describe the development of male gametophyte in pinus.
Answers
i. Development of Male Gametophyte before Pollination in Pinus.
The basic pattern of the development of male gametophyte of Pinus is similar to Ginkgo. First the pollen grains undergo endosporic development. The pollen nucleus then divides mitotically to produce a small lens-shaped first prothallial cell towards the proximal end and a large central cell on the distal end.
The central cell then cuts off a second prothallial cell and an antheridial initial. Both the prothallial cells are ephemeral and the second prothallial cell remain attached to the first prothallial cell.
The antheridial then initial divides to form a small antheridial cell and a large tube cell. The pollen grains are then released from the microsporangium at the 4-celled stage (2 prothallial cells, an antheridial cell and a tube cell).
ii. Development of Male Gametophyte after Pollination in Pynus-
After pollination, the 4-celled pollen stored in the pollen chamber and remains ungerminated for about 11 months. The pollen then develops the next spring. The tube cell of the pollen then comes out through the pollen aperture in the form of a pollen tube. The pollen tube further proceeds towards the archegonium, penetrating the nucellar tissue of the ovule. The antheridial cell within the pollen tube divides to form a stalk cell and a spermatogenous (body) cell.
The spermatogenous cell divides to form two male nuclei just prior to fertilisation. The male nuclei are basically the male gametes which are non-motile and ephemeral.
Hey Dear,
◆ Development of male gametophyte in pinus -
- Pollen grain is the male gametophyte i.e. microgametophyte of Pinus plant.
- Microspores of pinus are winged.
- During fertilization, 2 prothallial cells combine with 1 generative cell & 1 tube cell.
- After fertilization, 2 non-motile non-ciliated male gametophyte are produced from generative cell.
- This grow for a year and turn into mature male gametophyte of pinus.
Hope this helped you.