Introduction Chapter 1 Flashcards
what are the three developmental stages of the embryo ?
early development, embryonic stage and the fetal period. early development is 1-16 days, and the embryonic stage is usually weeks 3-8
What developmental stage is the period of greatest sensitivity ?
the embryonic stage or weeks 3 to 8
What is a malformation ?
errors that occur during the formation of structures mostly in organogenesis during the embryonic stage
What occurs in the period of early development ?
fertilization, implantation, growth, formation of trilaminar embryo and the placenta and the determination of the body exes (where the head, tail, left and right are)
What stages involves the formation of the organs and body parts in development or organogenesis
the embryonic period
During the fetal period or after 9 weeks, the increase in length of the fetus is _________ where as the increase in weight is not __________. It is greatest __________.
uniform, not uniform, prior to birth
What organs are still susceptible during the fetal period and subject to malformations ?
eyes, ears, brain, palate, teeth and the external genitalia
What is the definition of an anomaly?
something that is readily visible and can interfere with normal function or note detected until after death from natural causes (examples are horseshoe kidney(doesn’t impact function though, and cleft palate that does impact function
what are the four types of congenital abnormalities
malformations, disruptions, deformations, and dysplasia
malformations
they occur duirng organogenesis and result in abnormal structure
disruptions
result form external influences that cause alterations of completely formed structures
deformations
abnormal form resulting from mechanical force such as a club foot
dysplasia
abnormal organization of cells into tissue (sacrococcygeal teratoma)
genetic factors contribute to what percent of congenital abnormalities
28%
environmental agents contribute to what % of congenital abnormaliteis
3 to 4%
multifactorial (ie environmental and genetic) contribute to what % of congenital abnormalities
20-25%
agenesis
absence of an organ
aplasia
cells to form an organ never formed
association
anomalies ocurring together without determined cause
atresia
absence of an opening or lumen
syndrome
group of anomalies occuring together with a common cause
teratogen
substance affecting migration, proliferation, or interaction of cells which results in congenital abnormalities
primordial germs cells are responsible for forming the_______–
epiblast which gives rise to the ectoderm
primitive sex cords
supporting cells plus the undifferentiated germ cells (they are neither male or female yet)
what are the supporting cells of the female pgc’s?
follicular cells
what are the supporting cells of the male pgc’s?
sertoli cells
genital ridges
areas where the gonads are going to form
What are the four steps in spermiogenesis?
lose the cytoplasm, condense the nucleus, neck and tail, acrosome addition
what is the function of FSH
to stimulate the development of ovarian follicles and the production of estrogen
what is the function of LH
serves as a trigger for ovulation and stimulates the production of progesterone
What is the G0 phase of the cell cycle??
dead end stage for cells that are highly speciliazed and don’t futher divide later. not all cells go through all of the stages of the cell cycle
