Gamete Biology and Development

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Questions and Answers

What is the primary purpose of nuclear transfer in mammals?

To improve efficiency in ART procedures

To increase the number of oocytes available for fertilization

To evaluate placental defects in sheep

To generate a genetic copy of an individual (correct)

Which cell types were used for nuclear transfer as they developed over the years?

Fetal fibroblasts and embryonic blastomeres

Embryonic stem cells and cardiac muscle cells

Day 9 sheep embryo and adult mammary epithelial cells (correct)

Bone marrow cells and young oocytes

What was originally the limitation of embryo multiplication in nuclear transfer?

Connection to placental defects in animals

Limited by the number of cells available for transfer (correct)

Lack of genetic modification techniques

Restriction to adult cells only

What is a major challenge encountered with the use of ICSI in livestock species like cattle, sheep, and pigs?

Low efficiency in achieving fertilization Signup and view all the answers

Which of the following is NOT listed as a fetal abnormality associated with placental defects?

Neonatal diabetes Signup and view all the answers

What is the main role of the SRY gene in sex determination?

It represses the Dax1 gene. Signup and view all the answers

What characterizes the process of spermatocytogenesis?

It includes the multiplication of sperm stem cells. Signup and view all the answers

Which of the following correctly describes the major role of protein phosphorylation in oocytes?

It plays a significant role in oocyte maturation. Signup and view all the answers

In mammals, what distinguishes the germplasm from lower vertebrates?

Mammals have no germplasm. Signup and view all the answers

How does RNA localization contribute to the function of oocytes?

It restricts protein production spatially. Signup and view all the answers

What is a key feature of post-meiotic sperm?

They undergo structural changes during spermatogenesis. Signup and view all the answers

During oogenesis, what process varies significantly among different species?

Transcriptional activation. Signup and view all the answers

What is the typical duration of in vitro fertilization culture until the blastocyst stage in cattle?

7 days Signup and view all the answers

What is the primary purpose of capacitation in sperm?

To prepare sperm for fertilization. Signup and view all the answers

What type of signals are necessary for inducing the development of primordial germ cells in mice?

Extraembryonic signals. Signup and view all the answers

Study Notes

Gamete Biology

Ectoderm cells differentiate into tissues like neurons in the brain
Mesoderm cells become tissues like cardiac muscle
Endoderm cells form internal organs such as the thyroid
Pigs and humans have similar primordial germ cell (PGC) development pathways

Mouse Primordial Germ Cells (PGCs)

Proximal epiblast cells develop into PGCs via extraembryonic signals
PGCs originate from mesoderm
PGCs migrate to the gonad around embryonic day 10.5 in mice
Human and mouse PGCs arise from different progenitor cells

Sex Determination

Sex determination happens around embryonic day 11.5
The SRY gene activates in males
SRY suppresses Dax1 and X-linked genes

Spermatogenesis

Spermatocytogenesis involves sperm formation through sperm stem cell multiplication
Differentiated sperm stem cells undergo amplification and differentiation
Meiosis produces four spermatids from primary spermatocytes, leading to haploid sperm cells
Post-meiotic sperm cells are transcriptionally inactive
Post-meiotic sperm acquires motility in the epididymus
Acrosomal caps form from the Golgi apparatus
Primordial follicles form

Oogenesis

Oogenesis involves transcription, translation, and protein accumulation
mRNA and proteins are essential for sustaining development
Oocyte maturation, early development, and mRNA and protein storage are crucial aspects of oogenesis

Oocyte Storage and Regulation

RNA polyadenylation, RNA masking, RNA localization, and antisense RNA, as well as protein phosphorylation, are involved in oocyte storage and regulation.
Cytoplasmic polyadenylation depends on the length of the Poly-A tail
Short Poly-A tails prevent translation
RNA masking prevents translation by binding to ribonucleoproteins
RNA localization restricts protein production for germline establishment

RNA Localization

Oocyte polarity determines spatial restriction in protein production
Germplasm stores RNA and proteins, but mammals lack it
Protein phosphorylation plays a major role in oocyte maturation, activation, and signaling pathways

Maternal to Zygotic Transition

Mouse maternal-to-zygotic transition occurs at the 1-2 cell stage
Pig transition happens at the 4-8 cell stage
Sheep at the 8-16 cell stage
Cow transition is at the 8-16 cell stage
Xenopus occurs at the 4000 cell stage
In vitro gamete selection is relevant to livestock breeding

In Vitro Fertilization (IVF)

Oocyte maturation happens at 39 degrees Celsius in 5% CO2 for 24 hours in most species, but can take longer in pigs
Exogenous gonadotropins used in IVF
Sperm capacitation can be cryopreserved
Embryo development to blastocyst stage can be in vitro
Oocyte collection technique like OPU are used in species like sheep and pigs

Nuclear Transfer (NT)

Generating a genetic copy of an individual after transferring cell nuclei; using embryonic or somatic cells
Developmentally related to blastomere stage and species
Embryo Multiplication can be limited by cell number

Fetal Abnormalities

Fetal abnormalities such as hydroallantois, extended gestation can result from placental defects
Other abnormalities involve kidney, brain, cardiovascular, muscle, and skeletal systems

Intracytoplasmic Sperm Injection (ICSI)

ICSI is part of ART procedures
Success rates vary between species

Uses of NT

Cloning
Production of genetically modified animals
Preservation of rare breeds of livestock

Human Medicine and Agriculture uses

Transgenic animals used in biopharmaceuticals, nutraceuticals and xenotransplantation for human diseases, cell transplantation, and gene therapy in human medicine
In agriculture, transgenic animals are useful in disease research, disease prevention, genetic improvement, genetic preservation of rare breeds, and preserving superior genotypes

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Description

Explore the fascinating processes of gamete biology, including cell differentiation of ectoderm, mesoderm, and endoderm tissues. Understand the roles of primordial germ cells in both mice and humans, and learn about sex determination and spermatogenesis. This quiz covers essential concepts in reproductive biology.