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!
Pollen Tube Structure
The pollen tube in the stigma is filled with cytoplasm containing numerous mitochondria and dictyosomes. The number of dictyosome cisternae is reduced in the tubes. Large vesicles associated with dictyosome seem to be incorporated in the tube wall. Abundant ER and polysomes which are either in free form or attached to ER can also be seen. The pollen tube wall in the stigma and style show two distinct regions: the outer part of the wall (PAS positive), and the inner portion which is thicker, more homogeneous (much less reactive to PAS), and rich in callose. The dense cytoplasm contains vesicles of various sizes, ER, ribosomes, and a few poorly-developed plastids with swollen outer membranes. Dictyosomes are quite numerous with 4 or 5 cisternae, and produce vesicles.
The vesicles appear to fuse with the plasma membrane of the pollen tube. A very large population of small, spherical vesicles are scattered throughout the pollen tube cytoplasm. The ER in the pollen grains and during early growth of the pollen tube has extended cisternae and apparently serves as a storage site for proteins. As the pollen tube grows down the style, the ER shows the common variety of narrow cisternae indicating that protein present is being gradually utilized during tube growth. The ultra structure of the distal region of the pollen tube and the wide variety of cell organelles are indicative of active carbohydrate and protein metabolism. The part of the tube immediately behind the tip region shows less dense cytoplasm and more dispersed organelles. The more mature parts of pollen tube contain only a thin layer of cytoplasm closely appressed to the wall and a large vacuole occupies the rest of the space. Plugs of the wall material, mostly callose serve to separate the older parts of the pollen tube from the growing distill region. The plugs originate as rings on the inner side of the wall and grow inwards like the closing of an iris diaphragm.
Define Technique of Paper chromatography? Paper chromatography is used as 1. Ascending, 2. Descending or 3. Horizontal technique (circular paper chromatography) It is De
Which of the following is an effect of the following drugs? A. Drug A is an agonist of the Vasopressin2 Receptor (V2R). High levels of Drug A in the extracellular spaces surro
Describe Gastrovascular cavity in detail? The name given to the internal cavity of cnidarians. A blind-ended (incomplete) gut with only one opening. Food is to be digested and
Planning the Nursing Care 1) Maintain hydration and electrolyte balance. 2) Administer accurate and adequate antibiotics drugs. 3) Prevent the spread of infection.
Q. List the counselling skills? Slowly start winding up the contact with the client and the family by providing them support, motivating the client to take care of oneself with
Define Advantages of Using the Plate Counts Method? 1. It is simple and sensitive method. 2. It provides viable count as only live cells will grow and produce the colony.
What are the typical vegetation and the typical fauna of the taigas? Taiga, or the boreal forest, is characterized by coniferous trees, pine forests. There are also mosses, lic
Prevention of flap dehiscence Flap margin dehiscence (separation) is prevented by approximating the edges of the flap over healthy bone by handling the edges of the flap gently
The immune response involves the activities of proteins, cells, and the lymphatic system.
Procedure for Test the Presence of Sugar in Honey? 1. Mix 5 grams of honey with 5 ml ether in a mortar and pestle. 2. Decant off the ether extract into an evaporating dish.
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