1)Von bears postulates
Von Baer’s principles of embryonic differentiation constitute a
better guide to embryological evidence for evolution. These
principles are as follows:
1) General characteristics appear in the development early and
specialized characters latter on.
2) From the more general, the less general and finally the specialized
characters appear.
3) An animal during development departs progressively from the
form of other animals
4) Young stages of an animal do not resemble with their embryos
2)Teratology?
Teratology is the study of abnormalities of physiological development. It is often thought of as the study of human congenital abnormalities, but it is broader than that, taking into account other non-birth developmental stages, including puberty; and other organisms, including plants.
3)Stratification
is a process of treating seeds to simulate natural conditions that the seeds must experience before germination can occur. Many seed species have an embryonic dormancy phase, and generally will not sprout until this dormancy is broken.
4)Teratogen: Any agent that can disturb the development of an embryo or fetus. Teratogens may cause a birth defect in the child. Or a teratogen may halt the pregnancy outright. The classes of teratogens include radiation, maternal infections, chemicals, and drugs.
5)Acrosome:
The acrosome is a lysosomal-like compartment derived from the Golgi. It has a low pH and contains
soluble hydrolases (serine protease acrosin). In cross-section through the head of a sperm, one would
cross four membranes in traversing from the plasma membranes to the nuclear membrane. During the
acrosome reaction, fusion of the outer acrosomal membrane with the plasma membrane releases the
contents of the acrosome and exposes the inner acrosomal membrane as the functional outer boundary of
the sperm head
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