Favoritos de greensnake879

This is a series of three photos (40x, 100x, 400x) from a microscope slide, showing a stained, longitudinal section through a female moss gametophyte in the genus Mnium. The tip of the plant is shown, and the cluster of hair-like structures at the center includes a nice example of an archegonium, the plant's egg-producing structure. This is where mitosis will be used to make a haploid egg cell from a haploid cell of the gametophyte. The archegonium is to the right, and is the long dark structure with the pale oval at its center. (Look carefully at the base of that oval and you can see the egg cell). Plant archegonia are typically vase-shaped structures, with a wider base containing the egg and a neck-like tube of cells above it. Sperm cells will swim down through the tube to fertilize the egg.

This is a fusion of four photos (all 40x) from a microscope slide, showing a stained, longitudinal section through a male moss gametophyte (genus Polytricum). At the tip of the plant are several long, oval, deeply red-stained antheridia. Here, mitosis is used to produce haploid sperm cells from haploid cells of the gametophyte. The antheridia are now packed with developing sperm cells, giving a grainy look to their interiors. When rain hits the plant, mature antheridia will release their sperm cells to swim to neighboring female gametophytes.

These are photos of a microscope slide, magnification 40x, showing a stained, longitudinal section through the capsule of a moss sporophyte. Meiosis occurs in the young sporangium, making haploid spores (C: red cells inside capsule) from diploid sporophyte cells. The cap-like operculum (A) at the top of the mature capsule falls off, exposing the opening into the sporangium. It is surrounded by the peristome (B), which has tooth-like flaps of tissue that curl and straighten in response to humidity. Over time, the movements of these "teeth" flick spores (C) out of the capsule.