Features of First Meiotic Division

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What is the term used to describe the segments in the head region of the paraxial mesoderm?

Sclerotome

Somitomers

Neuromeres (correct)

Dermomyotome

How many pairs of somites are present by the end of the 5th week of development?

38 pairs

40 pairs

42 pairs (correct)

45 pairs

Which part of the somite gives rise to the musculature of the limbs and body wall?

Myotome (correct)

Intermediate mesoderm

Dermatome

Sclerotome

What is the role of the dermatome in somite differentiation?

Supplies skin components Signup and view all the answers

What is the function of the sclerotome in somite differentiation?

Gives cartilage and bone component Signup and view all the answers

Which part of the somite forms the vertebral column later in development?

Sclerotome Signup and view all the answers

What is the primary role of Type A spermatogonia in spermatogenesis?

To act as a continuous reserve of stem cells Signup and view all the answers

During spermiogenesis, which of the following events does NOT occur?

Duplication of the nucleus Signup and view all the answers

Which hormone is primarily responsible for stimulating spermatogenesis?

Both LH and testosterone Signup and view all the answers

What is the function of the Sertoli cells during spermatogenesis?

To provide support, nutrition, and assist in sperm release Signup and view all the answers

Which of the following is NOT considered an abnormality in male germ cells?

Normal size and shape Signup and view all the answers

What is the correct sequence of events during the first week of development?

Ovulation, fertilization, cleavage Signup and view all the answers

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. Signup and view all the answers

What is the primary function of the second meiotic division?

To separate sister chromatids into individual chromosomes. Signup and view all the answers

Which of the following statements about meiosis is incorrect?

It results in genetically identical daughter cells. Signup and view all the answers

What is the significance of the $30-40$ crossover events during meiosis I?

It increases the genetic diversity of the resulting gametes. Signup and view all the answers

Which type of chromosomal abnormality is characterized by the presence of an extra chromosome?

Trisomy Signup and view all the answers

What is the primary reason for the occurrence of meiosis before gamete formation?

To reduce the chromosome number from diploid to haploid. Signup and view all the answers

What is the functional layer of the endometrium called?

Decidua Signup and view all the answers

Which part of the decidua is tightly attached to the chorion frondosum?

Decidua basalis Signup and view all the answers

What happens to the decidua capsularis as pregnancy progresses?

It soon becomes thin and degenerates Signup and view all the answers

What is the result of the fusion between the chorion leave and the uterine wall?

Obliteration of the uterine lumen Signup and view all the answers

What is the placenta composed of?

Chorion frondosum and decidua basalis Signup and view all the answers

What is the purpose of the septa formed from the decidua in the placenta?

To divide the placenta into cotyledons Signup and view all the answers

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. Signup and view all the answers

During which period of development do the three germ layers give rise to specific tissues and organs?

Embryonic period Signup and view all the answers

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. Signup and view all the answers

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. Signup and view all the answers

Which of the following structures arise from the dilated cephalic part of the neural tube?

Brain vesicles Signup and view all the answers

Which of the following derivatives arise from neural crest cells?

Craniofacial skeleton, neurons for cranial ganglia, glial cells, melanocytes, arachnoid and pia mater Signup and view all the answers