LECOM- EMBRYOLOGY EXAM 1
QUESTIONS AND ANSWERS
malformation - Correct Answers -occurs during organogenesis (ex: 3 headed bicep)
disruption - Correct Answers -occurs after organogenesis (ex: amniotic band
strangulation)
deformation - Correct Answers -abnormal structure resulting from mechanical forces
(ex: club feet)
What is a congenital abnormality? - Correct Answers -An anomaly visible at birth,
detected inadvertently during life, or not detected until after death
Most susceptible developmental period - Correct Answers -embryonic period
What organs are still developing in the fetal period? - Correct Answers -eyes, ears,
brain, hard palate, teeth, and external genitalia
4 phases of early development - Correct Answers -1. fertilization & implantation
2. proliferation
3. formation of placenta
4. body axes
What percentage of infant deaths in North America are due to congenital malformation?
- Correct Answers -20%
What are the 3 main causes of congenital anomalies? - Correct Answers -genetic,
environmental, multifactorial/unknown
agenesis - Correct Answers -absences of an organ
atresia - Correct Answers -absences of an opening (lumen)
pachytene - Correct Answers -crossing over event; occurs in prophase 1 of meiosis 1
Where do PCG's come from? - Correct Answers -1. arise from the epiblast in week 2 of
development (known as germ cells)
2. migrate into the yolk sac (known as PCG's)
3. In week 4-6 they migrate to the posterior abd wall
4. Multiply via mitosis
, How do germ support cells form? - Correct Answers -PCG's cause the surrounding
body cells to become primitive sex cords. Then, the genital ridges form and nourish and
regulate development of the PCG's
spermatogenesis vs. spermiogenesis - Correct Answers -spermatogenesis=
development of spermatids from spermatogonia through mitosis and meiosis
spermiogenesis= maturation of spermatids into spermatozoa (sperm)
What forms the seminiferous tubules? - Correct Answers -Sertoli cells
What are the two types of spermatogonia? - Correct Answers -Type A
Dark= non-dividing
Pale= give rise to type A and B spermatogonia
Type B= give rise to primary spermatocytes
4 things that occur in spermiogenesis - Correct Answers -1. condensation of nucleus
2. loss of cytoplasm
3. formation of neck and tail
4. formation of acrosome
When, in development, do a population of primary oocytes enter their first meiotic phase
and go dormant? - Correct Answers -week 12 (month 4)
By what month have all oogonia become primary oocytes? - Correct Answers -month 5
primary oocyte + single layer of follicular cells = - Correct Answers -primordial follicle
pituitary hormones of ovarian cycle - Correct Answers -1. Hypothalamus secretes GnRH
2. Stimulates the pituitary to secrete LH and FSH at a steady increase
3. LH and FSH peak to induce ovulation
ovarian hormones of ovarian cycle - Correct Answers -1. Estrogen peaks just before
ovulation
2. Progesterone increases at a steady rate, reaching its peak at the beginning of the
luteal phase
sacrococcygeal teratoma - Correct Answers -results from persistence of primitive streak
Where do the neural tubes first make contact (day 22)? - Correct Answers -in the area
of the four occipital somites and first cervical somite
QUESTIONS AND ANSWERS
malformation - Correct Answers -occurs during organogenesis (ex: 3 headed bicep)
disruption - Correct Answers -occurs after organogenesis (ex: amniotic band
strangulation)
deformation - Correct Answers -abnormal structure resulting from mechanical forces
(ex: club feet)
What is a congenital abnormality? - Correct Answers -An anomaly visible at birth,
detected inadvertently during life, or not detected until after death
Most susceptible developmental period - Correct Answers -embryonic period
What organs are still developing in the fetal period? - Correct Answers -eyes, ears,
brain, hard palate, teeth, and external genitalia
4 phases of early development - Correct Answers -1. fertilization & implantation
2. proliferation
3. formation of placenta
4. body axes
What percentage of infant deaths in North America are due to congenital malformation?
- Correct Answers -20%
What are the 3 main causes of congenital anomalies? - Correct Answers -genetic,
environmental, multifactorial/unknown
agenesis - Correct Answers -absences of an organ
atresia - Correct Answers -absences of an opening (lumen)
pachytene - Correct Answers -crossing over event; occurs in prophase 1 of meiosis 1
Where do PCG's come from? - Correct Answers -1. arise from the epiblast in week 2 of
development (known as germ cells)
2. migrate into the yolk sac (known as PCG's)
3. In week 4-6 they migrate to the posterior abd wall
4. Multiply via mitosis
, How do germ support cells form? - Correct Answers -PCG's cause the surrounding
body cells to become primitive sex cords. Then, the genital ridges form and nourish and
regulate development of the PCG's
spermatogenesis vs. spermiogenesis - Correct Answers -spermatogenesis=
development of spermatids from spermatogonia through mitosis and meiosis
spermiogenesis= maturation of spermatids into spermatozoa (sperm)
What forms the seminiferous tubules? - Correct Answers -Sertoli cells
What are the two types of spermatogonia? - Correct Answers -Type A
Dark= non-dividing
Pale= give rise to type A and B spermatogonia
Type B= give rise to primary spermatocytes
4 things that occur in spermiogenesis - Correct Answers -1. condensation of nucleus
2. loss of cytoplasm
3. formation of neck and tail
4. formation of acrosome
When, in development, do a population of primary oocytes enter their first meiotic phase
and go dormant? - Correct Answers -week 12 (month 4)
By what month have all oogonia become primary oocytes? - Correct Answers -month 5
primary oocyte + single layer of follicular cells = - Correct Answers -primordial follicle
pituitary hormones of ovarian cycle - Correct Answers -1. Hypothalamus secretes GnRH
2. Stimulates the pituitary to secrete LH and FSH at a steady increase
3. LH and FSH peak to induce ovulation
ovarian hormones of ovarian cycle - Correct Answers -1. Estrogen peaks just before
ovulation
2. Progesterone increases at a steady rate, reaching its peak at the beginning of the
luteal phase
sacrococcygeal teratoma - Correct Answers -results from persistence of primitive streak
Where do the neural tubes first make contact (day 22)? - Correct Answers -in the area
of the four occipital somites and first cervical somite
