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Results for: 'embryo'

Gastrulation: cross section of the frog

By: HWC, Views: 1965

Gastrulation Most animals enter a phase early in development called gastrulation. In this phase, a tiny ball or disc of cells rearranges to form three embryonic layers of tissue, called germ layers. The germ layers of the embryo—now called a gastrula—are called the endoderm, mesoderm, and eco...

Uterine (menstrual) cycle - phases

By: HWC, Views: 3145

• The uterus goes through a cyclical developmental pattern to be ready for implantation and support of an embryo. • The uterine, or menstrual, cycle is under the control of ovarian horrnones. • The uterine cycle also has three phases: • Menstrual phase • Proliferative phase ...

Fertilization Animation

By: Administrator, Views: 195

At conception, the gender and other biologic traits of the new individual are determined. The zygote is genetically complete and immediately begins to divide, forming a solid mass of cells called a morula. When the developing embryo (stage of development between weeks 2 and 8) reaches the ute...

Cleavage and Implantation Animation

By: HWC, Views: 269

✔ ✔ ✔ Ask questions here: Follow us: ▶ Facebook: ▶ Review Us: Fertilization typically takes pl...

Embryonic development - week 1 and 2

By: HWC, Views: 3096

The first through eighth weeks after fertilization are called the embryonic. Week 1 • Within a day, the zygote begins mitotic cell division (cleavage) forming blastomeres. By the 4th day, the blastomeres have formed a solid ball called a morula. • The morula enters uterine cavity ar...

Embryonic development - Week 4

By: HWC, Views: 3053

• The flat trilaminar embryonic disc undergoes embryonic folding to form a three-dimensional cylinder shaped embryo. • Most organ systems continue, or start, to develop (organogenesis): • The nervous system and chorion continue to develop. • The heart and the rest of the cardiovas...

Embryonic development - Weeks 5 to 8

By: HWC, Views: 3148

• The second month of development is characterized by rapid development of the head and limbs as well as continued organogenesis. • During the fifth and sixth weeks growth of the brain, and therefore head, is rapid. • Hands and feets begin to form. • During week seven, even more deve...

Embryonic development - Week 3

By: HWC, Views: 2987

Week 3 (gastrulation) • Three primary germ layers are formed which provide cells for organ formation in the following months. • These germ cell layers are formed by a process known as gastrulation, which involves rearranging epiblast cells. • As cells from the epiblast migrate, a fain...

Hormonal regulation of pregnancy - weeks 2 through 38

By: HWC, Views: 3418

Weeks 2 through 16 • During the first few months of pregnancy, estrogen and progesterone are secreted primarily by the corpus luteum. • These hormones act to maintain nutritional support for the embryo and fetus. • hCG production increases, peaking at 8 weeks. • hCG triggers the c...