Anatomy lecture 2

Questions and Answers

What is the primary role of the amniotic sac during fetal development?

To assist in the formation of blood cells

To support the implantation process

To provide early nutritional support to the embryo

To cushion and protect the developing embryo and fetus (correct)

What layer contributes to the formation of the chorion?

Cytotrophoblast layer (correct)

Extraembryonic mesoderm

Hypoblast layer

Amnioblast layer

What is the primary function of the umbilical vesicle during early development?

To develop the outer protective layer

To provide early nutritional support to the embryo (correct)

To produce amniotic fluid

To create the amniotic cavity

Which cells line the primary umbilical vesicle?

Hypoblast cells Signup and view all the answers

What structure forms the cushioning environment for the fetus?

Amnion Signup and view all the answers

From which cavity does the umbilical vesicle originate?

Blastocyst cavity Signup and view all the answers

Which layer forms the amnion?

Amnioblasts Signup and view all the answers

What does the exocoelomic membrane eventually become?

Extraembryonic endoderm Signup and view all the answers

What are the two layers that the embryoblast differentiates into during the formation of the bilaminar embryonic disc?

Epiblast and Hypoblast Signup and view all the answers

Which structure is specifically formed from the hypoblast layer of the bilaminar embryonic disc?

Umbilical vesicle Signup and view all the answers

What is the primary function of the epiblast during embryonic development?

To give rise to all three germ layers Signup and view all the answers

In which week of embryological development does implantation occur?

End of first week Signup and view all the answers

Which of the following best describes the role of the chorion during embryological development?

Helps form the placenta Signup and view all the answers

What is the primary function of the chorion during development?

It facilitates the exchange of nutrients, gases, and wastes between maternal blood and the embryo. Signup and view all the answers

The lacunae formed in syncytiotrophoblasts are primarily responsible for which of the following?

Exchanging gases and nutrients with the maternal blood. Signup and view all the answers

Which extraembryonic mesoderm specifically surrounds the umbilical vesicle?

Extraembryonic splanchnic mesoderm. Signup and view all the answers

What structure becomes the umbilical cord during development?

Connecting stalk. Signup and view all the answers

What forms the maternal portion of the placenta?

Lacunae. Signup and view all the answers

Which component is crucial for the development of primary chorionic villi?

Syncytiotrophoblasts. Signup and view all the answers

What is the role of the extraembryonic coelom?

To fuse and form the chorionic cavity during development. Signup and view all the answers

Which layer of the chorion consists of extraembryonic somatic mesoderm and two layers of trophoblasts?

Chorionic sac. Signup and view all the answers

How does the developing fetus and amniotic cavity relate to the chorionic cavity over time?

They grow and expand to fill the chorionic cavity. Signup and view all the answers

What becomes of the small openings known as extraembryonic coelomic spaces?

They fuse to form the extraembryonic coelom. Signup and view all the answers

What characterizes primary spermatocytes in terms of ploidy and function?

They are diploid and undergo meiosis I. Signup and view all the answers

What is the outcome of the second meiotic division of secondary spermatocytes?

Formation of spermatids. Signup and view all the answers

During spermiogenesis, what happens to the cytoplasm of spermatids?

Excess cytoplasm is discarded. Signup and view all the answers

What role do fimbriae play in the female reproductive system?

They guide the oocyte into the uterine tube. Signup and view all the answers

At which stage does the oocyte leave the ovary?

Ovulation Signup and view all the answers

Which characteristic is true of spermatozoa after maturation?

They acquire motility and fertilizing capability. Signup and view all the answers

Which process is primarily responsible for the change in shape during embryonic development?

Morphogenesis Signup and view all the answers

What is the main role of spermatogonia in the male reproductive process?

They act as stem cells that produce sperm cells. Signup and view all the answers

Which process leads to the formation of the tail of the sperm?

Morphological Changes in Spermatids Signup and view all the answers

What is the function of the ampullae in the uterine tubes?

They are the site where fertilization occurs. Signup and view all the answers

What distinguishes secondary spermatocytes from primary spermatocytes?

Secondary spermatocytes are haploid. Signup and view all the answers

What describes the induction process in embryogenesis?

The pathway by which tissues influence genetic activity. Signup and view all the answers

What structural feature is primarily associated with the acrosome of the sperm?

It protects the nucleus in the head of the sperm. Signup and view all the answers

During which stage does the fertilized egg become a morula?

Cleavage Signup and view all the answers

What key event occurs when primary spermatocytes undergo meiotic division?

They produce secondary spermatocytes. Signup and view all the answers

What describes the role of pluripotent cells in differentiation?

Their density is influenced by cell lineage and environmental responses. Signup and view all the answers

What drives embryological development in relation to genetic plans?

The interaction of genetic plans with environmental factors. Signup and view all the answers

What does the term 'cleavage' refer to in the context of embryological development?

The series of cell divisions following fertilization. Signup and view all the answers

Which hormone is primarily produced by the ovary during ovulation?

Estrogen Signup and view all the answers

What is the main function of the uterine tube in reproduction?

To capture and transport the oocyte. Signup and view all the answers

Study Notes

Amnion and Amniotic Sac

Amniotic cavity forms as epiblast cells separate; amnion is a thin membrane from amnioblasts.
The amnion creates the amniotic sac, which encompasses and protects the developing fetus.
Functions of the amnion include cushioning the embryo/fetus with amniotic fluid and maintaining a stable environment.

Umbilical Vesicle (Yolk Sac)

Originates from the blastocyst cavity, forming the primary umbilical vesicle lined by hypoblast cells.
Surrounded by extraembryonic mesoderm, which supports and nourishes the embryo.
Provides early nutritional support before placenta formation and aids in blood cell formation and germ cell development.

Chorion

Formed from trophoblast layers of the blastocyst (cytotrophoblast and syncytiotrophoblast) with extraembryonic mesoderm.
Small openings fuse to form the extraembryonic coelom, surrounding the amniotic cavity and bilaminar disc.
Critical for placenta formation, facilitating nutrient, gas, and waste exchange via lacunae filled with maternal blood.

Structure Definitions

Chorion: Encompasses amniotic sac and embryo; essential for placenta development.
Chorionic Sac: Contains trophoblasts and lacunar network.
Chorionic Cavity: Surrounds amniotic sac, embryo, and umbilical vesicle, formed from extraembryonic coelom.
Connecting Stalk: Links chorion to amniotic cavity and becomes the umbilical cord.
Primary Chorionic Villi: Outgrowths from cytotrophoblast that develop into the placenta.

Spermatogenesis Overview

Primary Spermatocytes: Result from Type A spermatogonia; diploid (2n) and undergo meiosis I.
Secondary Spermatocytes: Haploid (n) cells from primary spermatocytes after meiosis I, undergo meiosis II.
Spermatids: Haploid cells from secondary spermatocytes after meiosis II; undergo spermiogenesis.
Spermatozoa: Mature sperm capable of fertilizing an ovum; gain motility and enter the male reproductive tract.

Processes Driving Embryological Development

Genetic interaction with the environment guides embryological development.
Growth involves mitosis and extracellular matrix production.
Morphogenesis refers to shape changes during development.
Differentiation is driven by pluripotent cell density influenced by lineage and environmental cues.
Induction involves intracellular messaging that regulates genetic activity during tissue development.

Week 1 of Embryological Development

Ovary: Releases oocyte during ovulation; secretes hormones like estrogen and progesterone.
Fimbriae: Finger-like projections that guide oocyte into the uterine tube.
Infundibulum: Funnel-shaped part of the uterine tube that transports oocyte.
Uterine/Fallopian Tube: Conduit for oocyte travel; site of sperm capacitation.
Ampullae: Wider uterine tube portion where fertilization occurs.
Blastocyst Formation: Introduction of embryoblast (epiblast and hypoblast) and trophoblast (syncytiotrophoblast and cytotrophoblast) during implantation.

Week 2 of Embryological Development

Bilaminar Embryonic Disc: Formed from inner cell mass, differentiates into epiblast and hypoblast.
Amnion: Derived from the epiblast; forms the amniotic sac for fetal protection.
Umbilical Vesicle: Also known as the yolk sac; nutritional source until placenta forms.
Chorion: Contributes to placenta formation and facilitates nutrient/gas exchange.

Bilaminar Embryonic Disc Development

Formed from inner cell mass of blastocyst, splits into epiblast (gives rise to germ layers) and hypoblast (contributes to yolk sac).
Epiblast cells undergo gastrulation to form three germ layers, paving the way for organ development.

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Description

This quiz focuses on the amniotic cavity and sac, detailing the formation and role of the amnion in embryo development. Explore how the epiblast cells contribute to these crucial structures and their importance in protecting the fetus during gestation.