Chapter 29- Pregnancy & Human Development Flashcards
Fertilization occurs in the ______ _____ about 12 -24 hours after ovulation. However, before fertilization can occur, the sperm must undergo _________ and the _______ _______
Fertilization occurs in the fallopian tube about 12 -24 hours after ovulation. However, before fertilization can occur, the sperm must undergo CAPACITATION and the ACROSOMAL REACTION.
Capacitation
weakening of the sperm/acrosome membrane, allowing for later fusion with a secondary oocyte
Acrosomal reaction: The sperm will surround the ovulated oocyte in the female and ______ _______from their acrosomes, mostly ________ When this occurs, disruption of the ______ ______ and the ____ _______ will follow. This release occurs from many of the sperm that surround the oocyte in the fallopian tube and will allow the entrance of only one of the sperm.
: The sperm will surround the ovulated oocyte in the female and release enzymes from their acrosomes, mostly HYALURONIDASE. When this occurs, disruption of the CORONA RADIATA. and the ZONA PELLUCIDA will follow. This release occurs from many of the sperm that surround the oocyte in the fallopian tube, and will allow the entrance of only one of the sperm.
Zygote is
the end result of fertilization
A zygote has
46 chromosomes and is 1 cell
Immediately when the sperm enters the secondary oocyte, there are changes in the structure and location of the “veils”, blocking the entrance of more sperm. Therefore, this reaction blocks ______.
Polyspermy
How many sperm are required for fertilization?
Thousands
(one will make it through)
What fuses together to form a zygote?
A male pronucleus and female pronucleus
Morula
A ball of cells in the fallopian tube
Usually, a woman ovulates 1 oocyte per month. However, some may ovulate 2. If both are fertilized, ________ _______ (________) result. They are no more genetically alike than any other siblings.
Usually, a woman ovulates 1 oocyte per month. However, some may ovulate 2. If both are fertilized, DIZYGOTIC TWINS ( FRATERNAL TWINS) result. They are no more genetically alike than any other siblings.
Zygote –>
Zygote –> Morula –> Blastocyst –> Embryoblast –> Trophoblast –> Blastocoele
What stage enters the uterus?
Blasocyst
Embryoblast
where the embryo comes from
Trophoblast
where the placenta comes from
Blastocoele
fluid filled pocket
When is implantation?
Around day 23
How long do spermatozoa survive?
5-7 days
How long is the oocyte viable once ovulated?
24 hours
Where does fertilization occur?
In the fallopian tube
Identical twins are called
Monozygotic twins
Monozygotic twins:
This occurs when __ oocyte is fertilized by __ sperm, but during development 2 areas of the inner cell mass develop _______. Or there is a separation of _______ into 2 groups of cells. This results in 2 genetically identical individuals. Both must be either be male or female.
This occurs when 1 oocyte is fertilized by 1 sperm, but during development 2 areas of the inner cell mass develop individually. Or there is a separation of blastomeres into 2 groups of cells. This results in 2 genetically identical individuals. Both must be either be male or female.
Conjoined twins
Monozygotic twins that are physically joined, due to abnormal cleavage
Dizygotic twins are
2 separate oocytes that both get fertilized from different spermatozoa
The first 2 weeks is considered the_____ ______ where the germ layers will form. The next few weeks (3-8 weeks of development) is considered the _____ PERIOD, and the subsequent months are considered the ____ PERIOD.
The first 2 weeks is considered the GERMINAL PERIOD where the germ layers will form. The next few weeks (3-8 weeks of development) is considered the EMBRYONIC PERIOD, and the subsequent months are considered the FETAL PERIOD.
After implantation, the embryoblast begins to differentiate into 3 germ layers:
Ectoderm
Mesoderm
Endoderm
Ectoderm
skin, nervous system
Mesoderm
Muscle, bone, connective tissue
Endoderm
internal organs (most viscera)
