A blastocyst is a(n)
a. solid ball of cells.
b. origin of the urinary bladder.
c. portion of the placenta.
d. extraembryonic membrane.
e. hollow ball of cells.
e. hollow ball of cells
After fertilization, the first cell division is completed
a. more than a day later.
b. within the hour.
c. within a few seconds.
d. in 12 hours.
e. about 6 hours later.
a. more than a day later
After ovulation, the layer of follicle cells that surround the unfertilized egg is called the
a. zona pellucida.
b. tunica follicularis.
c. corona radiata.
d. Graafian follicle.
e. functional zone.
c. corona radiata
During amphimixis,
a. the male and female pronuclei fuse.
b. sperm become capacitated.
c. gametes are formed.
d. meiosis occurs.
e. the ovum finishes meiosis II.
a. the male and female pronuclei fuse
During gastrulation,
a. the placenta penetrates the endometrium.
b. three germ layers are formed.
c. the blastomeres fuse.
d. the neural tube closes.
e. cells from the hypoblast move to the epiblast.
b. three germ layers are formed
Polyspermy results in
a. twins.
b. fetuses with different fathers.
c. a nonfunctional zygote.
d. haploid individuals.
e. chimeric adults.
c. a nonfunctional zygote
Proteolytic enzymes that digest a path through the zona pellucida include
a. relaxin and hyalouronidase.
b. hyaluronidase and hCG.
c. hyaluronidase and acrosin.
d. acrosin and collagenase.
e. acetic acid and hydrochloric acid.
c. hyaluronidase and acrosin
Sperm cannot fertilize an oocyte until they
a. undergo activation.
b. are activated by sustentacular cells of the vagina.
c. lose their acrosome.
d. are in the vagina for 3 days.
e. undergo capacitation.
e. undergo capacitation
The ectoderm forms
a. blood.
b. the urinary system.
c. neural tissues.
d. muscle.
e. the lining of the digestive tract.
c. neural tissues
The inner cell mass of the blastocyst will
a. provide nutrients for early growth.
b. form the placenta.
c. form the morula.
d. form blood vessels of the placenta.
e. form the embryo.
e. form the embryo
The mesoderm and the trophoblast combine to form the
a. amniotic sac.
b. inner cell mass.
c. chorion.
d. allantois.
e. amnion.
c. chorion
The penetration of the endometrium by the blastocyst is referred to as
a. embryogenesis.
b. cleavage.
c. placentation.
d. fertilization.
e. implantation.
e. implantation
The period of gestation that is characterized by rapid fetal growth and fat deposition is the ________ trimester.
a. third
b. fifth
c. fourth
d. second
e. first
a. third
The period of gestation when organs and organ systems complete most of their development and the fetus looks distinctly human is the ________ trimester.
a. second
b. fourth
c. third
d. first
e. fifth
a. second
The period of gestation when the rudiments of all major organ systems are established is the ________ trimester.
a. fourth
b. second
c. first
d. fifth
e. third
c. first
The process of cell division that divides the cytoplasm of the zygote among blastomeres is called
a. placentation.
b. embryogenesis.
c. implantation.
d. blastulation.
e. cleavage.
e. cleavage
The site where fertilization normally occurs is in the
a. cervix.
b. union of the vagina and uterus.
c. uterine wall near the fundus.
d. upper one-third of the uterine tube.
e. fimbrae.
d. upper one-third of the uterine tube
The solid ball of cells that has been likened to a mulberry is called a
a. morula.
b. gastrula.
c. blastula.
d. chorion.
e. blastocyst.
a. morula
The trophoblast has many of the characteristics of ________ cells.
a. rejuvenating
b. cancer
c. epithelial
d. cardiac
e. infectious
b. cancer
Protective water-filled sacs surrounding the embryo.
A) Yolk sac
B) Amnion
C) Allantois
D) Chorion
B) Amnion
Extra-embryonic membrane that develops from the tropoblast and forms part of the placenta.
A) Yolk sac
B) Amnion
C) Allantois
D) Chorion
D) Chorion
Site of early blood cell production, and site from which progenitors of the future germ cells migrate to reach the genital ridges.
A) Yolk sac
B) Amnion
C) Allantois
D) Chorion
A) Yolk sac
Structure in humans that is the structural base for the umbilical cord; the solid waste disposal site in nonplacental animals.
A) Yolk sac
B) Amnion
C) Allantois
D) Chorion
C) Allantois
(T or F?) Conceptus is a term used to describe the developing offspring in a woman.
True
(T or F?) The first weeks of gestation are called the "embryonic period.
False
(T or F?) Fertilization occurs while the egg is still in the ovarian follicle.
False
(T or F) By 72 hours after fertilization, the egg has divided into more than 160 cells and is called the morula.
False
(T or F?) A pregnancy test involves antibodies that detect GH levels in a woman's blood or urine.
False
(T or F) Of the three germ layers, the mesoderm forms more body parts.
True
(T or F?) The two hormones responsible for initiating labor are thyroxine and human chorionic thyrotropin.
False
(T or F?) The embryo is directly enclosed in and protected by the amnion.
True
(T or F?) An episiotomy is an incision made to widen the vaginal orifice, aiding fetal expulsion.
True
(T or F?) Surfactant production in premature infants is rarely a factor in providing normal respiratory activity.
False
Which of the following statements about the events of fertilization is not true?
A) The two pronuclei divide.
B) Hyaluronidase and proteinases of the sperm disperse the cells of the corona radiata of the oocyte.
C) The secondary oocyte completes the secon
A) The two pronuclei divide
Select the correct statement about the special fetal blood vessels.
A) The distal parts of the umbilical arteries form the superior vesical arteries.
B) The umbilical vein becomes the ligamentum teres.
C) The fossa ovalis becomes the foramen ovale.
D) The
B) The umbilical vein becomes the ligamentum teres
Derivatives of the endoderm include:
A) epithelium of the respiratory tract.
B) blood, bone marrow, and lymphoid tissue.
C) synovial membranes of the joints.
D) organs of the urogenital system.
A) epithelium of the respiratory tract
Derivatives of the mesoderm include:
A) epithelium of the digestive tract.
B) tooth enamel.
C) endothelium of blood and lymph vessels.
D) glandular derivatives of the digestive tract.
C) endothelium of blood and lymph vessels
Derivatives of the ectoderm include:
A) epithelium of the reproductive tract.
B) epithelium of the pineal and pituitary glands.
C) connective tissues.
D) serosae of the ventral body cavity.
B) epithelium of the pineal and pituitary glands
Cleavage as part of embryonic development is distinctive because it involves:
A) cell division by mitosis with little or no growth between successive divisions.
B) meiosis.
C) the fusion of gametes.
D) splitting the cell into two separate cells.
A) cell division by mitosis with little or no growth between successive divisions
During which stage of labor is the fetus delivered?
A) dilation stage
B) placental stage
C) expulsion stage
D) gastrula stage
C) expulsion stage
The cardiovascular system of a newborn must be adjusted after the infant takes its first breath. Which of the following is also true?
A) The foramen ovale between the atria of the fetal heart closes at the moment of birth.
B) The ductus venosus is disconn
C) The ductus arteriosus is shut off by contractions of the muscle in its wall
The trophoblast is responsible for forming the:
A) placental tissue.
B) lining of the endometrium.
C) allantois.
D) archenteron.
A) placental tissue
Implantation:
A) is usually completed by the sixth day after ovulation.
B) begins about 24 hours after fertilization.
C) signals the division of the trophoblast into two distinct layers.
D) begins as the inner cell mass adheres to the endometrial wall.
C) signals the division of the trophoblast into two distinct layers
During pregnancy, the corpus luteum normally produces estrogens and progesterone:
A) for about 12-13 weeks.
B) until the eight week of pregnancy.
C) only until the implantation of the embryo.
D) for the entire pregnancy.
A) for about 12-13 weeks
The correct sequence of pre-embryonic structures is:
A) blastocyst, morula, zygote.
B) zygote, morula, blastocyst.
C) zygote, blastocyst, morula.
D) None of the above are correct.
B) zygote, morula, blastocyst
Which of the following is not a germ layer?
A) epiderm
B) mesoderm
C) ectoderm
D) endoderm
A) epiderm
Relaxin is a hormone produced by the placenta and ovaries. The function of this hormone is to:
A) prevent morning sickness.
B) relax the pubic symphysis.
C) ensure the implantation of the blastula.
D) block the pain of childbirth.
B) relax the pubic symphysis
The result of polyspermy in humans is:
A) interruption of meiosis.
B) multiple births.
C) a nonfunctional zygote.
D) mitotic insufficiency.
C) a nonfunctional zygote
The first "milk" the mother produces is called ________.
Colostrum
The act of giving birth is called ________.
Parturition
The ________ cells of the blastocyst will take part in placental formation.
Trophoblast
________ is a tissue with star-shaped cells that are free to migrate widely throughout the embryo.
Mesenchyme
Neural tissue develops from the ________.
Ectoderm
The first axial support for the embryo is called the ________.
Notochord