Biology Chapter on Spermatogenesis and Oocyte Development

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Questions and Answers

Which bone is NOT considered a pharyngeal arch bone?

Malleus

Hyoid

Mandible

Frontal (correct)

What are the derivatives of neural crest cells mentioned in the content?

Melanocytes (correct)

Osteoblasts

Myocytes

Chondrocytes

Which of the following is FALSE about parafollicular cells?

They are distributed throughout the thyroid gland.

They are located in the adrenal medulla. (correct)

They synthesize calcitonin.

They are derived from neural crest cells.

How many ova does a woman typically ovulate during her reproductive period?

480 Signup and view all the answers

What happens to a primary oocyte during ovulation?

It completes meiosis I. Signup and view all the answers

Which cell type is incorrectly matched with its origin?

Chondrocytes – endoderm Signup and view all the answers

Which structure is responsible for the secretion of calcitonin?

Parafollicular cells Signup and view all the answers

Which of the following is NOT mentioned as a derivative of the neural crest?

Endocardial cushions Signup and view all the answers

What is formed at the end of telophase I during meiosis?

Two haploid cells Signup and view all the answers

At what point does the secondary oocyte remain arrested until it is fertilized?

Metaphase II Signup and view all the answers

During which stage does the secondary oocyte complete its meiotic division?

At fertilization Signup and view all the answers

What triggers the completion of meiosis I in the primary oocyte?

Luteinizing hormone surge Signup and view all the answers

What happens to the secondary oocyte if fertilization does not occur?

It degenerates Signup and view all the answers

What is the structure formed by the fusion of the female and male pronuclei?

Zygote Signup and view all the answers

What occurs as a result of the luteinizing hormone peak before ovulation?

Release of secondary oocyte and first polar body Signup and view all the answers

What happens to oocytes that are not protected by granulosa cells?

They undergo atresia Signup and view all the answers

At which level of spermatogenesis does the independent assortment of chromosomes occur?

Primary spermatocyte to secondary spermatocyte Signup and view all the answers

What is the expected fertilization window after ovulation for a woman with a regular 28-day menstrual cycle?

24 hours Signup and view all the answers

The conceptus reaches the uterine cavity at which stage and on which day?

16 cells, Day 5 Signup and view all the answers

At which stage is the oocyte retrieved during in-vitro fertilization treatment?

Secondary oocyte Signup and view all the answers

Which of the following is responsible for the arrest of the primary oocyte in the diplotene stage of prophase-1?

Oocyte maturation inhibitor Signup and view all the answers

Regarding prophase of meiosis-I, which of the following is a true statement?

Resultant cell is diploid Signup and view all the answers

In which phase of meiosis do Leptotene and Pachytene occur?

Prophase I Signup and view all the answers

Which chromosome is responsible for determining the sex of the resulting fetus?

Sex chromosomes Signup and view all the answers

How many primary ova are generally ovulated during a young woman's reproductive life with around 40,000 primary ovum cells in her ovary?

480 Signup and view all the answers

What is the process called that involves genetic recombinations during meiosis, resulting in offspring with different characteristics from their parents?

Crossing over Signup and view all the answers

In which stage is the secondary oocyte arrested just before ovulation?

Metaphase of meiosis II Signup and view all the answers

From which structure is the extra-embryonic mesoderm derived?

Epiblast Signup and view all the answers

What does the connecting stalk, which connects the amnion and extra coelomic cavities, become?

Primary umbilical cord Signup and view all the answers

When do chorionic villi begin to develop during embryonic development?

Day 15 Signup and view all the answers

Which structure is comprised of the central core of extraembryonic mesoderm covered by trophoblasts?

Tertiary chorionic villi Signup and view all the answers

What type of cells line the secondary stage of the sac formed by hypoblast cells during the second week of embryonic development?

Flattened endodermal cells Signup and view all the answers

At what stage are primary oocytes arrested during the fifth month in utero?

Diplotene of prophase I Signup and view all the answers

What initiates the resumption of oocyte development after puberty?

Surge of luteinizing hormone (LH) Signup and view all the answers

What is the result of nondisjunction during anaphase of meiosis?

Formation of gametes with an abnormal number of chromosomes Signup and view all the answers

Which phase involves the maximum condensation of homologous chromosomes during meiosis?

Diakinesis Signup and view all the answers

During which phase are secondary oocytes arrested before fertilization?

Metaphase of meiosis II Signup and view all the answers

What is synapsis in relation to meiosis?

Pairing of homologous chromosomes during meiosis I Signup and view all the answers

What inhibits the development of primary oocytes during their arrest?

Oocyte maturation inhibitor (OMI) Signup and view all the answers

What is the main consequence of sperm fusion with the secondary oocyte?

Stimulus for completion of meiosis Signup and view all the answers

Study Notes

Spermatogenesis

Independent assortment of chromosomes occurs during the transition from primary spermatocyte to secondary spermatocyte.

Ovulation and Fertilization

The expected fertilization window after ovulation for a woman with a regular 28-day cycle is approximately 24 hours.
The conceptus reaches the uterine cavity at the 16 cells stage (morula) on day 5.
The secondary oocyte is retrieved during in-vitro fertilization treatment.
Oocyte maturation inhibitor is responsible for arresting the primary oocyte in the diplotene stage of prophase-1.

Meiosis I

In prophase I of meiosis, homologous chromosomes pair up and exchange genetic material through crossing over.
Leptotene and pachytene occur during prophase I of meiosis.

Sex Determination and Chromosomes

The X and Y chromosomes determine the sex of the fetus.

Oocyte Development and Maturation

The primary oocyte is arrested in the diplotene stage of prophase I at birth and remains there until puberty.
A luteinizing hormone (LH) surge triggers the completion of meiosis I and the release of the secondary oocyte at ovulation.
The secondary oocyte is arrested in metaphase II of meiosis II until fertilization occurs.

Secondary Oocyte Completion

The secondary oocyte completes meiosis II and forms a mature ovum (egg) when fertilized by a sperm.
This forms a female pronucleus, which fuses with the male pronucleus to form a zygote.
A woman will typically ovulate around 480 ova during her reproductive life.

Meiosis II and Genetic Recombination

Crossing over is the process where genetic recombination in meiosis results in the exchange of large DNA segments, leading to offspring characteristics differing from their parents.
The secondary oocyte is arrested in metaphase II of meiosis II right before ovulation.

Embryonic Development

The extra-embryonic mesoderm is derived from the epiblast.
The connecting stalk, connecting the amnion and extra coelomic cavities, is the precursor of the primary umbilical cord.
Chorionic villi start developing around day 15.
Tertiary chorionic villi are composed of central fetal blood vessels surrounded by mesoderm and trophoblast.
The hypoblast cells of the bilaminar disc give rise to the yolk sac, lined by cuboidal endodermal cells.
Neural crest cells contribute to the development of the melanocytes, parafollicular cells (C cells) of the thyroid gland, and spinal ganglion cells.

Neural Crest Cells

Neural crest cells are a group of cells that migrate from the neural tube and contribute to a variety of tissues, including the peripheral nervous system, melanocytes, and certain endocrine cells.

Pharyngeal Arch Bones

Pharyngeal arch bones contribute to the development of the malleus, incus, stapes, mandible, and hyoid bones.

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Description

Test your knowledge on spermatogenesis, oocyte development, and the key processes involved in meiosis. This quiz covers topics such as independent assortment, fertilization window, and sex determination through chromosomes. Dive in to assess your understanding of reproductive biology!