Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
Primary Egg Envelopes
These are the egg envelopes which develop in the ovary between oocyte and follicle cells in the space occupied by the interdigitating microvilli. Such envelopes have been named variously in different animals.
a) It is named as vitelline envelope or vitelline membrane in insects, molluscs, amphibians and birds.
b) In tunicates and fishes, it is known as chorion. In many sharks and bony fishes the primary envelope has striated appearance and is referred to as zona radiata representing the degraded microvilli of the growing oocyte. The perforation in the zona radiata becomes the micropyle through which the spermatozoa can enter the egg.
c) In mammals, the unstriated and modified zona pellucida is formed as a result of joint efforts of egg and follicle cells. While escaping the Graafian follicle mammalian oocyte carries on the surface of zona pellucida a layer of follicle cells known as corona radiata. The primary envelopes usually stick closely to the egg surface. These later on participate in the formation of fertilization membrane.
Pharynx: Pharynx is a funnel shaped tube about 13cm long that starts at the internal nares and extends to the level of the cricoid cartilage. It lies posterior to the n
Metamorphosis in Amphibians Metamorphosis is radical in anurans, slight or not exists in urodeles. In anuran amphibians like toads and most frogs, metamorphosis is generally
Why would we evolve so that when we are stressed our immune system is suppressed? How would this increase survival?
ATP-sensitive potassium channel A. The channel is a spanning protein with a receptor site for ATP located on an intracellular region of the protein. B. When blood plasma lev
Members belonging to different species refrain from mating because of the behavioural differences between them. Such behavioural differences usually centre around specific courtshi
Figure shows the flow of energy through the trees in a forest ecosystem.The numbers represent inputs and outputs of energy in kilojoules per m 2 per year. (a) (i) On Figure,
Gene expression is controlled by chromatin state, _______ and _________. a. transcription factors and epigenetic regulators b. polymerases and control proteins c. delta and tau pro
Q. How does the poison cyanide act upon the aerobic respiration? Cyanide is a poison that restrains the last cytochrome of the respiratory chain, interrupting the ATP formation
Define Estimation of protein by Carcass nitrogen analysis method? Carcass nitrogen analysis: This method includes Nitrogen retention method Net protein utilization
Q. What do you mean by Punch cards? Punch cards are used when the number of taxa to be keyed out is large. In this type of cards the holes at numbers corresponding to a charact
Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd