Embryology

Question 1

A phenotypically normal women underwent a karyotype analysis for difficulties in conceiving. She was found to contain two Barr bodies, but no translocations or large deletions
Her karyotype would be best represented by which of the following?

Answer 1

If this woman has 2 Barr bodies, then she has three X chromosomes per cell. Two of them have be inactivated. This would give a total of 47 chromosomes and three of them would be X chromosome

Question 2

A 19-year-old female visits her primary care physician with complaints of nausea and vomiting when she wakes up in the morning. Pertinent history reveals a missed period and multiple sexual partners. The patient does not practice safe sex with the use of contraceptives. Her physician determines that she is in the 4th week of pregnancy.
Which of the following best describes the condition of the embryo at this time?

Answer 2

Neurulation is nearly complete – This is the correct answer. Neurulation begins late in week 3 with formation of the neural groove and neural folds. However, most of the process, including formation and completion of the neural tube, occurs during week 4.
TAKEAWAY: During neurulation, additional major events occur including much of somite differentiation, the appearance of the pharyngeal (branchial) apparatus, and the appearance of the upper limb bud.

Question 3

—————-is the process of formation of the trilaminar germ disc, that is, establishing the three germ layers: ectoderm, endoderm, and mesoderm. Gastrulation is the defining characteristic of week 3 of development. Remember “threes”: three germ layers in week 3.

Answer 3

Gastrulation

Question 4

Question 5

Question 6