Block 1 Review Flashcards
Spontaneous Generation Theory
began i.e. “new life arises from slime and decaying matter.
Held from the time of Galen for nearly 1500 years.
Suggested life came from inanimate objects
Preformation Theory
founded i.e., “sperm or ovum contain a germ that is completely formed bu minute and invisible and expands to visible size and form during development”
Suggested that there was a pre-formed individual in every gamete
Epigenesis Theory
founded, i.e., “egg lacks internal organization and develop into a new organism
Germ Layer Theory
founded i.e., “all animal embryos are composed of three primary germ layers, ectoderm, mesoderm, and endoderm”
Recapitulation Theory
founded, i.e. “ontogeny Recapitulates Phylogeny”
Embryo
the developing individual from fertilized until the end of the second month (8th week inclusive)
Fetus
the developing individual in utero from the end of the 2nd month (8th week) until birth
Zygote
the first diploid cell formed by the union of sperm and ovum
Gestation
the period of development prior to birth
Congenital Abnormalities
abnormalities or malformations detected at birth, or shortly thereafter
Anomaly
marked deviation from the average or normal standard. A congenital defect. May be structural or metabolic
Malformation
a morphological defect that results from an abnormal developmental process and usually causes a functional deficit
Variation
a morphological deviation from an assumed standard that causes no functional deficit
Syndrome
a “package” of congenital abnormalities that occurs in several organ systems as a result of a single factor
True Age
38 weeks (266 days) counting from the time of fertilzation or conception Embryologists use true age and it is the age used in Gross and Developmental Anatomy
Ovulation Age
True age + 1 day
because that oocyte has to be ovulated first and start its travel down the fallopian tube before it is normally fertilized
Copulation Age
True Age + 1 to 3 days
1 to 3 days represents the time period that a sperm is viable in the tract
Menstrual “Gestational” Age
True age + 14 days (290 days)
Obstetricians use menstrual age since this is the most practical from the clinical viewpoint. Two thirds of all deliveries occur 280 +/- 11 days from the onset of the mother’s LMP
Ovulation would have occurred about halfway through the female’s cycle - total cycle averages 28 days, so that extra 14 days is the time from LMP until ovulation
Mitosis vs. Meiosis
Mitosis: gives rise to two daughter cells, which are genetically identical to the parent cell
Meiosis: Process of reduction division of chromosomes
Takes place only in germ cells
Reduces number of chromosomes from a diploid (2N) to a haploid (1N) state
- Consists of two divisions
Spermatogenesis
Spermatogonium (2n) - @ puberty, increase in # by Mitosis They enlarge into primary spermatocytes (2n) -Meiosis I takes place- Secondary spermatocytes (1n) -Meiosis II takes place- Spermatids (1n) -Spermatogenesis- 4 mature sperm (1n)
spermiogenesis
when spermatids mature into mature sperm:
morphologic changes, including development of the acromosome and tail and an increase int he # of mitochondria
Oogenesis
Oogonium (2n) during early fetal life proliferate by mitosis [5,000,000 oogenia @ 12 weeks]
They enlarge into primary oocytes (diploid)
-[2,000,000 primary oocytes @ birth]
-Begin meoisis I (before birth)-
Completely meisos I (before ovulation) forming secondary oocyte (1n) and 1st polar body
-begin meiosis II at ovulation-
[300 needed and produced in lifetime]
Completely meiosis II at sperm penetration forming mature oocyte (1n) and 2nd polar body
Process of Fertilization
Passage of sperm through the corona radiate
Penetration of the zona pellucida
Fusion of plasma membranes of the two gametes
Completion of 2nd meiotic division of oocyte with formation of female pronucleus
Fusion of pronuclei, forming 2n zygote
Results of Fertilization
Completion of the 2nd meiotic division of the secondary oocyte (at fertilization)
Restoration of the 2n number of chromosomes in the zygote
Mixing of the ateral and maternal chromosomes to insure diversity of species
Determination of chromosomal sex
Initiation of cleavage