Human Development and Teratogens Quiz

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Questions and Answers

What is the correct sequence of the developmental stages of an embryo before implantation?

Morula, blastocyst, zygote

Zygote, blastocyst, morula

Blastocyst, morula, zygote

Zygote, morula, blastocyst (correct)

Which period of human development is defined from implantation to the 8th week of gestation?

Neonatal period

Preimplantation period

Fetal period

Embryonic period (correct)

What is the estimated length of pregnancy when counted from fertilization?

36 weeks

42 weeks

38 weeks (correct)

40 weeks

Why is it challenging to determine the Estimated Due Date (EDD) based on the last menstrual period (LMP)?

It assumes a 28-day cycle Signup and view all the answers

At what age does the branching system of the lungs fully develop?

At 7 years Signup and view all the answers

What is the primary function of the fimbriae during ovulation?

To capture the ovulated complex as it exits the ovary Signup and view all the answers

What are the phases of transport for the ovulated complex in the uterine tube?

Slow transport through the ampullary region and rapid transport to the uterus Signup and view all the answers

Which of the following is a major cause of infertility related to the uterine tube?

Blockage of the uterine tube Signup and view all the answers

What is the role of seminal fluid in the process of fertilization?

To supply nutrients and energy to spermatozoa Signup and view all the answers

How long can spermatozoa survive in the female reproductive tract after ejaculation?

80 hours Signup and view all the answers

What substances do prostatic and seminal vesicle secretions in seminal fluid provide?

Alkaline and acidic components for pH balance Signup and view all the answers

What is the main job of the smooth muscle cells in the uterine walls during ovulation?

To help transport the ovulated complex to the uterus Signup and view all the answers

Which component in seminal fluid provides energy for spermatozoa?

Fructose Signup and view all the answers

What is the first phase of gametogenesis?

Formation and migration of primordial germ cells Signup and view all the answers

During which week of gestation do primordial germ cells reenter the embryo?

5th to 6th week Signup and view all the answers

What structural mechanism is primarily involved in the migration of primordial germ cells?

Dynamic rearrangement of the cytoskeleton Signup and view all the answers

What type of tumor can form due to issues in the maturation and migration of primordial germ cells?

Teratomas Signup and view all the answers

Where can teratomas primarily occur in the body?

In the gonads or extragonadal sites Signup and view all the answers

Which phase involves a reduction in chromosomal number?

Meiosis phase Signup and view all the answers

What is a potential consequence of incorrect PGC movement during migration?

Formation of teratomas Signup and view all the answers

How long can it take for teratomas to become detectable?

Years Signup and view all the answers

What is the primary purpose of measuring Crown Rump Length (CRL) during the first trimester?

To determine gestational age of the fetus Signup and view all the answers

During which period is the embryo most susceptible to teratogenic effects?

Weeks 3-8 Signup and view all the answers

What are teratogens?

Agents that alter fetal morphology or function during development Signup and view all the answers

Which of the following causes of birth defects is characterized by both genetic and environmental factors?

Multifactorial inheritance Signup and view all the answers

What happens during the resistant period of embryonic development?

The embryo either survives unaffected or dies Signup and view all the answers

Which gene mutation is associated with Hutchinson-Gilford progeria syndrome?

LMNA Signup and view all the answers

What is the main focus of the organogenesis phase in embryonic development?

Developing the basic structure of organs Signup and view all the answers

What percentage of birth defect cases have unknown causes?

50%-60% Signup and view all the answers

Which period is characterized as a lower susceptibility period for teratogenic effects?

Week 9-38 Signup and view all the answers

What is the process of gametogenesis?

Production of gametes Signup and view all the answers

What signifies the transition from a mature Graafian follicle to the release of the secondary oocyte?

LH surge followed by FSH surge Signup and view all the answers

What happens to the remaining follicles when one becomes FSH independent?

They undergo apoptosis Signup and view all the answers

Which structure is formed from the cumulus oophorus during ovulation?

Corona radiata Signup and view all the answers

What is the primary role of estradiol during the follicular phase?

Prepares the female genital tract for gamete transport Signup and view all the answers

What initiates the inflammatory response leading to ovulation?

LH and FSH surges Signup and view all the answers

During which phase does the cumulus oophorus lose gap junctions with the oocyte?

Pre-ovulation phase Signup and view all the answers

What role does hyaluronic acid play during the maturation of the follicle?

Increases pressure in the antrum Signup and view all the answers

What is contained within the follicular fluid of the antrum?

Proteins similar to serum in low concentrations Signup and view all the answers

What is the primary role of Sertoli cells in the testis?

Support and maturation of spermatocytes Signup and view all the answers

During spermatogenesis, where does the process of meiosis primarily occur?

In the wall of the seminiferous tubules Signup and view all the answers

What marks the transition of spermatogonia to an antigenically different form?

Migration to the adluminal compartment Signup and view all the answers

What is the immune-privileged status of the testis primarily meant to protect against?

Auto-antigens and detrimental immune responses Signup and view all the answers

How long does the first meiotic division in spermatogenesis last?

24 days Signup and view all the answers

Which hormones primarily stimulate the maturation of somatic cells in the testis?

Testosterone Signup and view all the answers

What is the main function of Leydig cells in the testis?

Production of testosterone Signup and view all the answers

Which compartment of the seminiferous tubules contains spermatocytes undergoing early meiosis?

Basal compartment Signup and view all the answers

What process follows the completion of meiosis in sperm cells?

Spermiogenesis Signup and view all the answers

What is the total duration of spermatogenesis from the beginning of spermatogonia to the formation of spermatozoa?

64 days Signup and view all the answers

Study Notes

Periods of Human Development

Human development is considered in three trimesters from a medical perspective.
Embryological development has three sub-stages: the period of the egg, the period of the embryo, and the period of the fetus.
Development continues after birth, with ongoing maturation, and aging.

Dating Pregnancy

Determining the due date (EDD) can be tricky due to various factors, including the difficulty of accurately determining the precise moment of fertilization.
The EDD is often based on the last menstrual period (LMP), though a regular 28-day cycle is a standard assumption and may not always hold true.
Crown-rump length (CRL) is also used in early ultrasound imaging to estimate the gestational age of the fetus.

Teratogens

Teratogens are chemical, biological, or physical agents that can cause abnormalities in fetal development.
The impact varies based on the developmental stage of the fetus. Critical periods during embryonic development, especially during the first trimester, are vulnerable to teratogen effects.

Causes of Birth Defects

Genetics, such as chromosomal abnormalities or gene mutations, are a cause.
Environmental factors such as drugs, alcohol, viruses, radiation, and chemicals can be contributory factors.
Multifactorial inheritance, highlighting the combined influence of genetics and the environment.
In 50-60% of cases, the cause of birth defects remains unknown.

Male Genital Tract

The male reproductive tract includes the testes, epididymis, ductus deferens, seminal vesicles, prostate, and penis.
Spermatogenesis occurs within the seminiferous tubules of the testes.
Leydig cells within the testis produce testosterone, and Sertoli cells nourish and support developing sperm cells.

Women Genital Tract

Female reproductive structures include the ovaries, Fallopian tubes, uterus, and vagina.
Key components are primordial germ cells, oogonia, oocytes, and follicles.
The process of oogenesis proceeds through several phases, and involves meiosis.

Gametogenesis

Development of gametes involves stages including germ cell migration, increase in the number of germ cells, reduction of chromosome number by meiosis, and structural/functional gamete maturation.
The generation of gametes involves distinct phases of development.
Pacing of gametogenesis varies by sex, with females experiencing a limited number of mature gametes.

Meiosis

Meiosis in females is synchronous, with one meiotic division completing at ovulation.
Meiosis in males is asynchronous, allowing continuous spermatogenesis throughout life.

Spermatogenesis

Spermatogenesis involves several stages, starting with spermatogonia and proceeding through primary and secondary spermatocytes to spermatids and spermatozoa.
Spermatogenesis is a continuous process, and several unique structures are involved in its success.

Spermiogenesis

Spermiogenesis is the last stage of spermatogenesis.
It converts spermatids into mature spermatozoa, characterized by changes in cell morphology and the development of a tail.

Defects in Axonal Structure

Structural defects in the axonal parts of sperm cells can lead to problems with motility and subsequent infertility.

Sertoli Cells

Sertoli cells function within the testes to support the processes of spermatogenesis.
They are crucial components of spermatogenesis, supporting development.

Ovogenesis

Ovogenesis involves the development of the female egg in the ovaries.
This process begins before birth and continues into adulthood.
Three types of ovarian follicles are associated with the process (primordial, growing, and mature).

Follicular Cells

Follicular cells are somatic cells that support the oocyte in the ovary.
The follicular cells communicate with the developing oocyte via gap junctions and microvilli.
These interactions are fundamental in stimulating and supporting oocyte development.

Growing Follicles

Growing follicles are a significant part of oogenesis.
They undergo several developmental stages, culminating in the mature follicle.
Several types of cellular interactions drive the growth of follicles.

Ovulation

Ovulation is the release of the ovum (egg) from the ovarian follicle.
The process involves hormonal stimulation, and the eventual rupture of the follicle.
The ovulated egg is surrounded by several layers, including the corona radiata and zona pellucida.

Corpus Luteum

The corpus luteum is a temporary structure that forms in the ovary after ovulation.
It secretes hormones, including progesterone, which prepare the uterus for possible pregnancy.

Egg Capture

The capturing of the ovum is critical, and involves the fimbriae of the uterine tubes.
Two phases of transport occur, a slow phase and a rapid phase, ensuring the egg arrives at the uterus.

Sperm Transport

Sperm transport involves several steps, including ejaculation, and travel through the female reproductive tract.
Sperm transport and maturation are impacted by the various factors in the reproductive system itself.

Passage through the Cervix

The cervix plays a crucial role in the passage of sperm during ovulation.
Cervical mucous changes during the menstrual cycle, affecting sperm passage.

Sperm Chemotaxis

Sperm demonstrate chemotaxis, using chemical signals released by the cumulus oophorus to locate and reach the oocyte.

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Description

Explore the stages of human development from conception through pregnancy to birth. This quiz covers key concepts such as trimesters, estimating due dates, and the effects of teratogens on fetal development. Test your knowledge on how these factors play a crucial role in health and maturation.