Embryology Flashcards
Name 2 events in gamete production that creates genetic variability
Crossing over between segments of homologous chromosomes and independent assortment of chromosomes during meiosisFirst card
Define oogenesis
Development of female gamete which begins during fetal life and is completed only after fertilization
Put the following stages into their correct order: Secondary follicle, primary oocyte, mature follicle with antrum, primary follicle, ovulated ovum with zona pellucida and corona radiata
Primary oocyte → primary follicle → secondary follicle → mature follicle with antrum → ovulated ovum with zona pellucida and corona radiata
Approximately how long is the ovum fertilizable?
24 hours
Approximately how long are sperm viable in the female reproductive tract?
6 days
What cell contains an acrosome and what is its function?
a. Sperm
b. Contains enzymes that help penetrate the corona radiata and the zona pellucida
What cell contains cortical granules and what is their function?
a. Ova
b. To “toughen” the zona pellucida and block polyspermy, to protect the zygote until it reaches the uterus for implantation, to help hold dividing cells together
Put the following steps into the correct order: Two cell stage, blastula, zygote (fusion of male and female pronuclei), morula, implantation
a. Zygote (fusion of male and female pronuclei) → two cell stage → morula → blastula (the blastula is the first cavity that forms) → implantation
At one week the embryo consists of what two cell types?
a. Embryoblast (1st cells that will form the embryo) and the trophoblast
At 2 weeks what changes have occurred in the embryo?
a. Epiblast and hypoblast
b. The uterine wall has closed over the embryo and implantation is “complete.” The cranial-caudal axis is being set by the primitive streak. The amniotic cavity is first formed.
At 3 weeks, how many layers are there in the embryo? What are their names?
a. Three
b. Ectoderm, mesoderm, endoderm
By what process do the three germ layers form?
a. Gastrulation
By what process does the embryo begin to take its three-dimensional shape?
a. Lateral body folding and cranial-caudal body folding
Name the derivatives of ectoderm
a. Skin and its “decorations” (hair, nails, sweat and sebaceous glands), CNS, and neural crest cells
Name the derivatives of endoderm
a. The lining epithelium of the GI and Respiratory systems, also lower portion of the urinary system
Name the regions of the mesoderm
a. Notochord, paraxial (somites), intermediate, lateral plate (somatic and splanchnic)
Name the derivatives of mesoderm
a. Connective tissue (bone, tendon, ligaments, fascia, fat), Muscle (3 kinds), blood vessels and cells, lymphatic vessels and organs, upper urinary system, and internal reproductive organs
Name the three regions of the somite
a. Sclerotome, dermatome, and myotome
What three layers make up the chorion?
a. Syncytiotrophoblast, cytrophoblast, and extraembryonic mesoderm
What can be exchanged between maternal and fetal blood? What cannot?
a. Gases, nutrients, steroid hormones, immunoglobins, viruses, and some bacteria and protozoans can cross the placenta
b. Blood cells and protein hormones do not cross the barrier very easily, if at all
What structures grow from the embryo through the connecting stalk of extraembryonic mesoderm to invade the placenta?
a. Two umbilical arteries and one umbilical vein
The umbilical arteries/vein grow into a mesodermal core of a _______________?
a. Chorionic villus
Why are chorionic villi clinically 23) Why are chorionic villi clinically important?
a. One of the safest fetal tissues to sample for genetic analysis
How many pharyngeal arches are there?
a. Five: numbered 1,2,3,4,6
What is the name of the first pharyngeal arch?
a. Maxillary and mandibular processes
What bones will the first pharyngeal arch (maxillary and mandibular processes) produce?
a. Maxilla, mandible, palate, zygoma, part of the temporal bone (“bones of mastication”), and the incus and malleus of the inner ear
What is the function of muscles derived from the first pharyngeal arch?
a. Muscles of mastication
Which cranial nerve supplies the muscles of mastication?
a. The trigeminal nerve, mandibular division V3
What is the name of the second pharyngeal arch?
a. Hyoid arch
What bone will the second pharyngeal arch (hyoid arch) produce?
a. Hyoid bone
What is the function of the muscles derived from the second pharyngeal arch (hyoid arch)?
a. Muscles of facial expression
Which cranial nerve supplies the muscles of facial expression?
a. The facial nerve (VII)
What is the cranial nerve that belongs to the third branchial arch?
a. The glossopharyngeal nerve (IX)
What is the cranial nerve that belongs to the 4th and 6th pharyngeal arches (and wanders elsewhere, too!)?
a. The vagus nerve (X)
