30 Questions
What is the term used to describe the segments in the head region of the paraxial mesoderm?
Neuromeres
How many pairs of somites are present by the end of the 5th week of development?
42 pairs
Which part of the somite gives rise to the musculature of the limbs and body wall?
Myotome
What is the role of the dermatome in somite differentiation?
Supplies skin components
What is the function of the sclerotome in somite differentiation?
Gives cartilage and bone component
Which part of the somite forms the vertebral column later in development?
Sclerotome
What is the primary role of Type A spermatogonia in spermatogenesis?
To act as a continuous reserve of stem cells
During spermiogenesis, which of the following events does NOT occur?
Duplication of the nucleus
Which hormone is primarily responsible for stimulating spermatogenesis?
Both LH and testosterone
What is the function of the Sertoli cells during spermatogenesis?
To provide support, nutrition, and assist in sperm release
Which of the following is NOT considered an abnormality in male germ cells?
Normal size and shape
What is the correct sequence of events during the first week of development?
Ovulation, fertilization, cleavage
During the first meiotic division, what is the significance of the chiasma stage?
It represents the point at which homologous chromosomes exchange genetic material through crossing over.
What is the primary function of the second meiotic division?
To separate sister chromatids into individual chromosomes.
Which of the following statements about meiosis is incorrect?
It results in genetically identical daughter cells.
What is the significance of the $30-40$ crossover events during meiosis I?
It increases the genetic diversity of the resulting gametes.
Which type of chromosomal abnormality is characterized by the presence of an extra chromosome?
Trisomy
What is the primary reason for the occurrence of meiosis before gamete formation?
To reduce the chromosome number from diploid to haploid.
What is the functional layer of the endometrium called?
Decidua
Which part of the decidua is tightly attached to the chorion frondosum?
Decidua basalis
What happens to the decidua capsularis as pregnancy progresses?
It soon becomes thin and degenerates
What is the result of the fusion between the chorion leave and the uterine wall?
Obliteration of the uterine lumen
What is the placenta composed of?
Chorion frondosum and decidua basalis
What is the purpose of the septa formed from the decidua in the placenta?
To divide the placenta into cotyledons
Which of the following statements about the incidence of teratomas is correct?
Teratomas have an incidence of 1:37,000, making them the most common tumors in newborns.
During which period of development do the three germ layers give rise to specific tissues and organs?
Embryonic period
Which of the following statements about the molecular basis of neurulation is correct?
If Bone morphogenic protein (BMP-4) is absent or inactivated by proteins present in the primitive node and notochord, the area of ectoderm overlying the notochord becomes thick and transforms into the neural plate.
Which of the following statements about the closure of the neural tube is correct?
The connection of the tube with the amniotic cavity is ended when the cranial neuropore is closed at 25 days and the caudal neuropore at the 27th day.
Which of the following structures arise from the dilated cephalic part of the neural tube?
Brain vesicles
Which of the following derivatives arise from neural crest cells?
Craniofacial skeleton, neurons for cranial ganglia, glial cells, melanocytes, arachnoid and pia mater
Test your knowledge on the key features of the first meiotic division, including homologous chromosome pairing, cross over, chiasma stage, and chromosome separation resulting in two cells with double structured chromosomes.
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