Module 3

Birds produce through an?

egg

Two parts of Bird’s reproductive system

Ovary and oviduct

It develops and it is functional in all species of birds

Left pair (ovary and oviduct)

Both the left and right ovaries develop and only the left oviduct develops

Kiwis

contains follicles of various sizes and developmental stages

Single left ovary

developmental stages includes

quiescent primordial follicles, pre-hierarchical growing follicles and large yolk-filled follicles

It engulfs yolk, is a reservoir for spermatozoa, and a site of fertilization

Infundibulum

Size of Infundibulum

9 cm

Time spent in Infundibulum

18 minutes

Thick white or albumen (40%) is added here

Magnum

Size of Magnum

33 cm (largest portion)

Time spent in Magnum

2 hr 54 mins

Some albumen and inner & outer shell membranes are added here

Isthmus

Size of Isthmus

10 cm

Time spent in Isthmus

1 hr 15 mins

Shell (CaCO₃) is deposited here; pigmentation also occurs

Uterus/Shell gland

Size of Uterus/Shell gland

10–12 cm

Time spent in Uterus/Shell gland

20 hrs 40 mins

Cuticle is added and egg is expelled during oviposition

Vagina (Muscular portion)

Size of Vagina

12 cm

Time spent in Vagina

Minutes (very short)

Total length of female poultry reproductive tract

74 cm

Total time spent in egg formation

25–26 hours

What is the earliest stage of ovarian follicle development?

Primordial follicle

When do primordial follicles form in the ovary?

First five months of fetal development

What do primordial follicles consist of?

Oocyte + single layer of squamous follicular cells

What meiotic stage are oocytes in primordial follicles arrested at?

First meiotic division

When do primordial follicles begin to develop further?

At puberty

What do primordial follicles become as they develop?

Primary follicles

What triggers the development of primordial follicles into early primary follicles?

Start of each menstrual cycle

What is the first histological stage after the primordial follicle?

Early primary follicle

What separates the oocyte from the follicular cells in an early primary follicle?

Zona pellucida

What shape are the follicular cells in an early primary follicle?

Cuboidal

What is the zona pellucida made of?

Glycoproteins

What is the function of glycoproteins in the zona pellucida?

Bind to sperm surface proteins

What is the stratified epithelium of follicular cells called?

Zona granulosa

It is reached when the follicular cells proliferate into a stratified epithelium known as the zona granulosa.

Late primary follicle

The characteristic feature that distinguishes _____________ from primary follicles is the appearance of a follicular antrum within the granulosa layer

Secondary Follicle

It contains fluid which is rich in hyaluronan and proteoglycans

Antrum

At this stage, a layer of cells outside the follicle become evident. These cells compose the theca interna and contribute to the production of estrogens.

Secondary Follicle

 is the stage after the first meiotic division has completed but before ovulation. The oocyte is now a 2N haploid

Graafian Follicle

What stage follows completion of the first meiotic division?

Graafian follicle

What is the ploidy of the oocyte in the Graafian follicle?

2N haploid (secondary oocyte)

What is the most prominent feature of the Graafian follicle?

Large follicular antrum

Where is the oocyte located in the Graafian follicle?

Eccentrically (off-center)

What surrounds the oocyte in the Graafian follicle?

Zona pellucida and corona radiata

What structures are released into the oviduct during ovulation?

Oocyte, zona pellucida, corona radiata

•  give rise to primary oocytes by mitosis within the embryo
  
  

Oogonia

enveloped by a zona pellucida (glycoprotein membrane) and corona radiata (granulosa cells) at ovulation

Oocyte

secondary oocytes complete meiosis (Meiosis II) following fertilization, producing a fertilized?

oocyte

How many spermatozoa are released per ejaculate?

Several hundred million

What do spermatogonia give rise to?

Primary spermatocytes

What process transforms spermatids into spermatozoa?

Spermiogenesis

What are formed after Meiosis II?

Spermatids

removal of surface proteins that would impede contact with an oocyte

Capacitation

is the sperm cell’s need to uncover receptors that may recognize the chemicals in the female reproductive tract that in turn initiate changes in both motility in the form of hyperactivation as well as the morphological changes involved in the acrosome reaction.

Capacitation

A series of cell division which immediately after fertilization, follow upon one another in close succession.

Cleavage

The food material in the cytoplasm of an egg cell is

non-living and inert.`

It plays no part in mitosis except it exerts a retarding effect by the mechanical impediment it offers to the process.

Deutoplasm

the amount of yolk is meager (small) and fairly distributed throughout the cytoplasm.

Amphioxus

in mammalian egg with scanty yolk. _____________ egg undergoes a type of cleavage which is essentially unmodified mitosis.

Isolecithal (homolecithal)

ovum contains considerable amount of yolk and accumulation of yolk at one pole has crowded the nucleus and the active cytoplasm of the ovum toward the opposite pole.

Telolecithal

region of egg where yolk is accumulated

Vegetative pole

opposite region where nucleus and most of active cytoplasm is located.

Animal Pole

The process of segmentation is limited to the small disk of protoplasm lying on the surface of the yolk at the animal pole.

Discoidal Cleavage

What are the individual cells called that are formed during segmentation?

Blastomeres

What is cleavage where blastomeres are completely separated?

Holoblastic cleavage

What is cleavage where blastomeres are only partially separated?

Meroblastic cleavage

refers to the initial series of mitotic divisions by which the large zygote is fractionated into numerous “normal size” cells.

Cleavage

each daughter cell of the cleavage process is termed a

Blastomere

Cleavage begins with a?

Zygote

A solid ball of blastomeres, within a zona pellucida. Consists of 16-64 blastomeres = 4 to 6 cell divisions

Morula

is an early stage in embryo development in which the blastula reorganizes into the three germ layers

Gastrulation

Gastrulation occurs after cleavage but before?

neurulation and organogenesis.

August Rauber discovered that the two-layered chick embryo is a?

Blastoderm

a flat layer of embryonic cells that folds several times to become the later stages of an embryo, that gastrulation began to be understood.

Embryonic Disc

Chick gastrulation begins approximately _________ after fertilization.

seven to eight hours

In the chick epiblast, a totipotent primordial cell layer, cells begin to rearrange at the

Posterior end

generate the skin and neural tissue.

Ectoderm cell

become the lining of the gastrointestinal and the respiratory tracts.

Endoderm cells

differentiate into the circulatory system, kidneys, and skeletal compartments among many other features.

Mesoderm cells

The entire ovum is covered by

Plasma membrane called plasmalemma

 The embryonic disc of a sterile egg bears an accumulation of white material at its center

Unfertilized eggs

The __________ embryonic disc looks like a ring: it has a central area, lighter in color, which is to house the embryo.

Fertilized egg

Twins with the same genetic composition (identical), formed from one zygote that splits.

Monozygotic twins

Conjoined (Siamese) twins; result from later separations in embryonic development. Includes anomalies like double heads.

diplopagus twins

Fraternal twins from two or more zygotes developing independently during the same pregnancy.

dizygotic twins

Can dizygotic blastomeres merge? What is the result?

Yes; they can merge and produce a chimera

An individual with two different genotypes in its cells is called a

Chimera

It is present between ectoderm and endoderm. It occupies the entire blastoderm.

Mesoderm

The opening of foregut into midgut is called

anterior intestinal portal

What type of cells form blood islands?

Mesenchyme cells

What do blood islands give rise to?

Embryonic blood vessels

What are the thick edges of the primitive groove called?

Primitive folds

What is found at the anterior end of the primitive groove?

mass of closely packed cells called Hensen's node or primitive knob

What is the pit present at the center of Hensen’s node called?

Primitive pit

What does the primitive pit represent?

Vestige of the neuro-enteric canal