animal development

Elimination of cells by ____ plays an important role in animal development

apoptosis

During brain development, excess neurons are eliminated through apoptosis to refine neural circuits and connections

neural development

apoptosis plays a critical role in shaping various organs by removing unnecessary cells during their formation

organogenesis

In the thymus, immature t cells that fail to recognize self-antigens undergo apoptosis to prevent autoimmune reactions

Immune system development

During male development, the mullerian duct, which would otherwise form the female reproductive tract, is eliminated through apoptosis

regression of the mullerian duct in male mammals

In animals, division plane is specified by the placement of the _____, enabled by the orientation of the centrosome and astral microtubules. The orientation is controlled by maternal mRNA and proteins that are organized in a polarized orientation

spindle apparatus

Development accomplished two major objectives which are:

1. Generates cellular diversity and order within each generation

2. Ensures the continuity of life from one generation to the next

Production of the haploid egg and sperm

Gametogenesis

Fusion of the egg and sperm

Fertilization

Cell division creates a hollow ball of cells called a blastula made up of blastomeres

cleavage

Cells are rearranged into a three-layered gastrula ectoderm, mesoderm, and endoderm

Gastrulation

The three layers interact and move to give rise to organs

Organogenesis

The thickening and reduction of the nuclear size, condensation of the nuclear contents into the smallest space

Nuclear condensation

Forming a cap (acrosome) containing enzymes that play an important role in the penetration through the pellucid zone of the oocyte. During spermiogenesis, golgi apparatus is essential to manufacture the acrosome-modified lysosomal vesicle.

Acrosome formation

Generation of the sperm cell tail

Flagellum formation

Elimination of all unnecessary cytoplasm. Organelles - ribosomes, golgi, RER, SER, lysosomes- are pinched off in residual body

Cytoplasm reduction

Nucleus of the spermatid and sperm are ____

Haploid

Histones are replaced by _____ that cause the DNA to almost crystalize

protamines

____ are non-motlie and are moved from the site of ovulation towards the uterus via the movement of cilia of the fallopian tube which causes fluid current flow

Oocytes

______ consists of cumulus cells (somatic cells from the ovarian follicle) embedded in the ECM

Cumulus oophorous

Inner most layer of cumulus cells is called _____ which supplies nutrients to the egg

Corona radiata

What is the glycoprotein layer surrounding the plasma membrane of an oocyte and is secreted by both the oocyte and the follicular cells?

Zona pellucida

Serves as the structure that binds sperm and helps to initiate the acrosome reaction

the zona pellucida

_____ brings the haploid nuclei of sperm and egg together, forming a diploid zygote. The sperm’s contact with the egg’s surface initiates metabolic reactions in the egg that trigger the onset of embryonic development

Fertilization

To become competent to fertilize, ejaculated mammalian sperm must be modified by conditions must be modified by conditions in the female reproduction tract, a process called

Capacitation

Capacitation alters the lipid and glycoprotein composition of the sperm plasma membrane, increases sperm metabolism and motility, and markedly decreases the_______

Membrane potential (becomes more neg → membrane becomes more hyperpolarized)

Fertilization in mammals and other terrestrial animals is ______

internal

In mammalian fertilization, the sperm is attracted to the _____

Oviduct

Vagina has an acidic pH which is destructive to sperm

Vaginal pH

White blood cells, especially neutrophils detect sperm as foreign cells and attempt to destroy them

immune system

The tubes of female reproductive tract have numerous crypts in which sperm become stranded

physical barriers

At ovulation → cervical mucus is more liquid/less dense

Outside of ovulation →cervical mucus is thick and viscous

Cervical mucus

The fallopian tubes and uterus exert a suction forcer through _____

Rhythmic contractions

_____ of the semen neutralizes the pH and provides sugars to the sperm and helps to shield the sperm from the woman’s immune response

Seminal fluid

______ are important in getting the sperm into the oviduct

Uterine contractions

the region just from the ____ may slow down sperm and release them slowly

ampulla

Gamete binding in mammals also requires that the ____ be translocated

Oocyte

Ampulla is the normal site of ____

fertilization

The _____ is a highly specialized set of tissue that regulate the transport and maturity of the oocyte

female reproductive tract

In the vicinity of the oocyte the sperm become ____, tail moves with much more force and energy and moves to the oocyte by chemotaxis

hyperactive

Sperm use soluble gradient of signals secreted by the egg

Chemotaxis toward the egg

When the sperm binds a receptor in the zona pellucida, it triggers a ______

slow block to polyspermy (no fast block to polyspermy has been identified in mammals)

Once a capacitated sperm has been penetrated, the layer of ____ binds to the zona pellucida

follicle cells

sperm undergo the acrosome reaction and penetrate the _____ and bind to the zona pellucida

corona radiate

The side of the sperm binds receptors one the ______

plasma membrane microvilli

When the sperm fuses with the egg plasma membrane, it causes a local increase in _____, which spreads through the cell in a wave

cytosolic ca2+

The ca2+ waves activates the egg to begin development, and initiates the ____, in which the cortical granules release their contents by exocytosis

cortical reaction

The contents of the cortical granules include various enzymes that are released by the cortical reaction and change the structure of the zona pellucida. The altered zona becomes “hardened” so that the sperm no longer binds to it, it provides a block to ____

Polyspermy

Sperm nucleus enters the ____

egg cytoplasm

The cortical reaction modifies the PM (removes sperm R) and hardens the zona pellucida, the ECM of the egg, as a _____

slow block to polyspermy

Sperm nucleus and centriole separate from the _____ of the midpiece and the tail to enter the oocyte cytoplasm

mitochondria

Mitochondria typically do not enter the egg cytoplasm so the mitochondrial genome is _____

maternally derived

Centriole forms a centrosome and _____

nucleates mitochondria

The sperm pronucleus migrate toward the egg pronucleus and ______

merges and cell division begins

____ is a period of rapid cell division without cell growth

Cleavage

Cleavage partitions the cytoplasm of one large cell into many smaller cells called ____

Blastomeres

The positioning of the first cleavage plane may be dependent on the point of sperm entry and in mice a sperm born microRNA is required to ________

initiate this cell division

The first cleavage in mammas is a _____

meridional division

In the second cleavage one blastomere divides meridionally and the other equatorially. This type of division is called

Rotational cleavage

Mammals exhibit asynchronous division where not all the blastomeres divide

at the same time

Unlike almost all other animal genomes, the mammalian genome is activated during _____, and produces the proteins necessary for cleavage to occur

early cleavage

The blastula or blastocyst in mammals is a ball of cells with a fluid-filled cavity called a

Blastocoel

In the first cell division, newly synthesized gene product (oct4 protein), determines whether a cell will be a a ________

Trophoblast or an inner cell mass cell

In the second division each blastomere that will become the inner cell mass expresses 2 genes that allows the cell the remain ______

pluripotent