BIO 233 Lab 6- Pregnancy and Human Development 2

Blastodisc

Inner cell mass organizes into ____ made up of two cell layers

Epiblast

Superficial layer of blastodisc, consisting of high columnar cells

Hypoblast

deep layer consisting of small cuboidal cells, facing the blastocyst cavity

Amniotic cavity

The epiblast forms the floor of the _______. This is the cavity where the fetus exists.

Extraembyonic membranes

The _____ that form during the first two to three weeks of development include the yolk sac, amnion, chorion, and allantois.

Extraembryonic mesoderm

Cells from the yolk sac endoderm form a layer of connective tissue, the _____, which surrounds the amnion and yolk sac.

Yolk Sac

First membrane to appear, around the 10 day stage. Membranous sac that provides nutrients and oxygen to the embryo before the placenta fully develops

Amniotic fluid

By week 10, the amnion has mushroomed and envelops the embryo in a protective environment of ___. The liquid that protects a developing fetus.

Allantois

The ____ forms as a small out-pocketing of embryonic tissues at the caudal end of the yolk sac. In humans, it contributes to the structural base for the umbilical cord that links the embryo to the placenta and it ultimately becomes part of the urinary bladder

chorionic cavity

the chorion forms the wall of the chorionic sac, within the embryo and its amniotic and yolk sacs are suspended by the connecting stalk. The extraembryonic coelom is now called the ____.

Chorionic Villi

tiny fingerlike projections that penetrate the endometrium.

Lacunae

large blood-filled spaces that result from erosion of the endometrium

Placenta

The temporary organ through which nutrients, blood gases, and wastes are exchanged between the mother and the embryo

Chorion frondosum

where villi grow more strongly

Chorion laeve

villi decrease in number

Body stalk

the embryo is connected to the placenta by the ____.

Yolk stalk

where the yolk sac attaches to the endoderm of the embryo, and the body stalk together form the umbilical cord.

Umbilical arteries, umbilical vein

Inside the umbilical cord are two ____, which transport deoxygenated blood to the placenta, and a single ____, which return oxygenated blood to the embryo.

uterine cavity

the wall of the ____ is composed of inner epithelial endometrium and outer muscular myometrium.

Decidua capsularis

The rest of the endometrium, where the villi are absent, isolates the embryo from the uterine cavity and is called the _____.

Decidua basalis

The placenta is in contact with the area of the endometrium called the_____. This is the layer in between the embryo and the myometrium.

Decidua parietalis

the endometrium on the wall opposite to the embryo is called the _____. Plays a role in the overall support and maintenance of the uterus during pregnancy

Gastrulation, Gastrula

During week 3, cells begin to migrate in the process called _____, and the embryo at this stage may be referred to as a ____.

primitive streak

A groove with raised edges that appear on the dorsal surface of the embryonic disc

mesenchyme

a tissue of loosely arranged cells that develop into connective and skeletal tissues of the body.

Organogenesis

week 4-8, gives rise to all organ systems

Amnion

innermost membranous sac surrounding the developing fetus

chorion

Outermost layer of the two membranes surrounding the embryo. Forms fetal part of the placenta

Germ layers

Ectoderm, Mesoderm, Endoderm

Ectoderm

outermost germ layer of cells or tissue of an embryo in early development

Mesoderm

middle germ layer that is the source of many bodily tissues and structures

Endoderm

innermost layer of cells or tissue of an embryo in early development that develops into the lining of digestive and respiratory organs

primitive gut

Becomes the epithelial lining of the gastrointestinal and respiratory tracts. has three segments (foregut, midgut, hindgut)

foregut

develops into 5 folds and gives rise to the mucosal lining of the respiratory tract and upper GI tract as well as digestive glands such as liver, gallbladder, and pancreas.

Midgut

develops into the epithelial lining of the small and proximal end of the large intestines

hindgut

develops into mucosal lining of the distal colon, sigmoid and rectum, urinary bladder and most of the urethra

Neurulation

the first major event of organogenesis. The differentiation of ectoderm into brain and spinal cord

neural tube

the ectoderm at the cephalic end thickens and forms neural plate that invaginates and pinches off, forming a ____ which develops into 3 primary vesicles (forebrain, midbrain, hindbrain)

Optic vesicles

As rostral neural tube forms, two lateral outgrowths on each side of forebrain, _____ are apparent.

Notochord

a flexible rod of mesodermal cells that supports a chordates back.

Somites

Toward the end of the third week, the paraxial mesoderm differentiates and begins to divide into paired cuboidal bodies, the _____.

Heart tube, pericardium

Paired, longitudinal channels, the endocardial heart tubes-develop during the 3rd week and fuse to form a ____ surrounded by _____.

Ductus arteriosus

Temporary blood vessel in the fetal heart that connects the aorta and pulmonary artery. This allows oxygenated blood to bypass the lungs.

Aorta

From the left atrium, the blood passes to the left ventricle and leaves through the ascending _____.

Pulmonary trunk, Umbilical Arteries

The blood leaves through the ______, and most of it passes through the ductus arteriosus into the descending aorta to the fetal body and returns to the placenta through the _____.

Ductus venosus

Fetal blood vessel that connects the umbilical vein to the inferior vena cava, bypassing the fetal liver

Foramen ovale

Crucial part of the fetal circulatory system, serving as a temporary hole in the hearts septum(between the right and left atria of the heart), bypassing the lungs which are not yet functional.