Embryology Quiz 1

Questions and Answers

Which syndrome is primarily associated with a microdeletion on the paternal chromosome?

Intellectual disability

Fragile X Syndrome

Prader-Willi Syndrome (correct)

Down Syndrome

What is a common physical feature of Fragile X Syndrome?

Large ears (correct)

Obesity

Undescended testes

Simian crease

What condition results from the inability of the testes to descend?

Intellectual disability

Hypotonia

Hypogonadism (correct)

Obesity

Which of the following describes a condition that results from meiotic nondisjunction?

Down Syndrome Signup and view all the answers

Which stage occurs in spermatogenesis where primary spermatocytes undergo meiotic divisions?

Meiosis I Signup and view all the answers

What condition is characterized by hypotonia and obesity among other symptoms?

Prader-Willi Syndrome Signup and view all the answers

What structures are formed from the inner cell mass during blastocyst development?

Epiblast and Hypoblast Signup and view all the answers

What happens to the blastomeres with each mitotic division?

They get smaller. Signup and view all the answers

What occurs during days 11 and 12 after fertilization?

Maternal sinusinoids are eroded. Signup and view all the answers

What initiates the primitive uteroplacental circulation?

The complete embedding of the blastocyst. Signup and view all the answers

What phase is the uterus in during the time of implantation?

Secretory phase Signup and view all the answers

What type of cells do Epiblasts give rise to?

Amnioblasts Signup and view all the answers

What structure surrounds the primitive yolk sac?

Hypoblast Signup and view all the answers

What develops into the trophoblast during blastocyst formation?

Outer cell mass Signup and view all the answers

What role do gap junctions play in smooth muscle tissue?

They allow direct transmission of signals between cells. Signup and view all the answers

Which of the following is NOT one of the four families of paracrine signaling factors?

Insulin Signup and view all the answers

What is the primary function of Fibroblast Growth Factors (FGF)?

To stimulate the growth of fibroblasts in culture. Signup and view all the answers

Sonic signaling involves which protein binding to the Patched receptor?

SHH protein Signup and view all the answers

What happens when Patched stops inhibiting Smo during Sonic signaling?

Smo is activated. Signup and view all the answers

Which organ systems are affected by paracrine signaling during development?

All organ systems Signup and view all the answers

Which of the following statements about Sonic signaling is true?

It can produce hundreds of protein isoforms. Signup and view all the answers

Which layer of the endometrium is retained after menstruation?

Basal layer Signup and view all the answers

What is the first phase of fertilization?

Penetration of the corona radiata Signup and view all the answers

Which two layers does the trophoblast differentiate into during development?

Cytotrophoblast and Syncytiotrophoblast Signup and view all the answers

What forms the extraembryonic coelom?

Vacuoles developing in a tissue Signup and view all the answers

Which phase occurs after the penetration of the zona pellucida during fertilization?

Fusion of the oocyte and sperm membranes Signup and view all the answers

What is NOT a role of the corpus luteum?

Forming the placenta Signup and view all the answers

What are the two cavities formed during the early stages of embryonic development?

Amniotic cavity and Yolk sac Signup and view all the answers

What do epiblast cells give rise to?

All three germ layers Signup and view all the answers

Which structure is a derivative of the ectodermal germ layer?

Central Nervous System Signup and view all the answers

What initiates the formation of the notochord?

Prenotochordal cells moving forward Signup and view all the answers

How is the induction of the neural plate regulated?

Inactivation of growth factors like BMP4 Signup and view all the answers

Which region's development is influenced by WNT3a and FGF?

Hindbrain and Spinal Cord region Signup and view all the answers

Which of the following structures does NOT arise from the ectoderm?

Liver Signup and view all the answers

What is the function of the notochord during embryonic development?

It forms a midline axis for the skeletal system. Signup and view all the answers

What happens to the notochord after it forms during development?

It detaches from the endoderm. Signup and view all the answers

Study Notes

Smooth Muscle Pattern

Direct cellular communication occurs via gap junctions.
Essential in maintaining coordinated function among tightly connected muscle cells in organs like the heart, gut, lungs, and kidneys.

Paracrine Signaling Factors

Regulate development and differentiation of organ systems.
Four key families of signaling factors:
- Fibroblast Growth Factor (FGF)
- WNT
- Hedgehog
- Transforming Growth Factor-Beta (TGF-Beta)

Fibroblast Growth Factors (FGFs)

Promote growth of fibroblasts in culture.
Possess the ability to produce numerous protein isoforms through RNA splicing or alternate initiation codons.

Intellectual Disabilities and Syndromes

Fragile X Syndrome is characterized by:
- Intellectual disability
- Large ears and prominent jaw
Prader-Willi Syndrome features include:
- Hypotonia and obesity
- Intellectual disability
- Hypogonadism with undescended testes
Developmental issues sometimes arise from meiotic nondisjunction during oocyte formation.

Spermatogenesis

Involves the maturation of spermatogonia into spermatozoa.
Primordial germ cells (PGCs) remain dormant until puberty, then differentiate into spermatogonia.
Primary spermatocytes undergo meiosis to yield four spermatids.

Blastocyst Formation and Development

Post-fertilization, blastomeres decrease in size after each mitotic division, leading to compaction and the formation of a morula.
Roughly three to four days post-fertilization, the morula develops into a blastocyst with a developing cavity.
The inner cell mass differentiates into the embryo, while the outer cell mass forms trophoblast.

Uterus at Time of Implantation

Uterus enters the secretory phase featuring coiled uterine glands and arteries.
The blastocyst implants within the endometrium, primarily affecting the anterior or posterior wall.
In absence of fertilization, the menstrual cycle initiates.

Three Layers of the Endometrium

Compact layer: sheds during menstruation.
Spongy layer: also sheds during menstruation.
Basal layer: retained and regenerates during the next cycle.

Corpus Luteum

Formed from the empty follicle post-ovulation, producing progesterone during early pregnancy.
Plays a role in ovulation regulation and menstrual cycle regulation.

Phases of Fertilization

Phase 1: Penetration of the corona radiata.
Phase 2: Penetration of the zona pellucida.
Phase 3: Fusion of the oocyte and sperm cell membranes.

Actions During Phase 3

Membranes of oocyte and sperm fuse, leading to the formation of a zygote.
Establishment of three primary germ layers: endoderm, mesoderm, and ectoderm, from epiblast cells.

Derivatives of the Ectodermal Germ Layer

Ectoderm gives rise to structures in contact with the external environment:
- Central Nervous System (CNS)
- Peripheral Nervous System (PNS)
- Sensory epithelium of the ear, nose, and eye
- Skin, hair, and nails
- Glands (pituitary, mammary, sweat)
- Enamel of teeth

Formation of the Notochord

Prenotochordal cells advance toward the prechordal plate, intercalating into endoderm to form the notochordal plate, which later becomes the notochord.
Establishes the midline axis for embryonic development and axial skeleton foundation.

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Description

Explore the fascinating mechanics of smooth muscle, focusing on direct signal transmission between cells through gap junctions. This quiz will cover vital organs such as the heart, gut, and lungs, enhancing your understanding of biological communication pathways.