Stages of Ovarian Follicle, Menstrual Cycle, and Embryonic Development

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Name and identify the 4 stages of the ovarian follicle in an essay.

Primary follicle

  • contains an immature oocyte

Graafian (vesicular) follicle

  • growing follicle with a maturing oocyte


  • when the egg is mature the follicle ruptures
  • Occurs about every 28 days

Corpus luteum

  • Ruptured follicle.

Where is the site of fertilization? Where is the fertilized egg held during pregnancy? What hormone is released that allows the fertilized egg to be implanted? (refer back to endocrine lecture)

uterine(fallopian tubes) held at the uterus, progesterone.

Name and describe the three stages of the menstrual cycle.

Menses – functional layer of the endometrium is sloughed

  • Proliferative stage – regeneration of functional layer
  • Secretory stage – endometrium increases in size and readies for implantation

How does a sperm cell lock onto the oocyte/egg?

Human sperm have protein keys that recognize receptor protein locks on egg

Where in the female reproductive system does fertilization occur?

Occurs in Uterine tube

Match the human morphogen to what it does in embryonic development. Does its concentration matter to correct development? Why is this?

  • Signaling molecules that determine morphogenesis
  • Work on a concentration gradient – has different effects on cell development in embryo
  • Sonic Hedgehog (Shh) - Regulate growth of digits and limbs, organization of brain. In adults, implicated in some cancers
  • Retinoic acid (RA) - Helps determine position on anterior/posterior axis
  • Bone Morphogenetic protein (BMP) - Cause formation of bone and cartilage
  • Planar cell polarity (PCP) - Interpret orientation within plane of tissue.

Which hormone (if given choices): supports pregnancy for first 3 months? Maintain pregnancy after 3 months?

1) human chorionic gonadotropin, Then, placenta able to produce estrogens and progesterone

In an essay, name and describe the 3 germ layers of the developing embryo. What does each layer give rise to?

  • Ectoderm- outermost layer - skin epidermis, nervous system, hair and nails, parts of eye
  • Mesoderm- middle layer - muscles, connective tissue
  • Endoderm- innermost layer - lining of various organ systems

When does an embryo become a fetus in development? What is mainly occurring at this stage?

9th week of development, All organ systems are formed, Activities of growth and organ specialization, A stage of tremendous growth and change in appearance.

What are the sex hormones that determine a male or a female?

male xy, female xx

During what stage does the brain of the child grow ½ its final mass?


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