Morula
 Zygote
 Gamete
 Blastocyst
 Inner cell mass
 Outer cell mass
 Mittelschmerz
Quiz 3
 Trophoblast
 Morula
 Epiblast
 Embryoblast
 Hypoblast
 Cytotrophoblast
 Synctiotrophoblast
 Epiblast
 Chorionic cavity
 Amniotic cavity
 Exocoelomic cavity
 Lacunae
 Somatopleuric mesoderm
 Cytotrophoblastic
 Splanchnopleuric mesoderm
 Chorionic plate
 Endometrium/synctiotrophoblast
 Cytotrophoblast/synctiotrophoblast
 Synctiotrophoblast/endometrium
 Extraembryonic mesoderm/umbilical cord
 High levels of HCG
 Spotting 13th day of pregnancy
 Pain during ovulation
 Severe abdominal pain at about 6-7 weeks of gestation
Quiz 4
 Prechordal plate
 Notochord
 Yolk sac
 Cloacal membrane
 Chorionic cavity
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 Lacunae
 Exocoelomic cyst
 Buccopharyngeal membrane
 Allantois
 Blood flow
 Lefty-1
 Dynein
 Fate map
 Cytotrophoblastic
 Synctiotrophoblastic
 Endometrial
 Mesodermal
 Primary villi
 Anchoring villi
 Tertiary villi
 Free villi
 Holoprosencephaly
 Sirenomelia
 Sacrococcygeal teratoma
 Immotile cilia
 Primitive node
 Primitive streak
Quiz 5
 The hypoblast
 Epiblast
 Cytotrophoblast
 Yolk sac
 Neural tube
 Posterior neuropore
 Neural crest cells
 Neural folds
 Anterior neuropore
 Gut tube
 Neural crest cells
 Enamel of teeth
 Dorsal root ganglia (sensory)
 Melanocytes
 Autonomic postganglionic nerve cells
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Persistent truncus arteriosus
Sacrococcygeal teratoma
Sirenomelia
Situs inversus
Somatic mesoderm
Extraembryonic mesoderm
Visceral mesoderm
Amniotic mesoderm
Neuromeres
Paraxial
Lateral plate
Somitomeres
Dermomyotome
Sclerotome
Myotome
Dermatome
Splanchnic mesoderm
Endoderm
Somatic mesoderm
Ectoderm
Allantois
Vitelline duct
Oropharyngeal membrane
Cloacal plate
Notochord
Mesoderm
Embryonic period
Fetal period
Bilaminar period
Trilaminar period